Patent Publication Number: US-2009217524-A1

Title: Method and apparatus for manufacturing a honeycomb article

Description:
BACKGROUND 
     The present disclosure relates generally to a honeycomb article, a method of manufacturing the honeycomb article, and an apparatus for manufacturing the honeycomb article. More particularly, the disclosure relates to a method and apparatus for manufacturing a honeycomb article having an after-applied skin layer. 
     The use of honeycomb articles as filters for removing particulates (e.g., soot) from engine exhaust gases, and as substrates for supporting catalytic materials for purifying engine exhaust gases is well known. A particulate filter body may be, for example, a honeycomb article having a matrix of intersecting thin, porous walls that extend across and between its two opposing open end faces and form a large number of adjoining hollow passages, or cells, which also extend between and are open at the end faces. To form a filter, a first subset of cells is closed at one end face, and the remaining cells are closed at the other end face. A contaminated gas is brought under pressure to one face (the “inlet face”) and enters the filter body via the cells that are open at the inlet face (the “inlet cells”). Because the inlet cells are sealed at the remaining end face (the “outlet face”) of the body, the contaminated gas is forced through the thin, porous walls into adjoining cells that are sealed at the inlet face and open at the opposing outlet face of the filter body (the “outlet cells”). The solid particulate contaminants in the exhaust gas (such as soot), which are too large to pass through the porous openings in the walls, are left behind, and cleaned exhaust gas exits the outlet face of the filter body through the outlet cells. A substrate for supporting catalytic materials may similarly be a honeycomb article having a matrix of intersecting walls that extend across and between its two opposing open end faces and form a large number of adjoining hollow passages, or cells, which also extend between and are open at the end faces. The walls are coated with a catalytic material selected to reduce the amount of carbon monoxide (CO), nitrogen oxides (NOx), and/or unburned hydrocarbons (HC) in the exhaust gas as the exhaust gas passes through the cells. 
     Such honeycomb articles are typically formed by an extrusion process where a ceramic material is extruded in a green (uncured) form before the green form is fired to form the final ceramic material of the honeycomb structural article. Generally, as a function of the extrusion process, a solid external surface, or skin, is provided along the length of the extruded form. The extruded green forms can be any size or shape. However, the green forms have relatively low mechanical strength. When made sufficiently large, the extruded green forms may suffer damage or defects at the outer peripheral portion of the form due to, for example, the weight of the article itself causing cells in the outer peripheral portion of the form to collapse or deform, or causing cracks in the skin. 
     In view of the above, the outer peripheral portion (e.g., the skin and one or more cell layers) of the honeycomb article may be removed, typically after firing of the green form, so as to remove the deformed cells and to provide the honeycomb article with a desired size and shape. A new layer of material may then be applied using techniques known in the art to provide a solid external surface, or skin, along the length of the article. However, the process of forming of the after-applied skin may leave undesired artifacts on the surface of the skin that require further processing steps to remove. It would be advantageous to reduce the formation of undesirable artifacts on the after-applied skin and thereby reduce the processing steps needed to produce a finished honeycomb article. 
     SUMMARY 
     In one aspect, the invention provides a method of manufacturing a honeycomb article. In one implementation, the method comprises the steps of fixing a honeycomb body between a first support member and a second support member, the first support member positioned against a first end of the honeycomb body and the second support member positioned against a second end of the honeycomb body; applying a skin layer to the honeycomb body, wherein a first edge of the skin layer contacts the first support member and a second edge of the skin layer contacts the second support member; heating at least one of the first edge and the second edge of the skin layer; and thereafter removing the honeycomb body with the applied skin layer from between the first and second support members. 
     In another aspect, the present invention provides an apparatus for manufacturing a honeycomb article. In one implementation, the apparatus comprises a first support member and an opposed second support member, the first and second support members configured to hold a honeycomb body therebetween; an applicator configured to apply a skin layer to the honeycomb body, wherein a first edge of the skin layer contacts the first support member and a second edge of the skin layer contacts the second support member; and a heat source configured to heat at least one of the first edge and the second edge of the skin layer. 
     Additional features will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings. 
     It is to be understood that both the foregoing general description and the following detailed description present embodiments according to the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments according to the invention and together with the description serve to explain the principles and operations of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective illustration of a honeycomb article fabricated using conventional methods. 
         FIG. 2  is a perspective illustration of a honeycomb body after the honeycomb article of  FIG. 1  has been shaped and the outer skin removed. 
         FIG. 3  is a perspective illustration of a honeycomb body with an after-applied skin. 
         FIG. 4  is a schematic illustration of an apparatus for manufacturing a honeycomb article with an after-applied skin according to the invention. 
         FIG. 5  is an illustration of pull residue on an after-applied skin of a honeycomb article. 
         FIG. 6  is a flowchart illustrating a method of manufacturing a honeycomb article according to the invention. 
         FIG. 7  is an illustration of one embodiment of a support member for use with the apparatus of  FIG. 6  to reduce pull residue on an after-applied skin. 
         FIG. 8  is an illustration of another embodiment of a support member for use with the apparatus of  FIG. 6  to reduce pull residue on an after-applied skin. 
         FIG. 9  is an illustration of yet another embodiment of a support member for use with the apparatus of  FIG. 6  to reduce pull residue on an after-applied skin. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to embodiments according to the invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts. 
     Honeycomb articles used for solid particulate filtering, catalytic substrates, and other applications may be formed from a variety of porous materials including ceramics, glass-ceramics, glasses, metals, cements, resins or organic polymers, papers, or textile fabrics (with or without fillers, etc.), and various combinations thereof. Honeycomb articles having uniformly thin, porous and interconnected walls for solid particulate filtering applications are preferably fabricated from plastically formable and sinterable substances that yield a porous, sintered material after being fired to affect their sintering, such as metallic powders, ceramics, glass-ceramics, cements, and other ceramic-bases mixtures. According to certain embodiments, honeycomb articles may be formed from a porous ceramic material, such as cordierite, silicon carbide, or aluminum titanate. Cordierite is a synthetic ceramic composition (2MgO-2Al 2 O 3 -5SiO 2 ) having a very low thermal expansion coefficient, which makes the material resistant to extreme thermal cycling. Cordierite also exhibits high temperature resistance (˜1200° C.) and good mechanical strength. 
     One embodiment of an extruded honeycomb article is shown in  FIG. 1 , and is designated generally throughout by the reference numeral  10 . Honeycomb article  10  has a first end face  12 , a second end face  14 , and a plurality of hollow, open-ended channels or cells  16  that extend in a generally parallel fashion through honeycomb article  10 . Cells  16  are open at end faces  12 ,  14  of honeycomb article  10 , and are formed by a matrix of intersecting walls  18  that extend between end faces  12 ,  14 . Walls  18  have porosity suitable for the intended application of the honeycomb article (e.g., a filter or substrate), and may have either a uniform thickness or a non-uniform thickness, depending upon the intended application. The thickness and spacing of walls  18  are selected to provide a density of cells  16  as is desired for the intended application. In some applications, cell  16  density is in the range of 100-900 cells per square inch, although cell densities lower and higher than that range may also be used. An outer wall or skin  20  extends between end faces  12 ,  14 , bounding cells  16  and walls  18 . As used in this disclosure, the term “honeycomb article” is intended to include articles having a generally honeycomb structure and is not limited to articles with cells  16  having a generally square cross-sectional shape. For example, hexagonal, octagonal, triangular, square, rectangular, circular, oval, or any other suitable cell shape may be used. It should be noted that the relative dimensions of cells  16 , walls  18  and skin  20  are not to scale. 
     As described above, in some circumstances honeycomb article  10  is contoured or shaped after it is extruded (and before or after drying and firing of the green form) so as to remove deformed cells  16  and/or to provide a desired size and shape to the contoured article. Contouring or shaping of honeycomb article  10  can be accomplished by any means known in the art, including cutting or grinding away the exterior surface or skin  20  of honeycomb article  10  until the desired shape and size is reached. The final peripheral shape of the may be any possible shape, for example, round, oval, and the like. 
       FIG. 2  illustrates an embodiment of a honeycomb body  30  resulting from contouring or shaping honeycomb article  10 . As used herein, the term “honeycomb body” generally refers to a honeycomb article  10  to which an after-applied skin  120  (described below) is applied. The honeycomb body  30  retains a multiplicity of cells  16  defined by walls  18 . However, all or a portion of the outer wall or skin  20  of honeycomb article  10 , as shown in  FIG. 1 , may be removed during a shaping or contouring operation such that cells  16  at the periphery of the shaped honeycomb body  30  are open along the length of the body  30 . It should be noted that, although embodiments according to the invention are described herein with reference the application of an after-applied skin  120  to a honeycomb body  30  (from which all or a portion of the original skin  20  has been removed), the teachings of this disclosure are equally applicable to the application of an after-applied skin  120  over an existing skin  20 , such as may be required to bring a honeycomb article  10  to a desired size. Accordingly, use of the term “honeycomb body” should be understood to include bodies from which all, a portion, or none of the originally extruded skin  20  has been removed. 
     Referring now to  FIG. 3 , after honeycomb article  10  is shaped (and optionally dried and fired), a new external skin (i.e., an after-applied skin)  120  is applied to honeycomb body  30  to form a honeycomb article  110 . The after-applied skin  120 , as shown in  FIG. 3 , can be of any material known in the art. By way of example, the honeycomb body  30  can be comprised of cordierite, aluminum titanate, SiC, or other ceramic materials, or combinations thereof. After-applied skin  120  can comprise material that is compatible with the material of the honeycomb body  30 . For example, although not required, after-applied skin  120  can comprise material that is substantially identical to the material of the honeycomb body  30 . In one embodiment, after-applied skin  120  is a material that is primarily cordierite, with organic and/or inorganic binder components. In one embodiment, the after-applied skin  120  is applied after honeycomb body  30  has been fired and shaped to a desired shape and size. 
     In  FIG. 3 , selected ones of cells  16  of honeycomb article  110  have been blocked to form a filter body. The filter body may be formed by plugging, covering or otherwise blocking the open ends of a subset of cells  16  at one end face  12  of the structure, and further blocking all or a portion of the remaining cells  16  at the opposing end face  14  of the structure. In the exemplary embodiment shown in  FIG. 3 , alternate cells  16  have been blocked with plugs  28  at end face  12  in an exemplary checkerboard pattern. In one embodiment, the plugging pattern on end face  14  (hidden in  FIG. 3 ) is the reverse of that depicted on end face  12 . Alternate plugging patterns may be implemented in other embodiments. Selected cells  16  are plugged with a suitable plugging material, such as a sealant or cement mass, which extends from near end faces  12 ,  14  a short distance into cell  16 . Plugs  28  may be formed by any means known in the art. After forming, the sealant or cement forming plugs  28  is cured by any method suitable for the particular material selected so as to form a seal that will substantially block the flow of the gas being filtered. The result is a pattern of plugs arranged on inlet end  12  and outlet end  14  so that contaminate laden gas (such as engine exhaust gas) flows into the filter body, into the filter cells that are not plugged at inlet face  12 , through the porous walls  18  of cells  16 , and out of the filter body through cells  16  which are not plugged at outlet face  14 . 
       FIG. 4  schematically represents an apparatus  200  for manufacturing honeycomb article  110  according to the present invention, and specifically for applying after-applied skin  120  to honeycomb body  30 . The apparatus  200  may be used to apply skin  120  to a wide variety of honeycomb bodies  30 , particularly honeycomb bodies  30  comprised of ceramic or ceramic-forming material(s). The honeycomb bodies  30  can be formed into a flow through substrate (e.g., catalyst support) or filter, such as a particulate filter (e.g., comprising a plugged honeycomb body which may include alternately plugged channels). 
     Apparatus  200  includes a first support member  202  having a peripheral edge  204  and configured to rotate about a first longitudinal axis  206 , and a second support member  212  having a peripheral edge  214  and configured to rotate about a second longitudinal axis  216 . In the illustrated embodiment, first longitudinal axis  206  and second longitudinal axis  216  are coaxial, although the first and second longitudinal axis  206 ,  216  may be differently aligned in some applications, as is known in the art. As illustrated, first and second support members  202 ,  212  comprise plate-like structures, although other structural arrangements may also be used, such as hub and spoke arrangements, lattice structures, and the like. In addition, although support members  202 ,  212  are illustrated as having circular shapes, other shapes may be used in different embodiments. For instance, the peripheral shape of support members  202 ,  212  can comprise an oval shape, elliptical shape or other shape that may depend on the shape of a honeycomb body  30  being coated by apparatus  200 . 
     In use, a honeycomb body  30  is fixed between first and second support members  202 ,  212 . The fixation can be provided by compressing honeycomb body  30  between support members  202 ,  212 . Once compressed, the position of honeycomb body  30  is maintained by friction between the upper surface of the honeycomb body  30  and the lower surface of the second support member  212  and friction between the lower surface of the honeycomb body  30  and the upper surface of the first support member  202 . Once fixed, the outer peripheral surface of honeycomb body  30  is recessed with respect to the peripheral edges  204 ,  214  of first and second support members  202 ,  212 , respectively. 
     Apparatus  200  further includes an applicator  220  configured to apply skin layer  120  to the outer peripheral surface of honeycomb body  30 . Applicator  220  can comprise a wide variety of configurations to apply the material forming skin layer  120  in different ways, as are known in the art. For example, applicator  220  can comprise a nozzle  222  or other material dispensing device, and a knife  224 . The knife can be configured to simultaneously engage the peripheral edge  204 ,  214  of support members  202 ,  212 , respectively, when applying the material of skin  120  to the outer peripheral surface of honeycomb body  30 . As shown, first support member  202 , second support member  212 , and honeycomb body  30  fixed therebetween are rotated together in the direction of arrow  230  with respect to the applicator  220 . In another embodiment, applicator  220  can be designed to rotate while support members  202 ,  212  and honeycomb body  30  remain stationary. 
     As will be understood by those of skill in the art, wet ceramic material is deformable. The term “wet” for the purposes of this disclosure, means a material that has not been fired, dried, sintered, calcined or otherwise exposed to a treatment which causes the material to harden. Thus, as applicator  220  dispenses wet material to form skin  120  and knife simultaneously engages the peripheral edges  204 ,  214  of support members  202 ,  212 , respectively, the wet material is deformed and spread over honeycomb body  30  so as to be maintained in the space between knife, honeycomb body  30 , first support member  202  and second support member  212 . A skin  120  of substantially uniform thickness and having an outer peripheral shape matching that of peripheral edges  204 ,  214  is thus formed. 
     After skin  120  is formed over honeycomb body  30 , the honeycomb article  110  must be removed from apparatus  200 , and from support members  202 ,  212 , in particular. However, removing the honeycomb article  110  from support members  202 ,  212  may leave undesired artifacts. In particular, the wet material of skin  120  may be tacky and stick to support members  202 ,  212  such that when support members  202 ,  212  are pulled away, some of the wet material of after-applied skin  120  may deform and pull away from the skin  120 , leaving behind pull residue on the edges  122 ,  124  of skin  120  that are in contact with first and second support members  202 ,  212 , respectively.  FIG. 5  illustrates pull residue  126  on an edge of skin  120 . For the purposes of this disclosure, the term “pull residue” means deformation of skin  120  caused by the removal of one or both of support members  202 ,  212  from skin  120 . In most instances, this pull residue is removed by further processing steps, including cutting, smoothing, grinding or polishing, or any other technique or combination of techniques well known in the art. However, it would be desirable if the need for such additional processing steps (and their accompanying costs) was reduced or eliminated. 
     Accordingly, as illustrated in  FIG. 4 , apparatus  200  additionally includes at least one heat source  240 . Heat source  240  is configured to heat and thereby dry at least one of first edge  122  and second edge  124  of skin layer  120  (shown in section in  FIG. 4 ) at the interface with support members  202 ,  204  after wet material forming skin layer  120  has been applied to honeycomb body  30  by applicator  220 , and before the honeycomb article  110  is removed from support members  202 ,  212 . Heating edges  122 ,  124  reduces the adhesion of the wet material to support members  202 ,  212  by drying, or partially drying, the wet material, such that pull residue on edges  122 ,  124  of skin  120  is reduced or eliminated when honeycomb article  110  is removed from support members  202 ,  212 . More specifically, drying or partially drying the wet material by heating at one or both of edges  122 ,  124  results in a high cohesive strength in the material and a high adhesive force between the dried edges  122 ,  124  and the underlying matrix of honeycomb body  30 , thereby overcoming the adhesive force between skin  120  and support members  202 ,  212  and providing smooth edges  122 ,  124  on skin  120 . 
     Heat source  240  can comprise a wide variety of heat sources, as are known in the art. In one embodiment, heat source  240  comprises a directed flow of heated air, wherein the air is heated by any suitable means. In one embodiment, air heated to a temperature in the range of about 750° F. to about 1150° F. and having a flow rate in the range of about 250 SLPM (standard liters per minute) to about 400 SLPM is directed toward one or both edges  122 ,  124  of skin  120 . In another embodiment, heat source  240  comprises a radiant heat source, such as an infrared heat source, configured to heat one or both edges  122 ,  124  of skin  120 . In one embodiment, heat source  240  indirectly heats edges  122 ,  124 , such as by heating all or a portion of at least one of first and second support members  202 ,  212 , which in turn heats the adjacent edge  122 ,  124 . In one embodiment, heat source  240  is activated after the application of skin  120  is completed. In another embodiment, heat source  240  is activated before the application of skin  120  is completed. 
     In one embodiment, heat source  240  is configured to heat edges  122 ,  124  of skin  120  over as wide of arc of skin  120  as is practical for the particular configuration of apparatus  200 . A wider application of heat to edges  122 ,  124  generally allows faster drying of edges  122 ,  124 , and also reduces thermal gradients within skin  120 , which reduces the possibility of cracking or blistering skin  120  during heating. In one embodiment, heat source  240  is configured to heat the entire circumference of the honeycomb article  110  at the same time (i.e., over a 360° arc of skin layer  120 ). In one embodiment, heat source  240  is configured to heat an arc subtending less than 360° of skin layer  120 . In one embodiment, heat source is configured to heat skin layer  120  at more than one location about the circumference of skin  120 . In one embodiment, heat source  240  is configured to direct heat toward an arc subtending a total of at least about 10° of skin layer  120 . 
     As described above, in one embodiment, first support member  202 , second support member  212 , and honeycomb body  30  fixed therebetween are rotatable together in the direction of arrow  230 . Accordingly, in embodiments where heat source  240  heats an arc subtending less than 360° of skin layer  120 , support members  202 ,  212  and honeycomb article  110  are rotated with respect to heat source  240 , such that the entire circumference of skin  120  is exposed to heat source  240 . In another embodiment, heat source  240  can be designed to rotate while support members  202 ,  212  and honeycomb article  110  remain stationary. 
     A method of manufacturing a honeycomb article  110  is described with reference to the flowchart of  FIG. 6 . At  302 . a honeycomb body  30  is fixed between first and second support members  202 ,  212  such that first support member  202  is positioned against first end  12  of honeycomb body  30  and second support member  212  is positioned against second end  14  of honeycomb body  30 . In one embodiment, honeycomb body  30  has been contoured prior to being fixed between first and second support members  202 ,  204 . At  304 , skin layer  120  is applied to honeycomb body  30 , wherein first edge  122  of skin  120  contacts first support member  202 , and second edge  124  of skin layer  120  contacts second support member  212 . At  306 , at least one of first edge  122  and second edge  124  of skin layer  120  is heated to dry or partially dry the heated edge. In one embodiment, both first and second edges  122 ,  124  are heated. At  308 , honeycomb article  110  (i.e., honeycomb body  30  with skin layer  120  applied thereto) is removed from between the first and second support members  202 ,  212 . Upon removal, the heated edges  122 ,  124  retain the shape and surface contours of the support members  202 ,  212 . For example, when support members are substantially coplanar with ends  12 ,  14  of honeycomb body  30 , edges  122 ,  124  of skin  120  will likewise be substantially coplanar with ends  12 ,  14  of honeycomb body  30 . Similarly, if support members  202 ,  212  are shaped to provide a bevel or chamfer at edges  122 ,  124 , edges  122 ,  124  will retain the shape and texture of shaped support members  202 ,  212 . 
     Apparatus  200  in general, and heat source  240  in particular is controlled to prevent cracking or blistering of skin  120  during heating. Accordingly, the parameters for heating and drying of skin  120  (in terms of, for example, temperature of heat source  240 , temperature of skin  120 , exposure time of skin  120  to heat source  240 , and the like) are selected according to the properties of the material forming skin  120 . In general, higher temperatures require shorter heating times, but increase the possibility of cracking or blistering skin  120 . In one embodiment, the temperature of the heated edge  122 ,  124  is maintained below about 110° F. In one embodiment, the temperature of the heated edge  122 ,  124  is maintained in a range from about 85° F. to about 110° F. 
     In one embodiment, heat source  240  heats one or both of edges  122 ,  124  until the adhesion of the heated edge of skin  120  to the underlying honeycomb body  30  exceeds the adhesion between the heated edge  122 ,  124  and the support member  202 ,  212 . In one embodiment, heat source  240  heats one or both edges  122 ,  124  until the heated edge is substantially dry. Drying of the material forming skin  120  may be indicated, for example, by a material color change. In one embodiment, one or both of edges  122 ,  124  are heated until approximately 0.5 cm to 1.5 cm of skin  120  (as measured from the nearest support member  202 ,  212 ) is dried or adhered to the underlying honeycomb body  30 . 
     In one embodiment, the use of one or more heat sources  240  may be combined with other devices and methods for reducing pull residue. For example,  FIG. 7  illustrates one embodiment of a support member  212  having a nonstick or release layer  250  to reduce pull residue. A nonstick layer  250  may be formed from silicone, polytetrafluoroethylene (PTFE or Teflon®), ultra high molecular weight polyethylene (UHMW), or other known materials suitable for the purpose. A release layer  250  may include a sprayed on or introduced layer of release material such as silicon, starch, or oil. Use of release or nonstick layer  250  decreases the amount of heating and drying of edges  122 ,  124  required to reduce pull residue. 
     In one embodiment, as illustrated in  FIGS. 8 and 9 , one or more of support members  202 ,  212 , and/or nonstick or release layer  250 , may be shaped to provide a bevel or chamfer  252  to edges  122 ,  124  of skin  120 . Chamfered edges  122 ,  124  provide protection from chipping and flaking damage at the edges  122 ,  124 . As noted above, the heated edges  122 ,  124  substantially retain the shape and surface contours of the support members  202 ,  212  when removed therefrom, without unwanted pull residue. Accordingly, support members  202 ,  212  and/or nonstick or release layer  250  may be shaped such that edges  122 ,  124  of skin  120  will be chamfered in a desired profile when removed from support members  202 ,  212 . 
     Where honeycomb body  30  has been fired prior to the application of after-applied skin  120 , and it is not desirable to expose the fired sintered honeycomb body  30  to another high-temperature firing, it may be desirable to expose after-applied skin  120  to a drying step by exposing the honeycomb body  30  with after-applied skin  120  to temperatures that are not as severe as those used for a firing/sintering step, for example, temperatures below 300° C. 
     The foregoing description of the specific embodiments reveals the general nature of the invention that others can, by applying knowledge within the skill of the art, readily modify and/or adapt for various applications such specific embodiments, without undue experimentation and without departing from the general concept of the present invention. Such adaptations and modifications, therefore, are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance presented herein, in combination with the knowledge of one of ordinary skill in the art. 
     EXAMPLES 
     The invention will be further clarified by the following examples, in which honeycomb bodies (200 cells/in 2 ; 31 cells/cm 2 ) each having a diameter of approximately 12 inches (30 cm) and a length of 12 inches (30 cm) were fixed between support members and prepared with a skin layer formed of a cordierite-based material having a thickness of approximately 1 mm. A manifold was configured to direct heated air toward one edge of the skin at its interface with a support member, with the manifold covering approximately 10 cm of the circumference of the skin layer. The skinned articles were rotated past the manifold at a rotational speed of approximately 10 rpm. 
     Without any heating, removal of the support member resulted in visible pull residue on the edge of the skin. With heating, each of the following combinations of air temperature, air flow rate (in standard liters per minute) and drying time resulted in no visible pull residue when removing the support member from the honeycomb article. 
     
       
         
           
               
               
               
               
             
               
                   
               
               
                   
                   
                   
                 Drying time 
               
               
                 Sample No. 
                 Air Temp (° F.) 
                 Air Flow Rate (SLPM) 
                 (seconds) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 1 
                 935 
                 300 
                 15 
               
               
                 2 
                 935 
                 300 
                 10 
               
               
                 3 
                 1100 
                 250 
                 15 
               
               
                 4 
                 1100 
                 300 
                 30 
               
               
                 5 
                 1100 
                 300 
                 8 
               
               
                 6 
                 970 
                 300 
                 8 
               
               
                 7 
                 970 
                 300 
                 5 
               
               
                   
               
            
           
         
       
     
     It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.