High speed powder coating lines for heat sensitive substrates

Abstract

A system for applying a powder coating to a heat-sensitive substrate may include at least one radiant oven, at least one convection oven, and a powder application system. The powder application system may include a plurality of powder application devices configured to apply powder to at least a top surface of the heat-sensitive substrate while the heat-sensitive substrate is oriented in a horizontal orientation.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 63 / 278,329, filed November 11, 2021, which is incorporated by reference in its entirety.

[0002] The present disclosure relates to a process for applying a powder coating to a heat-sensitive substrate, and in particular to a powder coating system that allows for powder coating of such substrates on a high speed line. [Background technology]

[0003] Powder coatings can be applied to a variety of different substrates, and the applied powder coatings can exhibit beneficial properties such as high durability, desirable appearance, surface protection, and / or surface modification and texture. Traditional powder coating methods have involved the use of equipment such as ovens, powder chambers, and cooling tunnels. In this case, the method of applying powder coatings to large substrates such as doors included suspending the substrate and transporting the substrate through the coating application process. Additional methods of powder coating have also included electrostatically charging the substrate prior to applying the coating. Summary of the Invention

[0004] In a first embodiment of the present disclosure, a system for applying a powder coating to a heat-sensitive substrate is provided. In this case, the system may include at least one radiant oven, at least one convection oven, and a powder application system. The powder application system may include a plurality of powder application devices configured to apply powder to at least a top surface of the heat-sensitive substrate while the heat-sensitive substrate is oriented in a horizontal orientation.

[0005] In a second embodiment of the present disclosure, a method for applying a powder coat to a heat-sensitive substrate is provided. In this case, the method may include conveying the heat-sensitive substrate horizontally at a first conveying speed. The method may also include radiatively heating the heat-sensitive substrate in a horizontal orientation at the first conveying speed. The method may also include convectively heating the heat-sensitive substrate in a horizontal orientation at a second conveying speed. In some cases, the second conveying speed may be less than the first conveying speed. The method may also include applying the powder to the heat-sensitive substrate in a horizontal orientation. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 illustrates a top down view of one embodiment of a powder coating system as described in the present disclosure. [Figure 2A] 1 illustrates a front view of one embodiment of a radiant oven described in the present disclosure. [Figure 2B] FIG. 1 illustrates a side view of one embodiment of a radiant oven described in the present disclosure. [Diagram 3] 1 illustrates a side view of one embodiment of a convection oven as described herein. [Figure 4A] FIG. 1 illustrates a front view of one embodiment of a powder application system described in the present disclosure. [Figure 4B] FIG. 1 illustrates a side view of one embodiment of a powder application system described in the present disclosure. [Figure 5A] 1 illustrates a front view of one embodiment of a radiant oven described in the present disclosure. [Figure 5B] FIG. 1 illustrates a side view of one embodiment of a radiant oven described in the present disclosure. [Figure 6] FIG. 1 illustrates a side view of one embodiment of a convection oven described in this disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The invention described herein involves a combination of process steps that allow for high speed powder coating of horizontally (flat) oriented substrates, which can be accomplished in a smaller physical space than typical continuous powder coating systems. However, the specific embodiments discussed herein are merely illustrative of ways to make and use the invention, and do not necessarily limit the scope of the invention.

[0008] The present powder coating method may provide advantages over other powder coating techniques. For example, a common practice in the field of powder coating is to suspend a substrate from a conveying system such that when an electric charge is applied to the substrate and the powder coating is applied, the powder coating particles evenly coat the suspended substrate. However, this method has several drawbacks. In this case, such powder coating processes utilizing suspension are typically slow (e.g., low substrate throughput rates), and attempts to increase the processing speed of these powder coating lines may result in non-uniformity and / or poor adhesion of the coating on the substrate, as well as poor aesthetics of the final product. Furthermore, preheating, curing, and cooling of such substrates are typically performed in systems that require a large amount of floor space in a building (e.g., long lateral lengths). Thus, current powder coating techniques utilizing conventional designs may be considered large and slow, and attempts to increase the line speed of such systems may impair powder coating performance.

[0009] The present invention seeks to solve these problems by utilizing a combination of processing steps that allows for a relatively high throughput of horizontally oriented substrates through the powder coating process while maintaining the quality of the resulting powder coated end product, which may require less floor space than conventional continuous powder coating techniques. Thus, the invention described herein can be faster and smaller than conventional powder coating techniques, and can achieve powder coating application performance at least equal to, or better than, such conventional techniques.

[0010] I. Definition: For the purposes of the following detailed description, it should be understood that the present invention can take various alternative variations and sequences of steps unless expressly specified to the contrary. Moreover, other than in any example or unless otherwise indicated, all numbers expressing the amounts of ingredients used in the specification and claims, for example, should be understood in any case as being modified by the term "about". Thus, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations that may vary depending on the desired properties obtained by the present invention. At the very least, and without any attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed at least in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0011] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible, however, any numerical values ​​inherently contain certain errors necessarily resulting from the standard variation found in their respective testing measurements.

[0012] It is also to be understood that any numerical range recited herein is intended to include all subranges subsumed therein. For example, a range "1 to 10" is intended to have all subranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, i.e., minimum values ​​equal to or greater than 1 and maximum values ​​equal to or less than 10.

[0013] In this application, the use of the singular includes the plural and the plural encompasses the singular, unless otherwise specified. Additionally, in this application, although "and / or" may be expressly used in certain instances, the use of "or" means "and / or" unless otherwise specified. Furthermore, in this application, the use of "a" or "an" means "at least one" unless otherwise specified. For example, "a" polymer, "a" pigment, etc., refers to one or more than one of any of these items.

[0014] II.Powder coating process: 1 is an exemplary embodiment of a powder coating system 100. The powder coating system 100 comprises multiple components that can be configured to apply a powder coating to a substrate 101. These components can include an in-feed 105, a conveying system 106, a first radiant oven 110, a first convection oven 115, a powder application system 120, a second radiant oven 145, a second convection oven 150, a cooling tunnel 155, and an out-feed 160. Each of these components can be used in combination to powder coat a substrate 101, which can be in a horizontal orientation (e.g., flat), and in some cases, can coat substrate 101 at a relatively high speed, as described further herein.

[0015] As illustrated in FIG. 1, the powder coating system 100 may be arranged linearly. For example, the powder coating system 100 may be configured linearly and have a length 102 that may be about 525 feet long or less than about 525 feet, and a width 103 that may be about 60 feet wide or less than about 60 feet. As described further herein, either or both of the length 102 and width 103 may be smaller than conventional continuous powder coating techniques. However, it should be understood that the configuration of the powder coating system 100 may be of various shapes and / or sizes (e.g., non-linear configurations, partially linear configurations, etc.) to accommodate the size of the room in which it is located. Thus, although shown in a linear orientation, the powder coating system 100 may have any number of orientations. In any of these cases, the overall floor space occupied by the powder coating system 100 may be smaller than conventional continuous powder coating techniques.

[0016] The powder coating system 100 includes a substrate 101. The substrate 101 can be a heat-sensitive substrate. A heat-sensitive substrate includes a substrate composition that can be adversely affected by the application of either excessive heat (e.g., too high a temperature) and / or excessively rapid heating, while the exterior surface, internal structure, and / or chemical composition of the substrate 101 can be damaged by such heating. Examples of heat-sensitive substrates include wood, wood-based materials (e.g., medium density fiberboard (MDF), plywood, particle board, etc.), composites, and plastics. For powder coating heat-sensitive substrates, it is desirable to preheat the substrate 101 to a desired powder coating temperature prior to application of the powder coating. In this case, preheating allows for the desired adhesion properties of the powder coating particles to the substrate 101, which contributes to a higher performance resulting powder coating. However, the manner in which the substrate 101 is preheated and cured should avoid the deleterious effects that can be caused by either excessive heating and / or excessively rapid heating.

[0017] The substrate 101 may also be of a relatively large size, having a relatively long lateral length and / or horizontal width. Examples of such large substrates 101 may be doors, building products, veneers, pressed wood, panels, protective and decorative skins, fireplaces, and protective sheeting. As previously mentioned, conventional powder coating systems utilized to powder coat large substrates may require the substrate to be suspended and the powder coating applied while the substrate is in a vertical orientation. In this case, it may be beneficial to powder coat these relatively long and / or wide substrates 101 while in a flat (e.g., horizontal) orientation rather than a vertical orientation to accommodate such geometries.

[0018] The powder coating system 100 includes a transport system 106. The transport system 106 may be a transport system operable to move the substrate 101 between various components of the powder coating system 100. The transport system 106 may be a line-type conveyor that allows for horizontal movement of the substrate 101 about the powder coating system 100. Illustratively, the transport system 106 moves the substrate 101 laterally about the length 102, although in some cases (e.g., based on different arrangements of the components of the powder coating system 100), the transport system 106 may move the substrate 101 in various directions (e.g., adjacent, tangential, etc.) relative to the length 102.

[0019] The transport system 106 allows for the substrate 101 to be moved at relatively high speeds around the powder coating system 100. For example, the transport system 106 may allow for transport speeds of greater than 10 feet per minute, greater than 50 feet per minute, greater than 75 feet per minute, at or below 100 feet per minute, at or below 125 feet per minute, at or below 150 feet per minute, or any range or value encompassed by these endpoints. Thus, the transport system 106 may contribute to high throughput rates of the substrate 101 through such high line speeds.

[0020] The powder coating system 100 includes an in-feed 105. The in-feed 105 may be the point where the substrate 101 enters the powder coating system 100 and thus may be the entry point of the transport system 106. The in-feed 105 is loaded with the substrate 101, which may be by a manual process, an automatic process, or a combination of manual and automatic processes. The substrate 101 may be loaded into the in-feed 105 while in a horizontal (e.g., flat) orientation. The in-feed 105 allows for high speed processing of the substrate 101, however, the amount (e.g., quantity) of the substrate 101 fed by the in-feed 105 to the transport system 106 may be based on the processing speed of the powder coating system 100. In this case, the in-feed 105 may be designed to feed the substrate 101 at a speed of more than 100 feet per minute based on the processing of the substrate 101.

[0021] The powder coating system 100 includes a first radiant oven 110. Figure 1 illustrates a top-down view of the first radiant oven 110, and Figures 2A and 2B further illustrate front and side views of the first radiant oven 110. In combination, Figures 1, 2A, and 2B each illustrate the components of the first radiant oven 110, including a horizontal transport system 107, an oven enclosure 112, a first radiation emitter 113, and a second radiation emitter 114. Each of the components of the first radiant oven 110 can be used to rapidly pre-heat an exterior surface of the substrate 101 while the substrate 101 is in a horizontal (flat) orientation.

[0022] After being processed through infeed 105, substrate 101 travels along transport system 106 and is fed into a first radiant oven 110. In this case, substrate 101 is received by horizontal transport system 107 in a horizontal (flat) orientation and moved through oven enclosure 112. First radiant oven 110 may include two types of radiation emitters, a first radiation emitter 113 and a second radiation emitter 114, both of which may emit infrared radiation that contacts an exterior surface of substrate 101 and heats the top and sides of substrate 101 as it travels laterally through first radiant oven 110. For example, the first radiation emitter 113 may be positioned vertically above the substrate 101 and emit radiation vertically downward onto a top surface of the substrate 101, while the second radiation emitter 114 may be positioned obliquely on the top surface of the substrate 101 (e.g., at a 45 degree angle relative to the top surface of the substrate 101) and emit radiation toward a side of the substrate 101. In this case, the combination of the first radiation emitter 113 and the second radiation emitter 114 may be used to radiatively heat the top and side of the substrate 101 while the substrate 101 is passing through the oven enclosure 112 in a horizontal orientation.

[0023] Pre-heating the substrate 101 allows for effective adhesion of the powder coating particles to the surface of the substrate 101. In this regard, the infrared oven is effective in quickly and efficiently raising the surface temperature of the substrate 101 to a temperature setpoint to effectively adhere the powder coating particles to the surface of the substrate 101 during the powder coating process. In this case, the infrared heating may quickly and efficiently pre-heat the surface of the substrate 101 without affecting the interior portion of the substrate 101, thus creating a large temperature gradient between the surface of the substrate 101 and the area directly below the surface of the substrate 101. For example, the first radiant oven 110 may pre-heat the surface of the substrate 101 to a setpoint surface temperature of about 280-325 degrees Fahrenheit.

[0024] The first radiant oven 110 is configured to preheat the substrate 101 for a target time (e.g., dwell time, resonance time, etc.). In this case, the substrate 101 remains inside the active heating zone of the first radiant oven 110 for the desired dwell time, which may be based on the amount of time required to preheat the surface of the substrate 101 to the target temperature while avoiding damage to either the exterior or interior structure of the substrate 101. For example, the dwell time required to heat the surface of the substrate 101 to a target temperature of 280-325 degrees Fahrenheit may be approximately 30 seconds. In this case, the substrate 101 remains within the active heating zone of the first radiant oven 110 for 30 seconds while the surface of the substrate 101 reaches the preheat set point of 280-325 degrees Fahrenheit. However, in other cases, the dwell time required to reach the preheat temperature may be longer or shorter than 30 seconds based on various factors including the target surface temperature of the substrate 101 (e.g., a higher target temperature requiring a higher dwell time), the composition of the substrate 101 (e.g., a lower thermally conductive composition requiring a longer dwell time), and / or any other applicable factors. Thus, the 30 second dwell time may be adjusted based on different operating conditions and / or the composition of the substrate 101. Additionally, although described as utilizing only infrared radiation, the preheating of the substrate 101 may include other methods including infrared, ultraviolet, or any combination of thermal convection / conduction radiation. Thus, although described as being a radiant oven, the first radiant oven 110 may utilize any type of heating method to effectively preheat the substrate 101 in a short period of time. As an exemplary embodiment, the first radiant oven 110 may heat the substrate 101 using short wave infrared radiation, mid wave infrared radiation, or a combination of short wave and mid wave infrared radiation.

[0025] The first radiant oven 110 is designed to enable high line speeds and therefore high throughput rates of the powder coating system 100. In this case, the first radiant oven 110 can accommodate the high speed at which the substrate 101 is fed into the first radiant oven 110 (e.g., the high line speed of the transport system 106) and can rapidly preheat the substrate 101 to a target surface temperature. For example, the first radiant oven 110 can accommodate substrate feed rates of 100 feet per minute or more and can adjust, alone or in combination, the intensity of the radiation applied to the surface of the substrate 101, the wavelength of the radiation applied to the surface of the substrate 101, and / or the time that the radiation is applied to the surface of the substrate 101 to meet the target surface temperature. Thus, the first radiant oven 110 can provide greater flexibility than other powder coating methods, particularly the flexibility to accommodate the high line speeds / substrate throughput of the powder coating system 100.

[0026] Powder coating system 100 includes a first convection oven 115. Figure 1 illustrates a top down view of first convection oven 115, and Figure 3 further illustrates a side view of first convection oven 115. In combination, Figures 1 and 3 illustrate the components of first convection oven 115, including horizontal transport system 117 and layer 118. In this case, first convection oven 115 can be used to heat substrate 101 to a desired powder coating temperature and for a desired time while substrate 101 is in a horizontal orientation.

[0027] After being preheated by the first radiant oven 110, the substrate 101 is transferred by the transport system 106 to the first convection oven 115. The first convection oven 115 may be a thermal convection oven, while thermal energy provided by a thermal energy source (e.g., a combustion chamber) is circulated through a heating zone of the first convection oven 115 by one or more circulating devices (e.g., a blower, a fan, etc.) to convectively heat the substrate 101. However, while described as utilizing only convection thermal heating, it is understood that the heating of the substrate 101 by the first convection oven 115 may include other methods, including any combination of thermal convection / conductive radiation, infrared radiation, and / or ultraviolet radiation. Thus, while described as being a convection oven, the first convection oven 115 may utilize any type of heating method to effectively heat the substrate 101 to the desired powder coating temperature.

[0028] The horizontal transport system 117 receives the substrate 101, which moves in a horizontal orientation into a heating zone of the first convection oven 115. The first convection oven 115 is configured to continue to heat the substrate 101 to a desired powder coating temperature setpoint. As previously mentioned, the temperature at which the powder coating is applied to the surface of the substrate 101 can affect the quality of the resulting powder coating. However, overheating the heat-sensitive substrate 101 can result in damage to either the internal or external structure of the substrate 101. In this case, the first radiant oven 110 may first preheat the surface of the substrate 101 to a desired preheat temperature, and the first convection oven 115 may continue to heat the substrate 101 to the desired powder coating temperature for effective powder coating application. For example, the first radiant oven 110 may heat the external surface of the substrate 101 to 280-325 degrees Fahrenheit. However, the radiant heating provided by the first radiant oven 110 may have only a limited thickness penetrating the substrate 101, and therefore additional heating may be required to effectively heat the first substrate 101 to the desired powder coating temperature (e.g., heat the substrate 101 to a powder coating temperature at a desired thickness within the substrate 101). In this case, the thermal energy provided by the first convection oven 115 heats the surface of the substrate 101 more slowly than radiant heating with infrared energy, but may penetrate the surface of the substrate 101 to a greater extent and therefore heat the first substrate 101 more thoroughly than the first radiant oven 110. In this manner, the first radiant oven 110 and the first convection oven 115 may be used in combination to effectively heat the substrate 101 to the desired powder coating temperature.

[0029] In an exemplary embodiment, the first convection oven 115 is a multi-stage convection oven capable of processing and heating many individual substrates 101 simultaneously. For example, the first convection oven 115 accepts the substrates 101 from the horizontal transport system 117 and loads each of the substrates 101 onto a horizontal layer 119 in groups of charges. The charges on the substrates 101 are moved horizontally onto the layer 119 and into the heating zone of the first convection oven 115. Each of the layers 119 accommodates a defined amount of charge on the substrates 101, and once an amount of charge has been loaded onto the layer 119, the layer 119 begins to rise or fall vertically within the heating zone of the first convection oven 115. As the layer 119 rises or falls, further loading of additional charges of the substrates 101 onto the additional layers 119 is initiated.

[0030] Each of the charges on the substrate 101 remains within the heating zone of the first convection oven 115 for a desired dwell time to heat the substrate 101 to a target powder coating temperature. For example, the first convection oven 115 may be configured to heat the substrate 101 to a desired powder coating setpoint temperature of about 280-325 degrees and for a desired dwell time of 4 minutes. In this case, the charges on the substrate 101 may remain within the heating zone for the entirety of the dwell time as enabled by the horizontal and vertical movement of the charges on the substrate 101 around the layer 119 of the first convection oven 115.

[0031] Once the target residence time is reached, each of the charges on the substrate 101 are offloaded from the layer 119 in an order inversely proportional to the loading of such charge. For example, the first charge loaded onto the layer 119 of the convection oven 115 may be the first substrate offloaded from the layer 119 of the convection oven 115. Although described with respect to a four minute residence time, the amount of time the substrate 101 remains within the heating zone of the first convection oven 115 may be based on a variety of factors including the target powder coating temperature of the substrate 101 (e.g., a higher target temperature requiring a higher residence time), the composition of the substrate 101 (a lower thermally conductive composition requiring a longer residence time) and / or any other applicable factors. Thus, in any of the aforementioned cases, the residence time may be adjusted to reach the target powder coating temperature of the substrate 101.

[0032] The use of the layer 108 of the convection oven 115, particularly the combination of horizontal and vertical movement of the substrate 101 throughout the heating zone of the convection oven 115, may allow the substrate 101 to remain in the heating region of the first convection oven 115 for a relatively long residence time relative to the linear length of the oven, as compared to a conventional convection oven. In this case, the use of the layer 119 increases the effective horizontal length of the first convection oven 115, as compared to a conventional convection oven utilizing a single linear direction of movement, and thus the first convection oven 115 may be smaller (e.g., have a shorter linear length) than a similar convection oven used to heat the substrate 101 to a desired powder coating temperature. Thus, the smaller first convection oven 115 may contribute to a reduction in the length 102 of the powder coating system 100, as compared to a conventional powder coating system.

[0033] Additionally, the combination of the first radiant oven 110 and the first convection oven 115 may provide advantages over other powder coating techniques. As previously described, the first radiant oven 110 preheats the exterior surface of the substrate 101 rapidly (e.g., in 30 seconds) to a desired preheat temperature, while the first convection oven 115 continues to heat the substrate 101 to the desired powder coating temperature by using horizontal and vertical substrate 101 movement within the first convection oven 115. In this case, the rapid preheating of the substrate 101 by the first radiant oven 110 reduces the amount of thermal energy required to heat the substrate 101 to the powder coating temperature, and therefore the amount of residence time the substrate 101 needs to remain in the first convection oven 115 to reach the desired powder coating temperature. In this case, due to the relatively short residence time, the first convection oven 115 can be smaller than a conventional oven used to heat the substrate because less thermal energy is required to heat the substrate to the powder coating temperature. Additionally, and as previously discussed, the first radiant oven 110 and the first convection oven 115 can accommodate the high processing / line speed of the transport system 106. Thus, in combination, the use of the first radiant oven 110 and the first convection oven 115 allows for a smaller mechanical footprint (e.g., smaller length (L) 102) than conventional powder coating lines, while simultaneously accommodating higher throughput (e.g., processing more substrates 101) and higher line speeds (e.g., higher lateral speeds of the transport system 106) than conventional powder coating techniques.

[0034] Powder coating system 100 includes powder application system 120. FIG. 1 illustrates a top down view of powder application system 120, FIG. 4A illustrates a front view of powder application system 120, and FIG. 4B illustrates a side view of powder application system 120. In combination, each of FIGS. 1, 4A, and 4B illustrates components of powder application system 120 including powder recovery enclosure 125, powder delivery system 130, first powder application device 135, second powder application device 140, third powder application system 142, horizontal transport system 122, powder recovery device 132, and powder application device mount 434. Each of these components can be used in combination to powder coat substrate 101 in a horizontal orientation (e.g., substrate 101 oriented in a flat orientation) and, as previously described, can be used at high processing speeds.

[0035] After exiting the convection oven 115, the substrate 101 enters the powder application system 120. It is theorized that high powder coating performance depends on, among other factors, the amount of time between pre-heating the substrate 101 and the application of the powder coating. In this case, the closer the substrate 101 is to the desired powder coating temperature, the greater the adhesion of the powder coating particles to the surface of the substrate 101. Thus, reducing the time between pre-heating the substrate 101 and the application of the powder coat may lead to higher powder coating performance.

[0036] As previously discussed, the combination of the infeed 105, conveying system 106, first radiant oven 110, and first convection oven 115 allows for high throughput rates (e.g., line speeds in excess of 100 feet / minute) of the substrate 101 through the heated portion of the powder coating system 100. These high line speeds also minimize the amount of time between the heating of the substrate 101 (e.g., exit of the first convection oven 115) and the application of the powder coating, since it takes very little time for the substrate 101 to enter the powder application system 120 after being preheated. In this case, the high line speed minimizes surface temperature loss of the substrate 101 while the substrate 101 enters the powder application system 120 as close as possible to the powder coating setpoint temperature.

[0037] The powder application system 120 receives the substrate 101 from the transport system 106 at the horizontal transport system 122. The horizontal transport system 122 moves the substrate 101 laterally through the powder application system 120 while the powder coating is applied to the substrate 101 while the substrate 101 is in a horizontal (flat) orientation with respect to the horizontal transport system 122. As previously mentioned, conventional powder coating systems may require the substrate to be suspended in order to effectively powder coat the outer surface of the substrate. With the powder application system 120, the substrate 101 moves in a horizontal / linear manner, but the powder coating is applied to the substrate 101 without the need to vertically reorient the substrate 101 (e.g., no suspension of the substrate 101 is required). Thus, the powder coating system 100 is able to achieve high throughput speeds at least in part because the substrate 101 does not need to be reoriented to a vertical orientation during powder coating, but rather the substrate 101 can be moved quickly horizontally through the powder application system 120.

[0038] The powder application system 120 includes a powder recovery enclosure 125. The powder recovery enclosure 125 is an enclosure that houses various components used to powder coat substrate 101 and allows for the recovery of powder coating oversprayed during the powder coating process, as described in more detail below in connection with powder recovery device 132. The powder recovery enclosure 125 may also be air conditioned, while the conditioning maintains a constant temperature that may be optimal for the powder coating process. For example, the powder recovery enclosure 125 may be regulated to maintain an internal temperature of about 80 degrees Fahrenheit during the powder coating process. Although FIG. 4 illustrates the powder recovery enclosure 125 as a box-type enclosure, the powder recovery enclosure 125 may be arranged in any number of geometric shapes, such as a dome.

[0039] Powder application system 120 includes a powder delivery system 130. Powder delivery system 130 is external to powder recovery enclosure 125 and is operatively coupled (e.g., fluidly and / or pneumatically coupled) to powder recovery enclosure 125 that supplies powder to each of the powder spray applications of powder application system 120. In an exemplary embodiment, powder delivery system 130 comprises a primary bulk powder feeder, a redundant bulk powder feeder, and a powder sieve and distribution hopper. The combination of the primary bulk powder feeder, redundant bulk powder feeder, and powder sieve and distribution hopper are used to supply the various powder application devices of powder application system 120, including first powder application device 135, second powder application device 140, and third powder application device 142. The rate at which powder delivery system 130 feeds to the various spray devices of powder application system 120 may be based on a variety of factors, including the line speed of powder coating system 100 (e.g., higher feed rates for faster line speeds), the desired amount of powder coating thickness on substrate 101 (e.g., higher thicknesses requiring higher feed rates), the size of substrate 101 (e.g., longer / thicker substrates 101 requiring more powder), and / or any other applicable factors. Thus, powder delivery system 130 may be designed to accommodate a variety of line speeds, substrate sizes, and powder coating specifications.

[0040] Powder application system 120 includes multiple powder application devices used to powder coat substrate 101, including a first powder application device 135, a second powder application device 140, and a third powder application device 142. First powder application device 135, second powder application device 140, and third powder application device 142 are disposed within a powder collection enclosure 125 and configured to apply a powder coating to substrate 101 as substrate 101 moves laterally through powder collection enclosure 125 in a horizontal (flat) orientation.

[0041] The first powder application device 135 and the second powder application device 140 are configured to apply the powder coating in a vertical direction. In this case, the first powder application device 135 and the second powder application device 140 are positioned vertically above the substrate 101 and apply the powder coating to the substrate 101 from a vertical orientation above the top surface of the substrate 101. For example, the first powder application device 135 and the second powder application device 140 may be mounted on a powder application device mount 434, while the powder application device mount 434 is disposed in a vertical position above the horizontal transport system 122. In this case, the powder application device mount 434 comprises a series of lateral bars extending above the horizontal transport system 122 that can carry powder lines, electrical lines, data lines, fluid lines, powder coating lines, or other similar lines necessary to operate the first powder application device 135 and the second powder application device 140. It is also possible that the powder application device mount 434 may be a flat plate having mounting holes or other configured mounting surfaces capable of receiving the first and second powder application devices 135 and 140 .

[0042] As previously described, the horizontal conveying system 122 moves the substrate 101 laterally through the powder application system 120. The first powder application device 135 may be positioned proximate to the entrance to the powder collection enclosure 125 and therefore applies a first application of powder to the top surface of the substrate 101 while the substrate 101 moves laterally through the powder application system 120. For example, the first powder application device 135 may include a plurality of automated, high powered overhead rotary sprayers, such as about 15-20 automated, high powered overhead rotary sprayers, that spray powder onto the top surface of the substrate 101 while the substrate 101 is moved laterally through the powder application system 120 by the horizontal conveying system 122. The second powder application device 140 is positioned proximate to the first powder application device 135 and at a greater lateral distance from the entrance of the powder collection enclosure 125. In this case, the second powder application device 140 applies a second application of powder to the top surface of the substrate 101 while the substrate 101 moves laterally through the powder application system 120. For example, the second powder application device 140 may include a plurality of automated high powered overhead rotary sprayers, such as about four automated high powered overhead rotary sprayers, that spray powder onto the top surface of the substrate 101 while the substrate 101 moves laterally through the powder application system 120 by the horizontal conveying system 122 and after the first application of powder by the first powder application device 135.

[0043] The first powder application device 135 and the second powder application device 140 may be used in combination to apply a uniform powder coating layer to at least the top surface of the substrate 101. For example, the diameter of the nozzle used for the sprayer of the first powder application device 135 may be a smaller diameter than the diameter of the nozzle used for the sprayer of the second powder application device 140. Thus, the diameter of the distribution of the spray dispensed by each of the sprayers of the first powder application device 135 may be smaller than the diameter of the distribution of the spray dispensed by each of the sprayers of the second powder application device 140. Furthermore, there may be more sprayers included in the first powder application device 135 (e.g., 15-20 sprayers) compared to the second powder application device 140 (e.g., 4 sprayers). Thus, the first powder application device 135 may provide a higher density powder coating to the substrate 101 than the second powder application device 140. The combination of the first powder application device 135 and the second powder application device 140 enables a uniform density of powder coating applied to the substrate 101, while the leading edge, top surface, and trailing edge of the substrate 101 are evenly coated with powder as the substrate 101 moves laterally through the powder application system 120 in a horizontal (flat) orientation.

[0044] The third powder application device 142 is configured to apply a powder coating to a side of the substrate 101 while the substrate 101 moves laterally through the powder application system 120. For example, the third powder application device 142 includes a pair of horizontally opposed sprayers, each positioned laterally adjacent to an opposing vertical side of the substrate 101. In this case, each sprayer sprays a powder coating horizontally onto a side of the substrate 101 while the substrate 101 moves laterally through the powder application system 120 by the horizontal conveying system 122. Illustratively, the third powder application device 142 is generally aligned with the second powder application device 140 (e.g., at the same horizontal distance from the entrance of the powder collection enclosure 125), although the third powder application device 142 may be positioned differently in other embodiments. In some cases, third powder application device 142 includes multiple standard automated applicators, with each side of third powder application device 142 including two applicators positioned opposite each other about horizontal transport system 122 for a total of four applicators. However, it can be understood that in some embodiments, more or fewer applicators may be utilized.

[0045] While the substrate 101 is in a horizontal (flat) orientation, the first powder application device 135, the second powder application device 140, and the third powder application system 142 can each be used in combination to effectively powder coat the top and sides of the substrate 101. For example, as previously described, the first powder application device 135 applies an initial dense coating of powder to the substrate 101 as the substrate 101 begins to move through the powder collection enclosure 125 by the horizontal conveying system 122. After application of the first dense powder coating layer, the second powder application device 140 can apply a less dense coating of powder to the top of the substrate 101 while the third powder application device 142 simultaneously applies a powder coating to the sides of the substrate 101. Thus, a combination of first, second, and third powder application devices 135, 140, and 142 can be used in combination to apply a powder coating to the top and sides (e.g., top and two sides) of substrate 101 while substrate 101 is in a horizontal (flat) orientation as substrate 101 moves through powder collection enclosure 125. In this case, each of first, second, and third powder application devices 135, 140, and 142 can be designed to accommodate the high line speeds and / or throughput of powder coating system 100.

[0046] The powder application system 120 includes a powder recovery device 132. The powder recovery device 132 is used to recover overspread powder that did not adhere to the substrate 101 during the powder coating process. For example, the powder recovery device 132 may be a pair of blowers with a filter arrangement (e.g., a cyclone filter), while the powder and air mixture from the interior of the powder recovery enclosure 125 is drawn through the filter to remove non-adhering powder from the air. For example, the powder recovery devices 132 may each include a blower and a filter, but the inlet to the powder recovery device 132 is pneumatically coupled with the interior space of the powder recovery enclosure 125, and the negative pressure provided by the blower draws the air and powder mixture into the filter while the powder is removed from the air. In this case, the recovered powder can be reused in the powder application process.

[0047] As previously discussed, the combination of the first radiant oven 110 and the first convection oven 115 allows for rapid pre-heating of the substrate 101 at high line speeds. Additionally, the powder application system 120 allows for fast and effective powder coating of the substrate 101 while the substrate 101 is in a horizontal orientation. Thus, the combination of the first radiant oven 110, the first convection oven 115, and the powder application system 120 may be advantageous over conventional powder coating systems by allowing for a higher throughput of substrates (e.g., processing more substrates 101) and a higher line speed (e.g., a higher lateral speed of the conveying system 106) compared to conventional powder coating techniques, while occupying less space in a building (e.g., having a shorter length (L) 102).

[0048] The powder coating system 100 includes a second radiant oven 145. Figures 1A and 1B illustrate a top-down view of the second radiant oven 145, and Figures 5A and 5B further illustrate front and side views of the second radiant oven 145. In combination, Figures 1A, 1B, 5A, and 5B each illustrate the components of the second radiant oven 145, including a horizontal transport system 146, an oven enclosure 147, a first radiation emitter 148, and a second radiation emitter 149. Each of the components of the second radiant oven 145 can be used to rapidly heat the powder coated exterior surface of the substrate 101 while the substrate 101 is in a horizontal (flat) orientation.

[0049] After being powder coated by powder application system 120, substrate 101 travels along transport system 106 and is fed into second radiant oven 145. In this case, substrate 101 is received by horizontal transport system 146 in a horizontal (flat) orientation and moved through oven enclosure 112. Second radiant oven 145 may include two types of radiation emitters, a first radiation emitter 148 and a second radiation emitter 149, both of which may emit infrared radiation that contacts an exterior surface of substrate 101 and heats the top and sides of substrate 101 as substrate 101 travels laterally through second radiant oven 145. For example, the first radiation emitter 148 may be positioned vertically above the substrate 101 and emit radiation vertically downward onto the top surface of the substrate 101, while the second radiation emitter 149 is positioned obliquely on the top surface of the substrate 101 (e.g., at a 45 degree angle relative to the top surface of the substrate 101) and emits radiation toward the side of the substrate 101. In this case, the combination of the first radiation emitter 148 and the second radiation emitter 149 may be used to radiatively heat the top and side of the substrate 101 while the substrate 101 is passing through the oven enclosure 147 in a horizontal orientation.

[0050] Heating the powder coated substrate 101 cures the components of the applied powder coating on the substrate 101. For example, heating the applied powder coating bonds, liquefies, and crosslinks the components of the powder coating to form the final powder coating surface on the substrate 101. In this case, an infrared oven is effective to quickly and efficiently raise the surface temperature of the substrate 101 to a cure temperature setpoint. Initial heating of the surface of the powder coated substrate 101 may initiate curing of the powder coating components on the surface of the substrate 101 (e.g., may gel the powder coating particles), while additional heat can be provided to continue curing the powder coating. For example, infrared heating may quickly and efficiently heat the surface particles of the powder coating to a surface temperature of about 280-325 degrees Fahrenheit, while the powder coating components begin to gel on the top and sides of the substrate 101. In some cases, the curing temperature may be the same as the preheat temperature (e.g., substrate 101 preheated by second convection oven 145 to the same preheat temperature as first convection oven 115), or in other cases, may be a different temperature (e.g., second convection oven 145 heats substrate 101 to a temperature higher or lower than the preheat temperature of first convection oven 115).

[0051] The second radiant oven 145 is configured to heat the substrate 101 for a target time (e.g., dwell time). In this case, the substrate 101 remains inside the active heating zone of the second radiant oven 145 for the desired dwell time, which may be based on the amount of time required to heat the surface of the substrate 101 to the target cure temperature while avoiding damage to either the exterior or interior structure of the substrate 101. For example, the dwell time required to heat the surface of the substrate 101 to a target temperature of 280-325 degrees Fahrenheit may be approximately 30 seconds. In this case, the substrate 101 remains within the active heating zone of the second radiant oven 145 for 30 seconds while the surface of the substrate 101 reaches the cure set point of 280-325 degrees Fahrenheit. However, in other cases, the dwell time required to reach the preheat temperature may be longer or shorter than 30 seconds based on various factors including the target surface temperature of the substrate 101 (e.g., a higher target temperature requiring a higher dwell time), the composition of the powder coating (a lower thermally conductive composition requiring a longer dwell time), and / or any other applicable factors. Thus, the 30 second dwell time may be adjusted based on different operating conditions. Additionally, although described as utilizing only infrared radiation, the heating of the substrate 101 may include other methods including infrared, ultraviolet, or any combination of thermal convection / conduction radiation. Thus, although described as being a radiant oven, the second radiant oven 145 may utilize any type of heating method to effectively heat the substrate 101. As an exemplary embodiment, the second radiant oven 145 may heat the substrate 101 using short wave infrared radiation, mid wave infrared radiation, or a combination of short wave and mid wave infrared radiation.

[0052] The second radiant oven 145 is designed to allow for high line speeds and therefore high throughput rates of the powder coating system 100. In this way, the second radiant oven 145 can accommodate the high speed at which the substrate 101 is fed into the second radiant oven 145 (e.g., the high line speed of the transport system 106) and can rapidly heat the powder coated substrate 101 to the target curing temperature. For example, the second radiant oven 145 can accommodate substrate feed speeds of 100 feet per minute or more and can adjust, alone or in combination, the intensity of the radiation delivered to the surface of the substrate 101, the wavelength of the radiation delivered to the surface of the substrate 101, and the time that the radiation is delivered to the surface of the substrate 101 to meet the target surface temperature. Thus, the second radiant oven 145 can provide greater flexibility than other powder coating methods, particularly the flexibility to accommodate the high line speeds / substrate throughput of the powder coating system 100.

[0053] The powder coating system 100 includes a second convection oven 150. Figure IB illustrates a top down view of the second convection oven 150, and Figure 6 further illustrates a side view of the second convection oven 150. In combination, Figures 1 and 6 illustrate the components of the second convection oven 150, including a horizontal transport system 152 and a layer 154. In this case, the second convection oven 150 may be used to heat the powder coated substrate 101 to a desired powder coating cure temperature and for a desired time while the substrate 101 is in a horizontal orientation.

[0054] After being heated by the second radiant oven 145, the substrate 101 is transferred by the transport system 106 to the second convection oven 150. The second convection oven 150 may be a thermal convection oven, while thermal energy provided by a thermal energy source (e.g., a combustion chamber) is circulated through a heating zone of the second convection oven 150 by one or more circulating devices (e.g., a blower, a fan, etc.) to convectively heat the substrate 101. However, while described as utilizing only convection thermal heating, it is understood that the heating of the substrate 101 by the second convection oven 150 may include other methods, including any combination of thermal convection / conductive radiation, infrared radiation, and / or ultraviolet radiation. Thus, while described as being a convection oven, the second convection oven 150 may utilize any type of heating method to effectively heat the substrate 101 to a desired curing temperature.

[0055] The horizontal transport system 152 receives the substrate 101, which moves in a horizontal orientation into the heating zone of the second convection oven 150. The second convection oven 150 is configured to continue to heat the substrate 101 to a curing temperature setpoint. As previously mentioned, the applied powder coating may begin to cure at a defined temperature, and holding the powder coating at that temperature may allow the powder coating particles to cure onto the surface of the substrate 101. However, overheating the heat-sensitive substrate 101 may result in damage to either the internal or external structure of the substrate 101. In these cases, the second radiant oven 145 may first heat the surface of the substrate 101 to the desired curing temperature, and the second convection oven 150 may continue to heat the substrate 101 at the desired curing temperature for a time to fully cure the powder coating on the substrate 101. For example, the second radiant oven 145 may have heated the exterior surface of the substrate 101 to 280-325 degrees Fahrenheit, and the second convection oven 150 may hold the substrate 101 at the curing temperature for the amount of time necessary to fully cure the powder coating on the surface of the substrate 101. Thus, the second radiant oven 145 and the second convection oven 150 may be used in combination to effectively cure the powder coating on the surface of the substrate 101.

[0056] In an exemplary embodiment, the second convection oven 150 is a multi-stage convection oven capable of processing and heating many individual substrates 101 simultaneously. For example, the second convection oven 150 accepts the substrates 101 from a horizontal transport system 152 and loads each of the substrates onto a horizontal layer 154 in groups of charges. The charges on the substrates 101 are moved horizontally onto the layer 154 and into the heating zone of the second convection oven 150. Each of the layers 154 accommodates a defined amount of charge on the substrates 101, and once an amount of charge has been loaded onto the layer 154, the layer 154 begins to rise or fall vertically within the heating zone of the second convection oven 150. As the layer 154 rises or falls, further loading of additional charges of substrates onto the additional layers 154 is initiated.

[0057] Each of the charges on the substrate 101 remains within the heating zone of the second convection oven 150 for a desired dwell time to heat the powder coated substrate 101 to a target cure temperature. For example, the second convection oven 150 may be configured to heat the powder coated substrate 101 to a desired cure setpoint temperature of approximately 280-325 degrees and for a desired dwell time of 12 minutes. The charges on the substrate 101 may remain within the heating zone for the entirety of the dwell time as enabled by the horizontal and vertical movement of the charges on the substrate 101 around the layer 154 of the second convection oven 150.

[0058] Once the target dwell time is reached, each of the charges on the substrate 101 are offloaded from the layer 154 in an order inversely proportional to the loading of such charge. For example, the first charge of substrate 101 loaded onto layer 154 of the second convection oven 150 may be the first substrate 101 offloaded onto layer 154 of the second convection oven 150. Although described with respect to a 12 minute dwell time, the amount of time the substrate 101 remains in the heating zone of the second convection oven 150 may be based on a variety of factors including the target cure temperature of the powder coating (e.g., a higher target temperature requiring a longer dwell time), the composition of the powder coating (e.g., a lower thermally conductive composition requiring a longer dwell time), and / or any other applicable factors. Thus, in any of the above cases, the dwell time may be adjusted to reach the target cure temperature of the powder coated substrate 101.

[0059] The use of the second 150 layer 154, particularly the combination of horizontal and vertical movement of the substrate 101 throughout the heating zone of the second convection oven 150, may allow the substrate 101 to remain in the heating region of the second convection oven 150 for a relatively long residence time relative to the linear length as compared to a conventional convection oven. In this case, the use of the layer 154 increases the effective horizontal length of the second convection oven 150 as compared to a conventional convection oven utilizing a single linear direction of movement, and thus the second convection oven 150 may be smaller (e.g., have a shorter linear length) than a similar convection oven used to heat the substrate 101 to a desired powder coating temperature. Thus, the smaller second convection oven 150 may contribute to a reduction in the length 102 of the powder coating system 100 as compared to a typical powder coating system. In this case, the second convection oven 150 may be larger (e.g., have a longer linear length) than the first convection oven 115 because the residence time of the second convection oven 115 (e.g., 12 minutes) is greater than the first convection oven 115 (e.g., 4 minutes). In either case, however, the bed size (e.g., length) of both the first convection oven 115 and the second convection oven 150 may be smaller than a conventional convection oven.

[0060] Additionally, the combination of the second radiant oven 145 and the second convection oven 150 may provide advantages over other powder coating techniques. As previously discussed, the second radiant oven 145 rapidly heats the outer powder coating layer of the substrate 101 to a desired curing temperature (e.g., in 30 seconds), and the second convection oven 150 continues heating the powder coated substrate 101 for a desired period of time to fully cure the powder coating on the substrate 101. In this case, the rapid heating of the substrate 101 by the second radiant oven 145 reduces the amount of thermal energy required to heat the substrate 101 to the curing temperature, and therefore reduces the amount of residence time the substrate 101 needs to remain in the second convection oven 150 for the powder coating to be fully cured. In this case, because the residence time is relatively short, the second convection oven 150 can be smaller than a conventional oven used to cure the substrate, since less thermal energy is required to heat the substrate to the curing temperature. Additionally, as discussed above, the second radiant oven 145 and the second convection oven 150 can accommodate the high processing / line speeds of the transport system 106. Thus, the combined use of the second radiant oven 145 and the second convection oven 150 allows for a smaller mechanical footprint (e.g., smaller length (L) 102) than conventional powder coating lines, while simultaneously accommodating higher throughput (e.g., processing more substrates 101) and higher line speeds (e.g., higher lateral speeds of the transport system 106) than conventional powder coating techniques.

[0061] The powder coating system 100 includes a cooling tunnel 155. After being held in the second convection oven 150 for a period of time to effectively cure the powder coating on the substrate 101, the substrate 101 travels around the transport system 106 to the cooling tunnel 155. The cooling tunnel 155 can be a tunnel that utilizes forced convection cooling to rapidly cool the cured substrate 101. For example, the cooling tunnel 155 can be a box-shaped (or dome-shaped) tunnel, while cool air is forced (e.g., by a blower, fan, etc.) into the cooling tunnel 155, and convection heat transfer, supplied by the temperature difference between the powder coated substrate 101 and the air, rapidly cools at least the surface of the powder coated substrate 101 to a temperature that allows stacking and / or handling of the powder coated substrate 101. For example, the cooling tunnel 155 can cool the powder coated substrate 101 from a curing temperature of 280-325 degrees Fahrenheit to 100 degrees Fahrenheit in a very short period of time. In this case, the cooling tunnel design may allow for high line speeds / processing rates of the powder coating system 100.

[0062] The powder coating system 100 includes an outfeed 160. The outfeed 160 may be the point where the powder coated substrates 101 exit the powder coating system 100 and thus may be the exit point of the transport system 106. After being cooled by the cooling tunnel 155, the outfeed 160 may offload the powder coated substrates 101 and stack the powder coated substrates 101 for shipping. In this case, the offloading may be done by a manual process, an automatic process, or a combination of manual and automatic processes, and stacking may result in palletized powder coated substrates 101 ready for shipping. In this case, the substrates 101 may be offloaded by the outfeed 160 in a horizontal (e.g., flat) orientation. The outfeed 160 allows for high speed processing of the substrates 101, however, the amount (e.g., quantity) of substrates 101 offloaded by the outfeed 160 may be based on the processing speed of the powder coating system 100. In this case, the outfeed 160 may be designed to offload the powder coated substrate 101 at line speeds in excess of 100 feet per minute.

[0063] As previously described, the in-feed 105, conveying system 106, first radiant oven 110, first convection oven 115, powder application system 120, second radiant oven 145, second convection oven 150, cooling tunnel 155, and out-feed 160 may be used in combination to powder coat a heat-sensitive substrate in a horizontal (flat) orientation at higher line speeds (e.g., line speeds of 100 feet per minute or more) and over smaller areas (e.g., shorter longitudinal lengths 102) than conventional powder coating techniques. However, it should be understood that powder coating system 100 need not necessarily include all of the features of in-feed 105, conveying system 106, first radiant oven 110, first convection oven 115, powder application system 120, second radiant oven 145, second convection oven 150, cooling tunnel 155, and out-feed 160, but rather can include only some of these features and still achieve the advantageous high speed processing of horizontally oriented heat-sensitive substrates described in connection with each individual component.

[0064] Thus, while particular embodiments of the invention have been described above for purposes of illustration, it will be apparent to those skilled in the art that many changes can be made in the details of the invention without departing from the invention as defined in the appended claims.

Claims

1. 1. A system for applying a powder coating to a heat sensitive substrate, the system comprising: at least one radiant oven; at least one convection oven; a powder application system comprising a plurality of powder application devices configured to apply powder to at least a top surface of the heat-sensitive substrate while the heat-sensitive substrate is oriented in a horizontal orientation.

2. 10. The system of claim 1, wherein the at least one radiant oven is positioned in front of the powder application device and configured to pre-heat the heat sensitive substrate prior to the application of the powder.

3. 3. The system of claim 1 or 2, wherein the at least one radiant oven preheats the heat-sensitive substrate for 30 seconds or less.

4. The system of any one of claims 1 to 3, wherein the at least one radiant oven preheats the heat-sensitive substrate with infrared radiation.

5. 5. The system of claim 1, wherein the at least one radiant oven comprises a first radiant oven and a second radiant oven, the first radiant oven being positioned before the powder application system and the second radiant oven being positioned after the powder application system.

6. 6. The system of claim 5, wherein the first radiant oven is configured to pre-heat the heat sensitive substrate prior to the application of the powder and the second radiant oven is configured to heat the heat sensitive substrate to a curing temperature after the application of the powder.

7. 7. The system of claim 5 or 6, wherein the first radiant oven preheats the heat-sensitive substrate with infrared radiation for 30 seconds or less and the second radiant oven heats the heat-sensitive substrate with infrared radiation for 30 seconds or less.

8. 8. The system of claim 1, wherein the at least one convection oven is positioned in front of the powder application device and configured to heat the heat sensitive substrate prior to the application of the powder.

9. The system of any one of claims 1 to 8, wherein the at least one convection oven heats the heat-sensitive substrate for four minutes or less.

10. The system of any one of claims 1 to 9, wherein the at least one convection oven heats the heat-sensitive substrate by thermal convection heating.

11. 11. The system of any one of claims 1 to 10, wherein the at least one convection oven comprises a first convection oven and a second convection oven, the first convection oven being positioned before the powder application system and the second convection oven being positioned after the powder application system.

12. 12. The system of claim 10 or 11, wherein the first convection oven is configured to heat the heat sensitive substrate to a powder coating temperature prior to the application of the powder, and the second convection oven is configured to heat the heat sensitive substrate to a curing temperature after the application of the powder.

13. 13. The system of claim 10, wherein a first convection oven heats the heat-sensitive substrate for no more than 4 minutes and wherein the second radiant oven heats the heat-sensitive substrate for no more than 12 minutes.

14. the at least one radiant oven comprising a first radiant oven positioned in front of the powder application system and a second radiant oven position after the powder application system; the at least one convection oven comprising a first convection oven location in front of the powder application system and a second convection oven located after the powder application system; the first radiant oven and the first convection oven are configured to combine to heat the heat-sensitive substrate prior to the application of the powder; 10. The system of claim 1, wherein the second radiant oven and the second convection oven are configured to in combination heat the heat-sensitive substrate after the application of the powder.

15. 15. The system of claim 14, wherein the first radiant oven is configured to preheat the heat sensitive substrate and the first convection oven is configured to heat the preheated heat sensitive substrate to a powder coating temperature prior to the application of the powder.

16. 16. The system of claim 14 or 15, wherein the second radiant oven and the second convection oven are configured to heat the heat sensitive substrate to a curing temperature after the application of the powder.

17. 17. The system of any one of claims 1 to 16, wherein the plurality of powder application devices comprises a first type powder application device and a second type powder application device, both of the first type powder application device and the second type powder application device configured to apply the powder to the top surface of the heat sensitive substrate.

18. 18. The system of claim 17, wherein the first type of powder application device comprises a first plurality of powder applicators and the second type of powder application device comprises a second plurality of powder applicators, the first type of powder applicators having an applicator diameter less than an applicator diameter of the second plurality of powder applicators.

19. 19. The system of claim 17 or 18, wherein the first type of powder application device applies the powder at a higher density than the second type of powder application device.

20. 20. The system of any one of claims 17 to 19, wherein the first type of powder application device is configured to apply the powder prior to the application of the powder by the second type of powder application device.

21. The system of any one of claims 17 to 20, wherein the plurality of powder application devices further comprises a third type of powder application device configured to apply the powder to a side of the heat-sensitive substrate.

22. 1. A method for applying a powder coat to a heat sensitive substrate, the method comprising: Conveying the substrate in a horizontal direction at a first conveying speed; radiating heating the substrate in a horizontal orientation at the first transport speed; convectively heating the substrate in the horizontal orientation at a second conveying speed, the second conveying speed being less than the first conveying speed; applying a powder to said substrate in said horizontal orientation.

23. 23. The method of claim 22, wherein the first conveying speed is greater than 100 feet per minute.

24. 24. The method of any one of claims 22 or 23, wherein the substrate is preheated by radiative heating for 30 seconds or less prior to the application of the powder.

25. The method of any one of claims 22 to 24, wherein the substrate is convection heated for no more than 4 minutes prior to the application of the powder.

26. 26. The method of any one of claims 22 to 25, wherein the substrate is radiatively heated prior to the convection heating, and the substrate is convectionally heated prior to the application of the powder.

27. 27. The method of any one of claims 22 to 26, wherein the substrate is heated by radiative heating for 30 seconds or less after the application of the powder.

28. 28. The method of any one of claims 22 to 27, wherein the substrate is convection heated for no more than 12 minutes after the application of the powder.

29. A method according to any one of claims 22 to 28, wherein the substrate is radiatively heated after the application of the powder and before the convective heating.

30. The convection heating comprises: conveying the substrate laterally over a lateral distance; stacking the substrate with respect to one or more additional substrates; conveying the stacked substrates vertically; and holding the substrate stationary during a residence time.

31. 31. The method of claim 30, wherein the second conveying speed includes each of the lateral conveying, the stacking, the vertical conveying, and the holding of the substrate during the residence time.

32. 32. The method of any one of claims 22-31, wherein the application of the powder comprises a first powder application and a second powder application, the first powder application applying powder to a top side of the substrate and the second powder application applying powder to a side of the substrate.

33. 33. The method of claim 32, wherein the first powder application comprises applying a first layer of powder and a second layer of powder, the first layer of powder being applied more densely than the second layer of powder.

34. The method of any one of claims 22 to 33, wherein the powder coat is applied to the substrate at a linear speed in the range of 50 to 125 feet per minute.

35. The method of any one of claims 22 to 32, wherein the powder coat is applied to the substrate at a linear speed of 100 feet per minute or greater.

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