Methods, systems, and apparatus for testing characteristics of a material used in medication delivery devices

Abstract

A subassembly for testing one or more characteristics of a plastic. In some embodiments, the subassembly comprises a base and a test component that is removably attached to, and rotatable relative to, the base. In some embodiments, the base comprises a first contact surface; and a first engagement feature positioned around the first contact surface. In some embodiments, the test component comprises: a second contact surface that contacts the first contact surface and is formed of the plastic; and a second engagement feature positioned around the second contact surface and configured to engage the first engagement feature of the base.

Description

METHODS, SYSTEMS, AND APPARATUS FOR TESTING CHARACTERISTICS OF A MATERIAL USED IN MEDICATION DELIVERY DEVICESBACKGROUND

[0001] Aspects described herein pertain to methods, systems, and apparatus for testing characteristics of materials used in medication delivery devices. Medication delivery devices are often used to inject medications into a patient. Characteristics of the materials used in such devices can impact their performance and lifecycle. As such, the characteristics may be tested, and the test results may be used to inform design decisions and / or check the quality of a device composed of such materials.SUMMARY

[0002] According to an exemplary embodiment of the present disclosure, a subassembly for testing one or more characteristics of a plastic is provided. In some embodiments, the subassembly comprises: a base comprising: a first contact surface; and a first engagement feature positioned around the first contact surface; and a test component that is removably attached to, and rotatable relative to. the base, the test component comprising: a second contact surface that contacts the first contact surface and is formed of the plastic; and a second engagement feature positioned around the second contact surface and configured to engage the first engagement feature of the base.

[0003] According to an exemplary embodiment of the present disclosure, a system for testing one or more characteristics of a plastic. In some embodiments, the system comprises: a subassembly, comprising: a base; and a test component that is removably attached to, and rotatable relative to, the base; a force applicator configured to apply a force to the test component of the subassembly; a motor configured to rotate a portion of the subassembly while the force is applied to the test component; and at least one processor configured to determine the one or more characteristics of the plastic based on a result of applying the force to the test component and rotating the portion of the subassembly.

[0004] According to an exemplary embodiment of the present disclosure, a method for testing one or more characteristics of a plastic using a subassembly is provided. In someembodiments, the method comprises: applying a force to a test component of the subassembly; rotating a portion of the subassembly while the force is applied to the test component; and determining, based on a result of applying the force to the test component and rotating the portion of the subassembly, the one or more characteristics of the plastic.BRIEF DESCRIPTION OF DRAWINGS

[0005] Various aspects, techniques, and embodiments of the present technology disclosed herein are described below in reference to the accompanying drawings. It should be appreciated that the figures are not necessarily drawn to scale. Items appearing in multiple figures may be indicated by the same reference numeral. For purposes of clarity, not every component may be labeled in every figure. Features of the present technology will become more apparent and techniques for how to attain the features of the present technology will be better understood by reference to the following detailed description considered in conjunction with the accompanying drawings, wherein:

[0006] FIG. 1A and FIG. IB are exploded views of an example subassembly for testing one or more characteristics of a plastic, according to some embodiments of the technology described herein.

[0007] FIG. 2A, FIG. 2B, and FIG. 2C are cross-sectional views of the example subassembly of FIG. 1A and FIG. IB, according to some embodiments of the technology described herein.

[0008] FIG. 3A, FIG. 3B, FIG. 3C, and FIG. 3D are perspective views of a test component of the example subassembly shown in FIG. 1A and FIG. IB, according to some embodiments of the technology described herein.

[0009] FIG. 4A, FIG. 4B, FIG. 4C, and FIG. 4D are perspective view of a base of the example subassembly shown in FIG. 1 A and FIG. IB, according to some embodiments of the technology described herein.

[0010] FIG. 5 is a diagram of an example system for testing one or more characteristics of a plastic, according to some embodiments of the technology described herein.

[0011] FIG. 6 A, FIG. 6B, and FIG. 6C are diagrams showing examples of the system of FIG. 5 used to apply offset and angled forces to a subassembly for testing one or more characteristics of the plastic, according to some embodiments of the technology described herein.

[0012] FIG. 7 is a block diagram showing software configured to execute on processor(s) of the example system of FIG. 5 to perform various functions in connection with testing one or more characteristics of a plastic, according to some embodiments of the technology described herein.

[0013] FIG. 8A, FIG. 8B, FIG. 8C, and FIG. 8D are flowcharts of illustrative processes for testing one or more characteristics of a plastic, according to some embodiments of the technology described herein.

[0014] FIG. 9 is a schematic diagram of an illustrative computing device with which one or more aspects described herein may be implemented.DETAILED DESCRIPTION

[0015] Provided herein are examples of methods, systems, and apparatus for testing one or more characteristics of a plastic. For example, the plastic may be used to form at least a portion of a medication delivery device. In some embodiments, the apparatus for testing the one or more characteristics of the plastic is a subassembly that includes a base and a test component that is removably attached to, and rotatable relative to the base. Testing the one or more characteristics of the plastic using the subassembly may involve at least (i) applying a force to a test component of the subassembly, (ii) rotating a portion of the subassembly (e.g., the base or the test component) while the force is applied to the test component, and (iii) determining, based on a result of applying the force and rotating the portion, the one or more characteristics of the plastic. Nonlimiting examples of characteristics of a plastic that may be tested include the wear, wear rate, kinetic coefficient of friction (e.g., drag torque to continue motion), static coefficient of friction (e.g., drag torque to start motion), break-loose load limit, and / or static drag load limit.

[0016] Testing character! stic(s) of a plastic used in a medication delivery device can help to ensure that the device is functional and can be used to safely and effectively inject a dose of medication into a patient. The characteristic(s) may be evaluated to inform decisions about the design of the device and / or as part of quality control before a particular model of a medicationdelivery device is sold. For example, the characteristic(s) may provide input for suitability-of-selection of materials for use in medical devices to ensure that any device assembly-related design inadequacies (e.g., material degradation, wear, indigenous debris, unintended damage during use, etc.) are addressed early on during the design and development process.

[0017] Characteristics of a plastic can be tested by rotating a plastic test specimen against a separate metal or plastic material. Conventional techniques for testing the characteristics of a plastic utilize separate specimen holders that, when aligned, can be used the rotate the plastic test specimen against a corresponding contact material (e.g., the metal or plastic material). The contact material is loaded into a stationary specimen holder, while the test specimen is loaded into a rotary specimen holder that can be rotated relative to the stationary specimen holder. The test specimen is held inside the rotary specimen holder using bolts. A load is applied to the stationary specimen holder as the rotary specimen holder is rotated.

[0018] The inventors have recognized that there are multiple limitations associated with the conventional techniques for testing characteristics of a plastic. First, the conventional techniques are limited because they do not enable the testing of a plastic under off-centered or angled loading conditions that may be typical for the plastic’s intended use case. In particular, using the conventional techniques, the stationary and rotary specimen holders must be aligned with one another along the same axis in order for the test specimen to make sufficient contact with the contact material for the purpose of testing. Otherwise, the test specimen would not uniformly contact the contact material, resulting in inaccurate test results (e.g., inaccurate measures of the coefficient or friction, wear, etc.). The inability to off-center or angle the specimen holders prevents off-centered and / or angled loads from being applied to the test specimen. This, in turn, prevents the conventional techniques from accurately characterizing those plastics under conditions that mimic their intended use case (e.g., for use in a medication delivery device).

[0019] The conventional techniques further fail to accurately simulate the conditions under which the plastic would be placed in a medication delivery device because they involve testing a piece of plastic that is bolted into a specimen holder, and which is separate and detached from the material against which it is tested. By contrast, a medication delivery device includes plastic components that are attached to and interact with other materials in the device.Consequently, the test results may not realistically represent the characteristics of the plastic when it is put to use in a medication delivery device, making the results unreliable.

[0020] Accordingly, the inventors have developed techniques for testing characteristics of a plastic that address the above-described limitations associated with the conventional techniques. In some embodiments, the techniques developed by the inventors include testing a plastic using a subassembly that includes a base and a test component that is removably attached to and rotatable relative to the base. In some embodiments, testing the characteristics of the plastic using the subassembly involves: (i) applying a force to the test component, (ii) rotating a portion (e.g., the test component or the base) of the subassembly, and (iii) determining the characteristic(s) of the plastic based on a result of the rotation and application of force.

[0021] By using a subassembly, rather than separate pieces fitted for specimen holders, the techniques developed by the inventors more accurately simulate the conditions applied to a plastic used in a medication delivery device. For example, the plastic test component may be attached to the base of the subassembly, which more closely resembles the interaction between components of a medication delivery device (e.g., as compared to separate and distinct pieces).

[0022] Furthermore, because the subassembly itself is used to hold the test component in contact with the base, it is possible to test the plastic without the restrictions imposed by the specimen holders. For example, either the base or test component may be fixed, while the other component is free of a specimen holder. During testing, a force may be applied to the free surface of the component. Because the base and test component remain aligned regardless of the application of force, the force may be applied at any angle or position without impacting the contact between the two components. Thus, the techniques and subassembly developed by the inventors enable more robust, and therefore more accurate and reliable testing of characteristics of a plastic (e.g., that may be used in a medication delivery device).

[0023] FIGS. 1A-1B and FIGS. 2A-2C are views of an example subassembly 1 for testing one or more characteristics of a plastic. The subassembly 1 includes a base 20 and a test component 10 that is formed of the plastic. Additional views of the example base 20 are shown in FIGS. 4A-4D. Additional views of the example test component 10 are shown in FIGS. 3A-3D.

[0024] In some embodiments, the test component 10 includes an external shell composed of at least a top surface (e.g., upper surface 8 and / or lower surface 9) and a side surface 5. Thelower surface 9 may be recessed from the upper surface 8 and connected to side surface 5 directly or indirectly via connecting portion 7. For example, connecting portion 7 may extend radially outward and at angle relative lower surface 9, such that connecting portion 7 connects the lower surface 9 and the side surface 5.

[0025] An inner surface 11 may be formed on the face of the test component 10 that is opposite to the face comprising the upper and lower surfaces 8 and 9. In some embodiments, contact surface 2 protrudes from the inner surface 11.

[0026] The contact surface 2 may be an annular surface configured to contact a corresponding contact surface 22 of the base 20. The surface area of the contact surface 2 may be defined by an inner radius 44 and an outer radius 46, shown in FIG. 3C. In some embodiments, the surface area is a surface area between 110 mm2and 250 mm2, between 120 mm2and 240 mm2, between 130 mm2and 230 mm2, between 140 mm2and 220 mm2, between 150 mm2and 210 mm2, between 160 mm2and 200 mm2, between 170 mm2and 190 mm2, or within any other suitable range of surface areas, as aspects of the technology described herein are not limited in this respect. For example, the surface area may be exactly or approximately 180 mm2, 181 mm2, 182 mm2, 183 mm2, 184 mm2, 185 mm2. 186 mm2, 187 mm2, 188 mm2, 189 mm2, or any other suitable surface area. The contact surface 2 may be planar or textured. In some embodiments, the surface area of contact surface 2 is larger (or smaller) than the surface area of contact surface 22 to account for lateral movement between the two contact surfaces during testing.

[0027] In some embodiments, an engagement feature 4 is positioned around the contact surface 2. For example, with reference to FIG. 3C, the engagement feature 4 may be positioned along a circumference that shares a center 40 with the annular contact surface 2. The circumference along which the engagement feature 4 is positioned may have a radius 48 that is larger than an outer radius 46 of the contact surface 2. With reference to FIG. 2B, the displacement (h2) between the upper surface 8 and the engagement feature 4 may be greater than the displacement (hl) between the upper surface 8 and the contact surface 2. In the examples shown in FIGS. 1A-2C and 3C-3D, the engagement feature 4 is formed on the inner face 5a of the side surface 5.

[0028] In the examples shown in FIGS. 1A, 2A-2C, and 3C-3D, the engagement feature 4 is a lip that extends radially inward towards the center 40. For example, the lip may includeone or more protrusions extending from the inner face 5a of the side surface 5. For example, the lip may include a continuous protrusion along the entire circumference defined by the inner face 5a of the side surface 5. Alternatively, the lip may include one or more protrusions that are not continuous along the circumference defined by the inner face 5a. However, it should be appreciated that the engagement feature 4 may include an engagement feature other than a lip and / or protrusion(s). as aspects of the technology described herein are not limited in this respect. For example, the engagement feature may include any feature suitable for engaging the corresponding engagement feature 26a-d of the base 20.

[0029] The test component 10 may additionally include an inner annular ring 6 protruding from the inner surface 11. The inner annular ring 6 may share a center 40 with annular contact surface 2, as shown in FIG. 3C. The inner annular ring 6 may have a radius 42 that is smaller than an inner radius 44 of the contact surface 2.

[0030] In some embodiments, base 20 includes disk 30 having upper face 30a and lower face 30b. As shown in FIGS. IB, 2A-2C, and 4A-4B, contact surface 22 may protrude from the upper face 30a of disk 30. The contact surface 22 may be an annular surface configured to contact a corresponding contact surface 2 of the test component 10. The surface area of the contact surface 22 may be defined by an inner radius 54 and an outer radius 56. In some embodiments, the surface area is a surface area between 110 mm2and 250 mm2, between 120 mm2and 240 mm2, between 130 mm2and 230 mm2, between 140 mm2and 220 mm2, between 150 mm2and 210 mm2, between 160 mm2and 200 mm2, between 170 mm2and 190 mm2, or within any other suitable range of surface areas, as aspects of the technology described herein are not limited in this respect. For example, the surface area may be exactly or approximately 180 mm2, 181 mm2, 182 mm2, 183 mm2, 184 mm2, 185 mm2, 186 mm2, 187 mm2, 188 mm2, 189 mm2, or any other suitable surface area. In some embodiments, the contact surface 22 is larger than contact surface 2. The contact surface 22 may be planar or textured. In some embodiments, the surface area of contact surface 22 is smaller (or larger) than the surface area of contact surface 2 to account for lateral movement between the two contact surfaces during testing.

[0031] In some embodiments, an engagement feature 26a-d is positioned around the contact surface 22. For example, with reference to FIG. 4A, the engagement feature 26a-d may be positioned along a circumference that shares a center 60 with the annular contact surface 22.The circumference along which the engagement feature 26a-d is positioned may have a radius 58 that is larger than an outer radius 56 of the contact surface 22.

[0032] In the examples shown in FIGS. 1A-2B and 4A-4B, the engagement feature 26a-d is formed on an outer face of an outer annular ring 24 the protrudes from the upper face 30a disk 30. In these examples, engagement feature 26a-d comprise a plurality of teeth (e.g., four teeth 26a. 26b. 26c, and 26c). each of which extends radially outward from the center 60 and at angle directed towards the plane defined by disk 30. For example, the plurality of teeth may be evenly or unevenly spaced along the outer face of the outer annular ring 24. Alternatively, the engagement feature may include a single tooth disposed along the outer face of the outer annular ring 24. The single tooth may extend continuously around the entire circumference of the outer face of the outer annular ring (e.g., similar to engagement feature 4), or around a portion of the circumference. However, the engagement feature 26a-d may include an engagement feature other than one or more teeth, as aspects of the technology described herein are not limited in this respect. For example, the engagement feature may include any feature suitable for engaging the corresponding engagement feature 4 of the test component 10. As described herein, the engagement feature 4 may engage (e.g., snap onto) the engagement features 26a-d to ensure the alignment of contact surface 2 and contact surface 22.

[0033] The base 20 may additionally include an inner annular ring 28 protruding from the upper face 30a of the disk 30. The inner annular ring 28 may share a center 60 with annular contact surface 22, as shown in FIG. 4A. The inner annular ring 28 may have a radius 52 that is smaller than an inner radius 54 of the contact surface 22.

[0034] In some embodiments, a fixture ring 32 extends from the lower face 30b of disk 30. When testing the plastic using the subassembly 1, the fixture ring may extend into or otherwise engage a fixture (e.g., fixture 140 shown in FIG. 5) configured to hold the base 20. However, it should be appreciated that the base may include one or more additional or alternative features that may be used to fix the base to a fixture. For example, the features may be incorporated based on specifications of an existing fixture.

[0035] The subassembly 1 may be assembled by attaching the test component 10 to the base 20. Cross-sectional views of an exemplary assembled subassembly 1 are shown in FIGS.2A-2C. In some embodiments, the subassembly 1 is assembled using the engagement feature 4of the test component 10 and the engagement feature 26a-d of the base 20. For example, the subassembly 1 may be assembled by (i) aligning the test component 10 to the base 20 (e.g., by aligning the center 40 to the center 60), and (ii) applying pressure to the test component 10, the base 20, or both, to cause the engagement features 4 and 26a-d to engage one another. For example, this may involve causing the engagement feature 4 to slide over the engagement feature 26a-d, thereby allowing the test component 10 to “snap” onto the base 20. In some embodiments, the subassembly 1 may be disassembled by pulling the test component 10 and / or base 20 apart from one another using a force that is sufficient to pull engagement feature 4 back over the engagement feature 26a-d.

[0036] As shown in FIGS. 2A-2C, once the subassembly 1 is assembled, the contact surface 2 contacts contact surface 22. In some embodiments, due to the design of the test component 10 and base 20, the contact between the contact surfaces 2 and 22 may be the only substantial contact between the test component 10 and the base 20. For example, as shown in FIG. 2A, there may be a separation 12 between test component 10 and base 20. As such, there may be little to no contact between the engagement features 4 and 26a-d, except when test component 10 and base 20 are pulled in opposite directions (e.g., when disassembling the subassembly 1). The dimensions of the test component 10. base 20, and their corresponding engagement features 4 and 26a-d may be designed to ensure that the engagement features 4 and 26a-d do not contact one another during testing for a wide range of plastics.

[0037] In some embodiments, another point of contact may include contact between the inner annular ring 6 of the test component 10 and the inner annular ring 28 of the base. For example, as shown in FIG. 2A, the inner annular rings 6 and 28 may share the same center but have different radiuses that allows the outer surface of one to contact the inner surface of another. For example, the inner annular ring 6 may have a smaller radius than the inner annular ring 28. enabling contact between the outer surface of annular ring 6 and inner surface of annular ring 28. This contact may help to decrease lateral motion between the test component 10 and base 20 to help maintain the separation 12 and / or ensure that the torque resulting from the contact between contact surfaces 2, 22 is the torque used to determine the characteristics of the plastic.

[0038] As described herein, in some embodiments, to account for any lateral motion between the contact surfaces 2, 22, the surface area of one contact surface (e.g., contact surface 2) may be larger than the surface area of the other contact surface (e.g., contact surface 22). Such a design may help to maintain contact between the two contact surfaces 2, 22, despite any lateral motion.

[0039] In some embodiments, the material of the base 20 depends on the characteristic that is being tested. For example, when testing the wear or wear rate of the test plastic, then the base 20 may be formed of a metal or a plastic. For example, the base may be formed of steel (e.g., 1018 steel, 1018 steel hardened to 20 HRC, etc.). When testing characteristics other than wear (e.g., the coefficient of friction, break-loose load, static drag load, etc.), the base 20 may be formed of a plastic. The plastic used to form the base 20 may be the same plastic as the test plastic, or a different plastic.

[0040] The subassembly 1 is manufactured, in some embodiments, using injection molding. For example, separate die cavities may be used for manufacturing the test component 10 and the base 20. In some embodiments, to prevent molding defects on the contact surfaces 2, 22, additional material is loaded into the die cavities. As shown in FIGS. 1A and IB, the additional material may result in the formation of depression 31 on the base 2 (FIG. 1A) and the formation of upper surface 8 on the test component (FIG. IB).

[0041] In some embodiments, a textured insert may be inserted into a respective die cavity (e.g., by screwing it into the die cavity) to produce a test component 10 and / or base 20 with a contact surface having a textured surface finish. The ability to use the same die cavities with different inserts allows for flexible design of different subassemblies.

[0042] It should be appreciated that the subassembly may be manufactured using any other suitable manufacturing techniques, as aspects of the technology described herein are not limited to injection molding.

[0043] FIG. 5 is a diagram of an example system 100 for testing one or more characteristics of a plastic, according to some embodiments of the technology described herein. The example system 100 may be configured to test the plastic using a subassembly 101 that comprises a test component 110 and a base 120. For example, the test component 110 may be thetest component 10 described herein including at least with respect to FIG. 1 A-3D. The base 120 may be the base 20 described herein including at least with respect to FIG. 1A-2C and 4A-4D.

[0044] As shown in FIG. 5. system 100 may include a test system 105 communicably coupled to processor(s) 150. For example, one or more components of the test system 105 may communicate with the processor(s) 150 via at least one communication network, such as the Internet or any other suitable communication network(s), as aspects of the technology descried herein are not limited in this respect.

[0045] As described herein, the processor(s) 150 may be configured to perform one or more functions in connection with testing the characteristic(s) of the plastic. For example, the processor(s) 150 may receive measurements from one or more components of the test system 105 and determine the characteristics using the measurements. Additionally or alternatively, the processor(s) 150 may transmit instructions to one or more components of the test system 105 that are configured to cause those component(s) to perform one or more functions. For example, the processor(s) 150 may transmit instructions to a motor configured to cause rotation of the motor. Additionally or alternatively, processor(s) 150 may transmit instructions to a force subsystem configured to cause the force subsystem (e.g., a force applicator) to apply a force to the subassembly 101.

[0046] As shown in FIG. 5, the test system 105 may include a sensor 144, a motor 142, a motor shaft 138, a fixture 140, a force subsystem 130, and / or a balance 146. The force subsystem 130 may include a force applicator 136, a weight 132, and / or a weight shelf 134.

[0047] In some embodiments, the fixture 140 is used to fix the base 120. The fixture 140 may include a clamp or any other suitable type of holder used to fix the base 120. For example, the fixture 140 may be configured to engage a fixture ring (e.g., fixture ring 32 shown in FIGS.1A-2C and 4B-4D). The fixture 140 may be attached to motor shaft 138.

[0048] The motor 142 and motor shaft 138 may be configured to apply a torque to the fixture 140. For example, the applied torque may cause the fixture 140 and the base 120 fixed within fixture 140 to rotate relative to the test component 110. The motor may be an electric motor such as a direct current (DC) motor or an alternating current (AC) motor, or any other suitable type of motor that can be configured to drive rotation, as aspects of the technology described herein are not limited in this respect.

[0049] In some embodiments, sensor 144 is a torque sensor and / or torque transducer. The sensor 144 may be coupled to the motor 142 and configured measure torque applied to the subassembly 101 when the motor is used to rotate the motor shaft 138. As described herein, including at least with respect to FIGs. 8A-8D, the torque measurements may be used to determine the one or more characteristics of the plastic.

[0050] The force subsystem 130 may be configured to apply a force to the test component 110 of the subassembly 101. For example, the force subsystem 130 may include a force applicator 136 configured to contact the test component 110 to apply the weight supplied by the weight 132. In some embodiments, the force applicator 136 includes an elastomeric component that contacts the test component 110. For example, the elastomeric component may grip the test component 110 through friction to fix it and enable rotation of the base 120 relative to the test component 110. The force subsystem 130 may additionally include a controller (not shown) configured to adjust the weight and / or control the position of the force applicator 136 relative to the subassembly 101.

[0051] As described herein, one of the advantages of using a subassembly for testing characteristic(s) of a plastic is the ability to apply off-centered and / or angled loads to the plastic. In some embodiments, this may be accomplished by altering the dimensions of the force applicator 136 and / or changing the lateral position of the force applicator 136. FIGS. 6A-6C show examples of force applicators having different dimensions and positions. For example, each of the example force applicators 136-1, 136-2, and 136-3 is off-centered (e.g., its center has a different x-coordinate) relative to the axis of symmetry of the subassembly 101. Additionally, each of the example force applicators 136-1, 136-2, and 136-3 has an angled contact edge, such that the load will be applied to the subassembly 101 at a specific angle. For example, the example force applicator 136-1 is configured to apply a load at angle 0i (e.g., 30°), the example force applicator 136-2 is configured to apply a load at angle 02 (e.g., 45°), and the example force applicator 136-3 is configured to apply a load at angle 03 (e.g., 60°). For example, the angle 0 may be an angle between 0° and 85°, 5° and 80°, 10° and 75°, 15° and 70°, 20° and 70°, 25° and 65°, 30° and 60°. 35° and 55°, 40° and 50°, or an angle within any other suitable range of angles, as aspects of the technology described herein are not limited in this respect.

[0052] In some embodiments, the system 105 additionally includes a balance 146 configured to measure the mass of the test component 110. For example, as described herein, the mass of the test component 110 may be used to measure a wear and / or wear rate of the test component.

[0053] An alternative to system 105 may include a rearrangement of at least some of the components shown in FIG. 5. For example, the position of the torque sensor 144, motor 142, and motor shaft 138 may be swapped with the position of the force subsystem 130, such that force is applied to the base 120 while the test component 110 is rotated. In such an embodiment, the motor shaft 138 (or some intermediate component) may include an elastomeric component used to grip the test component 110.

[0054] In some embodiments, system 105 is implemented using an automated testing system by Zwick / Roell.

[0055] FIG. 7 is a block diagram showing software 160 configured to execute on processor(s) of the example system 100 of FIG. 5 to perform various functions in connection testing one or more characteristics of plastic(s) in contact (e.g., contact surface 2 and / or contact surface 22 shown in FIGS. 1A-2C), according to some embodiments of the technology described herein. In some embodiments, software 160 includes a plurality of modules. A module may include processor-executable instructions that, when executed by at least one computer hardware processor, cause the at least one computer hardware processor to perform function(s) of the module. Such modules are sometimes referred to herein as “software modules,” each of which includes processor-executable instructions configured to perform one or more acts of one or more processes, such as the processes 200, 300, 400, and 500 shown in FIGs. 8A-8D.

[0056] In some embodiments, software 160 includes a plastic characteristic(s) determination module 162 configured to determine one or more characteristics of a plastic. For example, the one or more characteristics of the plastic may include a kinetic coefficient of friction (e.g., a drag torque to continue motion), a static coefficient of friction (e.g., a drag torque to start motion), a wear, a wear rate, a static drag load limit, and / or a break-loose load limit. In some embodiments, the plastic characteristic(s) determination module 162 determines the characteristic(s) based on data received from test system 105, obtained from data store(s) 170, and / or provided by a user (e.g., via the user interface module 166). For example, the data mayinclude values indicative of the force (e.g., normal force) applied to the subassembly, measurements of torque, data indicative of a number of revolutions and / or rotational speed of the motor, measurements of mass, and / or any other suitable data, as aspects of the technology described herein are not limited in this respect. Example techniques for determining one or more characteristics of a plastic are described herein including at least with respect to FIGs. 8A-8D.

[0057] Software 160 additionally includes plastics testing automation module 164 (“automation module 164”). In some embodiments, the automation module 164 is configured to automatically or semi-automatically control test system 105. Controlling the test system 105 may involve controlling one or more components of the test system 105, such as motor 142, sensor 144, balance 146, and / or force subassembly 130. To control a particular component of the test system 105, the automation module 164 may transmit instructions (e.g., via a wired or wireless connection) to the particular component that cause the particular component to perform a particular function. For example, the automation module 164 may transmit instructions to the force subsystem 130 configured to cause the force subsystem 130 to apply a particular force (e.g., centered, off-centered, angled, or not angled) to the subassembly 101. Additionally or alternatively, the automation module 164 may transmit instructions to the motor 142 configured to cause the motor 142 to rotate the motor shaft 138. Additionally or alternatively, the automation module 164 may transmit instructions to the balance 146 configured to cause the balance 146 to measure a mass. Additionally or alternatively, the automation module 164 may transmit instructions to the sensor 144 configured to cause the sensor 144 to measure a torque. In some embodiments, the automation module 164 controls the component(s) of the test system 105 in response to receiving user input. For example, the automation module 164 may obtain the input from user interface module 166. In some embodiments, the automation module 164 automatically controls the component(s) of the test system 105 based on stored instructions. For example, the automation module 164 may be configured to perform its functions according to a stored automation schedule. For example, the automation module 164 may obtain stored instructions from data store(s) 170.

[0058] Software 160 additionally includes user interface module 166. User interface module 166 may be configured to generate a graphical user interface (GUI) through which user(s) may provide input and / or view information generated by software 160. In someembodiments, the user interface module 166 may be a webpage or web application accessible through an Internet browser. In some embodiments, the user interface module 166 may generate a GUI of an app executing on a user’s mobile device. In some embodiments, the user interface module 166 may generate a number of selectable elements through which a user may interact. For example, the user interface module 280 may generate dropdown lists, checkboxes, text fields, or any other suitable element.

[0059] As shown in FIG. 7, system 100 additionally includes one or more data stores 170. In some embodiments, the data store(s) 170 are configured to store data obtained from test system 105. For example, the data store(s) 170 may be configured to store measurements of torque, measurements of mass, values of applied force, data indicative of a number of revolutions (e.g.. of a motor shaft), data indicative of the motor’s rotational speed, and / or any other suitable data from test system 105, as aspects of the technology described herein are not limited in this respect. Additionally or alternatively, the data store(s) 170 may be configured to store automation instructions and / or an automation schedule that may be used by automation module 164. Additionally or alternatively, the data store(s) 170 may be configured to store output from the plastic characteristic(s) determination module 162 such as one or more characteristic(s) determined by the plastic characteristic(s) determination module 162. The data store(s) 170 may include any suitable type of data store (e.g., a flat file, a database system, a multi-file, etc.) and may store data in any suitable format, without limitation. The data store(s) 170 may be part of software 160 (not shown) or excluded from software 160, as shown in FIG. 7.

[0060] FIGs. 8A-8D are flowcharts of illustrative process 200, 300, 400, and 500 for determining one or more characteristics of plastic(s) in contact (e.g., contact surface 2 and / or contact surface 22 shown in FIGS. 1A-2C), according to some embodiments of the technology described herein. One or more of the acts of processes may be performed automatically by any suitable computing device(s). For example, act(s) may be performed by processor(s) 150 shown in FIGS. 5 and 7, computing system 900 shown in FIG. 9, a laptop computer, a desktop computer, a mobile device, one or more servers, in a cloud computing environment, and / or in any other suitable way, as aspects of the technology described herein are not limited in this respect.

[0061] It should be appreciated that performance over the lifecycle of plastic products can be influenced by environmental conditions such as heat, humidity, load-ageing, and / or shelflife during storage and usage. Consequently, one or more of processes 200, 300, 400, and 500 may be performed in natural or accelerated test environments (e.g., environments modeling potential influential environmental condition(s)). The resulting data can provide insights into risk of material failure during early risk management phases of a medical device program.

[0062] Moreover, texture on one or more contact surfaces of a plastic can impact the characteristics of the contact surface. Thus, in some embodiments, one or more of processes 200, 300, 400, and 500 may be performed using a subassembly having one or more textured contact surface(s) (e.g., contact surface 2 and / or 22 shown in FIGS. 1A-2C, 3C-3D, and 4A-4D). As described herein, a textured contact surface may be implemented using die inserts during manufacturing of the test and / or base components.

[0063] In some embodiments, a process (e.g., process 200, 300, 400, and / or 500) may be performed under the environmental conditions (e.g., natural or accelerated), using textured contact surface(s), or using a combination of environmental conditions and textured contact surface(s).

[0064] Coefficient of Friction

[0065] FIG. 8A shows an illustrative process 200 for determining a coefficient of friction of a plastic, according to some embodiments of the technology described herein.

[0066] “Coefficient of friction,” IJ. or refers to the ratio of the friction force (F) between two bodies (e.g., surfaces) to the normal force (N) applied to those bodies. For example, the coefficient of friction may be calculated using Equation 1 := (Equation 1) where T refers to the torque applied to the contact surface of the test component, r refers to a radius of the contact surface of the test component, and N is the normal force pressing the contact surface of the test component and the contact surface of the base together. The radius r of the contact surface of the test component may be determined by determining the average radius given an outer radius (e.g., radius 46 shown in FIG. 3C) and an inner radius (e.g., radius 44 shown in FIG. 3C) of an annular contact surface (e.g., contact surface 2). For example, the average radius may be equal to the sum of radii 46 and 44, divided by 2. Torque refers to thereaction of a tendency to turn due to friction forces between bodies traveling in a substantially circular path, and may be measured using a torque sensor (e.g., sensor 144 shown in FIG. 5).

[0067] Some embodiments distinguish between the static coefficient of friction and the kinetic coefficient of friction. The “static coefficient of friction” refers to the ratio of the frictional force required to move one body over another to the normal force ( ) applied to those bodies, at the instant the motion starts. The “kinetic coefficient of friction” refers to the ratio of the frictional force required to move one body over another to the normal force (Al) applied to those bodies, once the motion is in progress.

[0068] At act 202 of process 200, a force is applied to the test component of a subassembly. For example, the test component may be test component 10 of subassembly 1 shown in FIGS. 1A-3D and / or test component 110 of subassembly 101 shown in FIGS. 5-6C. In some embodiments, the force is applied using a force subassembly, such as force subassembly 130 shown in FIG. 5. The force may be applied centered or off-centered relative to the test component. Additionally or alternatively, the force may be applied at an angle substantially perpendicular to, or at an angle that is not substantially perpendicular to the contact surface of the test component.

[0069] At act 204, a portion of the subassembly (e.g., the base) is rotated while the force is applied to the test component. In some embodiments, rotating the portion of the subassembly includes using a motor (e.g., motor 142 shown in FIG. 5) to apply a torque to the portion of the subassembly. The torque may be applied until the portion of the subassembly begins to rotate relative to the test component. When determining the static coefficient of friction, process 200 may proceed to act 206 after the portion of the subassembly begins rotating. Else, when determining the kinetic coefficient of friction, act 204 may be continued. For example, the portion of the subassembly may be rotated for a predetermined number of revolutions (e.g., one revolution).

[0070] At act 206, a torque applied to the contact surface of the test component is measured. In some embodiments, act 206 is performed contemporaneously with act 204. For example, the torque may be measured while torque is applied to the base using the motor at act 204. The torque may be measured using a sensor (e.g., sensor 144 shown in FIG. 5) of a test system.

[0071] At act 208, a coefficient of friction of the plastic is determined based on the measured torque and the force applied at act 202. For example, the coefficient of friction may be determined using Equation 1. The measurement of torque used to determine a static coefficient of friction may be the torque measured at the instant the portion of the subassembly begins to rotate relative to the test component. The measurement of torque used to determine the kinetic coefficient of friction may be a torque or average torque measured during rotation of the portion of the subassembly relative to the test component.

[0072] It should be appreciated that, if using Equation 1 to determine the coefficient of friction at act 208, the normal force N refers to the normal force pressing the two contact surfaces of the subassembly together. In some cases, the normal force N may only be a component of the force applied to the test component of the subassembly at act 202. For example, if the applied force was off-centered and / or angled, then the normal force N may include only the component of the applied force that is normal relative to the contact surface of the test component.

[0073] Wear Rate

[0074] FIG. 8B shows an illustrative process 300 for determining a wear and / or a wear rate of a plastic, according to some embodiments of the technology described herein.

[0075] “Wear” refers to damage to a solid surface, generally involving progressive loss of material, due to relative motion between that surface and a contacting substance or surface. In some embodiments, wear is measured by measuring change(s) in volume (AV) (e.g., “wear volume”) of the test material. The wear volume (AV) may be determined using Equation 2:AV = (Equation 2)where Am refers to the mass loss of specimens and p refers to the density of the sample. For example, the change in mass may represent a difference between a first mass of a test component (e.g., test component 10 shown in FIGS. 1 A-3D) measured at a first time and a second mass measured at a second time (e.g., later then the first time).

[0076] ‘Wear rate” refers to the rate of material removal, or dimensional change due to wear per unit of exposure parameter (e.g., quantity of material removed (mass, volume, thickness). The wear rate ( / Cs) may be determined using Equation 3:AV AmKc — — (Equation 3) LxFNLxFNXpwhere L is the distance travel and FNis the normal load. For example, the distance traveled may be determined based on (i) a circumference of at least a portion of the contact surface of the test component, and (ii) the number of revolutions that occur during rotation of the test component and the base relative to one another.

[0077] At act 302, a first mass of the test component of the subassembly is measured. For example, the test component may be detached from the base of the subassembly, and its mass measured using a balance (e.g., balance 146 shown in FIG. 5).

[0078] At act 304, the subassembly is assembled. For example, the subassembly may be assembled by causing an engagement feature of the test component to engage a corresponding engagement feature of the base. In this example, the test component may be snapped onto the base (e.g., by pushing the test component and base together).

[0079] At act 306, a force is applied to the test component. In some embodiments, the force is applied using a force subassembly, such as force subassembly 130 shown in FIG. 5. The force may be applied centered or off-centered relative to the test component. Additionally or alternatively, the force may be applied at an angle substantially perpendicular to, or at an angle that is not substantially perpendicular to the contact surface of the test component.

[0080] At act 308, a portion of the subassembly (e.g., the base) is rotated relative to the test component. In some embodiments, rotating the portion of the subassembly includes using a motor (e.g., motor 142 shown in FIG. 5) to apply a torque to the base. In some embodiments, the portion of the subassembly is rotated relative to the test component for a predetermined number of revolutions and / or for a predetermined duration of time.

[0081] At act 310. the subassembly is disassembled. For example, the subassembly may be disassembled by causing an engagement feature of the test component to disengage a corresponding engagement feature of the base. In this example, the test component may be snapped off of the base (e.g., by pulling the test component and base apart from one another).

[0082] At act 312, a second mass of the test component is measured. For example, its mass may be measured using the balance used at act 302.

[0083] At act 314, a wear rate and / or a wear of the plastic is determined. For example, the wear and / or wear rate may be determined using Equation 2.

[0084] Break-Loose Load Limit

[0085] FIG. 8C shows an illustrative process 400 for determining a break-loose load limit of a plastic, according to some embodiments of the technology described herein.

[0086] “Break-loose load limit” refers to the magnitude of normal force that, when applied to two contacting bodies, causes the bodies to begin moving (e.g., rotating) relative to one another.

[0087] At act 402, a torque is applied to a portion of the subassembly (e.g., the base). In some embodiments, a motor (e.g., motor 142 shown in FIG. 5) is used to apply the torque to the portion of the subassembly.

[0088] At act 404, starting from zero, a force is applied to the test component and incrementally increased until the portion of the subassembly begins to rotate relative to the test component. The force may be applied using a subassembly, such as the force subassembly 130 shown in FIG. 5. The force may be applied centered or off-centered relative to the test component. Additionally or alternatively, the force may be applied at an angle substantially perpendicular to. or at an angle that is not substantially perpendicular to the contact surface of the test component.

[0089] At act 406, a break-loose load limit of the plastic is determined. For example, the break-loose load limit may be determined to be the magnitude of the force applied to the test component at the instant the portion of the subassembly begins to rotate at act 406.

[0090] Static Drag Load Limit

[0091] FIG. 8D shows an illustrative process 500 for determining a static drag load limit of a plastic, according to some embodiments of the technology described herein.

[0092] “Static drag load limit” refers to the magnitude of normal force that, when applied to two contacting bodies, causes the bodies to stop moving (e.g., rotating) relative to one another.

[0093] At act 502, a portion of a subassembly is rotated relative to the test component of the subassembly. In some embodiments, rotating the portion of the subassembly includes using a motor (e.g., motor 142 shown in FIG. 5) to apply a torque to the portion of the subassembly. In some embodiments, the portion of the subassembly is rotated relative to the test component for a predetermined number of revolutions.

[0094] At act 504, a force is applied to the test component and incrementally decreased until the portion of the subassembly stops rotating. In some embodiments, the force is appliedusing a force subassembly, such as force subassembly 130 shown in FIG. 5. The force may be applied centered or off-centered relative to the test component. Additionally or alternatively, the force may be applied at an angle substantially perpendicular to, or at an angle that is not substantially perpendicular to the contact surface of the test component.

[0095] At act 506, a static drag load limit of the plastic is determined. For example, the static drag load limit may be determined to be the magnitude of the force applied to the test component at the instant the portion of the subassembly stops rotating at act 504.

[0096] Computer Implementation

[0097] An illustrative implementation of a computer system 900 that may be used in connection with any of the embodiments of the technology described herein (e.g., such as the processes 200, 300, 400, and 500 shown in FIGs. 8A-8D) is shown in FIG. 9. The computer system 900 includes one or more processors 910 and one or more articles of manufacture that comprise non-transitory computer-readable storage media (e.g., memory 920 and one or more non-volatile storage media 930). The processor 910 may control writing data to and reading data from the memory 920 and the non-volatile storage media 930 in any suitable manner, as the aspects of the technology described herein are not limited to any particular techniques for writing or reading data. To perform any of the functionality described herein, the processor 910 may execute one or more processor-executable instructions stored in one or more non-transitory computer-readable storage media (e.g., the memory 920), which may serve as non-transitory computer-readable storage media storing processor-executable instructions for execution by the processor 910.

[0098] Computing system 900 may include a network input / output (I / O) interface 940 via which the computing device may communicate with other computing devices. Such computing devices may be interconnected by one or more networks in any suitable form, including a local area network or a wide area network, such as an enterprise network, and intelligent network (IN) or the Internet. Such networks may be based on any suitable technology and may operate according to any suitable protocol and may include wireless networks, wired networks or fiber optic networks.

[0099] Computing system 900 may also include one or more user TO interfaces 950, via which the computing device may provide output to and receive input from a user. The user I / Ointerfaces may include devices such as a keyboard, a mouse, a microphone, a display device (e.g., a monitor or touch screen), speakers, a camera, and / or various other types of I / O devices.[000100] Further, it should be appreciated that a computer may be embodied in any of a number of forms, such as a rack-mounted computer, a desktop computer, a laptop computer, or a tablet computer, as examples. Additionally, a computer may be embedded in a device not generally regarded as a computer but with suitable processing capabilities, including a Personal Digital Assistant (PDA), a smartphone, a tablet, or any other suitable portable or fixed electronic device.[000101] The above-described embodiments can be implemented in any of numerous ways. For example, the embodiments may be implemented using hardware, software, or a combination thereof. When implemented in software, the software code can be executed on any suitable processor (e.g., a microprocessor) or collection of processors, whether provided in a single computing device or distributed among multiple computing devices. It should be appreciated that any component or collection of components that perform the functions described above can be generically considered as one or more controllers that control the above-described functions. The one or more controllers can be implemented in numerous ways, such as with dedicated hardware, or with general purpose hardware (e.g., one or more processors) that is programmed using microcode or software to perform the functions recited above.[000102] In this respect, it should be appreciated that one implementation of the embodiments described herein comprises at least one computer-readable storage medium (e.g., RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or other tangible, non-transitory computer-readable storage medium) encoded with a computer program (i.e., a plurality of executable instructions) that, when executed on one or more processors, performs the above-described functions of one or more embodiments. The computer-readable medium may be transportable such that the program stored thereon can be loaded onto any computing device to implement aspects of the techniques described herein. In addition, it should be appreciated that the reference to a computer program which, when executed, performs any of the above-described functions, is not limited to an application program running on a host computer. Rather, the terms computer program andsoftware are used herein in a generic sense to reference any type of computer code (e.g., application software, firmware, microcode, or any other form of computer instruction) that can be employed to program one or more processors to implement aspects of the techniques described herein.[000103] The terms “program” or “software” are used herein in a generic sense to refer to any type of computer code or set of computer-executable instructions that can be employed to program a computer or other processor to implement various aspects as described above.Additionally, it should be appreciated that according to one aspect, one or more computer programs that when executed perform methods of the present disclosure need not reside on a single computer or processor but may be distributed in a modular fashion among a number of different computers or processors to implement various aspects of the present disclosure.[000104] Computer-executable instructions may be in many forms, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically, the functionality of the program modules may be combined or distributed as desired in various embodiments.[000105] Also, data structures may be stored in computer-readable media in any suitable form. For simplicity of illustration, data structures may be shown to have fields that are related through location in the data structure. Such relationships may likewise be achieved by assigning storage for the fields with locations in a computer-readable medium that convey relationship between the fields. However, any suitable mechanism may be used to establish a relationship between information in fields of a data structure, including through the use of pointers, tags or other mechanisms that establish relationship between data elements.[000106] When implemented in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single computer or distributed among multiple computers.[000107] The foregoing description of implementations provides illustration and description but is not intended to be exhaustive or to limit the implementations to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the implementations. In other implementations the methodsdepicted in these figures may include fewer operations, different operations, differently ordered operations, and / or additional operations. Further, non-dependent blocks may be performed in parallel.[000108] It will be apparent that example aspects, as described above, may be implemented in many different forms of software, firmware, and hardware in the implementations illustrated in the figures.[000109] It should be understood that various alterations, modifications, and improvements may be made to the structures, configurations, and methods discussed above, and are intended to be within the spirit and scope of the technology disclosed herein. Further, although advantages of the present technology are indicated, it should be appreciated that not every embodiment of the present technology will include every described advantage. Some embodiments may not implement any features described as advantageous herein. Accordingly, the foregoing description and attached drawings are by way of example only.[000110] It should be understood that some aspects of the present technology may be embodied as one or more methods, and acts performed as part of a method of the present technology may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than shown and / or described, which may include performing some acts simultaneously, even though shown and / or described as sequential acts in various embodiments.[000111] Various aspects of the present technology may be used alone, in combination, or in a variety of arrangements not specifically discussed in the embodiments described in the foregoing and is therefore not limited in its application to the details and arrangement of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in connection with one embodiment may be combined in any manner with aspects described in connection with one or more other embodiments.[000112] Use of ordinal terms such as “first,” “second,” “third,” etc., in the description and the claims to modify an element does not by itself connote any priority, precedence, or order of one element over another, or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one element or act having a certain name from anotherelement or act having a same name (but for use of the ordinal term) to distinguish the elements or acts.[000113] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.[000114] The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.”[000115] As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified.[000116] As used herein in the specification and in the claims, the phrase “equal” or “the same” in reference to two values (e.g.. distances, widths, etc.) means that two values are the same within manufacturing tolerances. Thus, two values being equal, or the same, may mean that the two values are different from one another by ±5%.[000117] The phrase “and / or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and / or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and / or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and / or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.[000118] As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in a list, “or” or “and / or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of’ or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e., “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law.[000119] Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Use of terms such as “including,” “comprising,” “having,” “containing,” and “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.[000120] The terms “approximately” and “about” if used herein may be construed to mean within ±20% of a target value in some embodiments, within ±10 % of a target value in some embodiments, within ±5% of a target value in some embodiments, and within ±2% of a target value in some embodiments. The terms “approximately” and “about” may equal the target value.[000121] The term “substantially” if used herein may be construed to mean within 95% of a target value in some embodiments, within 98% of a target value in some embodiments, within 99% of a target value in some embodiments, and within 99.5% of a target value in some embodiments. In some embodiments, the term “substantially” may equal 100% of the target value.[000122] While various embodiments have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible.Accordingly, the embodiments described herein are examples, not the only possible embodiments and implementations. Furthermore, the advantages described above are not necessarily the only advantages, and it is not necessarily expected that all of the described advantages will be achieved with every embodiment.[000123] Various aspects are described in this disclosure, which include, but are not limited to, the following aspects:[000124] 1. A subassembly for testing one or more characteristics of a plastic, the subassembly comprising: a base comprising: a first contact surface; and a first engagement feature positioned around the first contact surface; and a test component that is removably attached to. and rotatable relative to, the base, the test component comprising: a second contact surface that contacts the first contact surface and is formed of the plastic; and a second engagement feature positioned around the second contact surface and configured to engage the first engagement feature of the base.[000125] 2. The subassembly of aspect 1, wherein the base comprises an outer annular wall that is concentric with the first contact surface, and wherein the first engagement feature is formed on the outer annular wall.[000126] 3. The subassembly of aspect 2, wherein a radius of the outer annular wall is greater than a radius of the first contact surface.[000127] 4. The subassembly of any of aspects 1-3, wherein the base comprises a first inner annular wall that is concentric with the first contact surface, and wherein the test component comprises a second inner annular wall that is concentric with the second contact surface and contacts the first inner annular wall.[000128] 5. The subassembly of aspect 4, wherein the first and second inner annular walls maintain a space between the first and second engagement features.[000129] 6. The subassembly of any of aspects 4-5, wherein a radius of the first inner annular wall is less than an inner radius of the first contact surface, and wherein a radius of the second inner annular wall is less than an inner radius of the second contact surface.[000130] 7. The subassembly of any of aspects 1-6, wherein the first contact surface and the second contact surface each have a respective surface area between 140 mm2and 200 mm2.[000131] 8. The subassembly of aspect 7, wherein the first contact surface and the second contact surface each have a surface area of 184 mm2.[000132] 9. The subassembly of any of aspects 1-8, wherein the first engagement feature comprises one or more teeth, and wherein the second engagement feature comprises a lip.[000133] 10. The subassembly of any of aspects 1-9, wherein the plastic is a first plastic, wherein the subassembly is used for testing a coefficient of friction of the first plastic, and wherein the first contact surface is formed of a second plastic.[000134] 11. The subassembly of aspect 10, wherein the first contact surface and / or the second contact surface are textured.[000135] 12. The subassembly of any of aspects 1-9, wherein the subassembly is used for testing a wear of the plastic, and wherein the first contact surface is formed of metal.[000136] 13. A system for testing one or more characteristics of a plastic, the system comprising: a subassembly, comprising: a base; and a test component that is removably attached to, and rotatable relative to, the base; a force applicator configured to apply a force to the test component of the subassembly; a motor configured to rotate a portion of the subassembly while the force is applied to the test component; and at least one processor configured to determine the one or more characteristics of the plastic based on a result of applying the force to the test component and rotating the portion of the subassembly.[000137] 14. The system of aspect 13, wherein the force applicator is configured to apply an off-centered force to the subassembly.[000138] 15. The system of any of aspects 13-14, wherein the force applicator is configured to apply an angled force to the subassembly.[000139] 16. The system of any of aspects 13-15, wherein the force applicator comprises an elastomeric component that contacts the subassembly.[000140] 17. The system of any of aspects 13-16, wherein the base of the subassembly is fixed, and wherein the motor is configured to rotate the test component of the subassembly.[000141] 18. The system of any of aspects 13-16, wherein the test component of the subassembly is fixed, and wherein the motor is configured to rotate the base of the subassembly.[000142] 19. The system of any of aspects 13-18, wherein the at least one processor is configured to: transmit first instructions to a force subsystem configured to cause the force applicator to apply a force to the subassembly; and transmit second instructions to the motor configured to cause the motor to rotate the portion of the subassembly.[000143] 20. The system of any of aspects 13-19, further comprising a sensor configured to measure a torque applied to at least a portion of the test component.[000144] 21. The system of aspect 20, wherein the at least one processor is configured to determine a coefficient of friction of the plastic based on the measured torque and the force applied to the test component.[000145] 22. The system of any of aspects 13-21, further comprising an instrument configured to measure a mass of at least a portion of the test component.[000146] 23. The system of aspect 22, wherein the at least one processor is configured to determine wear of the plastic based on the measured mass of at least the portion of the test component.[000147] 24. The system of any of aspects 13-23, wherein the at least one processor is configured to determine, based on the result of applying the force to the test component and rotating the portion of the subassembly, a static drag load limit or a break-loose load limit of the plastic.[000148] 25. The system of any of aspects 13-24, wherein the base of the subassembly comprises: a first contact surface; and a first engagement feature positioned around the first contact surface, and wherein the test component of the subassembly comprises: a second contact surface that contacts the first contact surface and is formed of the plastic; and a second engagement feature positioned around the second contact surface and configured to engage the first engagement feature of the base.[000149] 26. A method for testing one or more characteristics of a plastic using a subassembly, the method comprising: applying a force to a test component of the subassembly; rotating a portion of the subassembly while the force is applied to the test component; and determining, based on a result of applying the force to the test component and rotating the portion of the subassembly, the one or more characteristics of the plastic.[000150] 27. The method of aspect 26, further comprising: measuring a torque applied to the test component, wherein determining the one or more characteristics of the plastic comprises determining a coefficient of friction of the plastic based on the measured torque and the force applied to the test component.[000151] 28. The method of any of aspects 26-27, further comprising: measuring a mass of at least a portion of the test component after applying the force to the test component androtating the portion of the subassembly, wherein determining the one or more characteristics of the plastic comprises determining a wear of the plastic based on the measured mass.[000152] 29. The method of aspect 28, further comprising removing the test component from the base before measuring the mass of at least the portion of the test component.[000153] 30. The method of any of aspects 26-29, further comprising: incrementally decreasing the force applied to the test component until the portion of the subassembly stops rotating, wherein determining the one or more characteristics of the plastic comprises determining a static drag load limit of the plastic based on the decreased force.[000154] 31. The method of any of claims 26-30, wherein applying the force to the test component comprises, starting at zero and incrementally increasing the force applied to the test component until the portion of the subassembly begins rotating, and wherein determining the one or more characteristics of the plastic comprises determining a break-loose load limit based on the increased force.[000155] 32. The method of any of aspects 26-31. wherein applying the force to the test component comprises applying an off-centered force to the test component.[000156] 33. The method of any of aspects 26-32, wherein applying the force to the test component comprised applying an angled force to the test component.[000157] 34. The method of any of aspects 26-33, wherein the subassembly comprises: a base comprising: a first contact surface; and a first engagement feature positioned around the first contact surface, and the test component of the subassembly, wherein the test component is removably attached to, and rotatable relative to, the base, and comprises: a second contact surface that contacts the first contact surface and is formed of the plastic; and a second engagement feature positioned around the second contact surface and configured to engage the first engagement feature of the base, the method further comprising assembling the subassembly before applying the force and rotating the portion of the subassembly.[000158] 35. The method of aspect 34, wherein assembling the subassembly comprises snapping the test component onto the base by causing the second engagement feature of the test component to slide over the first engagement feature of the base.

Claims

CLAIMS1. A subassembly for testing one or more characteristics of a plastic, the subassembly comprising:a base comprising:a first contact surface; anda first engagement feature positioned around the first contact surface; and a test component that is removably attached to, and rotatable relative to, the base, the test component comprising:a second contact surface that contacts the first contact surface and is formed of the plastic; anda second engagement feature positioned around the second contact surface and configured to engage the first engagement feature of the base.

2. The subassembly of claim 1, wherein the base comprises an outer annular wall that is concentric with the first contact surface, and wherein the first engagement feature is formed on the outer annular wall.

3. The subassembly of claim 2, wherein a radius of the outer annular wall is greater than a radius of the first contact surface.

4. The subassembly of any of claims 1-3, wherein the base comprises a first inner annular wall that is concentric with the first contact surface, and wherein the test component comprises a second inner annular wall that is concentric with the second contact surface and contacts the first inner annular wall.

5. The subassembly of claim 4, wherein the first and second inner annular walls maintain a space between the first and second engagement features.

6. The subassembly of any of claims 4-5, wherein a radius of the first inner annular wall is less than an inner radius of the first contact surface, and wherein a radius of the second inner annular wall is less than an inner radius of the second contact surface.

7. The subassembly of any of claims 1-6. wherein the first contact surface and the second contact surface each have a respective surface area between 140 mm2and 200 mm2.

8. The subassembly of claim 7, wherein the first contact surface and the second contact surface each have a surface area of 184 mm2.

9. The subassembly of any of claims 1-8, wherein the first engagement feature comprises one or more teeth, and wherein the second engagement feature comprises a lip.

10. The subassembly of any of claims 1-9. wherein the plastic is a first plastic, wherein the subassembly is used for testing a coefficient of friction of the first plastic, and wherein the first contact surface is formed of a second plastic.

11. The subassembly of claim 10, wherein the first contact surface and / or the second contact surface are textured.

12. The subassembly of any of claims 1-9, wherein the subassembly is used for testing a wear of the plastic, and wherein the first contact surface is formed of metal.

13. A system for testing one or more characteristics of a plastic, the system comprising:a subassembly, comprising:a base; anda test component that is removably attached to. and rotatable relative to, the base;a force applicator configured to apply a force to the test component of the subassembly;a motor configured to rotate a portion of the subassembly while the force is applied to the test component; andat least one processor configured to determine the one or more characteristics of the plastic based on a result of applying the force to the test component and rotating the portion of the subassembly.

14. The system of claim 13, wherein the force applicator is configured to apply an off-centered force to the subassembly.

15. The system of any of claims 13-14, wherein the force applicator is configured to apply an angled force to the subassembly.

16. The system of any of claims 13-15, wherein the force applicator comprises an elastomeric component that contacts the subassembly.

17. The system of any of claims 13-16, wherein the base of the subassembly is fixed, and wherein the motor is configured to rotate the test component of the subassembly.

18. The system of any of claims 13-16, wherein the test component of the subassembly is fixed, and wherein the motor is configured to rotate the base of the subassembly.

19. The system of any of claims 13-18, wherein the at least one processor is configured to:transmit first instructions to a force subsystem configured to cause the force applicator to apply a force to the subassembly; andtransmit second instructions to the motor configured to cause the motor to rotate the portion of the subassembly.

20. The system of any of claims 13-19, further comprising a sensor configured to measure a torque applied to at least a portion of the test component.

21. The system of claim 20. wherein the at least one processor is configured to determine a coefficient of friction of the plastic based on the measured torque and the force applied to the test component.

22. The system of any of claims 13-21, further comprising an instrument configured to measure a mass of at least a portion of the test component.

23. The system of claim 22, wherein the at least one processor is configured to determine wear of the plastic based on the measured mass of at least the portion of the test component.

24. The system of any of claims 13-23, wherein the at least one processor is configured to determine, based on the result of applying the force to the test component and rotating the portion of the subassembly, a static drag load limit or a break-loose load limit of the plastic.

25. The system of any of claims 13-24,wherein the base of the subassembly comprises:a first contact surface; anda first engagement feature positioned around the first contact surface, and wherein the test component of the subassembly comprises:a second contact surface that contacts the first contact surface and is formed of the plastic; anda second engagement feature positioned around the second contact surface and configured to engage the first engagement feature of the base.

26. A method for testing one or more characteristics of a plastic using a subassembly, the method comprising:applying a force to a test component of the subassembly;rotating a portion of the subassembly while the force is applied to the test component; anddetermining, based on a result of applying the force to the test component and rotating the portion of the subassembly, the one or more characteristics of the plastic.

27. The method of claim 26, further comprising:measuring a torque applied to the test component, wherein determining the one or more characteristics of the plastic comprises determining a coefficient of friction of the plastic based on the measured torque and the force applied to the test component.

28. The method of any of claims 26-27, further comprising:measuring a mass of at least a portion of the test component after applying the force to the test component and rotating the portion of the subassembly, wherein determining the one or more characteristics of the plastic comprises determining a wear of the plastic based on the measured mass.

29. The method of claim 28, further comprising removing the test component from the base before measuring the mass of at least the portion of the test component.

30. The method of any of claims 26-29, further comprising:incrementally decreasing the force applied to the test component until the portion of the subassembly stops rotating, wherein determining the one or more characteristics of the plastic comprises determining a static drag load limit of the plastic based on the decreased force.

31. The method of any of claims 26-30, wherein applying the force to the test component comprises, starting at zero and incrementally increasing the force applied to the test component until the portion of the subassembly begins rotating, andwherein determining the one or more characteristics of the plastic comprises determining a break-loose load limit based on the increased force.

32. The method of any of claims 26-31, wherein applying the force to the test component comprises applying an off-centered force to the test component.

33. The method of any of claims 26-32, wherein applying the force to the test component comprised applying an angled force to the test component.

34. The method of any of claims 26-33, wherein the subassembly comprises:a base comprising:a first contact surface; anda first engagement feature positioned around the first contact surface, and the test component of the subassembly, wherein the test component is removably attached to, and rotatable relative to, the base, and comprises:a second contact surface that contacts the first contact surface and is formed of the plastic; anda second engagement feature positioned around the second contact surface and configured to engage the first engagement feature of the base, the method further comprising assembling the subassembly before applying the force and rotating the portion of the subassembly.

35. The method of claim 34, wherein assembling the subassembly comprises snapping the test component onto the base by causing the second engagement feature of the test component to slide over the first engagement feature of the base.

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