Abstract:
A method of manufacturing an article of footwear includes providing a powder including a plurality of particles each comprising ethylene vinyl acetate, delivering the powder to a cavity of a mold, the mold being at an elevated temperature, pressing the powder in the cavity of the mold between the mold and a counter-mold, the counter-mold being at an elevated temperature, to fuse the particles of the powder and thereby provide a first portion of the article of footwear, removing the first portion of the article of footwear from the cavity of the mold, cooling the first portion of the article of footwear, providing a second portion of the article of footwear, and coupling the first portion of the article of footwear to the second portion of the article of footwear.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/790,840, filed on Mar. 15, 2013, which is incorporated by reference herein in its entirety for all purposes. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to methods of manufacturing an article of footwear. More specifically, the present invention relates to methods of manufacturing an article of footwear that includes sintering a copolymer powder to form one or more components of the article of footwear. 
       BACKGROUND 
       [0003]    Various types of articles of footwear include one or more components formed via injection molding processes to provide various advantageous characteristics. For example, many types of soles are formed via injection molding to facilitate relative comfort. 
         [0004]    Unfortunately, components formed in such a manner also have various disadvantages. For example, forming footwear components via injection molding processes, like many injection molding processes, involves removing a significant amount of excess material from the components. In many cases, the excess material takes the form of molded features formed in passageways that deliver molten material to an injection molding cavity (commonly referred to as “sprues”, “runners”, and “gates”). This excess material significantly increases the cost associated with manufacturing these components and the associated articles of footwear. 
         [0005]    As another example, it is typically difficult for injection molding processes to provide footwear components having appropriate mechanical characteristics, such as hardness or the like. Similarly, it is typically difficult for injection molding processes to provide features having intricate shapes, such as gripping features disposed on the lower surface of a sole. 
       SUMMARY 
       [0006]    A method of manufacturing an article of footwear according to some embodiments of the present invention includes collecting excess material from a manufacturing process after the excess material has undergone an injection molding process, wherein the excess material comprises ethylene vinyl acetate, processing the excess material to form powder, delivering the powder to a cavity of a mold, applying pressure to the powder in the cavity of the mold using a counter-mold, and heating the powder in the cavity of the mold to thereby, together with applying pressure to the powder using the counter-mold, fuse the particles of the powder and form a portion of the article of footwear. 
         [0007]    A method of manufacturing an article of footwear according to some embodiments of the present invention includes providing a powder including a plurality of particles each comprising ethylene vinyl acetate, delivering the powder to a cavity of a mold, the mold being at an elevated temperature, pressing the powder in the cavity of the mold between the mold and a counter-mold, the counter-mold being at an elevated temperature, to fuse the particles of the powder and thereby provide a first portion of the article of footwear, removing the first portion of the article of footwear from the cavity of the mold, cooling the first portion of the article of footwear, providing a second portion of the article of footwear, and coupling the first portion of the article of footwear to the second portion of the article of footwear. 
         [0008]    A method of manufacturing an article of footwear according to some embodiments of the present invention includes providing a powder including a plurality of particles each comprising ethylene vinyl acetate, delivering the powder to a cavity of a mold, applying pressure to the powder in the cavity of the mold using a counter-mold, heating the powder in the cavity of the mold to thereby, together with applying pressure to the powder using the counter-mold, fuse the particles of the powder and form a first portion of the article of footwear, removing the first portion of the article of footwear from the cavity of the mold, cooling the first portion of the article of footwear, providing a second portion of the article of footwear, and coupling the first portion of the article of footwear to the second portion of the article of footwear. 
         [0009]    While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  illustrates an exemplary method of manufacturing an article of footwear according to embodiments of the present invention; 
           [0011]      FIG. 2  illustrates a partial perspective view of an exemplary article of footwear manufactured according to the method of  FIG. 1 ; 
           [0012]      FIG. 3  illustrates a copolymer powder used by the method of  FIG. 1 ; 
           [0013]      FIG. 4  illustrates a partial perspective view of an elevated temperature mold used by the method of  FIG. 1 ; 
           [0014]      FIG. 5  illustrates a partial side sectional view of the mold along line  5 - 5  of  FIG. 4 ; 
           [0015]      FIG. 6  illustrates a partial side sectional view of the mold along line  5 - 5  of  FIG. 4  receiving the copolymer powder of  FIG. 3 ; 
           [0016]      FIG. 7  illustrates a perspective view of an elevated temperature counter-mold used by the method of  FIG. 1 ; 
           [0017]      FIG. 8  illustrates a bottom view of the counter-mold of  FIG. 7 ; 
           [0018]      FIG. 9  illustrates a partial side sectional view of the mold of  FIG. 4  receiving the powder of  FIG. 3 , and the powder being pressed by the counter-mold of  FIG. 7 ; 
           [0019]      FIG. 10  illustrates a bottom view of an outsole formed by the method of  FIG. 1 ; 
           [0020]      FIG. 11  illustrates a partial perspective view of the outsole of  FIG. 10 ; 
           [0021]      FIG. 12  illustrates a partial side sectional view of the outsole along line  12 - 12  of  FIG. 10 ; 
           [0022]      FIG. 13  illustrates a bottom view of the outsole of  FIG. 10  connected to another portion of the sole of the article of footwear; 
           [0023]      FIG. 14  illustrates another exemplary method of manufacturing an article of footwear according to embodiments of the present invention; 
           [0024]      FIG. 15  illustrates a partial perspective view of an elevated temperature mold used by the method of  FIG. 14 ; 
           [0025]      FIG. 16  illustrates a partial side sectional view of the mold along line  16 - 16  of  FIG. 14  receiving a copolymer powder; 
           [0026]      FIG. 17  illustrates a partial side sectional view of the mold of  FIG. 15  receiving the powder, and the powder being pressed by a counter-mold; 
           [0027]      FIG. 18  illustrates a top view of a panel or sheet formed by the method of  FIG. 14 ; 
           [0028]      FIG. 19  illustrates a partial side sectional view of the sheet along line  19 - 19  of  FIG. 18 ; 
           [0029]      FIG. 20  illustrates a top view of the panel of  FIG. 18  being cut to provide an outer layer of an upper; and 
           [0030]      FIG. 21  illustrates a top view of an inner layer of the upper to be connected to the outer layer of  FIG. 20 . 
       
    
    
     DETAILED DESCRIPTION 
       [0031]      FIG. 1  illustrates an exemplary method of manufacturing the article of footwear  200  shown in  FIG. 2 . The article of footwear  200  may be, for example, a casual shoe as shown in  FIG. 2 , a running shoe, a golf shoe, a walking shoe, a tennis shoe, a molded shoe, a shoe with cleats, a shoe without cleats, a hiking boot, a ski boot, a roller skate shoe, a roller blade shoe, an ice skating shoe, a sandal, or any other kind of shoe or footwear. Generally, the method illustrated in  FIG. 1  includes sintering a powder to form a portion of the article of footwear  200 . In some embodiments, the sintered portion of the article of footwear  200  may be, for example, a portion of the sole  202 , specifically a portion of the outsole  204 . The exemplary method illustrated in  FIG. 1  is described as forming an article of footwear  200  including a sintered outsole  204 . It is to be understood, however, that in some embodiments the sintered portion may be another portion of the article of footwear  200 . 
         [0032]    The method begins at block  100  by obtaining powder  300  (see  FIG. 3 ) that includes a plurality of individual particles  302 . The particles  302  comprise one or more materials, for example, a copolymer resin foam, particularly ethylene vinyl acetate (EVA). A powder including a plurality of particles in which each of the plurality of particles comprises EVA may also be intermixed with other particles which do not comprise EVA or which are not primarily EVA. For example, a plurality of particles in which each of the particles comprises EVA may be intermixed with other particles that are contaminants or other products, but such other products may be of a concentration that is small enough so as to not affect the outcome of the processes described herein. In some embodiments, the particles  302  may be between about 40 mesh to 50 mesh (that is, the particles  302  are sufficiently small to pass through a screen or sieve having a mesh size of about 40 and sufficiently large to be retained by a screen or sieve having a mesh size of about 50). 
         [0033]    The powder  300  may be formed using recycled materials obtained in various manners. In some embodiments, the powder  300  is obtained by first separating excess material (or production “scraps”) from footwear components (for example, clogs, soles, or the like) formed by one or more different manufacturing processes, such as injection molding and the like. In this case, the excess material may be molded features formed in passageways that deliver molten material to an injection molding cavity. These excess injection molding features are commonly referred to as “sprues”, “runners”, and “gates”. The excess material may be processed in various manners, such as grinding, cutting, and the like, to form the powder  300 . 
         [0034]    In some embodiments, the powder  300  is obtained by first receiving excess material produced during manufacture of other types of products including one or more copolymers, such as footwear, furniture, and the like. The other types of products may be formed by one or more different manufacturing processes, such as injection molding and the like. In this case, the excess material may take the form of sprues, runners, and gates as described above. The excess material may be received from other manufacturing lines of the same facility that performs the present methods or other facilities, such as other manufacturing locations of the same corporation, manufacturing locations of one or more different corporations, combinations thereof, and the like. For example, in the manufacture of molded foam footwear from EVA, for example molded clogs having an upper and a sole that are integrally injection molded in EVA, excess EVA material is produced. Normally, only a small portion of such excess material may be recycled or reused in the manufacturing process; for example, in some cases the manufacturing tolerances and quality control parameters may dictate that only 5% by volume of recycled EVA material may be mixed into the stream of new EVA raw material entering the molds. Methods according to embodiments of the present invention permit, for example, one hundred percent of the excess material to be used, though in a different process (sintering) to form a different type of final article. The excess material may be processed in various manners, such as grinding, cutting, and the like, to form the powder  300 . 
         [0035]    In some embodiments, the powder  300  is obtained by first receiving returned products, such as articles of footwear. The products may be, for example, excess inventory returned by a distributor, undesired or defective products returned by an end user, defective products returned by an internal quality control department, used products returned in a recycling program (that is, returning used products upon purchasing a new product), combinations thereof, or the like. Portions of the products that include appropriate copolymer materials, such as the soles, are separated from other portions and may be subjected to intermediate processing steps, such as washing, cleaning, or the like. The portions that include the appropriate copolymer materials may be processed in various manners, such as grinding, cutting, and the like, to form the powder  300 . 
         [0036]    The method continues at block  102  by delivering the powder  300  to a cavity  402  of a mold  400  (shown separately in  FIGS. 4 and 5  and shown with the powder  300  in  FIG. 6 ). The mold  400  includes a plurality of surfaces that define the cavity  402  and together form, in part, the inverse shape of the outsole  204 . The surfaces include side surfaces  404  that together define a perimeter shape of the outsole  204 . For example and as shown in  FIGS. 4 and 5 , the side surfaces  404  may provide a rain drop-like perimeter shape. In some embodiments, the side surfaces  404  may provide various other types of perimeter shapes. In some embodiments, the side surfaces  404  provide a draft angle of at least two degrees to facilitate removal of the outsole  204  from the cavity  402  after sintering. 
         [0037]    The plurality of surfaces also includes a lower surface  406  that defines a lower surface of the outsole  204 . In some embodiments, the lower surface  406  of the mold  400  may include a plurality of features that provide the outsole  204  with the inverse features. On the outsole  204 , such features may serve functional purposes (for example, to provide improved traction) and/or aesthetic purposes. For example and as shown in  FIGS. 4 and 5 , the lower surface  406  includes a plurality of “zig-zag”-shaped grooves or channels  408  disposed between a plurality of zig-zag-shaped protrusions or ridges  410 . The lower surface  406  further includes two linearly-extending protrusions or ridges  412  that together define an “X” shape. In some embodiments, the lower surface  406  of the mold  400  may include various other shapes and/or types of features. 
         [0038]    In some embodiments, the plurality of features defined by the lower surface  406  of the mold  400  may have a height of up to 30 percent of a desired nominal thickness (or height) of the outsole  204 . In some embodiments, the plurality of features defined by the lower surface  406  of the mold  400  may have a height of up to 50 percent of the desired nominal thickness or height of the outsole  204 . 
         [0039]    The mold  400  is at an elevated temperature relative to its environment and the powder  300 . The elevated temperature may be facilitated by a heating system (not shown) coupled to the mold  400 , such as a system including resistive heating elements that extend through or are coupled to the mold  400 . In some embodiments, the elevated temperature is less than the melting temperature of the copolymer material but sufficiently high to cause, when pressure is applied to the powder  300  for a certain time period, atomic diffusion within the powder  300 . This action fuses the particles  302  and forms single-piece component (that is, the powder  300  is sintered). In some embodiments, the elevated temperature is between about 170 and 180 degrees Celsius. 
         [0040]    In some embodiments, the volume of the powder  300  that is delivered to the cavity  402  of the mold  400  depends on the desired volume of the outsole  204 , the desired density of the outsole  204 , and the density of the powder  300 . In some embodiments, the volume of the powder  300  that is delivered to the cavity  402  is determined according to the following equation: 
         [0000]        V   0 =( D   1   /D   0 )· V   1  
 
         [0000]    where 
         [0041]    V 0  is the volume of the powder  300  that is delivered to the cavity  402 ; 
         [0042]    D 0  is the density of the powder  300 ; 
         [0043]    V 1  is the desired volume of the outsole  204 ; and 
         [0044]    D 1  is the desired density of the outsole  204 . 
         [0000]    As an example, the density of the powder  300  may be 0.25 g/cm 3  and the desired density of the outsole  204  may be 0.66 g/cm 3 . Thus, the above equation takes the following form: 
         [0000]        V   0 =2.64 ·V   1    
         [0000]    In some embodiments, the density of the powder  300  and the desired density of the outsole  204  may vary. For example, the density of the powder  300  may vary depending on multiple factors, such as the size of the particles  302  or the like. 
         [0045]    At block  104  and as shown in  FIG. 6 , the method continues by uniformly distributing the powder  300  in the cavity  402  by using, for example, a blade (not shown). That is, the powder  300  is uniformly distributed to ensure that all portions of an upper surface  602  of the powder  300  are disposed at substantially the same elevation. 
         [0046]    The method continues at block  106  by pressing the powder  300  in the mold cavity  402  with a counter-mold  700  (shown separately in  FIGS. 7 and 8  and shown with the mold  400  and powder  300  in  FIG. 9 ). The counter-mold  700  includes a lower surface  702  that applies pressure to the powder  300  in the mold cavity  402 . The lower surface  702  is substantially flat and parallel relative to the lower surface  406  of the mold cavity  402 . This provides the outsole  204  with a substantially uniform thickness (besides any features formed by the lower surface  406  of the mold cavity  402 , such as those formed by the channels  408  and ridges  410 ). 
         [0047]    In some embodiments, the counter-mold  700  further includes vent passageways (not shown) disposed proximate the edges of the counter-mold  700 . The vent passageways receive air that was previously disposed between the particles  302  of the powder  300  when the powder  300  is pressed by the counter-mold  700 . As such, the vent passageways facilitate compacting the powder  300  and displacing the individual particles  302  toward each other. In some embodiments, the vent passageways extend through the lower surface  702  of the counter-mold  700  and vertically through the counter-mold  700 . 
         [0048]    The counter-mold  700  further includes side surfaces  706  that may have substantially the same draft angle as the side surfaces  404  of the mold cavity  402  (for example, at least two degrees). The side surfaces  706  are spaced apart from the side surfaces  404  of the mold cavity  402  to facilitate formation of side walls on the outsole  204 . These side walls are explained in further detail below. 
         [0049]    The counter-mold  700  is at an elevated temperature relative to the environment and the powder  300 . The elevated temperature may be facilitated by a heating system (not shown) coupled to the counter-mold  700 , such as a system including resistive heating elements that extend through or are coupled to the counter-mold  700 . In some embodiments, the elevated temperature of the counter-mold  700  is substantially the same as the elevated temperature of the mold  400 . That is, the elevated temperature of the counter-mold  700  is less than the melting temperature of the copolymer material but sufficiently high to sinter the powder  300 . In some embodiments, the elevated temperature is between about 170 and 180 degrees Celsius. 
         [0050]    The method continues at block  108  by sintering the powder  300  in the mold cavity  402  for a predetermined time period. That is, the counter-mold  700  maintains pressure on the powder  300  in the mold cavity  402  for the predetermined time period. The mold  400  and the counter-mold  700  also heat the powder  300  in the mold cavity  402  via, for example, conductive heat transfer, during the predetermined time period. In some embodiments, the predetermined time period is between about three minutes and five minutes depending on, for example, the dimensions of the outsole  204 . In some embodiments, the force applied to the powder  300  by the counter-mold  700  is about 200 tons. 
         [0051]    After expiration of the predetermined time period and at block  110 , the counter-mold  700  disengages the outsole  204  and the mold  400 . At block  112 , the outsole  204  is removed from the mold cavity  402  and transported to a cooling location (not shown) apart from the mold  400  and counter-mold  700 . The cooling location may take various forms. For example, in some embodiments the cooling location may be the surface of a table that facilitates free convective heat transfer from the heated outsole  204  to the environment. 
         [0052]    The above actions may provide, for example, the outsole  204  illustrated in  FIGS. 10-12 . The outsole  204  includes a main body  1202  (see  FIG. 12 ) having an upper surface  1204  formed by the lower surface  702  of the counter-mold  700 . The upper surface  1204  is substantially flat, although it may include small protrusions (not shown) formed by the vent passageways in the counter-mold  700 . 
         [0053]    The main body  1202  also includes a ground-engaging lower surface  1006  formed by the lower surface  406  of the mold  400 . In some embodiments, the lower surface  1006  of the outsole  204  includes features that may serve functional purposes (for example, to provide improved traction) and/or aesthetic purposes. For example, the lower surface  1006  may include a plurality of plurality of zig-zag-shaped grooves or channels  1008  disposed between a plurality of zig-zag-shaped protrusions or ridges  1010  formed by the inverse features of the lower surface  406  of the mold  400  (that is, the protrusions  410  and grooves  408 , respectively). In some embodiments, the lower surface  1006  of the outsole  204  includes two linearly-extending grooves or channels  1012  formed by the linearly-extending protrusions  412  of the lower surface  406  of the mold  400 . The linearly-extending grooves or channels  1012  together define an “X” shape. 
         [0054]    The thickness of the main body  1202  may be uniform to facilitate uniform mechanical properties for the outsole  204 . In some embodiments including the grooves  1008  and  1012  and the protrusions  1010 , the main body  1202  may be considered to have a uniform thickness if the thickness at all locations on the main body  1202  is within 50 percent of a nominal thickness. In other embodiments including the grooves  1008  and  1012  and the protrusions  1010 , the main body  1202  may be considered to have a uniform thickness if the thickness at all locations on the main body  1202  is within 30 percent of a nominal thickness. In some embodiments, the main body  1202  has a nominal thickness of 6 mm, 4 mm, or 1.5 mm. 
         [0055]    The outsole  204  further includes side walls  1214  (see  FIG. 12 ) formed in the gap between the side surfaces  404  and  706  of the mold  400  and counter-mold  700 . The side walls  1214  extend upwardly from the perimeter of the main body  1202 . The side walls  1214  also extend outwardly (that is, horizontally) from the perimeter of the main body  1202  due to the draft angle of the side surfaces  404  and  706  of the mold  400  and counter-mold  700 . In some embodiments, the side walls  1214  may have a height of at most 50 percent of the nominal thickness of the main body  1202 . 
         [0056]    The outsole  204  may have mechanical properties similar to those of outsoles manufactured using other methods. In some embodiments, the outsole  204  may have a durometer hardness (determined using the ASTM 2240 testing method) of about 82 Asker C, a resilience rebound (ASTM 2632) of about 46 percent, a tensile strength (ASTM D412) of about 60.8 kg/cm 2 , an elongation (ASTM D412) of about 514 percent, an abrasion resistance (DIN 53516) of about 154 mm 3 , and a specific gravity (ASTM D792 B) of about 0.93 g/cm 3 . 
         [0057]    At block  114 , another portion of the article of footwear  200  is provided. The other portion of the article of footwear  200  may be, for example, the upper  206  of the article of footwear  200 , another portion of the sole  202 , such as another portion of the outsole  208  (see  FIG. 2 ) or the midsole (not shown), or the like. The other portion of the article of footwear  200  may be manufactured in various manners. For example and as described in further detail below, if the other portion of the article of footwear  200  is the upper  206 , it may be manufactured in a similar manner as the outsole  204 . As another example, if the other portion of the article of footwear  200  is another portion of the sole  202 , it may be manufactured in an injection molding process. Specifically, the other portion of the sole  202  may be manufactured in the manner described in U.S. Pat. No. 6,439,536, the disclosure of which is hereby incorporated by reference. 
         [0058]    At block  116  and as shown in  FIG. 13 , the outsole  204  is connected to the other portion of the article of footwear  200 . For example, if the other portion of the article of footwear  200  is another portion of the sole  202 , it may be adhered to the outsole  204 . At block  118 , further portions of the article of footwear  200  are provided and connected, such as the upper  206 , laces (not shown), and the like, to form the completed article of footwear  200  (see  FIG. 2 ). 
         [0059]      FIG. 14  illustrates another exemplary method of manufacturing an article of footwear. Like the above method, this method generally includes sintering a powder to form a portion of the article of footwear. In some embodiments, the sintered portion of the article of footwear may be, for example, a layer of the upper  206  (see  FIG. 2 ), specifically an outer layer  210  of the upper  206 . The exemplary method illustrated in  FIG. 14  is described as forming an article of footwear including a sintered outer layer  210  of the upper  206 . It is to be understood, however, that in some embodiments the sintered portion may be another portion of the article of footwear. 
         [0060]    The method begins at block  1400  by obtaining a copolymer powder, which may be as described above. The powder may be obtained in one or more of the manners described above. 
         [0061]    The method continues at block  1402  by delivering the powder to a cavity  1502  of a mold  1500  (shown separately in  FIG. 15  and shown with the powder  1600  in  FIG. 16 ). The mold cavity  1502  includes side surfaces  1504  that together define a substantially rectangular perimeter shape. In some embodiments, the side surfaces  1504  provide a draft angle of at least two degrees to permit removal of the outer layer  210  of the upper  206  from the cavity  1502  after sintering. The mold cavity  1502  further includes a lower surface  1506  that defines the outer surface of the outer layer  210  of the upper  206 . In some embodiments and as shown in the figures, the lower surface  1506  of the mold cavity  1502  is substantially flat. 
         [0062]    The mold  1500  is at an elevated temperature relative to its environment and the powder  1600 . The elevated temperature may be facilitated by a heating system (not shown) coupled to the mold  1500 , such as a system including resistive heating elements that extend through or are coupled to the mold  1500 . The elevated temperature is sufficiently high, when pressure is applied to the powder  1600  for a certain time period, to sinter the powder  1600 . In some embodiments, the elevated temperature is between about 170 and 180 degrees Celsius. 
         [0063]    In some embodiments, the volume of the powder that is delivered to the cavity  1502  of the mold  1500  depends on the desired volume of the outer layer  210  of the upper  206 , the desired density of the outer layer  210  of the upper  206 , and the density of the powder. In some embodiments, the volume of the powder that is delivered to the cavity  1502  is determined according to the following equation: 
         [0000]        V   0 =( D   1   /D   0 )· V   1  
 
         [0000]    where 
         [0064]    V 0  is the volume of the powder that is delivered to the cavity  1502 ; 
         [0065]    D 0  is the density of the powder; 
         [0066]    V 1  is the desired volume of the outer layer  210  of the upper  206 ; and 
         [0067]    D 1  is the desired density of the outer layer  210  of the upper  206 . 
         [0068]    As an example, the density of the powder may be 0.25 g/cm 3  and the desired density of the outer layer  210  of the upper  206  may be 0.66 g/cm 3 . Thus, the above equation takes the following form: 
         [0000]        V   0 =2.64· V   1  
 
         [0000]    In some embodiments, the density of the powder and the desired density of the outer layer  210  of the upper  206  may vary. For example, the density of the powder may vary depending on multiple factors, such as the size of the particles of the powder or the like. 
         [0069]    At block  1404  and as shown in  FIG. 16 , the method continues by uniformly distributing the powder  1600  in the cavity  1502  by using, for example, a blade (not shown). That is, the powder  1600  is uniformly distributed to ensure that all portions of an upper surface  1602  of the powder  1600  are disposed at substantially the same elevation. 
         [0070]    The method continues at block  1406  by pressing the powder  1600  in the mold cavity  1502  with a counter-mold  1700  (shown with the mold  1500  and powder  1600  in  FIG. 17 ). The counter-mold  1700  includes a lower surface  1702  that applies pressure to the powder  1600  in the mold cavity  1502 . The lower surface  1702  is substantially flat and parallel relative to the lower surface  1506  of the mold cavity  1502 . This provides the sintered component with a substantially uniform thickness. 
         [0071]    The counter-mold  1700  further includes vent passageways (not shown) disposed proximate the edges of the counter-mold  1700 . The vent passageways receive air previously disposed between the particles of the powder  1600  when the powder  1600  is pressed by the counter-mold  1700 . As such, the vent passageways facilitate compacting the powder  1600  and displacing the individual particles toward each other. In some embodiments, the vent passageways extend through the lower surface  1702  of the counter-mold  1700  and vertically through the counter-mold  1700 . 
         [0072]    The counter-mold  1700  further includes side surfaces  1706  that may have substantially the same draft angle as the side surfaces  1504  of the mold cavity  1502  (for example, at least two degrees). The side surfaces  1706  are spaced apart from the side surfaces  1504  of the mold cavity  1502  to facilitate formation of side walls on the sintered component. 
         [0073]    The counter-mold  1700  is at an elevated temperature relative to the environment and the powder  1600 . The elevated temperature may be facilitated by a heating system (not shown) as described above. The elevated temperature is sufficiently high, when the counter-mold  1700  applies pressure to the powder  1600  for a certain time period, to sinter the powder  1600 . In some embodiments, the elevated temperature is between about 170 and 180 degrees Celsius. 
         [0074]    The method continues at block  1408  by sintering the powder  1600  in the mold cavity  1502  for a predetermined time period. That is, the counter-mold  1700  maintains pressure on the powder  1600  in the mold cavity  1502  for the predetermined time period. The mold  1500  and the counter-mold  1700  also heat the powder  1600  in the mold cavity  1502  via, for example, conductive heat transfer, during the predetermined time period. In some embodiments, the predetermined time period is between about three minutes and five minutes depending on, for example, the desired thickness of the outer layer  210  of the upper  206 . In some embodiments, the force applied to the powder  300  by the counter-mold  1700  is about 200 tons. 
         [0075]    After expiration of the predetermined time period and at block  1410 , the counter-mold  1700  disengages the outer layer  210  of the upper  206  and the mold  1500 . At block  1412 , the outer layer  210  of the upper  206  is removed from the mold cavity  1502  and transported to a cooling location (not shown) apart from the mold  1500  and counter-mold  1700 . The cooling location may take various forms. For example, in some embodiments the cooling location may be the surface of a table that facilitates free convective heat transfer from the outer layer  210  to the environment. 
         [0076]    The above actions may provide, for example, the outer layer  210  of the upper  206  in the intermediate form of a panel or sheet  1800  as illustrated in  FIGS. 18 and 19 . The sheet  1800  includes a main body  1802  having an upper surface  1804  that is formed by the lower surface  1702  of the counter-mold  1700 . The upper surface  1804  may be substantially flat, although it may include small protrusions (not shown) formed by the vent passageways in the counter-mold  1700 . The main body  1802  also includes a lower surface  1906  (see  FIG. 19 ) formed by the lower surface  1506  of the mold  1500 . The lower surface  1906  may be substantially flat. The thickness of the main body  1802  may be uniform to facilitate uniform mechanical properties for the outer layer  210  of the upper  206 . In some embodiments, the main body  1802  has a nominal thickness of 6 mm, 4 mm, or 1.5 mm. 
         [0077]    The sheet  1800  further includes side walls  1814  formed in the gap between the side surfaces  1504  and  1706  of the mold  1500  and counter-mold  1700 . The side walls  1814  extend upwardly from the perimeter of the main body  1802 . The side walls  1814  also extend outwardly (that is, horizontally) from the perimeter of the main body  1802  due to the draft angle of the side surfaces  1504  and  1706  of the mold  1500  and counter-mold  1700 . In some embodiments, the side walls  1814  may have a height of at most 50 percent of a nominal thickness of the main body  1802 . 
         [0078]    At block  1414  and as shown in  FIG. 20 , the sheet  1800  is cut, for example, using a knife (not shown) or the like, to form an appropriately-shaped outer layer  210  of the upper  206 . In some embodiments, the sheet  1800  is cut such that the outer layer  210  of the upper  206  does not include portions of the side walls  1814 . At block  1416 , a remainder  2002  of the sheet  1800  is separated from the outer layer  210  of the upper  206 . The remainder  2002  of the sheet  1800  may be processed to form the powder described above. 
         [0079]    At block  1418  and as shown in  FIG. 21 , another portion of the article of footwear is provided. The other portion of the article of footwear may be, for example, an inner layer  2100  of the upper  206 . The other portion of the article of footwear may be manufactured in various manners. For example, if the other portion of the article of footwear is an inner layer  2100  of the upper  206 , it may be manufactured by cutting a fabric sheet (not shown) or the like. 
         [0080]    At block  1420 , the outer layer  210  of the upper  206  is connected to the other portion of the article of footwear. For example, if the other portion of the article of footwear is an inner layer  2100  of the upper  206 , it may be adhered to the outer layer  210 . At block  1422 , further portions of the article of footwear are provided and connected, such as laces (not shown), the sole, and the like, to form the completed article of footwear. 
         [0081]    In some embodiments and as briefly described above, the above methods may be combined to provide an article of footwear that includes both a sintered outsole and a sintered upper. Similarly, in some embodiments the article of footwear includes different combinations of sintered components. For example, methods according to some embodiments of the present invention may create multiple sintered outsole portions, each having different lower surface features, colors, and the like, that together form an article of footwear. 
         [0082]    In some embodiments, the powder may be provided to and uniformly distributed in the mold cavity in other manners. For example, the powder may be delivered to and uniformly distributed in the mold cavity in a melted form via the injector of an injection molding machine (not shown). The mold and the counter mold may then sinter the material as described above. 
         [0083]    Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, while the embodiments described above refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the above described features.