Robotic repair systems and methods

Abstract

An abrasive article is presented that includes a backing, an abrading surface comprising an abrasive material adhered to the backing. The abrasive article also includes a coupling surface comprising a coupling feature configured to removably couple the abrasive article to a tool. The abrasive article also includes a resistance force relief feature. The abrasive article is configured to be used with a fluid during an abrading operation. The resistance force relief feature is configured to reduce a resistance force between the abrasive article and a worksurface comprising the fluid.

Description

ROBOTIC REPAIR SYSTEMS AND METHODSBACKGROUND

[0001] Clear coat repair is one of the last operations to be automated in the automotive original equipment manufacturing (OEM) sector. Techniques are desired for automating this process as well as other paint applications (e.g., primer sanding, clear coat defect removal, clear coat polishing, etc.) amenable to the use of abrasives and / or robotic inspection and repair.

[0002] Prior efforts to automate the detection and repair of paint defects include the system described in US Patent Publication No. 2003 / 0139836, which discloses the use of electronic imaging to detect and repair paint defects on a vehicle body. The system references the vehicle imaging data against vehicle CAD data to develop three-dimensional paint defect coordinates for each paint defect. The paint defect data and paint defect coordinates are used to develop a repair strategy for automated repair using a plurality of automated robots that perform a variety of tasks including sanding and polishing the paint defect.SUMMARY

[0003] An abrasive article is presented that includes a backing, an abrading surface comprising an abrasive material adhered to the backing. The abrasive article also includes a coupling surface comprising a coupling feature configured to removably couple the abrasive article to atool. The abrasive article also includes a resistance force relief feature. The abrasive article is configured to be used with a fluid during an abrading operation. The resistance force relief feature is configured to reduce a resistance force between the abrasive article and a worksurface comprising the fluid.BRIEF DESCRIPTION OF THE DRAWINGS

[0004] In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

[0005] FIGS. 1A and IB are schematics of a robotic paint repair system in which embodiments of the present invention are useful.

[0006] FIGS. 2A-2D illustrate schematics of tool configurations for a robotic repair unit in accordance with embodiments herein.

[0007] FIG. 3 illustrates a method of detecting and repairing a defect on a work surface in accordance with embodiments herein.

[0008] FIGS. 4A-5C illustrate exemplary embodiments of pressure reducing features in accordance with embodiments herein.

[0009] FIGS. 6A-6C illustrate exemplary micro-abrasive abrasive features, and abrasive disc constructions including the same, in accordance with embodiments herein.

[0010] FIGS. 7A-7E illustrate exemplary backup pad configurations in accordance with embodiments herein.

[0011] FIGS. 8A-9B illustrate abrasive discs and backup pads described in greater detail in the Examples.DETAILED DESCRIPTION

[0012] Robotic autobody clear coat finishing relies on a robotic arm to sand and buff out defects after painting and applying clear coat to the car body. The robot is informed of the location of a defect by a vision system that identifies the defect location. The robot positions a random orbital sander, or other suitable tool, as its end of arm tool at the defect location to remove the defect. Water, or another fluid is sprayed by the robot prior to sanding to aid in cutting. An abrasive article is removably coupled to a backup pad, which couples to the random orbital sander (or other suitable tool). A force control unit applies a force to the backup pad, which urges the abrasive article in contact with the surface.

[0013] Unfortunately, the cutting slurry of water, broken down sandpaper, and clear coat can create a seal between the abrasive article and the worksurface, resulting in sufficient forces to remove the sanding disc from the tool upon its departure. It is suspected that the adhesion to the worksurface was the result of suction. The abrasive disc creates a sufficiently flat surface on both itself and the workpiece. The applied force from the robotic system pushing down then creates a low pressure area between the abrasive article and the worksurface that creates a suction force that would be larger than the coupling force of the abrasive article to the back-up pad, thus resulting in the abrasive article remaining stuck to theworksurface as the robotic system is retracted from the worksurface.

[0014] This is problematic as the robot will no longer have the abrasive disc in place for any subsequent operation. This issue could be mitigated by sensing for the disc’s presence at the completion of each repair. However, such a solution would negatively impact cycle time and robotic cell cleanliness. Additionally, the disc remaining stuck to the worksurface can result in additional defects in production steps performed by a robotic system contacting the worksurface in a next defect location without an abrasive disc between the worksurface and a backup pad. It could also cause excessive use of consumables, secondary defects caused by buffing over stuck discs, etc. Wet sanding is often preferred to dry sanding for paint removal applications as defect repair often happens before the paint is fully cured. When abraded, the paint forms a paste. Adding a fluid to the surface assists in dispersing and breaking up paint swarf during the sanding process. If sanding were done dry, the paint would load the abrasive disc rapidly, causing the abrasive disc to become unusable at an unacceptable rate, also potentially creating secondary defects from the areas of stuck swarf on the disc.

[0015] An improved abrasive system is desired that reduces the suction forces generated during a wet sanding abrasive operation such that the abrasive disc is removed from the surface as expected.

[0016] Abrasive systems herein include abrasive discs that are designed for use in a wet sanding operation, e.g. with water or another suitable fluid. Abrasive systems herein include a resistance force relief feature. A resistance force relief feature, in some embodiments, is incorporated into the abrasive article. In some embodiments, however, a resistance force relief feature is incorporated into a backup pad.

[0017] In embodiments where the abrasive article includes the resistance force relief feature, the suction relief feature may include a deformation in the abrasive article that causes the abrasive article to be nonplanar. A crease, as illustrated in FIGS. 5A-5B for example, may reduce the suction force generated between the abrasive article and a worksurface. A slit in the abrasive article may achieve a similar reduction in suction.

[0018] In some embodiments, the abrasive article includes one or more apertures that extend through the abrasive article, such that air can flow through the abrasive article. The apertures are sized to allow air, but not significant amounts of swarf (sanding debris) through the abrasive disc, as debris can contaminate the surface of the backup pad and decrease a coupling force between the backup pad and the abrasive disc. The apertures may be sizedsuch that the worksurface does not contact the backup pad directly, which could cause damage to the backup pad. It is desired that, swarf not clog hook and / or loop connection features on the surface of the backup pad, in embodiments using hook and loop coupling between the backup pad and the abrasive article.

[0019] Smaller aperture sizes are therefore preferred to reduce damage to the backup pad from a worksurface and / or from sanding debris. Similarly, it is desired to keep a large portion of the abrasive article intact and available for abrading. Apertures may be sized to account for some narrowing due to swarf clogging.

[0020] Abrasive articles with apertures have been used before in the context of dry abrasive operations where a significant amount of dust is created. Abrasive articles designed for such applications can include a number of holes extend through the abrasive article such that a vacuum can pull dust through the abrasive article. However, it is noted that, while wet sanding operations do produce debris, the debris mixes in with the sanding fluid and is not picked up by a vacuum unit.

[0021] PCT Publication WO 2007 / 143400, published February 21, 2008, describes design considerations for dust extraction abrasive article design. Larger holes are used in designing abrasive articles for dust extraction, e.g. up to 3mm in diameter, and a larger area of the abrasive article is removed, e.g. at least 5% of the area. A large number of holes is also recommended.

[0022] The present application, wet sanding, presents significantly different challenges. The composition of the abrasive article is different - with a waterproof or water-resistant backing required for a wet-sanding operation. Smaller abrasive articles are used for defect repair - the surface of a painted vehicle is reflective, it is desired to minimize the area sanded as defect repair can introduce visible differences in the surface. The abrasive articles used for defect removal herein are similar in diameter to a shaft of an abrading tool.

[0023] It is desired, in the context of defect repair, to reduce the size of apertures in an abrasive article so as to maintain a larger area of abrasive material. In some embodiments herein, a single hole, or a small number of holes - e.g. less than 30, less than 20, less than 10, or less than 5 holes can accomplish the desired suction relief. Including more holes present in abrasive articles herein could increase the risk of damaging the backup pad.

[0024] In contrast to dust removal applications where a separate vacuum unit is required for dust extraction, embodiments herein seek to remove or reduce a naturally formingresistance force formed between a worksurface and the abrasive article.

[0025] A suction force is a low risk for abrasive articles used in dry sanding operations. In addition to having little or no liquid, which is what causes the suction force described herein, abrasive articles used in dry sanding operations often use larger abrasive particles coupled to a backing through a resin-based make coat.

[0026] Abrasive articles in at least some embodiments herein may be more prone to a suction force than those used in dust removal applications because of the nature of the abrasive layer. At least some embodiments herein utilize a structured abrasive material to form the abrasive material. In some embodiments herein, an abrasive layer includes a three- dimensional structure constructed with a plurality of regularly arranged three-dimensional elements having a predetermined shape, for example as described in U.S. Pat. 6,773,475, issued August 10, 2004, FIGS. 2-6 and the associated description of which are incorporated by reference herein. Defect removal for reflective surfaces often requires very fine grade abrasive - e.g. as low as P1500, or even as low as P2500, or even as low as P3000, or even finer, using the FEPA “P” grading scale. Abrasive articles using larger abrasive particles may naturally include small air channels between adjacent abrasive particles which may allow for enough airflow to sufficiently reduce suction. However, the small size of abrasive material used for paint defect removal does not leave sufficient space for suction-reducing airflow.

[0027] In some embodiments, a sanding disc is adhered to the tool using a hook and loop attachment construction. An alternative adhesion method is using a pressure sensitive adhesive backing. However, it is expressly contemplated that, while hook and loop is illustrated as one type of fastener, other removeable fastening mechanisms may also benefit from the designs herein. For example, an improved coupling between a backup pad and an abrasive disc may be achieved.

[0028] To combat the suction effect, systems and methods herein provide a pressure reducing feature on the surface of the abrasive article. Some suction reducing features described herein include one or more apertures that allow airflow through the abrasive disc, which can prevent sticking. In some embodiments, relief vents were cut into the working surface of the abrasive disc. In some embodiments, rounded apertures were cut into the working surface. However, the designs illustrated herein are intended to be by example only and it is expressly contemplated that other suitable designs are possible.

[0029] As used herein, the term “vehicle” is intended to cover a broad range of mobilestructures that receive at least one coat of primer, paint, or clear coat during manufacturing. While many examples herein concern automobiles, it is expressly contemplated that methods and systems described herein are also applicable to trucks, trains, boats (with or without motors), airplanes, helicopters, etc.

[0030] As used herein, the term “robotic repair unit” refers to a robotic repair system that interacts with a surface to remove a defect. The robotic repair unit may be a stationary unit, that operates on a stationary surface, in some embodiments. In other embodiments, the robotic repair unit is a mobile repair unit that can move along a rail, track, or other mechanism such that it can address a defect on a moving surface. Additionally, it is also possible that the repair unit is stationary and the subject of repair moves. The robotic repair unit may have one or more end effectors with one or more tools, such as those described in U.S. Provisional Patent Applications with Serial Nos. 62 / 940950 and 62 / 940960, both fded November 2, 2019, both herein incorporated by reference. However, other robotic repair unit constructions are also expressly contemplated.

[0031] As used herein, the term “resistance force,” as used herein, refers to any force exerted on an abrasive article during a removal step, where the abrasive article is removed from a surface after an abrasive operation. The term “resistance force” is intended to broadly cover any forces that contribute to a suction between the abrasive article and the worksurface that need to be overcome for successful removal of the abrasive article including, for example, vacuum forces, surface tension forces, etc.

[0032] As used herein, the term “abrasive grain” or “abrasive particle” are used to refer to a single abrasive element that may be secured to a backing. In some embodiments herein, abrasive particles are “shaped,” e.g. formed through a molding process such that a formed abrasive particle takes the shape of a mold cavity. Shaped abrasive particles, once removed from the mold, are generally placed individually on a backing, e.g. not coupled directly to an adjacent abrasive particle. Examples of sol-gel-derived abrasive particles from which the abrasive particles can be isolated, and methods for their preparation can be found, in U.S. Pat. Nos. 4,314,827 (Eeitheiser et al.); 4,623,364 (Cottringer et al.); 4,744,802 (Schwabel), 4,770,671 (Monroe et al.); and 4,881,951 (Monroe et al.). It is also contemplated that the abrasive particles could comprise abrasive agglomerates such, for example, as those described in U.S. Pat. Nos. 4,652,275 (Bloecher et al.) or 4,799,939 (Bloecher et al.).

[0033] As used herein, the term “abrasive element” or “abrasive composite” refers to an abrasive structure formed of a flowable mixture of abrasive particles and curable binder. Abrasive elements or composites may be formed using a production tool, and adjacent abrasive elements are coupled together, using the production tool, such that a microreplicated abrasive structure is formed having a three-dimensional structure constructed with a plurality of regularly arranged three-dimensional abrasive elements having a predetermined shape Abrasive elements and / or composites as well as their construction is described in greater detail in U.S. Pat. No. 5,152,917 (Pieper et al.); 5,435,816 (Spurgeon et al.); 5,672,097 (Hoopman et al.); 5,946,991 (Hoopman et al.); 5,975,987 (Hoopman et al.); and 6,129,540 (Hoopman et al.).

[0034] FIG. 1A is a schematic of a robotic paint repair system in which embodiments of the present invention are useful. System 100 generally includes two units, a visual inspection system 110 and a defect repair system 120. Both systems may be controlled by a motion controller 112, 122, respectively, which may receive instructions from one or more application controllers 150. The application controller may receive input, or provide output, to a user interface 160. Repair unit 120 includes a force control unit 124 that can be aligned with an end-effector 126. As illustrated in FIG. 1A, end effector 126 includes two tools 128, which may be arranged, in one embodiment, as further described such as those described in U.S. Provisional Patent Applications with Serial Nos. 62 / 940950 and 62 / 940960, both fded November 2, 2019. However, other arrangements are also expressly contemplated. Visual inspection unit 110 may detect defects on a vehicle surface 130, which may be repaired by repair unit 120.

[0035] The presence of a sufficiently capable inspection system 110 is important for identifying and addressing defects for repair by repair unit 120. The current state of the art in vehicle paint repair is to use fine abrasive and / or polish systems to manually sand / polish out the defects, with or without the aid of a power tool, while maintaining the desirable finish (e.g., matching specularity in the clear coat). An expert human executing such a repair leverages many hours of training while simultaneously utilizing their senses to monitor the progress of the repair and make changes accordingly. Such sophisticated behavior is hard to capture in a robotic solution with limited sensing.

[0036] Additionally, abrasive material removal is a pressure-driven process while many industrial manipulators, in general, operate natively in the position tracking / control regimeand are optimized with positional precision in mind. The result is extremely precise systems with extremely stiff error response curves (i.e., small positional displacements result in very large corrective forces) that are inherently bad at effort control (i.e., joint torque and / or Cartesian force)). Closed-loop force control approaches have been used (with limited utility) to address the latter along with more recent (and more successful) force -controlled flanges that provide a soft (i.e., not stiff) displacement curve much more amenable to sensitive force / pressure-driven processing.

[0037] Some repair processes use fluids to accelerate or otherwise aid the abrasive removal process. For example, fluid may assist in swarf removal, reduce abrasive clogging, and extend the life of the abrasive article while improving the consistency of cut during use. For example, some sanding operations are wet sanding operations, requiring water, or another fluid, to be dispersed on the repair area prior to, or during, an abrading operation. Additionally, polishing often requires polish to be dispensed before, or during, the polishing operation. Water, or another removal solvent, may be dispensed to remove debris after the repair is completed. The presence of water on a work surface can cause resistance forces to form between the worksurface and the abrasive article. If the resulting suction force is greater than a coupling force holding the abrasive article to the backup pad, the abrasive disc will be released from the backup pad and remains on the worksurface.

[0038] FIG. IB is a schematic of a paint repair robot which may be useful in embodiments of the present invention. A robotic repair unit 200 has a base 210, which may be stationary, in some embodiments. In other embodiments, base 210 can move in any of six dimensions, translations or rotations about an x-axis, y-axis, and / or z-axis. For example, robot 200 may have a base 210 fixed to a rail system configured to travel along with a vehicle being repaired. Depending on a defect location, robot 200 may need to move closer, or further away from a vehicle, or may need to move higher or lower with respect to the vehicle. A moveable base 210 may make repairing difficult-to-reach defects easier.

[0039] Robotic repair unit 200 has one or more tools 256 that can interact with a worksurface. Tool 256 may include a backup pad, in one embodiment, or another suitable abrasive tool. During an abrasive operation, tool 256 may have an abrasive disc, or other suitable abrasive article, attached using adhesive, hook and loop, clip system, vacuum or other suitable attachment system. As mounted to the robotic repair unit 200, tool 256 has the ability to be positioned within the provided degrees of freedom by the robotic repair unit200 (6 degrees of freedom in most cases) and any other degrees of freedom (e.g., a compliant force control 230 unit) with its reference frame.

[0040] Robotic repair unit 260 has several joints 260, each of which can move in x and y directions, as illustrated in FIG. IB. Additionally, in some embodiments where joints 260 are ball joints, they may each also allow for movement in a z direction.

[0041] FIGS. 2A-2B illustrate tool configurations for a robotic repair unit which may be useful in embodiments herein. FIG. 2A illustrates a view of a two-tool end-effector system in a use-position. Robot arm 300 may have a cable mounting configuration 302. A robot arm 300 has a dual-mounted end effector system 320 mounted on a mounting plate 348. Robot arm 300 can move end effector system 320 rotationally, using rotational plate 310 and vertically, using joint 315, in order to place a first tool 330 or a second tool 340 in position to interact with a workpiece. Each of first and second tool 330, 340 have a connector 332, 342, respectively, that connects to an end effector unit 320a, 320b, respectively.

[0042] FIG. 2A illustrates end effector system 320 in one of two use positions, with second tool 340 in position to engage a workpiece. As discussed in U.S. Provisional Patent Application with Serial No. 62 / 940,950, filed November 2, 2019, a system 320 uses a single force control to operate both first and second tool 330, 340. First and second use position have one of tools 330, 340 aligned in parallel with force control. FIG. 2B illustrates a sideview of end effector system 320.

[0043] FIG. 2C is an image of an robot-driven abrasive operation 350 on a worksurface. A robot drive shaft 352 urges backup pad 354 against a worksurface 358. An abrasive article (not shown) is coupled to backup pad 354 and in contact with surface 358. As illustrated in FIG. 2C, a slurry 356 is formed on surface 350 during the abrading operation. The abrasive article is removably coupled to the backup pad and in temporary contact with surface 358. It is desired that abrasive articles be easily changed out as needed - e.g. a coupling element between backup pad 354 and the abrasive article cannot be so strong as to prevent removal of a used abrasive article. The coupling element may be a hook and loop system, an adhesive, or another removeable coupling.

[0044] FIG. 2D is an exploded view of the abrading operation 350, showing a backup pad 364 coupled to an end effector 366. The slurry 372, formed by a sanding fluid and abrasive debris, facilitates the forming of a suction force 374 which pulls abrasive article362 toward the slurry-coated surface. A coupling force 376, formed by a coupling element that couples abrasive article 362 to backup pad 365 pulls the abrasive article 362 toward the end effector 366. If the suction force 374 is greater than the coupling force 376, abrasive article 362 will decouple from backup pad 364 and remain on the slurry-coated surface.

[0045] In some embodiments herein, abrasive article 362 is free of stearate or a similar dry-sanding lubricant material. In some embodiments herein, abrasive article 362 includes a waterproof, or water-resistant, backing material. The backing material, in some embodiments, is a fdm. The film may be a polymeric film, in some embodiments herein. In accordance with some embodiments herein, abrasive article 362 includes shaped abrasive particles, wherein the shaped abrasive particles are arranged into a predetermined shape or structure, and wherein the predetermined shape or structure is repeated across the surface of the abrasive article. In some embodiments herein the abrasive articles include Trizact™ abrasive technology, available from 3M Company.

[0046] A suction relief element is desired that will reduce the suction force 374 below coupling force 376 to reduce the risk of abrasive article 362 decoupling from backup pad 364. The suction relief element may be incorporated solely into abrasive article 362, into backup pad 364. Multiple suction relief elements may be present, incorporated into either or both of abrasive article 362 or backup pad 364.

[0047] It is noted in FIGS. 2C and 2D that a robotic wet sanding system is a vacuumless system. As illustrated in the image of FIG. 2C, debris from sanding a surface is often captured into the slurry material.

[0048] It is also noted that the footprint of system 350 is relatively small. The shaft 352 has a similar diameter to that of backup pad 354. Abrasive articles used for defect repair on reflective surfaces, such as painted vehicles, are smaller in size than many of those used in other applications. It is important to efficiently abrade surface 358, which includes using abrasive discs with smaller surfaces and increasing the area available to abrade surface 358.

[0049] FIG. 3 illustrates a method of detecting and repairing a defect on a work surface in accordance with embodiments herein. Method 400 may be performed by a robotic abrading system, such that a defect is detected and sanded automatically. A robotic abrading system may sand a number of defects on a surface with a single abrasive article before it is needed to exchange the used abrasive article for a new abrasive article.

[0050] In block 410, a defect area is detected and instructions related to the detecteddefect are received by a repair unit from a robot controller, such as application controller 150 in FIG. 1A, for example. Without limitation to the embodiments discussed herein, the defect area can be detected by an image 402 of the surface or can be associated with a position on the vehicle, as indicated in block 404.

[0051] Blocks 420, 430, and 440 concern the steps of repairing a detected defect. Defects may be repaired in one or more abrasive operations. For example, a defect area may first be sanded, then polished. A defect may be inspected in between the sanding and polish step and, depending on whether the defect was successfully repaired, the steps of sanding and / or polishing may be repeated.

[0052] In block 420, an abrasive article is put in contact with a vehicle surface. In many applications, a fluid is also dispensed onto a repair area. Other fluids may also be dispensed, depending on the repair operation.

[0053] When the abrasive article is brought into contact with a surface in the presence of a fluid, the applied pressure by the back-up pad may cause a resistance force to form between the abrasive article and the surface. While this may not cause a problem during an abrading step, it may prevent removal of the abrasive article, during a removal step.

[0054] The abrasive article may include a suction relief fixture configured to, while the abrasive article is in contact with the surface, relieve a suction force between the abrasive article and the surface.

[0055] A backup pad may include a backup pad suction relief feature 412, such as protrusions or grooves that allow for airflow, in some embodiments. The abrasive article may include a suction relief feature 414, in addition to, or in alternative to, the backup pad suction relief feature 412.

[0056] In some embodiments, the abrasive suction relief feature 414 may include one or more apertures that extend through a thickness of the abrasive article, for example, which may allow airflow into the space between the abrasive article and the surface, allowing for reduction of a suction force. The abrasive article may include, in some embodiments, a slit extending through a surface. In some embodiments, the abrasive article includes a crease, such that the abrasive article, absent an applied force, is non-planar.

[0057] In block 430, the defect is abraded. Abrading a defect may include a sanding operation 422, a polishing operation 426, or another operation 428. Abrading the defect includes bringing a tool into contact with the defect area. Abrading may occur after, orsimultaneously with the fluid dispensing of block 420.

[0058] In block 440, the abrasive article is removed from the vehicle surface. As noted above, the combination of abrasive article degradation, abraded swarf removed from the vehicle surface, the downward applied force, and the dispensed fluid can cause suction to build between the abrasive surface and the worksurface. In some cases, the suction force is greater than a force keeping the abrasive article in contact with the robotic system and the abrasive article comes loose from the robotic system and is stuck to the surface.

[0059] While a human operator would be able to see that an abrasive article has come free of a tool, most robotic systems are not usually built with sensors that can detect that the abrasive article is no longer in contact with the robotic system. Such systems take space, increase cost and complexity of a robotic system. A solution is desired that reduces the suction force between the abrasive article and a worksurface, allowing for the abrasive article to come free from the surface.

[0060] Several different options for remedying the suction problem were tried, with limited success. For example, attempts to increase adhesion with loftier loops or alternate hooks improved disc adhesion but not sufficiently. Adjusting the force / rpm profile near the conclusion of the repair also proved insufficient to eliminate the issue. Creasing the sandpaper may present a difficult form factor to both produce and consume. Peeling the disc off the surface (as opposed to lifting normal to the surface) also showed improved adhesion but also had failures and has significant implantation challenges with collision avoidance. Reducing the slurry amount (by decreasing the water dispensed) was a strong lever but had the unacceptable counterbalance of greatly reduced material removal during the sanding process. Use of several surfactants in the dispensed water, applied directly to the abrasive media, or applied directly to the surface in variety of amounts were beneficial but still had failures.

[0061] It was surprisingly found that a small aperture extending through the thickness of the abrasive disc was sufficient to reduce the suction force present between the surface and the abrasive disc below the strength of a coupling force between the backup pad and the abrasive article, increasing the frequency of successful removal abrasive articles from the surface. While a single aperture may be sufficient, it is expressly contemplated that one or more apertures may be present.

[0062] The abrasive article may have a diameter less than 4 centimeters, in someembodiments. In some embodiments, the abrasive article has a diameter of about 3 centimeters. In some embodiments, a total area of the one or more apertures present is at least 0.18 mm2. In some embodiments, a a total area of the one or more apertures is at least 0.20 mm2. In some embodiments, a total area of the one or more apertures is less than about 20 mm2. In some embodiments, a total area of the one or more apertures is less than about 10 mm2. In some embodiments, a total area of the one or more apertures is less than about 1.0 mm2. The aperture, or apertures, may be positioned closer to the center of the abrasive article in some embodiments. The center of an abrasive article, which has a lower surface velocity than an edge, has the lowest rate of abrasion. Placing the aperture, or apertures, nearer the center of an abrasive article may therefore achieve the desired affect of reducing the suction force without significantly reducing the abrasive efficacy of an abrasive article. For example, the one or more apertures may be present in a center area of an abrasive article. For example, within an interior half of the area of the abrasive article, or within a smaller space. For example, the one or more apertures may be positioned within a center area of the abrasive article, wherein the center area is defined by a second radius, the second radius being less than a first radius of the abrasive article. The second radius is less than about half the first radius.

[0063] FIGS. 4A-4B illustrate embodiments of abrasive discs with pressure reduction features that were shown to reduce the suction force. Abrasive disc 510 has a circular aperture positioned in the center which allows air to flow through the abrasive disc. In some embodiments, the circular aperture is not part of a coupling mechanism between the disc 510 and a backup pad. For example, apertures herein are not sized to receive a tool shaft. The aperture of disc 510, in some embodiments herein, are large enough to allow for sufficient air flow to reduce resistance forces, but not so large as to allow additional swarf to pass through and foul the backup pad.. In some embodiments, a single aperture placed in or near the center of the abrasive article is preferred as any swarf leak-through is then limited to the center of the backup pad, which has a lower abrasive efficacy than the edges of the backup pad. However, it is expressly contemplated that one or more apertures may be placed anywhere on the abrasive article. In the illustrated embodiment, the aperture of disc 520 is 2.2 mm in diameter.

[0064] As used herein, the term “center” refers to an interior area of the abrasive disc. It is noted that, in some embodiments, one or more apertures may be present within aninterior area of an abrasive disc, but may not be “centered” geometrically. The center of an abrasive disc may be found using any accepted geometrical definition - e.g. for a circle, a center is equidistant from all points on the circle. It is noted that, in some embodiments herein, abrasive discs have scalloped or otherwise textured edges - a center may be defined as a position that is at the intersection of any two distinct diameters. It is expressly contemplated that an aperture may be placed “off-center,” e.g. not at the intersection of any two distinct diameters of the abrasive disc. However it is also contemplated that, in some embodiments, the one or more apertures are centered on an abrasive disc. In embodiments where an abrasive article is not a circle or a textured circle (e.g. having scallops or another repeating pattern about the edge), a center of gravity definition could be used.

[0065] In some embodiments herein, the one or more apertures are not equally spread over the surface of the abrasive disc, but are clustered in a smaller area. For example, in one embodiment, an aperture area is defined by a second radius. The second radius may, in some embodiments, extend from a center of the abrasive disc such that the aperture area is centered with respect to the disc. The aperture area may, for example, have a radius that is less than or equal to half the radius of the disc (e.g. Raperture area = ' / zRdisc). The aperture area may be even more confined, for example defined by a radius that is less than or equal to 1 / 3 the radius of the abrasive disc, or even !4 the radius of the abrasive disc. The aperture area could be larger as well, for example with a radius that is greater than i the radius of the disc, for example between i and 2 / 3 the radius of the disc, or greater than 2.3 the radius of the disc.

[0066] In some embodiments, a plurality of apertures are spaced about the surface, as illustrated in abrasive disc 530. While the apertures of disc 530 are illustrated as evenly spaced about the surface, it is expressly contemplated that a different pattern, or random placement, may also be suitable for some embodiments.

[0067] However, it is expressly contemplated that, while symmetrical aperture positions are illustrated in FIGS. 4A-4B, it is expressly contemplated that other designs may be sufficient. For example, if an aperture were positioned close to the edge of the abrasive article, but in an area where a coupling mechanism is present (e.g. hooks and loops of the abrasive article and backup pad), it may allow sufficient airflow to reduce suction.

[0068] While some aperture designs are illustrated in FIG. 4A, FIG. 4B illustrates a number of other designs 542-574 that may also be suitable. Further, it is expresslycontemplated that one or more slits may be sufficient to reduce suction forces. Additionally, while round apertures are illustrated in FIGS. 4A-4B, it is expressly contemplated that other shapes may be suitable.

[0069] FIGS. 5A-5C illustrate some suction relief options, in accordance with embodiments herein. FIGS. 5A-5B illustrate a creased abrasive article. View 610 is from a position above the abrasive article while view 620 illustrates a perspective view. A crease may be induced in an abrasive article during manufacturing or, for example, during use. A backup pad may, after an abrasive article has been attached, press the abrasive article against a surface that causes a crease to form, for example. The shape of the backup pad may also be designed to cause a crease. The presence of a crease may change a shape of the abrasive article from planar to nonplanar, or cone-shaped.

[0070] FIG. 5C illustrates an abrasive article that, instead of a crease, includes a slit 650, which may be induced in any suitable manner.

[0071] FIGS. 6A-6C illustrate abrasive articles in accordance with embodiments herein. In some embodiments herein, an abrasive article is formed of a backing on which a number of abrasive articles are adhered.

[0072] FIG. 6A illustrates a number of micro-abrasive features 702 arranged in a repeating 3-Dimensional structure to form a 3D element 314. Repeating elements 314 form the macro structure of the abrasive article surface. While pyramidal shapes are illustrated in FIG. 6A, it is expressly contemplated that abrasive particles 702 may take any number of suitable shapes such as, for example, those illustrated in FIGS. 2-5 of U.S. Pat. 6,773,475, issued August 10, 2004, incorporated herein by reference, as well as other suitable shapes.

[0073] FIG. 6B illustrates an abrasive article 710 having a number of 3D elements 714, separated by channels 712. FIG. 6C illustrates a schematic side-view of two 3D elements 722 separated by a channel 726. 3D elements 722 may have an element height 724. Channel 726 may have a channel distance 728, and a channel height equivalent to abrasive element height 724. In some embodiments herein, an aspect ratio of the individual structures of elements 722 may be such that an air flow channel may is built into an abrasive article between adjacent features 722.

[0074] An abrasive article, in accordance with embodiments herein, generally includes abrasive material adhered to a backing by a make coat, which may include a resin or other adhesive material.

[0075] Some examples of a backing material may include polymer film, paper, cloth, metal film, vulcanized fiber, non-woven base material, a combination thereof, and a processed product thereof.

[0076] The backing may be, in embodiments herein, a polymer film such as, for example, any of a polyester film, a polyethylene film, a polypropylene film, a polyimide film, a nylon film, a polyethylene terepthalate (PETG) film, a polyurethane film, an aluminum oxide film, and / or a polyvinyl chloride film. Other polymeric film materials may also be suitable. The polymer film may be undercoated with a material such as polyethylene acrylic acid in order to promote bonding to the base material of the abrasive composite. The backing, in embodiments herein, is formed of a water-resistant material. Water-resistant abrasive articles herein are designed to withstand exposure to water or other liquids without losing its effectiveness or deteriorating. The water-resistant properties of the abrasive article help to prevent premature wear or degradation, allowing it to maintain its cutting or grinding capabilities even when used in wet conditions.

[0077] In some embodiments herein the backing is formed of a water-proof material. Water-proof abrasive articles in embodiments herein are completely impervious to water or other water-based liquids. Unlike water-resistant abrasive articles, which can withstand exposure to water without significant damage, water-proof abrasive articles are completely impermeable to water and will not absorb or be affected by it.

[0078] As abrasive articles in embodiments herein are configured for wet sanding, the abrasive article is formed free of a stearate or other dry sanding lubricant component.

[0079] The abrasive article includes an abrasive layer. The abrasive layer has an abrasive composite containing a matrix of a binder and abrasive grains dispersed therein as construction components. The abrasive grains may be arranged in a micro-replicated pattern into one or more 3D elements, as illustrated in FIGS. 6A-6C, for example.

[0080] The abrasive composite is formed from a slurry containing a plurality of abrasive grains dispersed in the binder which is in an unhardened or ungelated state. In hardening or gelation, the abrasive composite is solidified, i.e. is fixed to have a predetermined shape and a predetermined structure.

[0081] The dimension of the abrasive grains, or abrasive feature, may vary depending on the type of the abrasive grains or the intended use of the abrasive material. For example, the dimension is 1 to 20 pm, preferably 1 to 10 pm, more preferably 1 to 7 pm for the finalfinishing abrasion . Preferable examples of the abrasive grains for the present invention include diamond, cubic boron nitride, cerium oxide, fused aluminum oxide, heat-treated aluminum oxide, sol-gel aluminum oxide, silicon carbide, chromium oxide, silica, zirconia, alumina zirconia, iron oxide, garnet, and a mixture thereof.

[0082] The binder may be hardened or gelated to form an abrasive layer. Preferable examples of the binder include phenolic resin, resol-phenolic resin, aminoplast resin, urethane resin, epoxy resin, acrylate resin, polyester resin, vinyl resin, melamine resin, acrylated isocyanurate resin, urea-formaldehyde resin, isocyanurate resin, acrylated urethane resin, acrylated epoxy resin, and a mixture thereof. The binder may be a thermoplastic resin.

[0083] The binder may be radiation-curing, in some embodiments. The radiation-curing binder is a binder that is at least partially hardened or is at least partially polymerizable by radiation energy. Depending on the binder to be used, an energy source such as heat, infrared radiation, electron beam radiation, ultraviolet radiation, or a visible light radiation is used.

[0084] Typically, these binders are polymerized by a free radical mechanism. Preferably, these binders are selected from the group consisting of acrylated urethane, acrylated epoxy, an aminoplast derivative having an a, [3 unsaturated carbonyl group, an ethylenic unsaturated compound, an isocyanurate derivative having at least one acrylate group, isocyanate having at least one acrylate group, and a mixture thereof.

[0085] If the binder is hardened by ultraviolet radiation, a photoinitiator is required to start free radical polymerization. Preferable examples of the photoinitiator to be used for this purpose include organic peroxides, azo compounds, quinones, benzophenones, nitroso compounds, acryl halides, hydrazones, mercapto compounds, pyrylium compounds, triacrylimidazole, bisimidazole, chloroalkyltriazine, benzoin ether, benzyl ketal, thioxanthone, and acetophenone derivatives. A preferable photoinitiator is 2,2-dimethoxy- 1 ,2-diphenyl- 1 -ethanone .

[0086] If the binder is hardened by visible light radiation, it is necessary that a photoinitiator starts a free radical polymerization. Preferable examples of the photoinitiator for this purpose are disclosed in U.S. Pat. No. 4,735,632, column 3, line 25 to column 4, line 10, column 5, lines 1 to 7, and column 6 lines 1 to 35, which are incorporated herein by reference.

[0087] The weight proportion of the abrasive grains to the binder is typically within arange of about 1.5 to 10 parts of abrasive grains with respect to one part of the binder, preferably about 2 to 7 parts by weight of abrasive grains with respect to one part of the binder. This proportion may vary depending on the size of the abrasive grains, the type of the binder to be used, and the intended purpose of the abrasive material.

[0088] In smoothly and finely abrading a hard material such as an end surface of an optical fiber connector, the concentration of the abrasive grains contained in the abrasive composite is preferably within a range of 43 to 90 wt % if the abrasive grains are made of silicon carbide; 70 to 90 wt % if the abrasive grains are made of spherical abrasive particles of alumina, silica, or the like; 37 to 90 wt % if the abrasive grains are made of alumina; and 39 to 90 wt % if the abrasive grains are made of diamond.

[0089] The abrasive composite may contain a material other than the abrasive grains and the binder. For example, the abrasive material may contain ordinary additives such as a coupling agent, a lubricant, a dye, a pigment, a plasticizer, a filler, a stripping agent, an abrasive aid, and a mixture thereof.

[0090] The abrasive composite can contain a coupling agent. Addition of the coupling agent can considerably reduce the covering viscosity of a slurry to be used for formation of the abrasive composite. Preferable examples of the coupling agent for the present invention include organic silane, zircoaluminate, and titanate. The amount of the coupling agent is typically less than 5 wt %, preferably less than 1 wt %, of the binder.

[0091] The abrasive layer has a three-dimensional structure constructed with a plurality of regularly arranged three-dimensional elements having a predetermined shape, the elements formed from a number of abrasive particles arranged in a repeating pattern. The abrasive grains illustrated in FIG. 6A, for example each have a tetrahedral shape in which ridges are connected at a point on the top. In this case, the angle a formed between two ridges is typically 30 to 150°, preferably 45 to 140°. The three-dimensional elements 104 may have a pyramidal shape. In this case, the angle a formed between two ridges is typically 30 to 150°, preferably 45 to 140°.

[0092] The points on the top of the three-dimensional elements 104 are located on a plane parallel to the surface of the base material substantially over an entire region of the abrasive material. A height of each of the abrasive particles, from the surface of the base material, may range from about 2 to about 20 pm. For example, the abrasive particles may have a height greater than about 2 pm. The abrasive particles may have a height less thanabout 20 un, in some embodiments, or less than about 15 pun, or less than about 12 pun, or even less than about 10 pun. The abrasive particles may even have a height less than about 9 pm, or even less than about 8 pm, or even less than about 7 pm, or even less than about 6 pm. The variation of the height of the abrasive particles is preferably less than 20%, more preferably less than 10%, from particle to particle.

[0093] The abrasive particles may be arranged in a number of suitable predetermined configurations. In FIG. 6A, the abrasive particles are most closely packed. In some embodiments herein, the abrasive particles are repeated with a predetermined period to form a 3D element. This repetitive shape can be one -directional or two-directional.

[0094] In embodiments herein, the abrasive grains do not significantly protrude beyond the surface of the shape of the three-dimensional elements. In other words, the three- dimensional elements are constructed with flat planes. For example, the surfaces constituting the three-dimensional elements have a surface roughness Ra of less than 2 pm, preferably less than 1 pm.

[0095] As an abrasive article performs an abrading operation, a tip of each of the abrasive particles 702 contacts and abrades a surface. As the abrasive article continues an abrading operation, the three-dimensional elements are decomposed starting from the top portion, thereby allowing unused abrasive grains to appear. Therefore, in order to increase the abrasive property of the abrasive material, the concentration of the abrasive grains in the abrasive composite located in the top portion of the three-dimensional element is preferably increased to be as high as possible so that the abrasive material may have a higher abrasive property to be suited for abrading a hard material. The concentration of the abrasive grains in the abrasive composite located in the top portion of the three-dimensional element more preferably exceeds the critical pigment volume concentration.

[0096] Generally, the critical pigment volume concentration is considered to be the pigment volume concentration where there is just sufficient binder to coat pigment surfaces and provide a continuous phase throughout the film. The critical pigment volume concentration as used herein means a volume concentration of abrasive grains when the gaps among the grains are just filled with a binder. In the case where the binder is liquid, the mixture has fluidity if the concentration is less than the critical pigment volume concentration, whereas the mixture loses its fluidity if the concentration exceeds the critical pigment volume concentration. If the concentration of the abrasive grains in the abrasivecomposite located in the top portion of the three-dimensional element is less than or equal to the critical pigment volume concentration, the abrasive property of the abrasive material will be insufficient, so that the abrasive material will not be suitable for abrasion of a hard material such as an end surface of an optical fiber connector.

[0097] Abrasive elements 700 may be formed using a number of suitable processes. Some embodiments herein include abrasive elements formed according to the process described in U.S. Pat. 6,773,475, specifically FIGS. 6a-6e and the associated description, both of which are incorporated by reference herein.

[0098] First, an abrasive slurry is prepared which contains abrasive grains, a binder, and a solvent. The abrasive slurry to be used herein is a composition containing the binder, the abrasive grains, and optional additives such as a photoinitiator in sufficient amounts to constitute an abrasive composite and further containing a volatile solvent in a sufficient amount to impart fluidity to the mixture. Even if the content of the abrasive grains in the abrasive composite exceeds the critical pigment volume concentration, the fluidity can be maintained by allowing the abrasive slurry to contain a volatile solvent.

[0099] A preferable volatile solvent is an organic solvent that dissolves the binder and shows volatility at room temperature to 170° C. Specific examples of the organic solvent include methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, ethanol, isopropyl alcohol, ethyl acetate, butyl acetate, tetrahydrofiiran, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate. Another preferable solvent is water.

[0100] Next, a mold sheet is prepared which has a plurality of regularly arranged recesses tapered toward the bottom. The shape of the recesses may be an inverse of the three-dimensional elements to be formed. The mold sheet may be made of a metal such as nickel or plastics such as polypropylene. For example, a thermoplastic resin such as polypropylene is preferable because it can be embossed at its melting point on a metal tool to form recesses of a predetermined shape. Further, if the binder is a radiation-curing type resin, it is preferable to use a material that transmits ultraviolet rays and visible light.

[0101] The obtained mold sheet is filled with an abrasive slurry.

[0102] The mold sheet can be filled with the abrasive slurry by applying the abrasive slurry onto the mold sheet by means of a coating apparatus such as a roll coater. The viscosity of the abrasive slurry for application may be adjusted to be 10 to 106 cps, particularly 100 to 105 cps.

[0103] The solvent is evaporated and removed from the abrasive slurry. In doing this, the mold sheet filled with the abrasive slurry is heated to 50 to 150° C. for 0.2 to 10 minutes. If the binder is a thermoplastic resin, the mold sheet may be heated at its curing temperature for simultaneously performing a hardening step. If the volatility of the solvent is high, the mold sheet may be left to stand at room temperature for several minutes to several hours.

[0104] The mold sheet is further filled with a binder for lamination to fill the recesses with the binder. The lamination binder may be the same as or different from the one used in preparing the abrasive slurry. A binder having a good adhesion to the base material is preferable as the lamination binder.

[0105] Preferable examples of the lamination binder is acrylate resin, epoxy resin, and urethane resin. The mold sheet may be filled with the lamination binder in the same manner as the abrasive slurry.

[0106] A base material may is superposed on the mold sheet to allow the binder to adhere to the base material. The adhesion is carried by pressing with a roll for lamination. However, it is expressly contemplated that, in some embodiments, abrasive particles 702 have a single unitary composition.

[0107] The binder is hardened. The term “hardening” as used herein means that the binder is polymerized into a solid state. After the hardening, the specific shape of the abrasive layer does not change. The hardening of the binder in the abrasive slurry and the hardening of the lamination binder introduced alone at the later step may be performed either separately or simultaneously.

[0108] The binder is hardened by heat, infrared radiation, or by electron beam radiation, ultraviolet radiation, or by another radiation energy such as visible light radiation. The amount of radiation energy to be applied may vary depending on the type of the binder and the radiation energy source. Usually, those skilled in the art can suitably determine the amount of radiation energy to be applied. The period of time required in hardening may vary depending on the thickness, density, temperature of the binder, the properties of the composition, and others.

[0109] For example, the binder may be hardened by radiating ultraviolet rays (UV) from above the transparent base material. The mold sheet is the removed to produce an abrasive material composed of the base material and the abrasive layer having a three-dimensional structure. The binder may be hardened after the mold sheet is removed.

[0110] FIGS. 7A-7E illustrate schematics of abrasive article coupling mechanisms in accordance with embodiments herein.

[0111] FIG. 7A illustrates a backup pad 800 having a surface covered with coupling features 802. In some embodiments, the coupling features include hook-and-loop (e.g., Hook-it™ available from 3M Company) surface features that receive corresponding features on a coupling surface of an abrasive article. FIG. 7B illustrates a schematic 820 where an abrasive article 810 is coupled to the backup pad 800. As illustrated, abrasive article 810, while covered with abrasive elements, has a relatively smooth surface. While abrasive articles may have some surface variability, as discussed with respect to FIGS. 6A- 6C, generally the small size of the abrasive particles, in combination with small variances in particle size and shallow channels between abrasive elements, results in a surface that is smooth enough that it wets completely, without leaving sufficient space for air pockets or air flow. The smooth surface, therefore, can result in significant suction forces holding the abrasive side to a worksurface. The effect is increased when used in wet or damp abrading conditions.

[0112] FIG. 7C illustrates a schematic 830 where an abrasive article in accordance with embodiments herein is coupled to a backup pad. The abrasive disc includes an aperture 812 that extends through the thickness of the abrasive disc, which provides pressure relief, reducing an amount of suction between the disc and a worksurface. Apertures 812 allows for pressure relief channels 816 to form.

[0113] FIGS. 7D-1 and 7D-2 illustrate different configurations of a backup pad 840 having a number of resistance force relief features 842 on the surface. Coupling features (e.g. hook-and-loop features) are not shown for ease of understanding. Features 842 include a number of grooves 842 which may be machined into, or built onto, a surface of a backup pad 840. While a number of groves are illustrated as having equal spacing therebetween in FIG. 7D-2, in a parallel configuration, it is expressly contemplated that fewer, or more, grooves may be present in other embodiments, and may be positioned relative to each other in a number of suitable configurations. FIG. 7D-2 illustrates an embodiment where two grooves 842 intersect on the surface. While FIG. 7D-2 illustrates a symmetrical design with the grooves intersecting in the center of the surface, it is expressly contemplated that an intersection between two grooves may be positioned elsewhere on the surface. Additionally,a single groove that intersects with an aperture 844, may be sufficient. Other configurations are expressly contemplated.

[0114] FIG. 7E illustrates the function of suction relief features 842. Pressure relief channels are illustrated by arrows 846. Pressure relief features 842 allow for pressure to be released at the edge of the backup pad 840. While linear channels are illustrated, it is expressly contemplated that other patterns or shapes are possible - for example radial channels, cross-hatched or grid patterns, or other suitable designs.

[0115] In some embodiments herein, a contact surface between a backup pad and an abrasive article is at least 50% of the original disc surface, when the pressure reduction features are considered.

[0116] Additionally, while FIG. 7E illustrates an embodiment where a backup pad and an abrasive disc include pressure relief features, it is expressly contemplated that only the backup pad or only the abrasive disc include a pressure relief feature in some embodiments. Additionally, while an abrasive article having a single aperture design is illustrated in FIG. 7E, it is expressly contemplated that any suitable pressure relief feature - e.g. multiple apertures, slits, creases, etc., may be present in some embodiments.

[0117] Including pressure relief features on a backup pad may allow for embodiments herein to be implemented using abrasive articles that couple to a backup pad using adhesive (e.g. Stik-it™ abrasive discs available from 3M Company).

[0118] It is noted that, while FIGS. 7A-7E illustrate a backup pad with coupling features 802 evenly distributed about the surface, that it may be preferable to remove such features in the vicinity of an aperture 844. It is desired that the coupling features 802 not contact a surface being abraded directly (which may cause scratches, etc.). In some embodiments herein, coupling features 802 are removed in an area corresponding to an aperture, e.g. aperture 814 or 844. It may be desired to remove coupling features 802 in a larger area than that corresponding exactly to the area of an aperture, as an abrasive article may not be placed exactly centered on a backup pad.

[0119] An abrasive article includes a backing, an abrading surface including an abrasive material adhered to the backing, a coupling surface including a coupling feature configured to removably couple the abrasive article to a tool, and a resistance force relief feature. The abrasive article is configured to be used with a fluid during an abrading operation. Theresistance force relief feature is configured to reduce a resistance force between the abrasive article and a worksurface including the fluid.

[0120] The backing may include a film.

[0121] The film may include a polymeric film.

[0122] The abrasive material may include abrasive particles. The abrasive particles may include shaped abrasive particles.

[0123] The abrasive material may include a three-dimensional abrasive structure constructed with a plurality of regularly arranged three-dimensional abrasive elements having a predetermined shape.

[0124] The three-dimensional structure may be a first three-dimensional structure. The abrading surface may include a second three-dimensional structure. A channel may separate the first and second three-dimensional structures. The resistance force relief feature may include the channel.

[0125] The channel may have a channel depth. The three-dimensional structure may have a feature height. A distance from the channel depth to the feature height may be at least 100 pm.

[0126] The abrasive article may be stearate-free.

[0127] The abrasive article may have a diameter of at least about 0.5 inches.

[0128] The abrasive article may have a diameter of less than about 4 inches.

[0129] The abrasive article may have a diameter of less than about 3 inches.

[0130] The abrasive material may have a FEPA grade of at least P1200.

[0131] The abrasive material may have a FEPA grade of at least Pl 500.

[0132] The abrasive material may have a FEPA grade of at least P3000.

[0133] The abrasive article may have a non-circular perimeter.

[0134] The non-circular perimeter may include a repeating pattern.

[0135] The repeating pattern may include a wave.

[0136] The abrasive article may be nonplanar.

[0137] The resistance force relief feature may include a deformation of the abrasive article.

[0138] The deformation may include a crease.

[0139] The deformation may include a slit extending through the backing.

[0140] The resistance force relief feature may include one or more apertures extending through the abrasive article from the coupling surface to the abrading surface.

[0141] A total area of the one or more apertures may be at least 0.18 mm2.

[0142] A total area of the one or more apertures may be at least 0.20 mm2.

[0143] A total area of the one or more apertures may be less than about 20 mm2.

[0144] A total area of the one or more apertures may be less than about 10 mm2.

[0145] A total area of the one or more apertures may be less than about 1.0 mm2.

[0146] The abrasive article may have a diameter of about 3 cm.

[0147] The abrasive article may have a diameter of less than 4 cm.

[0148] The one or more apertures may be within a center area of the abrasive article. The center area is defined by a second radius, the second radius being less than a first radius of the abrasive article.

[0149] The second radius may be less than about a quarter of the first radius.

[0150] The second radius may be less than about half the first radius.

[0151] The coupling feature may include a plurality of hooks or a plurality of loops.

[0152] The coupling feature may include an adhesive.

[0153] The backing may include a waterproof material.

[0154] A robotic abrading system includes an abrasive article including an abrasive layer coupled to a first side of a backing, the second side of the backing including a coupling feature, the backing including a waterproof material. A backup pad is removably coupled to the coupling feature. A movement mechanism is configured to move the abrasive article with respect to a worksurface. A force control unit is configured to apply force to the backup pad. A resistance force relief element is configured to reduce a resistance force generated by movement of the abrasive article against the worksurface during a wet abrading process.

[0155] The robotic abrading system may be a vacuum-less abrading system.

[0156] The robotic abrading system may be free of a shroud.

[0157] During the wet abrading process, a resistance force is formed between the abrasive layer and the worksurface. The resistance force relief element reduces the vacuum force below a coupling force exerted by the coupling feature.

[0158] The coupling feature may include a plurality of hooks, a plurality of loops, or an adhesive.

[0159] The vacuum force may be reduced below about 10 N.

[0160] The vacuum force may be reduced below about 8 N.

[0161] The backup pad has a backup pad diameter, the abrasive article has an abrasive article diameter. The abrasive article diameter is larger than the backup pad diameter.

[0162] The backing may include a film.

[0163] The film may include a polymeric film.

[0164] The abrasive particles may include shaped abrasive particles.

[0165] The abrasive material may include a three-dimensional structure constructed with a plurality of regularly arranged three-dimensional elements having a predetermined shape.

[0166] The three-dimensional structure is a first three-dimensional structure. The abrading surface includes a second three-dimensional structure. A channel separates the first and second three-dimensional structures. The resistance force relief feature includes the channel.

[0167] A height of the channel may be at least a height of the first three-dimensional structure.

[0168] The abrasive article may be stearate-free.

[0169] The abrasive article may have a diameter of at least about 0.5 inches.

[0170] The abrasive article may have a diameter of less than about 4 inches.

[0171] The abrasive article may have a diameter of less than about 3 inches.

[0172] The abrasive material may have a FEPA grade of at least P1200.

[0173] The abrasive material may have a FEPA grade of at least Pl 500.

[0174] The abrasive material may have a FEPA grade of at least P3000.

[0175] The abrasive article may have a non-circular perimeter.

[0176] The non-circular perimeter may include a repeating pattern.

[0177] The repeating pattern may include a wave.

[0178] The abrasive article may be nonplanar.

[0179] The resistance force relief feature may include a deformation of the abrasive article.

[0180] The deformation may include a crease.

[0181] The deformation may include a slit extending through the backing.

[0182] The resistance force relief feature may include one or more apertures extending through the abrasive article from the coupling surface to the abrading surface.

[0183] A combined total area of the one or more apertures may be at least 0.18 mm2.

[0184] A combined total area of the one or more apertures may be at least 0.20 mm2.

[0185] A combined total area of the one or more apertures may be less than about 20 mm2.

[0186] A combined total area of the one or more apertures may be less than about 10 mm2.

[0187] A combined total area of the one or more apertures may be less than about 1.0 mm2.

[0188] The abrasive article may have a diameter of about 3 cm.

[0189] The abrasive article may have a diameter of less than 4 cm.

[0190] The one or more apertures may be within a center area of the abrasive article. The center area is defined by a second radius, the second radius being less than a first radius of the abrasive article.

[0191] The backup pad may include the resistance force relief feature.

[0192] The backup pad may include a channel configured to allow airflow between a backup pad surface and the second side of the backing.

[0193] The coupling feature may include a plurality of first coupling features. The backup pad includes a plurality of second coupling features configured to receive the first coupling features. An area of the backup pad is free of second coupling features.

[0194] The abrasive article may include an aperture. The area is sized to overlap with the aperture.

[0195] A depth of the resistance force relief feature may be at least 0.01 inches.

[0196] A width of the resistance force relief feature may be at least 0.01 inches.

[0197] A method of abrading a surface includes applying a fluid to the surface, moving an abrasive article proximate the surface using a movement mechanism, and abrading the surface with the abrasive article in the presence of the fluid. The abrasive article may be removably coupled to a backup pad by a coupling mechanism. A suction force may form between the surface and the abrasive article during abrading. The abrasive article may be removed from the surface. The abrasive article includes a resistance force relief feature configured to reduce a suction force between the surface and the abrasive article.

[0198] The coupling mechanism may include a hook and loop system. The resistance force relief feature reduces a suction force below a threshold force exerted by the hook and loop system.

[0199] Abrading the surface may include applying a force to the abrasive article.

[0200] Abrading may include producing a slurry including abrasive debris mixed into the fluid.

[0201] The suction force may be reduced below about 10 N.

[0202] The suction force may be reduced below about 8 N.

[0203] The abrasive article may include a water-resistant backing.

[0204] The abrasive article may include a water-proof backing.

[0205] The abrasive article may include an abrading surface having a surface roughness Ra of less than about 2 pm.

[0206] The backing may include a film.

[0207] The film may include a polymeric film.

[0208] The abrasive particles may include shaped abrasive particles.

[0209] The abrasive material may include a three-dimensional structure constructed with a plurality of regularly arranged three-dimensional elements having a predetermined shape.

[0210] The three-dimensional structure may be a first three-dimensional structure. The abrading surface may include a second three-dimensional structure. A channel may separate the first and second three-dimensional structures. The resistance force relief feature includes the channel.

[0211] The channel may have a channel depth. The three-dimensional structure may have a feature height. A distance from the channel depth to the feature height may be at least 100 pm.

[0212] The abrasive article may be stearate-free.

[0213] The abrasive article may have a diameter of at least about 0.5 inches.

[0214] The abrasive article may have a diameter of less than about 4 inches.

[0215] The abrasive article may have a diameter of less than about 3 inches.

[0216] The abrasive material may have a FEPA grade of at least P1200.

[0217] The abrasive material may have a FEPA grade of at least Pl 500.

[0218] The abrasive material may have a FEPA grade of at least P3000.

[0219] The abrasive article may have a non-circular perimeter.

[0220] The non-circular perimeter may include a repeating pattern.

[0221] The repeating pattern may include a wave.

[0222] The abrasive article may be nonplanar.

[0223] The resistance force relief feature may include a deformation of the abrasive article.

[0224] The deformation may include a crease.

[0225] The deformation may include a slit extending through the backing.

[0226] The resistance force relief feature may include one or more apertures extending through the abrasive article from the coupling surface to the abrading surface.

[0227] A combined total area of the one or more apertures may be at least 0.18 mm2.

[0228] A combined total area of the one or more apertures may be at least 0.20 mm2.

[0229] A combined total area of the one or more apertures may be less than about 20 mm2.

[0230] A combined total area of the one or more apertures may be less than about 10 mm2.

[0231] A combined total area of the one or more apertures may be less than about 1.0 mm2.

[0232] The abrasive article may have a diameter of about 3 cm.

[0233] The abrasive article may have a diameter of less than 4 cm.

[0234] The one or more apertures may be within a center area of the abrasive article. The center area may be defined by a second radius. The second radius may be less than a first radius of the abrasive article.

[0235] All of the one or more apertures may be within the center area.

[0236] The second radius may be less than about a third of the first radius.

[0237] The second radius may be less than about half of the first radius.

[0238] The backup pad may include a channel configured to allow airflow between a backup pad surface and the second side of the backing.

[0239] The coupling feature may include a plurality of first coupling features. The backup pad may include a plurality of second coupling features configured to receive the first coupling features. An area of the backup pad may be free of second coupling features.

[0240] The abrasive article may include an aperture. The area may be sized to overlap with the aperture.

[0241] A method of abrading a surface includes moving, using a robotic abrading system, an abrasive article proximate a defect location on a surface. The abrasive article includes an abrading surface opposite a coupling surface. The abrasive article is coupled to a backup pad using a coupling mechanism on the coupling surface. The coupling mechanism exerts a coupling force on the abrasive article along the coupling surface. A fluid is applied to thesurface proximate the defect location. The surface is abraded. Abrading includes applying a force, using a force control unit of the robotic abrading system, to the backup pad, and moving the abrasive article at a rotational speed on the surface. The abrasive article is removed from the surface. The abrasive article includes a resistance force relief feature. The resistance force relief feature reduces a suction force between the abrasive article and the surface below the coupling force.

[0242] The suction force may be reduced below about IO N.

[0243] The suction force may be reduced below about 8 N.

[0244] The robotic abrading system may be a vacuum-less abrading system.

[0245] The robotic abrading system may be free of a shroud.

[0246] The coupling feature may include a plurality of hooks, a plurality of loops, or an adhesive.

[0247] The backup pad has a backup pad diameter, the abrasive article has an abrasive article diameter, and the abrasive article diameter is larger than the backup pad diameter.

[0248] The backing may include a film.

[0249] The film may include a polymeric film.

[0250] The abrasive particles may include shaped abrasive particles.

[0251] The abrasive material may include a three-dimensional structure constructed with a plurality of regularly arranged three-dimensional elements having a predetermined shape.

[0252] The three-dimensional structure is a first three-dimensional structure. The abrading surface includes a second three-dimensional structure. A channel separates the first and second three-dimensional structures. The resistance force relief feature includes the channel.

[0253] The channel has a channel depth. The three-dimensional structure has a feature height. A distance from the channel depth to the feature height is at least 100 pm.

[0254] The abrasive article may be stearate-free.

[0255] The abrasive article may have a diameter of at least about 0.5 inches.

[0256] The abrasive article may have a diameter of less than about 4 inches.

[0257] The abrasive article may have a diameter of less than about 3 inches.

[0258] The abrasive material may have a FEPA grade of at least P1200.

[0259] The abrasive material may have a FEPA grade of at least Pl 500.

[0260] The abrasive material may have a FEPA grade of at least P3000.

[0261] The abrasive article may have a non-circular perimeter.

[0262] The non-circular perimeter may include a repeating pattern.

[0263] The repeating pattern may include a wave.

[0264] The abrasive article may be nonplanar.

[0265] The resistance force relief feature may include a deformation of the abrasive article.

[0266] The deformation may include a crease.

[0267] The deformation may include a slit extending through the backing.

[0268] The resistance force relief feature may include one or more apertures extending through the abrasive article from the coupling surface to the abrading surface.

[0269] A combined total area of the one or more apertures may be at least 0.18 mm2.

[0270] A combined total area of the one or more apertures may be at least 0.20 mm2.

[0271] A combined total area of the one or more apertures may be less than about 20 mm2.

[0272] A combined total area of the one or more apertures may be less than about 10 mm2.

[0273] A combined total area of the one or more apertures may be less than about 1.0 mm2.

[0274] The abrasive article may have a diameter of about 3 cm.

[0275] The abrasive article may have a diameter of less than 4 cm.

[0276] The one or more apertures may be within a center area of the abrasive article. The center area is defined by a second radius. The second radius is less than a first radius of the abrasive article.

[0277] The backup pad may include the resistance force relief feature.

[0278] The backup pad may include a channel configured to allow airflow between a backup pad surface and the second side of the backing.

[0279] The robotic abrading system may include a coupling feature that includes a plurality of first coupling features. The backup pad includes a plurality of second coupling features configured to receive the first coupling features. An area of the backup pad is free of second coupling features.

[0280] The abrasive article may include an aperture. The area is sized to overlap with the aperture.ExamplesEXAMPLE 1

[0281] FIGS. 8A-8B illustrate abrasive discs having one or more holes therethrough. The illustrated discs underwent a damp sanding process to determine whether sanding slurry would leak through the holes.Example 1A:

[0282] FIG. 8A shows a 1 3 / 8” sanding disc (model number 464LA A5, available from 3M™ Company, St. Paul, MN) that has an array of holes throughout the disc. The backup pad used was a Finesse-It™ Roloc™ Medium density 29mm backup pad (model number 65741, available from 3M™ Company, St. Paul, MN) which utilizes a hook and loop attachment system with the sanding disc. FIG. 9A demonstrates that some amount of sanding slurry was able to leak through the holes and onto the backup pad in several different spots. When removing and applying a new disc of the same hole design, the slurry was able to continue leaking through onto more locations on the backup pad.Example IB:

[0283] FIG. 8B shows a 1 3 / 8” sanding disc (model number 464LA A5, available from 3M™ Company, St. Paul, MN) with a hole in only the center of the disc. The backup pad being used was a Finesse-It™ Roloc™ Medium density 29mm backup pad (model number 65741, available from 3M™ Company, St. Paul, MN) which utilizes a hook and loop attachment system with the sanding disc. FIG. 9B demonstrates that some amount of sanding slurry was able to leak through the hole and onto the backup pad. However, even with changing the disc and adding a new one with the same hole pattern, the slurry that leaked through was always kept towards the center of the backup pad. This prevented slurry from leaking onto the remaining attachment surface of the backup pad.

[0284] Both comparative examples A and B succeeded at eliminating and adhesion between the sanding disc and the substrate, however, it may be more preferred to keep the slurry that leaks through the disc to only be at the center of the backup pad, rather than in many different parts of the backup pad. This can help the backup pad last longer since the slurry is not wetting out the entirety of the hook-it attachment surface.EXAMPLE 2Sample preparation

[0285] Scalloped edge discs (3M™ Trizact™ Finesse-it™ Film Disc 464LA, A7, 3M Company, St. Paul, MN) were placed one at a time under a DataLogic VL 2104-1330 DPSS Green System and resonator with scan head, wavelength 532nm, nominal Power 10W laser. The laser was activated and a single hole was cut from the nominal center point of each of the discs. The total area of the hole size ranged from 0.03 mm2to 20.27 mm2.Peel Force Test Method

[0286] An industrial robot arm was fitted at the end of arm with an active compliant tool (model number 6530, available from 3M™ Company, St. Paul, MN) and a servo random orbital sander motor (model number 77539, 3M™ Company, St. Paul, MN). The sander motor was attached directly to the active compliant tool. A Hookit™ Roloc™ Disc Pad (model number 28655, available from 3M™ Company, St. Paul, MN) was attached to the end of the sander motor.

[0287] A painted panel (model number 57080 black painted panel, available from ACT Test Panels LLC, Hillsdale, MI) was secured with tape to the top of a force measuring device (model number 2001-02 Force Plate, available from Bertec™ Corporation, Columbus, OH). A disc that was made as described in the Sample Preparation section was affixed to the disc pad.

[0288] Approximately 0.12g of water was sprayed onto the painted panel directly below the disc. The disc was pressed down onto the panel with 20N of downward force. The servo motor was spun up to 4900rpm while simultaneously beginning a spiral movement in the X- Y plane of the painted panel. The spiral began at a radius of 3mm and spiraled outward to a radius of 9mm at a traverse speed of 0.03m / s for a total spiral time of 9 seconds. The robot arm then retracted the servo motor away from the painted panel.

[0289] As the motor was retracting away from the painted panel, the force between the disc and painted panel was measured by the measuring device and recorded. The disc was then discarded and 4 other discs with the same center hole area were also tested. So in total, each disc type was measured 5 times and recorded. 5 unmodified discs with no center hole (center hole area 0.00) were also tested and recorded.

[0290] Table 1 shows the average sticking force between the tested discs and painted panelTable 1

[0291] Reference throughout this specification to “one embodiment,” “certain embodiments,” “one or more embodiments,” or “an embodiment,” whether or not including the term “exemplary” preceding the term “embodiment,” means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the certain exemplary embodiments of the present disclosure. Thus, the appearances of the phrases such as “in one or more embodiments,” “in certain embodiments,” “in one embodiment,” or “in an embodiment” in various places throughout this specification are not necessarily referring to the same embodiment of the certain exemplary embodiments of the present disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

Claims

CLAIMSWhat is claimed is:

1. An abrasive article comprising: a backing; an abrading surface comprising an abrasive material adhered to the backing; a coupling surface comprising a coupling feature configured to removably couple the abrasive article to a tool; and a resistance force relief feature, wherein the abrasive article is configured to be used with a fluid during an abrading operation, and wherein the resistance force relief feature is configured to reduce a resistance force between the abrasive article and a worksurface comprising the fluid.

2. The abrasive article of claim 1, wherein the backing comprises a film.

3. The abrasive article of claim 2, wherein the film comprises a polymeric film.

4. The abrasive article of any of claims 1-3, wherein the abrasive material comprises abrasive particles, and wherein the abrasive particles comprise shaped abrasive particles.

5. The abrasive article of any of claims 1-4, wherein the abrasive material comprises a three-dimensional abrasive structure constructed with a plurality of regularly arranged three-dimensional abrasive elements having a predetermined shape.

6. The abrasive article of claim 5, wherein the three-dimensional structure is a first three- dimensional structure, wherein the abrading surface comprises a second three- dimensional structure, and wherein a channel separates the first and second three- dimensional structures, wherein the resistance force relief feature comprises the channel.

7. The abrasive article of claim 6, wherein the channel has a channel depth, wherein the three-dimensional structure has a feature height, and wherein a distance from the channel depth to the feature height is at least 100 pm.

8. The abrasive article of any of claims 1-7, wherein the abrasive article is stearate-free.

9. The abrasive article of any of claims 1-8, wherein the abrasive article has a diameter of at least about 0.5 inches.

10. The abrasive article of any of claims 1-9, wherein the abrasive article has a diameter of less than about 4 inches.

11. The abrasive article of any of claims 1-10, wherein the abrasive article has a diameter of less than about 3 inches.

12. The abrasive article of any of claims 1-11, wherein the abrasive material has a FEPA grade of at least P1200.

13. The abrasive article of any of claims 1-12, wherein the abrasive material has a FEPA grade of at least P1500.

14. The abrasive article of any of claims 1-13, wherein the abrasive material has a FEPA grade of at least P3000.

15. The abrasive article of any of claims 1-14, wherein the abrasive article has a noncircular perimeter.

16. The abrasive article of claim 15, wherein the non-circular perimeter comprises a repeating pattern.

17. The abrasive article of claim 16, wherein the repeating pattern comprises a wave.

18. The abrasive article of any of claims 1-17, wherein the abrasive article is nonplanar.

19. The abrasive article of claim 18, wherein the resistance force relief feature comprises a deformation of the abrasive article.

20. The abrasive article of claim 19, wherein the deformation comprises a crease.

21. The abrasive article of claim 20, wherein the deformation comprises a slit extending through the backing.

22. The abrasive article of any of claims 1-21, wherein the resistance force relief feature comprises one or more apertures extending through the abrasive article from the coupling surface to the abrading surface.

23. The abrasive article of claim 22, wherein a total area of the one or more apertures is at least 0.18 mm2.

24. The abrasive article of claim 22, wherein a total area of the one or more apertures is at least 0.20 mm2.

25. The abrasive article of claim 22, wherein a total area of the one or more apertures is less than about 20 mm2.

26. The abrasive article of claim 22, wherein a total area of the one or more apertures is less than about 10 mm2.

27. The abrasive article of claim 22, wherein a total area of the one or more apertures is less than about 1.0 mm2.

28. The abrasive article of claim 22, wherein the abrasive article has a diameter of about 3 cm.

29. The abrasive article of claim 22, wherein the abrasive article has a diameter of less than 4 cm.

30. The abrasive article of claim 22, wherein the one or more apertures are within a center area of the abrasive article, wherein the center area is defined by a second radius, the second radius being less than a first radius of the abrasive article.

31. The abrasive article of claim 30, wherein the second radius is less than about a quarter of the first radius.

32. The abrasive article of claim 28, wherein the second radius is less than about half the first radius.

33. The abrasive article of any of claims 1-32, wherein the coupling feature comprises a plurality of hooks or a plurality of loops.

34. The abrasive article of any of claims 1-33, wherein the coupling feature comprises an adhesive.

35. The abrasive article of any of claims 1-34, wherein the backing comprises a waterproof material.

36. A robotic abrading system comprising: an abrasive article comprising an abrasive layer coupled to a first side of a backing, the second side of the backing comprising a coupling feature, the backing comprising a waterproof material; a backup pad removably coupled to the coupling feature; a movement mechanism configured to move the abrasive article with respect to a worksurface; a force control unit configured to apply force to the backup pad; and a resistance force relief element configured to reduce a resistance force generated by movement of the abrasive article against the worksurface during a wet abrading process.

37. The robotic abrading system of claim 36, wherein the robotic abrading system is a vacuum-less abrading system.

38. The robotic abrading system of claim 36 or 37, wherein the robotic abrading system is free of a shroud.

39. The robotic abrading system of any of claims 36-38, wherein, during the wet abrading process, a resistance force is formed between the abrasive layer and the worksurface, and wherein the resistance force resistance force relief element reduces the vacuum force below a coupling force exerted by the coupling feature.

40. The robotic abrading system of claim 39, wherein the coupling feature comprises a plurality of hooks, a plurality of loops, or an adhesive.

41. The robotic abrading system of claim 39, wherein the vacuum force is reduced below about IO N.

42. The robotic abrading system of claim 39, wherein the vacuum force is reduced below about 8 N.

43. The robotic abrading system of any of claims 36-42, wherein the backup pad has a backup pad diameter, the abrasive article has an abrasive article diameter, and wherein the abrasive article diameter is larger than the backup pad diameter.

44. The robotic abrading system of any of claims 36-43, wherein the backing comprises a film.

45. The robotic abrading system of claim 37, wherein the film comprises a polymeric film.

46. The robotic abrading system of any of claims 36-45, wherein the abrasive particles comprise shaped abrasive particles.

47. The robotic abrading system of any of claims 36-46, wherein the abrasive material comprises a three-dimensional structure constructed with a plurality of regularly arranged three-dimensional elements having a predetermined shape.

48. The robotic abrading system of claim 47, wherein the three-dimensional structure is a first three-dimensional structure, wherein the abrading surface comprises a second three-dimensional structure, and wherein a channel separates the first and second three-dimensional structures, wherein the resistance force relief feature comprises the channel.

49. The robotic abrading system of claim 48, wherein a height of the channel is at least a height of the first three-dimensional structure.

50. The robotic abrading system of any of claims 36-49, wherein the abrasive article is stearate-free.

51. The robotic abrading system of any of claims 36-50, wherein the abrasive article has a diameter of at least about 0.5 inches.

52. The robotic abrading system of any of claims 36-51, wherein the abrasive article has a diameter of less than about 4 inches.

53. The robotic abrading system of any of claims 36-52, wherein the abrasive article has a diameter of less than about 3 inches.

54. The robotic abrading system of any of claims 36-53, wherein the abrasive material has a FEPA grade of at least P 1200.

55. The robotic abrading system of any of claims 36-54, wherein the abrasive material has a FEPA grade of at least P 1500.

56. The robotic abrading system of any of claims 36-55, wherein the abrasive material has a FEPA grade of at least P3000.

57. The robotic abrading system of any of claims 36-56, wherein the abrasive article has a non-circular perimeter.

58. The robotic abrading system of claim 57, wherein the non-circular perimeter comprises a repeating pattern.

59. The robotic abrading system of claim 58, wherein the repeating pattern comprises a wave.

60. The robotic abrading system of any of claims 36-59, wherein the abrasive article is nonplanar.

61. The robotic abrading system of claim 60, wherein the resistance force relief feature comprises a deformation of the abrasive article.

62. The robotic abrading system of claim 61, wherein the deformation comprises a crease.

63. The robotic abrading system of claim 62, wherein the deformation comprises a slit extending through the backing.

64. The robotic abrading system of any of claims 36-63, wherein the resistance force relief feature comprises one or more apertures extending through the abrasive article from the coupling surface to the abrading surface.

65. The robotic abrading system of claim 64, wherein a combined total area of the one or more apertures is at least 0.18 mm2.

66. The robotic abrading system of claim 64, wherein a combined total area of the one or more apertures is at least 0.20 mm2.

67. The robotic abrading system of claim 64, wherein a combined total area of the one or more apertures is less than about 20 mm2.

68. The robotic abrading system of claim 64, wherein a combined total area of the one or more apertures is less than about 10 mm2.

69. The robotic abrading system of claim 64, wherein a combined total area of the one or more apertures is less than about 1.0 mm2.

70. The robotic abrading system of claim 64, wherein the abrasive article has a diameter of about 3 cm.

71. The robotic abrading system of claim 64, wherein the abrasive article has a diameter of less than 4 cm.

72. The robotic abrading system of claim 64, wherein the one or more apertures are within a center area of the abrasive article, wherein the center area is defined by a second radius, the second radius being less than a first radius of the abrasive article.

73. The robotic abrading system of any of claims 36-72, wherein the backup pad comprises the resistance force relief feature.

74. The robotic abrading system of claim 73, wherein the backup pad comprises a channel configured to allow airflow between a backup pad surface and the second side of the backing.

75. The robotic abrading system of claim 73, wherein the coupling feature comprises a plurality of first coupling features, and wherein the backup pad comprises a plurality of second coupling features configured to receive the first coupling features, and wherein an area of the backup pad is free of second coupling features.

76. The robotic abrading system of claim 75, wherein the abrasive article comprises an aperture, and wherein the area is sized to overlap with the aperture.

77. The robotic abrading system of claim 73, wherein a depth of the resistance force relief feature is at least 0.01 inches.

78. The robotic abrading system of claim 73, wherein a width of the resistance force relief feature is at least 0.01 inches.

79. A method of abrading a surface, the method comprising: applying a fluid to the surface; moving an abrasive article proximate the surface, using a movement mechanism, wherein the abrasive article is removably coupled to a backup pad by a coupling mechanism;abrading the surface with the abrasive article in the presence of the fluid, wherein a suction force forms between the surface and the abrasive article during abrading; and removing the abrasive article from the surface, wherein the abrasive article comprises a resistance force relief feature configured to reduce a suction force between the surface and the abrasive article.

80. The method of claim 79, wherein the coupling mechanism comprises a hook and loop system, and wherein the resistance force relief feature reduces a suction force below a threshold force exerted by the hook and loop system.

81. The method of claim 79 or 80, wherein abrading the surface comprises applying a force to the abrasive article.

82. The method of any of claims 79-81, wherein abrading comprises producing a slurry comprising abrasive debris mixed into the fluid.

83. The method of any of claims 79-82, wherein the suction force is reduced below about IO N.

84. The method of any of claims 79-83, wherein the suction force is reduced below about 8 N.

85. The method of any of claims 79-84, wherein the abrasive article comprises a water- resistant backing.

86. The method of any of claims 79-85, wherein the abrasive article comprises a waterproofbacking.

87. The method of any of claims 79-86, wherein the abrasive article comprises an abrading surface having a surface roughness Ra of less than about 2 pm.

88. The method of any of claims 79-87, wherein the backing comprises a fdm.

89. The method of claim 88, wherein the film comprises a polymeric film.

90. The method of any of claims 79-89, wherein the abrasive particles comprise shaped abrasive particles.

91. The abrasive article of any of claims 79-90, wherein the abrasive material comprises a three-dimensional structure constructed with a plurality of regularly arranged three- dimensional elements having a predetermined shape.

92. The method of claim 91, wherein the three-dimensional structure is a first three- dimensional structure, wherein the abrading surface comprises a second three-dimensional structure, and wherein a channel separates the first and second three- dimensional structures, wherein the resistance force relief feature comprises the channel.

93. The method of claim 92, wherein the channel has a channel depth, wherein the three- dimensional structure has a feature height, and wherein a distance from the channel depth to the feature height is at least 100 pm.

94. The method of any of claims 79-93, wherein the abrasive article is stearate-free.

95. The method of any of claims 79-94, wherein the abrasive article has a diameter of at least about 0.5 inches.

96. The method of any of claims 79-95, wherein the abrasive article has a diameter of less than about 4 inches.

97. The method of any of claims 79-96, wherein the abrasive article has a diameter of less than about 3 inches.

98. The method of any of claims 79-97, wherein the abrasive material has a FEPA grade ofat least P1200.

99. The method of any of claims 79-98, wherein the abrasive material has a FEPA grade ofat least Pl 500.

100. The abrasive article of any of claims 79-99, wherein the abrasive material has a FEPA grade of at least P3000.

101. The method of any of claims 79-100, wherein the abrasive article has a noncircular perimeter.

102. The method of claim 101, wherein the non-circular perimeter comprises a repeating pattern.

103. The method of claim 102, wherein the repeating pattern comprises a wave.

104. The method of any of claims 79-103, wherein the abrasive article is nonplanar.

105. The method of claim 104, wherein the resistance force relief feature comprises a deformation of the abrasive article.

106. The method of claim 105, wherein the deformation comprises a crease.

107. The method of claim 105, wherein the deformation comprises a slit extending through the backing.

108. The method of any of claims 79-107, wherein the resistance force relief feature comprises one or more apertures extending through the abrasive article from the coupling surface to the abrading surface.

109. The method of claim 108, wherein a combined total area of the one or more apertures is at least 0.18 mm2.

110. The method of claim 109, wherein a combined total area of the one or more apertures is at least 0.20 mm2.

111. The method of claim 109, wherein a combined total area of the one or more apertures is less than about 20 mm2.

112. The method of claim 109, wherein a combined total area of the one or more apertures is less than about 10 mm2.

113. The method of claim 109, wherein a combined total area of the one or more apertures is less than about 1.0 mm2.

114. The method of claim 109, wherein the abrasive article has a diameter of about 3 cm.

115. The method of claim 109, wherein the abrasive article has a diameter of less than 4 cm.

116. The method of claim 109, wherein the one or more apertures are within a center area of the abrasive article, wherein the center area is defined by a second radius, the second radius being less than a first radius of the abrasive article.

117. The method of claim 116, wherein all of the one or more apertures are within the center area.

118. The method of claim 116, wherein the second radius is less than about a third of the first radius.

119. The method of claim 116, wherein the second radius is less than about half of the first radius.

120. The method of any of claims 79-119, wherein the backup pad comprises a channel configured to allow airflow between a backup pad surface and the second side of the backing.

121. The robotic abrading system of claim 120, wherein the coupling feature comprises a plurality of first coupling features, and wherein the backup pad comprisesa plurality of second coupling features configured to receive the first coupling features, and wherein an area of the backup pad is free of second coupling features.

122. The robotic abrading system of claim 121, wherein the abrasive article comprises an aperture, and wherein the area is sized to overlap with the aperture.

123. A method of abrading a surface, the method comprising: moving, using a robotic abrading system, an abrasive article proximate a defect location on a surface, wherein the abrasive article comprises an abrading surface opposite a coupling surface, the abrasive article being coupled to a backup pad using a coupling mechanism on the coupling surface, the coupling mechanism exerting a coupling force on the abrasive article along the coupling surface; applying a fluid to the surface proximate the defect location; abrading the surface, wherein abrading comprises applying a force, using a force control unit of the robotic abrading system, to the backup pad, and moving the abrasive article at a rotational speed on the surface; and removing the abrasive article from the surface, wherein the abrasive article comprises a resistance force relief feature, wherein the resistance force relief feature reduces a suction force between the abrasive article and the surface below the coupling force.

124. The method of claim 123, wherein the suction force is reduced below about IO N.

125. The method of claim 123 or 124, wherein the suction force is reduced below about 8 N.

126. The method of any of claims 123-125, wherein the robotic abrading system is a vacuum-less abrading system.

127. The method of any of claims 123-126, wherein the robotic abrading system is free of a shroud.

128. The method of any of claims 123-127, wherein the coupling feature comprises a plurality of hooks, a plurality of loops, or an adhesive.

129. The method of any of claims 123-128, wherein the backup pad has a backup pad diameter, the abrasive article has an abrasive article diameter, and wherein the abrasive article diameter is larger than the backup pad diameter.

130. The method of any of claims 123-129, wherein the backing comprises a film.

131. The method of claim 130, wherein the film comprises a polymeric film.

132. The method of any of claims 123-131, wherein the abrasive particles comprise shaped abrasive particles.

133. The method of any of claims 123-132, wherein the abrasive material comprises a three-dimensional structure constructed with a plurality of regularly arranged three-dimensional elements having a predetermined shape.

134. The method of claim 133, wherein the three-dimensional structure is a first three-dimensional structure, wherein the abrading surface comprises a second three- dimensional structure, and wherein a channel separates the first and second three- dimensional structures, wherein the resistance force relief feature comprises the channel.

135. The method of claim 134, wherein the channel has a channel depth, wherein the three-dimensional structure has a feature height, and wherein a distance from the channel depth to the feature height is at least 100 pm.

136. The method of any of claims 123-135, wherein the abrasive article is stearate- free.

137. The method of any of claims 123-136, wherein the abrasive article has a diameter of at least about 0.5 inches.

138. The method of any of claims 123-137, wherein the abrasive article has a diameter of less than about 4 inches.

139. The method of any of claims 123-138, wherein the abrasive article has a diameter of less than about 3 inches.

140. The method of any of claims 123-139, wherein the abrasive material has a FEPA grade of at least P1200.

141. The method of any of claims 123-140, wherein the abrasive material has a FEPA grade of at least Pl 500.

142. The method of any of claims 123-141, wherein the abrasive material has a FEPA grade of at least P3000.

143. The method of any of claims 123-142, wherein the abrasive article has a noncircular perimeter.

144. The method of claim 143, wherein the non-circular perimeter comprises a repeating pattern.

145. The method of claim 144, wherein the repeating pattern comprises a wave.

146. The method of any of claims 123-145, wherein the abrasive article is nonplanar.

147. The method of claim 146, wherein the resistance force relief feature comprises a deformation of the abrasive article.

148. The method of claim 147, wherein the deformation comprises a crease.

149. The method of claim 147, wherein the deformation comprises a slit extending through the backing.

150. The method of any of claims 123-149, wherein the resistance force relief feature comprises one or more apertures extending through the abrasive article from the coupling surface to the abrading surface.

151. The method of claim 150, wherein a combined total area of the one or more apertures is at least 0.18 mm2.

152. The method of claim 150, wherein a combined total area of the one or more apertures is at least 0.20 mm2.

153. The method of claim 150, wherein a combined total area of the one or more apertures is less than about 20 mm2.

154. The method of claim 150, wherein a combined total area of the one or more apertures is less than about 10 mm2.

155. The method of claim 150, wherein a combined total area of the one or more apertures is less than about 1.0 mm2.

156. The method of claim 150, wherein the abrasive article has a diameter of about 3 cm.

157. The method of claim 150, wherein the abrasive article has a diameter of less than 4 cm.

158. The method of claim 150, wherein the one or more apertures are within a center area of the abrasive article, wherein the center area is defined by a second radius, the second radius being less than a first radius of the abrasive article.

159. The method of any of claims 123-158, wherein the backup pad comprises the resistance force relief feature.

160. The method of claim 159, wherein the backup pad comprises a channel configured to allow airflow between a backup pad surface and the second side of the backing.

161. The method of any of claims 123-160, wherein the coupling feature comprises a plurality of first coupling features, and wherein the backup pad comprises a plurality of second coupling features configured to receive the first coupling features, and wherein an area of the backup pad is free of second coupling features.

162. The method of any of claims 123-161, wherein the abrasive article comprises an aperture, and wherein the area is sized to overlap with the aperture.

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