Patent Publication Number: US-2023141479-A1

Title: Heat sealing apparatuses and methods of use thereof

Description:
FIELD OF THE INVENTION 
     The invention generally relates to a heat sealing apparatus, and more particularly to a heat sealing apparatus having a configurable heat sealing surface and methods of using the same. 
     BACKGROUND OF THE INVENTION 
     A heat sealing machine may be used to seal one or more end surfaces of a package, such as an overwrap for absorbent articles. The package may then be subjected to a further heat shrinking process to achieve a tight wrap around the contents of the package. In some cases, the seals created by conventional heat sealing machines result in nonuniform heat shrinking, which may cause visual defects in the package such as bunching, wrinkling, and/or stretching. These visual defects may be particularly evident when the package includes graphics printed or otherwise formed in or on the package. The graphics may, for example, become distorted and/or change color, resulting in an undesirable visual appearance that may detract from a customer&#39;s impression of the product and/or manufacturer. 
     SUMMARY OF THE INVENTION 
     In accordance with an aspect of the present disclosure, a heating block assembly is disclosed, the heating block assembly comprising: one or more configurable insulator segments; and a heater block comprising a first surface configured to removably receive the one or more configurable insulator segments, in which each of the one or more configurable insulator segments covers only a portion of the first surface. 
     Each of the one or more configurable insulator segments may comprise an inner surface positioned adjacent to the first surface of the heater block and an outer surface opposite the inner surface. Each of the one or more configurable insulator segments may comprise a thickness of between 2.9 and 3.1 mm, in which the thickness is defined between the inner and outer surfaces. A temperature of the outer surface of each of the one or more configurable insulator segments may be between 20% and 30% less than a temperature of the first surface of the heater block. 
     The first surface of the heater block may comprise a first extension and a second extension, in which each of the one or more configurable insulator segments may comprise a first corresponding channel and a second corresponding channel configured to receive the respective first and second extensions. 
     The heater block may comprise aluminum, and each of the one or more configurable insulator segments may comprise polyether ether ketone. 
     The heater block may be configured to receive a heating cartridge, and the heater block may comprise a thermally conductive material. 
     The heating block assembly may further comprise one or more configurable conductor segments each comprising a thermally conductive material. The one or more configurable insulator segments may comprise a first insulator segment and a second insulator segment, in which the first and second insulator segments may be spaced apart from each other along a longitudinal length of the heater block by at least one of the one or more configurable conductor segments to define at least one heating zone. The first insulator segment may comprise a first length, and the second insulator segment may comprise a second length that is the same as or different from the first length. 
     In accordance with another aspect of the present disclosure, a heat sealing apparatus is disclosed, the heat sealing apparatus comprising at least a first heating block assembly and a second heating block assembly, each of which comprise: one or more configurable insulator segments; and a heater block comprising a first surface configured to removably receive the one or more configurable insulator segments, in which each of the one or more configurable insulator segments covers only a portion of the first surface. 
     The first heating block assembly may comprise a first insulator segment, and the second heating block assembly may comprise a second insulator segment, in which top edges and/or bottom edges of the first and second insulator segments may be horizontally aligned with each other when the first and second heating block assemblies are positioned side-by-side. 
     The heat sealing apparatus may further comprise a plurality of configurable conductor segments, in which the first heating block assembly may comprise first and second insulator segments spaced apart from each other along a longitudinal length of the heater block of the first heating block assembly by at least one of the plurality of configurable conductor segments and the second heating block assembly may comprise third and fourth insulator segments spaced apart from each other along a longitudinal length of the heater block of the second heating block assembly by at least one of the plurality of configurable conductor segments. The first and second heating block assemblies may be positioned side-by-side, in which top edges and/or bottom edges of the first and third insulator segments may be horizontally aligned with each other and/or top edges and/or bottom edges of the second and fourth insulator segments may be horizontally aligned with each other. 
     The first heating block assembly may be positioned to at least partially define a first heat sealing surface configured to seal a portion of a first end surface of a package, and the second heating block assembly may be positioned opposite the first heating block assembly to at least partially define a second heat sealing surface configured to seal a portion of a second end surface of the package. 
     In accordance with a further aspect of the present disclosure, a heat sealing apparatus is disclosed, the heat sealing apparatus comprising: a configurable heat sealing surface comprising one or more heating zones each defined by one or more configurable insulator segments and one or more configurable conductor segments, in which each of the one or more configurable insulator segments covers only a portion of the configurable heat sealing surface. 
     The configurable heat sealing surface may comprise a first configurable heat sealing surface, and the heat sealing apparatus may further comprise a second configurable heat sealing surface that may comprise one or more second heating zones each defined by one or more second configurable insulator segments and one or more second configurable conductor segments, in which each of the one or more second configurable insulator segments covers only a portion of the second configurable heat sealing surface. The first configurable heat sealing surface may comprise a first insulator segment configuration, and the second configurable heat sealing surface may comprise a second insulator segment configuration that is the same as or different from the first insulator segment configuration. The first configurable heat sealing surface may comprise one or more first heating block assemblies, each of which may comprise a first heater block with a first surface configured to removably receive the one or more configurable insulator and conductor segments, and the second configurable heat sealing surface may comprise one or more second heating block assemblies, each of which may comprise a second heater block with a first surface configured to removably receive the one or more second configurable insulator and conductor segments. The one or more configurable insulator segments may each cover only a portion of the first surface of the first heater block, and the one or more second configurable insulator segments may each cover only a portion of the first surface of the second heater block. 
     The one or more first heating block assemblies may comprise a first plurality of heating block assemblies, which may comprise a first pair of heating block assemblies and a second pair of heating block assemblies positioned side-by-side with the first pair of heating block assemblies, in which the heat sealing apparatus may further comprise a controller operatively coupled to each of the first plurality of heating block assemblies and configured to selectively operate the first and second pairs of heating block assemblies. The first pair of heating block assemblies may comprise a first insulator segment configuration, and the second pair of heating block assemblies may comprise a second insulator segment configuration that is different from the first insulator segment configuration, in which the controller may be configured to selectively provide power to the first and second pair of heating block assemblies such that the one or more heating zones of the first pair of heating block assemblies may comprise a first temperature and the one or more second heating zones of the second pair of heating block assemblies may comprise a second temperature that is different from the first temperature. 
     In accordance with a further aspect of the present disclosure, a method for sealing at least one portion of a package is disclosed, the method comprising: providing a configurable heat sealing surface; selectively adjusting a configuration of the configurable heat sealing surface to define one or more heating zones; and advancing the package along the configurable heat sealing surface adjacent to the one or more heating zones to seal the at least one portion of the package. 
     Selectively adjusting the configuration of the configurable heat sealing surface may comprise adjusting (i) a number of heating zones, (ii) a vertical location of the one or more heating zones, (iii) a horizontal location of the one or more heating zones, and/or (iv) a dimension of the one or more heating zones. 
     The configurable heat sealing surface may comprise a plurality of heating block assemblies each comprising a heater block with one or more configurable insulator segments and one or more configurable conductor segments that define the one or more heating zones. Selectively adjusting the configuration of the configurable heat sealing surface may comprise, for each heating block assembly, selectively positioning the one or more configurable insulator and conductor segments along a longitudinal length of the heater block to define the one or more heating zones. 
     The plurality of heating block assemblies may comprise a first pair of heating block assemblies and a second pair of heating block assemblies, in which the method may further comprise selectively operating the first and second pairs of heating block assemblies to seal the at least one portion of the package. The first and second pair of heating block assemblies may be positioned side-by-side. The package may comprise a first package, in which the method may further comprise: selectively providing power to the first pair of heating block assemblies to seal the at least one portion of the first package; after sealing the at least one portion of the first package, advancing a second package along the configurable heat sealing surface; and selectively providing power to the second pair of heating block assemblies to seal at least one portion of the second package. The first pair of heating block assemblies may comprise a first insulator segment configuration, and the second pair of heating block assemblies may comprise a second insulator segment configuration different from the first insulator segment configuration. 
     The configuration of the configurable heat sealing surface may comprise a first configuration, in which the method may further comprise, after sealing the at least one portion of the package, selectively adjusting the configuration of the configurable heat sealing surface to comprise a second configuration defining one or more second heating zones, the second configuration being different from the first configuration. The method may further comprise advancing a second package along the configurable heat sealing surface adjacent to the one or more second zones to seal at least one portion of the second package. 
     The one or more heating zones may comprise a first heating zone and a second heating zone that is positioned above or below the first heating zone, in which the package may comprise a first package and the method may further comprise: positioning a second package above or below the first package; and advancing the second package along the configurable heat sealing surface with the first package, in which one of the first or the second heating zone seals the at least one portion of the first package and the other of the first or the second heating zone simultaneously seals at least one portion of the second package. 
     The configurable heat sealing surface may comprise a first configurable heat sealing surface, in which the method may further comprise: providing a second configurable heat sealing surface positioned opposite the first configurable heat sealing surface; and selectively adjusting a configuration of the second configurable heat sealing surface to define one or more second heating zones. The at least one portion of the package may comprise a first end surface, and advancing the package along the first configurable heat sealing surface may seal at least a section of the first end surface of the package. The at least one portion of the package may further comprise a second end surface positioned opposite the first end surface, in which the method may further comprise advancing the package along the second configurable heat sealing surface adjacent to the one or more second heating zones to seal at least one section of the second end surface of the package. The package may be advanced along the first and second configurable heat sealing surfaces such that the at least one sections of the first and second end surfaces of the package are sealed simultaneously. 
     The method may further comprise, after advancing the package along the configurable heat sealing surface, subjecting the package to a heat shrinking process. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as forming the present invention, it is believed that the invention will be better understood from the following description which is taken in conjunction with the accompanying drawings in which like designations are used to designate substantially identical elements, and in which: 
         FIG.  1    is an exploded view of a heating block assembly, in accordance with the present disclosure; 
         FIG.  2    is a perspective view of one example of the heating block assembly of  FIG.  1    following assembly; 
         FIG.  3    is an end view of the heating block assembly taken along view line  3 - 3  in  FIG.  2   ; 
         FIG.  4    is a perspective view of another example of the heating block assembly of  FIG.  1    following assembly; 
         FIG.  5    is a perspective view of an exemplary heat sealing apparatus, in accordance with the present disclosure. 
         FIG.  6    is a perspective view of another exemplary heat sealing apparatus, in accordance with the present disclosure; 
         FIG.  7    is a perspective view of a further exemplary heat sealing apparatus, in accordance with the present disclosure 
         FIG.  8    is a perspective view of a heat sealing apparatus comprising a plurality of heating block assemblies positioned opposite one another; 
         FIG.  9    is a partial cross-sectional view taken along line  9 - 9  in  FIG.  8   ; 
         FIG.  10    is a partial cross-sectional view similar to  FIG.  9    of another exemplary heat sealing surface; 
         FIG.  11    is an end view of a package sealed with a heat sealing apparatus, in accordance with the present disclosure; 
         FIGS.  12 - 15    are photographs of packages formed using conventional methods and methods in accordance with the present disclosure; 
         FIG.  16    is a flow diagram illustrating an exemplary method for sealing at least one portion of a package, in accordance with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present disclosure relates to a heat sealing apparatus having a configurable heat sealing surface and methods of use thereof. The heat sealing surface comprises configurable insulator and conductor segments that permit greater control over sealing of packages by minimizing a size of a heating zone to that necessary to form a minimally sufficient seal that serves to hold the package ends together long enough to undergo a subsequent heat shrinking process. 
     As described herein, a package may be formed by folding a plastic overwrap, e.g., polyethylene, over and around a matrix of one or more articles and closing one or more ends of the overwrap by folding end flaps in an overlapping relationship, e.g., an envelope folding pattern, and delivering the package to a heat sealing section where heat is applied to the end surface(s) of the package to fuse together the layers of material of the end flaps. The package then enters a heat shrink tunnel where heat, e.g., convective heat, is applied to all sides of the package, which causes the plastic overwrap to expand before shrinking to create a tight fit around the matrix of articles. Conventional heat sealing machines generally provide a single, large heating zone that extends across an entirety of the heat sealing surface, such that substantially an entirety of the end surface of the package is subjected to heating while in the heat sealing section. It was found that this large heat sealing surface causes the overwrap material to undergo heat shrinking at the heat sealing section and leads to complete sealing of the end prior to entering the heat shrink tunnel. This premature heat shrinking creates a boundary where the overwrap material is prevented from naturally flowing during the heat shrink process, which produces localized bunching of the overwrap material. The overwrap often contains ink from, for example, graphics printed on one or more display panels, and the bunching of the overwrap material on the ends causes undesirable collection of the ink and distortion of the graphics (referred to herein as “veining”). 
     A heat sealing apparatus with a configurable heat sealing surface in accordance with the present disclosure enables a size of the heating zone to be reduced and minimizes a heat affected area on the end surface of the package. The smaller heating zone reduces or eliminates premature heat shrinking, which allows the overwrap material to flow properly during heat shrinking and reduces veining on the display panel(s). The configurable heat sealing surface may be tailored to create a heating zone with the size needed for each specific matrix of articles and may be configured to provide two or more heating zones. As described herein, one or more properties of the heating zone(s) may be altered quickly and easily, without the need to disassemble portions of the heat sealing apparatus. 
     With reference to  FIG.  1   , a heating block assembly  10  is shown, which may include a heater plate or block  12 , one or more configurable insulator segments  30   a - 30   e , and one or more configurable conductor segments  32   a - 32   c . The heater block  12  may comprise a first surface  12 - 1  that is configured to removably receive the one or more configurable insulator segments  30   a - 30   e  and conductor segments  32   a - 32   c , as described in more detail below. The first surface  12 - 1  of the heater block  12  may be substantially planar or smooth, as shown in in  FIG.  1   . 
     The heater block  12  comprises a first end  14  and a second end  16 . The first end  14  may comprise a threaded bore  14 - 3 , and the second end  16  may comprise a similar threaded bore (not visible), in which the threaded bore  14 - 3  at the first end  14  and the threaded bore at the second end  16  are configured to receive a fastener  50 ,  54 , respectively, as described herein. The first end  14  comprises a first opening  14 - 1  and a second opening  14 - 2 , as shown in  FIG.  1   . In the example shown, the first opening  14 - 1  may be configured to receive a heating element  58  that extends along at least a portion of a longitudinal length L 12  of the heater block  12  and provides heat to the heating block assembly  10 . In the example shown, the heating element  58  comprises a cartridge heater, which may include a single zone or a multi zone cartridge heater. The second opening  14 - 2  may be configured to receive a temperature sensor  70  such as a thermocouple or a resistance temperature detector. As described in more detail below, the heating element  58  and the temperature sensor  70  may be operatively coupled to a controller  72  that receives temperature data from the temperature sensor  70  and adjusts operation of the heating element  58  to achieve a desired temperature. Although the heater block  12  in  FIG.  1    is depicted as being configured to receive a cartridge heater, it is understood that other types of heating elements  58  could be used, such as a tubular heater. With reference to the end view shown in  FIG.  3   , the second end  16  of the heater block  12  may comprise a first opening  16 - 1 , which may be connected to the first opening  14 - 1  in the first end  14 . 
     As shown in  FIGS.  1  and  3   , the first surface  12 - 1  of the heater block  12  includes a first extension  18  and a second extension  22  that extends in a direction opposite the first extension  18 . The first and second extensions  18 ,  22  define respective first and second channels  20 ,  24 , which may extend along an entirety of the longitudinal length L 12  of the heater block  12 . The heater block  12  may include a first width W 12-1  at or near a second surface  12 - 2 , a second width W 12-2  defined by the channels  20 ,  24 , and a third width W 12-3  defined by the extensions  18 ,  22 . The first width W 12-1  may be a maximum width of the heater block  12 , and the second width W 12-2  may be a minimum width of the heater block  12 . The third width W 12-3  may fall between the first and second widths W 12-1 , W 12-2  such that the extensions  18 ,  22 , the channels  20 ,  24 , and the first surface  12 - 1  of the heater block  12  may together define a capital “T” shape. The first surface  12 - 1  of the heater block  12 , specifically the extensions  18 ,  22  and the channels  20 ,  24 , may be configured to removably receive the one or more configurable insulator and conductor segments  30   a - 30   e ,  32   a - 32   c.    
     With reference to the detailed view in  FIG.  3   , the insulator segment  30   b  may comprise an inner surface  30   b - 1  and an outer surface  30   b - 2  that is opposite the inner surface  30   b - 1 , in which the inner surface  30   b - 1  of the insulator segment  30   b  is positioned adjacent to the first surface  12 - 1  of the heater block  12 . The insulator segment  30   b  may further comprise a first sidewall  34  with a first lip  36  and a second sidewall  38  with a second lip  40 . The first and second lips  36 ,  40  extend inward toward each other and may be substantially perpendicular to the first and second sidewalls  34 ,  38  and substantially parallel to the inner and outer surfaces  30   b - 1 ,  30   b - 2  of the insulator segment  30   b , such that the inner surface  30   b - 1 , the sidewalls  34 ,  38 , and the lips  36 ,  40  of the insulator segment  30  may together define a slot in the shape of a capital “T.” The first lip  36  is received in the first channel  20  of the heater block  12 , and the second lip  40  is received in the second channel  24  to secure the insulator segment  30   b  to the heater block  12 . A width (not separately labeled) of an outer surface of the first and second sidewalls  34 ,  38  may be substantially similar to the first width W 12-1  of the heater block  12 , such that sides of the heating block assembly  10  are substantially smooth and seamless. A portion of the outer surface  30   b - 2  adjacent to the sidewalls  34 ,  38  may comprise a chamfer or slope to minimize impacts along edges of the insulator segment  30   b  and to ensure that packages and other objects move smoothly along the outer surface  30   b - 2 . 
     Although not labeled, it can be seen in  FIG.  1    that all of the insulator and conductor segments  30   a ,  30   c - 30   e ,  32   a - 32   c  comprise a structure that is substantially similar to the insulator segment  30   b  shown in detail in  FIG.  3   . As shown in  FIG.  1   , the insulator and conductor segments  30   a - 30   e ,  32   a - 32   c  may be installed on the heater block  12  from the first or the second end  14 ,  16  by sliding the insulator and conductor segments  30   a - 30   e ,  32   a - 32   c  onto the first surface  12 - 1  of the heater block  12  in a direction indicated by arrow A. With reference to  FIG.  3   , it can be seen that engagement between the lips  36 ,  40  of the insulator segment  30   b  and the channels  20 ,  24  of the heater block  12  prevents movement of the insulator segment  30   b  in any direction other than the direction indicated by arrow A in  FIG.  1   . The insulator and conductor segments  30   a ,  30   c - 30   e ,  32   a - 32   c  shown in  FIG.  1    may similarly be secured to the heater block  12 . 
     One or more of the insulator segments  30   a - 30   c  and the conductor segments  32   a - 32   c  may be installed on the heater block  12  of  FIG.  1    to generate the heating block assemblies  10 ,  10 ′ depicted in  FIGS.  2 - 4   . Following installation of the insulator and conductor segment(s)  30   a - 30   e ,  32   a - 32   c  onto the heater block  12 , the fasteners  50 ,  54  may be used to secure the insulator and conductor segments  30   a - 30   e ,  32   a - 32   c  and prevent movement of the insulator and conductor segments  30   a - 30   e ,  32   a - 32   c  in the direction indicated by arrow A. As shown in  FIGS.  1 ,  2 , and  4   , the fastener  50 , e.g., a screw, may extend through a washer  52  and be received in the threaded bore  14 - 3  formed in the first end  14  of the heater block  12 . The washer  52  extends above the first surface  12 - 1  of the heater block  12  to prevent the insulator and conductor segments  30   a - 30   e ,  32   a - 32   c  from moving past the first end  14 . Similarly, as shown in  FIGS.  1  and  3   , the fastener  54  may extend through a washer  56  and be received in the threaded bore (not shown) formed in the second end  16  of the heater block  12 , in which the washer  56  extends above the first surface  12 - 1  of the heater block  12  to prevent the insulator and conductor segments  30   a - 30   e ,  32   a - 32   c  from moving past the second end  16 . 
     The heating block assembly  10 ,  10 ′ shown in  FIGS.  1 - 4   , including the heater block  12  and the one or more insulator and conductor segments  30   a - 30   e ,  32   a - 32   c , may define a respective configurable heat sealing surface  60 ,  60 ′ or a portion thereof. A configuration of the configurable heat sealing surface  60 ,  60 ′ may be altered by changing one or more of a number, dimension, and location of the one or more insulator and conductor segments  30   a - 30   e ,  32   a - 32   c , as described herein. 
     With reference to the heating block assembly  10  shown in  FIG.  2   , the heater block  12  comprises insulator segments  30   a  and  30   b  and conductor segment  32   a , which define one exemplary heat sealing surface  60  or portion thereof. The insulator segment  30   a  is positioned adjacent to the first end  14  of the heater block  12 , the insulator segment  30   b  is positioned adjacent to the second end  16  of the heater block  12 , and the conductor segment  32   a  is positioned between the insulator segments  30   a ,  30   b  to space the insulator segments  30   a ,  30   b  apart from each other along the longitudinal length L 12  of the heater block  12 . 
     The heating block assembly  10 ′ in  FIG.  4    comprises insulator segments  30   c - 30   e  and conductor segments  32   b ,  32   c , in which the insulator segment  30   c  is positioned adjacent to the first end  14  of the heater block  12 , the insulator segment  30   e  is positioned adjacent to the second end  16  of the heater block  12 , and the insulator segment  30   d  is positioned between the insulator segments  30   c ,  30   e . The conductor segment  32   b  is positioned between the insulator segments  30   c ,  30   d , and the conductor segment  32   c  is positioned between the insulator segments  30   d ,  30   e  to space the insulator segments  30   c - 30   e  apart from each other along the longitudinal length Lie of the heater block  12  and to define another exemplary heat sealing surface  60 ′ or portion thereof. 
     The insulator segments  30   a - 30   e  may comprise a material with low thermal conductivity, e.g., from about 0.15 to about 0.95 W/(m·K)±0.02 W/(m·K), such as polyetheretherketone (PEEK), which may have an average thermal conductivity of about 0.25 W/(m·K). Another example of a material with low thermal conductivity may include polytetrafluoroethylene. The heater block  12  and the conductor segments  32   a - 32   c  may comprise a material with a high thermal conductivity, e.g., greater than about 200 W/(m·K), such as one or more metals (e.g., aluminum or copper), alloys (e.g., brass or bronze), or combinations thereof. The heater block  12  may be made from a single (monolithic) piece of material such as anodized aluminum that is a good thermal conductor, resists wear and oxidation, and provides a lower coefficient of friction to enable the insulator and conductor segments  30   a - 30   e ,  32   a - 32   c  to slide on and off more easily. The heater block  12  and the conductor segments  32   a - 32   c  may comprise the same material, e.g., aluminum, or may comprise one or more different materials as compared to each other. 
     The one or more insulator segments  30   a - 30   e  may cover only a portion of the first surface  12 - 1  of the heater block  12 . As shown in  FIGS.  2  and  4   , in examples comprising two or more insulator segments  30   a - 30   e , the insulator segments  30   a - 30   e  may be spaced apart from each other via one or more conductor segments  32   a - 32   c . The heat sealing surface  60 ,  60 ′ may comprise one or more heating zones  62 ,  62 ′,  64 ′ that are defined by the conductor segments  32   a - 32   c , specifically by a position of the insulator segments  30   a - 30   e  with respect to the conductor segments  32   a - 32   c  along the longitudinal length L 12  of the heater block  12 . When heat is applied to the heater block  12 , e.g., via the heating element  58  shown in  FIG.  1   , the insulator segments  30   a - 30   e  reduce the amount of heat transmitted to corresponding portions of the heat sealing surface  60 ,  60 ′, while the conductor segments  32   a - 32   c  conduct the heat from the heater block  12  to corresponding portions of the heat sealing surface  60 ,  60 ′. For example, with reference to  FIG.  2   , the heat sealing surface  60  comprises one large heating zone  62  that is located toward a longitudinal center of the heater block  12  and is defined by insulator segments  30   a ,  30   b  and conductor segment  32   a . In  FIG.  4   , the heat sealing surface  60 ′ comprises two smaller heating zones  62 ′,  64 ′ that are defined by insulator segments  30   c - 30   e  and conductor segments  32   a ,  32   b.    
     The insulator and conductor segments  30   a - 30   e ,  32   a - 32   c  may be manufactured to have any desired longitudinal length. With reference to  FIGS.  2  and  4   , the insulator segments  30   a - 30   e  may each comprise a respective length L 30a -L 30c , and the conductor segments  32   a - 32   c  may each comprise a respective length L 32a -L 32c . The lengths L 30a -L 30c  of the insulator segments  30   a - 30   e  within the heating block assembly  10 ,  10 ′ may be the same as or different from each other. For example, as shown in  FIG.  2   , the length L 30a  of the insulator segment  30   a  is different from, i.e., less than, the length L 30b  of the insulator segment  30   b . As shown in  FIG.  4   , the length L 30d  of the insulator segment  30   d  is the same as the length L 30e  of the insulator segment  30   e , while the length L 30e  of the insulator segment  30   c  is different from, i.e., less than, the lengths L 30d , L 30e  of the insulator segments  30   d ,  30   e . The lengths L 32a -L 32c  of the conductor segments  32   a - 32   c  within the heating block assembly  10 ,  10 ′ may likewise be the same as or different from each other. For example, as shown in  FIG.  4   , the length L 32b  of the conductor segment  32   b  is the same as the length L 32c  of the conductor segment  32   c.    
     A configuration of the heat sealing surfaces  60 ,  60 ′ may be selectively adjusted to define the one or more heating zones  62 ,  62 ′,  64 ′. In particular, an insulator and/or conductor configuration of the heating block assemblies  10 ,  10 ′ in  FIGS.  2 - 4    may be altered to achieve a desired number of heating zones  62 ,  62 ′,  64 ′ with the desired dimension(s) and/or desired vertical location(s) along the longitudinal length L 12  of the heater block  12 . One or more of the insulator and/or conductor segments  30   a - 30   e ,  32   a - 32   c  may be removed from the heater block  12  by sliding them off of the first or second end  14 ,  16  of the heater block  12  in the direction indicated by arrow A in  FIG.  1    and replacing them with one or more additional insulator and/or conductor segments having a different length that are selectively positioned along the longitudinal length L 12  of the heater block  12  (e.g., by sliding the one or more additional insulator and/or conductor segments onto the first surface  12 - 1  of the heater block  12  in the direction indicated by arrow A). 
     Although the insulator segments  30   a - 30   e  in  FIGS.  2  and  4    are depicted as being separated by one conductor segment  32   a - 32   c  each, it should be understood that the insulator segments  30   a - 30   e  may be separated by two or more conductor segments  32   a - 32   c  that are positioned adjacent to each other along the longitudinal length L 12  of the heater block  12  without insulator segments  30   a - 30   c  positioned therebetween. Likewise, two or more insulator segments  30   a - 30   e  may be positioned adjacent to each other along the longitudinal length L 12  of the heater block  12  without conductor segment(s)  32   a - 32   c  positioned therebetween. In addition, although  FIG.  4    depicts two heating zones  62 ′,  64 ′, it should be understood that any number of heating zones, including three or more, may be possible. 
     With reference to  FIGS.  1  and  3   , a temperature of the outer surface  30   b - 2  of the insulator segment  30   b  may be between 20% and 30% less than a temperature of the first surface  12 - 1  of the heater block  12  due to the insulator segment  30   b  being comprised of a material with low thermal conductivity. The insulator segment  30   b  may comprise a thickness T 30b  of between 2.9 and 3.1 mm, as measured between the inner and outer surfaces  30   b - 1 ,  30   b - 2  shown in  FIG.  3   . A central portion of the inner surface  30   b - 1  of the insulator segment  30   b  may be spaced apart from an adjacent portion of the first surface  12 - 1  of the heater block  12  to define an air gap  68  therebetween. The air gap  68  serves to further reduce conduction of heat from the heater block  12  to the outer surface  30   b - 2  of the insulator segment  30   b . The air gap  68  may be between 0.9 and 1.1 mm, such that the outer surface  30   b - 2  of the insulator segment  30   b  is spaced apart from the first surface  12 - 1  of the heater block  12  by about 4 mm. The other insulator segments  30   a ,  30   c - 30   e  shown in  FIGS.  1 ,  2 , and  4    may comprise substantially similar structures and thicknesses and may achieve similar temperature differences between their respective outer surfaces (not labeled) and the first surface  12 - 1  of the heater block  12 . The conductor segments  32   a - 32   c , which do not define an air gap, may comprise a corresponding thickness (not shown) of about 4 mm so that substantially an entirety of inner surfaces (not labeled) of the conductor segments  32   a - 32   c  contact the first surface  12 - 1  of the heater block  12  and outer surfaces (not labeled) of the conductor segments  32   a - 32   c  are flush with the outer surfaces of the insulator segments  30   a - 30   e , as seen in  FIGS.  2  and  4   , to ensure that packages and other objects move smoothly along the heat sealing surface  60 ,  60 ′ (see also  FIGS.  9  and  10   ). A temperature of an outer surface (not labeled) of the conductor segments  32   a - 32   c  may be substantially similar to a temperature of the heater block  12  due to the conductor segments  32   a - 32   c  being comprised of a material with a high thermal conductivity. 
       FIGS.  5 - 7    illustrate exemplary heat sealing apparatuses  100 ,  200 ,  300  comprising a respective configurable heat sealing surface  160 ,  260 ,  360 , in accordance with the present disclosure. As used herein, the term “vertical” may be used to refer to a location, position, or dimension in a direction parallel to the longitudinal length L 12  of the heater block  12  shown in  FIGS.  1 ,  2 , and  4   , while the terms “horizontal” or “lateral” may be used to refer to a location, position, or dimension in a direction parallel to the width W 12  of the heater block  12  shown in  FIG.  3   . Only a portion of the elements in  FIGS.  5 - 7    are labeled in order to illustrate other aspects of each heat sealing apparatus  100 ,  200 ,  300  in detail. It should be understood that unless indicated otherwise, the heating block assemblies  110 ,  210 / 210 ′,  310 / 310 ′ within each heat sealing apparatus  100 ,  200 ,  300  may all include components that are substantially similar to each other. 
     With reference to  FIG.  5   , the heat sealing apparatus  100  comprises a plurality of heating block assemblies  110  that each comprise insulator segments  130   a - 130   c  and conductor segments  132   a ,  132   b . The insulator segment  130   a  may be positioned adjacent to a first end  114  of a heater block  112 , the insulator segment  130   c  may be positioned adjacent to a second end  116  of the heater block, and the insulator segment  130   b  may be positioned between the insulator segments  130   a ,  130   c . The conductor segment  132   a  may be positioned between insulator segments  130   a ,  130   b , and the conductor segment  132   b  may be positioned between insulator segments  130   b ,  130   c  to space apart the respective insulator segments  130   a - 130   c  and define respective heating zones  162 ,  164  in each heating block assembly  110 . The heating block assemblies  110  may be horizontally aligned, side-by-side, along their longitudinal lengths (not labeled; see  FIG.  1   ) to define one exemplary configurable heat sealing surface  160 . An insulator and/or conductor segment configuration may be the same across all of the heating block assemblies  110 . 
     The heat sealing apparatus  200  of  FIG.  6    comprises a plurality of heating block assemblies  210 ,  210 ′ horizontally aligned, side-by-side, along their longitudinal lengths (not labeled; see  FIG.  1   ) to define another exemplary configurable heat sealing surface  260 , in which the heating block assemblies  210  comprise a different insulator and/or conductor segment configuration than the heating block assemblies  210 ′. The heating block assemblies  210  may each comprise two insulator segments  230   a ,  230   b  that are spaced apart by a conductor segment  232   a  to define a heating zone  262 . The heating block assemblies  210 ′ may each comprise two insulator segments  230   a ′,  230   b ′ that are spaced apart by a conductor segment  232   a ′ to define a heating zone  262 ′. It can be seen that the insulator segments  230   a ′ comprise a length (not labeled) that is much larger than a length (not labeled) of the insulator segments  230   a  and that the conductor segments  232   a  comprise a length (not labeled) that is much larger than a length (not labeled) of the conductor segments  232   a ′. The insulator segments  230   b ,  230   b ′ may have a length that is substantially the same, such that the heating zone  262  of the heating block assemblies  210  is larger than the heating zone  262 ′. 
       FIG.  7    depicts a heat sealing apparatus  300  comprising a further exemplary configurable heat sealing surface  360 . The heat sealing apparatus  300  may comprise a plurality of heating block assemblies  310 ,  310 ′ horizontally aligned, side-by-side, along their longitudinal lengths (not labeled; see  FIG.  1   ), in which the heating block assemblies  310  comprise a different insulator and/or conductor segment configuration than the heating block assemblies  310 ′. The heating block assemblies  310  may be substantially similar to the heating block assemblies  110  shown in  FIG.  5    and may each comprise three insulator segments  330   a - 330   c  that are spaced apart by conductor segment  332   a ,  332   b  to define two heating zones  362 ,  364 . The heating block assemblies  310 ′ may be substantially similar to the heating block assemblies  210  shown in  FIG.  6    and may each comprise two insulator segments  330   a ′,  330   b ′ that are spaced apart by a conductor segment  332   a ′ to define a heating zone  362 ′. 
     In some examples, top and/or bottom edges of one or more of the insulator segments within adjacent heating block assemblies may be horizontally aligned with each other. As shown in  FIG.  5   , because the heating block assemblies  110  all comprise the same insulator and conductor segment configuration, top edges  130   a - 1  and bottom edges  130   a - 2  of the insulator segments  130   a  are horizontally aligned with each other across all of the heating block assemblies  110 . Top and bottom edges  130   b - 1 ,  130   b - 2  of the insulator segments  130   b  and top and bottom edges  130   c - 1 ,  130   c - 2  of the insulator segments  130   c  are likewise all horizontally aligned with each other. 
     In  FIGS.  6  and  7   , the heating block assemblies  210 ,  210 ′ and  310 ,  310 ′ comprise different insulator and/or conductor segment configurations, such that the top and/or bottom edges of one or more of the insulator segments may not be aligned with each other. For example, as shown in  FIG.  6   , top edges  230   a - 1  of the insulator segments  230   a  in the heating block assemblies  210  are horizontally aligned with top edges  230   a - 1 ′ of the insulator segments  230   a ′ in the heating block assemblies  210 ′, but bottom edges  230   a - 2  of the insulator segments  230   a  are not aligned with bottom edges  230   a - 2 ′ of the insulator segments  230   a ′. Top edges  230   b - 1 ,  230   b - 1 ′ and bottom edges  230   b - 2 ,  230   b - 2 ′ of the insulator segments  230   b ,  230   b ′ are horizontally aligned with each other across all of the heating block assemblies  210 ,  210 ′. 
     In  FIG.  7   , top and bottom edges  330   a - 1 ,  330   a - 2  of the insulator segments  330   a  in the heating block assemblies  310  are horizontally aligned with top and bottom edges  330   a - 1 ′,  330   a - 2 ′ of the insulator segments  330   a ′ in the heating block assemblies  310 ′, and top and bottom edges  330   c - 1 ,  330   c - 2  of the insulator segments  330   c  are horizontally aligned with top and bottom edges  330   b - 1 ′,  330   b - 2 ′ of the insulator segments  330   b ′. However, top and bottom edges  330   b - 1 ,  330   b - 2  of the insulator segments  330   b  in the heating block assemblies  310  are not horizontally aligned with top and/or bottom edges of any of the insulator segments  330   a ′,  330   b ′ in the heating block assemblies  310 ′. 
     With continued reference to  FIGS.  5 - 7   , each heating block assembly  110 ,  210 / 210 ′,  310 / 310 ′ comprises a respective heating element  158 ,  258 ,  358 , while every other heating block assembly  110 ,  210 / 210 ′,  310 / 310 ′ comprises a respective temperature sensor  170 ,  270 ,  370 . The heating block assemblies  110 ,  210 / 210 ′,  310 / 310 ′ may be controlled in pairs. As shown in  FIG.  5   , the four heating block assemblies  110  may comprise two pairs  128   a ,  128   b , in which each pair  128   a ,  128   b  comprises two heating elements  158  and one temperature sensor  170 . In  FIG.  6   , the four heating block assemblies  210 ,  210 ′ may likewise comprise two pairs  228   a ,  228   b , in which each pair  228   a ,  228   b  comprises two heating elements  258  and one temperature sensor  270 . In  FIG.  7   , 12 heating block assemblies  310 ,  310 ′ are shown, which may comprise six pairs  328   a ,  328   b  (only two pairs are labeled), in which each pair  328   a ,  328   b  comprises two heating elements  358  and one temperature sensor  370 . As shown in  FIG.  5   , in some examples, the insulator and/or conductor configuration of one pair  128   a  of the heating block assemblies  110  may be the same as the insulator and/or conductor configuration of an adjacent pair  128   b  of the heating block assemblies  110 . As shown in  FIGS.  6  and  7   , the insulator and/or conductor configuration of one pair  228   a ,  328   a  of the heating block assemblies  210 ,  310  may be different from the insulator and/or conductor configuration of an adjacent pair  228   b ,  328   b  of the heating block assemblies  210 ′,  310 ′. 
     A controller (not shown; see  FIG.  1   ) may be operatively coupled to the heating elements  158 ,  258 ,  358  and temperature sensors  170 ,  270 ,  370 . The controller may receive temperature sensor data from one heating block assembly  110 ,  210 / 210 ′,  310 / 310 ′ within each pair  128   a ,  128   b ,  228   a ,  228   b ,  328   a ,  328   b  and may control operation of both heating elements  158 ,  258 ,  358  within each pair  128   a ,  128   b ,  228   a ,  228   b ,  328   a ,  328   b  based on the temperature sensor data. In particular, in some instances as described herein, the controller may selectively control operation of the pairs  128   a ,  128   b ,  228   a ,  228   b ,  328   a ,  328   b  of heating block assemblies  110 ,  210 / 210 ′,  310 / 310 ′, e.g., by selectively providing power to the heating block assemblies  110 ,  210 / 210 ′,  310 / 310 ′, to achieve a desired configuration of the respective heat sealing surface  160 ,  260 ,  360 . Selectively providing power to the pairs  128   a ,  128   b ,  228   a ,  228   b ,  328   a ,  328   b  of heating block assemblies  110 ,  210 / 210 ′,  310 / 310 ′ may comprise adjusting a horizontal location of the one or more heating zones within the heat sealing surfaces  160 ,  260 ,  360 , as the heating block assemblies  110 ,  210 / 210 ′,  310 / 310 ′ and their respective heating zones are located at different horizontal locations within the respective heat sealing apparatus  100 ,  200 ,  300 . 
       FIG.  8    depicts an exemplary heat sealing section  401 , which may be positioned within a larger wrapping and sealing device (not shown). A heat sealing apparatus  400  within the heat sealing section  401  may comprise a first configurable heat sealing surface  460  and a second configurable heat sealing surface  460 ′ for sealing one or more portions of a package  1000 . The package  1000  comprises a folded plastic overwrap, e.g., polyethylene, and at least a portion of the package  1000  may comprise one or more graphics  1003 . For example, as shown panels  1001 - 1 ,  1001 - 2  comprise one or more graphics  1003 , which are indicated with dashed lines. 
     The package  1000  may be delivered to a conveyer  403 , e.g., a conveyer belt, that advances the package  1000  through the heat sealing section  401  along the first and second configurable heat sealing surfaces  460 ,  460 ′ in a direction indicated by arrow B. A sealing belt  405  may be positioned between the package  1000  and the first configurable heat sealing surface  460 . Although not shown, a sealing belt would similarly be positioned on the right side of the heat sealing apparatus  400  between the second configurable heat sealing surface  460 ′ and the package  1000 . After passing through the heat sealing section  401 , the package  1000  may then enter a heat shrink tunnel (not shown) where the package  1000  undergoes a heat shrinking process and the overwrap material shrinks to create a tight fit. 
     The first configurable heat sealing surface  460  may be positioned to seal one or more sections of a first end surface  1000 - 1  of the package  1000  and may comprise a plurality of heating block assemblies (not shown, obscured by the sealing belt  405 ; see  FIGS.  9  and  10   ). The second configurable heat sealing surface  460 ′ may be positioned opposite the first configurable heat sealing surface  460  to seal one or more sections of a second end surface  1000 - 2  of the package  1000 , the second end surface  1000 - 2  of the package  1000  being opposite the first end surface  1000 - 2 . The second configurable heat sealing surface  460 ′ may similarly comprise a plurality of heating block assemblies  410 ′ (the sealing belt on the right side of the heat sealing apparatus  400  is removed to show the heating block assemblies  410 ′ and several components of the heating block assemblies  410 ′ are omitted to illustrate other aspects in detail). The one or more sections of the first and second end surfaces  1000 - 1 ,  1000 - 2  may be sealed substantially simultaneously, e.g., by advancing the package  1000  through the heat sealing section  401  and applying heat to both end surfaces  1000 - 1 ,  1000 - 2  simultaneously from the first and second configurable heat sealing surfaces  460 ,  460 ′. 
     The heating block assemblies  410 ′ of the first and second configurable heat sealing surfaces  460 ,  460 ′ may comprise any insulator and/or conductor segment configuration described herein. As discussed in more detail with respect to  FIGS.  9  and  10   , the insulator and/or conductor segment configuration of the heating block assemblies  410 ′ in the first and second configurable heat sealing surfaces  460 ,  460 ′ may be selectively adjusted to achieve a desired a number of heating zones (not labeled; see  FIGS.  9  and  10   ), a vertical location of the one or more heating zones, a horizontal location of the one or more heating zones, and/or a dimension of the one or more heating zones. Heat from the heating block assemblies  410 ′ through the sealing belts  405  and into one or more sections of the end surfaces  1000 - 1 ,  1000 - 2  of the package  1000  as the package  1000  is advanced along the first and second configurable heat sealing surfaces  460 ,  460 ′ adjacent to the one or more heating zones. The sealing belts  405  may also help to advance the package  1000  through the heat sealing section  401 . 
     The first and second configurable heat sealing surfaces  460 ,  460 ′ may each comprise 24 heating block assemblies  410 ′ for a total of 48 heating block assemblies in the heat sealing apparatus  400 . The 24 heating block assemblies  410 ′ of the second configurable heat sealing surface  460 ′ are horizontally aligned, side-by-side, with each other along their longitudinal lengths (not labeled; see  FIG.  1   ) as shown, and the 24 heating block assemblies (not visible) of the first configurable heat sealing surface  460  are horizontally aligned, side-by-side, with each other along their longitudinal lengths. The heating block assemblies  410 ′ are also aligned with corresponding ones of the 24 heating block assemblies in the first configurable heat sealing surface  460 . The heating block assemblies  410 ′ may be controlled in pairs, as described herein in detail. In some examples, the heat sealing apparatus  400  may comprise 24 heating sections defined by one pair of heating block assemblies, with each of the first and second configurable heat sealing surfaces  460 ,  460 ′ comprising 12 respective heating sections. In some instances, a pair of heating block assemblies in the first configurable heat sealing surface  460  and a pair of heating block assemblies  410 ′ in the second configurable heat sealing surface  460 ′ immediately opposite the pair of heating block assemblies in the first configurable heat sealing surface  460  may comprise the same insulator and/or conductor segment configuration. In other instances, the pairs of opposing heating block assemblies  410 ′ in the first and second configurable heat sealing surfaces  460 ,  460 ′ may comprise different insulator and/or conductor segment configurations. In both instances, the pairs of opposing heating block assemblies  410 ′ may be operated at a same temperature or at a different temperature. 
     With reference to  FIGS.  9  and  10   , exemplary heating block assemblies  510 ,  610  are depicted with respect to one or more packages  2000 ,  2000 A,  2000 B. The heating block assembly  510  may at least partially define a configurable heat sealing surface  560 . The heating block assembly  510  may comprise an insulator and/or conductor segment configuration that is substantially similar to the heating block assemblies  10 ,  210 ,  310 ′ depicted in  FIGS.  2 ,  6 , and  7    and may comprise insulator segments  530   a ,  530   b  spaced apart by a conductor segment  532   a  to define one large heating zone  562 . Heat passes from the conductor segment  532   a  through a sealing belt  505  and into a first end surface  2000 - 1  of the package  2000  to seal one or more sections of the first end surface  2000 - 1 . In particular, heat from the heating zone  562  seals one or more sections of an overwrap  2002  that is formed around a matrix of articles  2004  (depicted with dashed lines), e.g., absorbent articles such as boxes of facial tissue, packages of diapers, etc., by fusing together two or more layers of a material of the overwrap  2002  adjacent to the heating zone  562 . 
     The heating block assembly  610  in  FIG.  10    may at least partially define a configurable heat sealing surface  660 . The heating block assembly  610  may comprise an insulator and/or conductor segment configuration that is substantially similar to the heating block assemblies  10 ′,  110 ,  310  depicted in  FIGS.  4 ,  5 ,  7    and may comprise insulator segments  630   a - 630   c  and conductor segments  632   a ,  632   b , in which the insulator segments  630   a ,  630   b  are spaced apart by the conductor segment  632   a  and the insulator segments  630   b ,  630   c  are spaced apart by the conductor segment  632   b . The conductor segments  632   a ,  632   b  define first and second heating zones  662 ,  664 , respectively. The heating block assembly  610  may be used to seal one or more sections of a first package  2000 A and a second package  2000 B, in which the first package  2000 A is positioned above or stacked on top of the second package  2000 B and advances with the second package  2000 B through the heat sealing section (see  FIG.  8   ). Heat passes from the conductor segment  632   a  through a sealing belt  605  and into a first end surface  2000 A- 1  of the first package  2000 A to seal one or more sections of the first end surface  2000 A- 1 . In particular, heat from the first heating zone  662  seals one or more sections of an overwrap  2002 A that is formed around a matrix of articles  2004 A (shown with dashes lines) by fusing together two or more layers of a material of the overwrap  2002 A adjacent to the first heating zone  662 . Heat similarly passes from the conductor segment  632   b  through the sealing belt  605  and into a first end surface  2000 B- 1  of the second package  2000 B, such that heat from the second heating zone  664  fuses together two or more layers of a material of an overwrap  2002 B to substantially simultaneously seal one or more sections of the first end surface  2000 B- 1 , e.g., one or more sections of the overwrap  2002 B that is formed around a matrix of articles  2004 B (shown with dashed lines). 
     Although two packages  2000 A,  2000 B are depicted in  FIG.  10   , it may be understood that three or more packages may be stacked on top of each other. In addition, it should be understood that the heat sealing surface  660  depicted in  FIG.  10    may also be used to seal two or more sections of an end surface of a single package, e.g., package  2000  as shown in  FIG.  9   , in which the package comprises dimensions that place portions of the end surface adjacent to both the first and second heating zone  662 ,  664 . It should further be understood that a heating block assembly in accordance with the present disclosure may comprise three or heating zones (not shown) that may be used to seal one or more sections of one or more packages. 
     A second configurable heat sealing surface (not shown; see  FIG.  8   ) may be positioned opposite the heat sealing surface  560  in  FIG.  9    and may comprise an insulator and/or conductor segment configuration that is similar to the configuration of the heat sealing surface  560  in order to seal one or more sections of a second end surface (not shown; see  FIG.  8   ) of the package  2000 . A second configurable heat sealing surface (not shown; see  FIG.  8   ) may likewise be positioned opposite the heat sealing surface  660  in  FIG.  10    and may comprise an insulator and/or conductor segment configuration that is similar to the configuration of the heat sealing surface  660  in order to seal one or more sections of a second end surface (not shown; see  FIG.  8   ) of the first and second package  2000 A,  2000 B. The one or more sections of the first and second end surfaces  2000 - 1 ,  2000 A- 1 ,  2000 B- 1  of the respective packages  2000 ,  2000 A,  2000 B may be sealed substantially simultaneously, e.g., by advancing the packages  2000 ,  2000 A,  2000 B through a heat sealing section similar to that shown in  FIG.  8    in which heat is applied to both end surfaces of the package from a series of aligned heating block assemblies. 
       FIG.  11    depicts an envelope folding pattern and a heat-affected zone  2006  in the first end surface  2000 - 1 ,  2000 A- 1 ,  2000 B- 1  that may be generated after the packages  2000 ,  2000 A,  2000 B are advanced along a respective one of the configurable heat sealing surfaces  560 ,  660  in  FIGS.  9  and  10   . For comparison, a conventional heat-affected zone  2008  is shown. The conventional heat-affected zone  2008  is generated using a conventional heat sealing apparatus as described herein, in which a single, large heating zone extending across an entirety of the heat sealing surface subjects substantially an entirety of the end surface of the package to heating. Portions of overwrap material in the large, conventional heat-affected zone  2008  undergo premature heat shrinking and generate a complete seal of the first end surface  2000 - 1 ,  2000 A- 1 ,  2000 B- 1  prior to entering the heat shrink tunnel, which leads to bunching and veining. A vertical dimension of the heat-affected zone  2006  produced by the heat sealing surfaces  560 ,  660  in accordance with the present disclosure is much smaller, as compared to the conventional heat-affected zone  2008 . This smaller vertical dimension of the heat-affected zone  2006  minimizes or eliminates premature heat shrinking, which allows the overwrap material to flow properly during heat shrinking and reduces veining on the display panel(s) (not labeled), as shown below. In some instances, because the heat-affected zone  2006  produced in accordance with the present disclosure is smaller than the conventional heat-affected zone  2008 , additional heating time and/or higher temperatures may be needed to ensure that the seal between the layers of the overwrap material has enough strength to avoid separation during conveyance and/or during the heat shrinking process. Although only one heat affected zone  2006  is depicted in  FIG.  11   , it is understood that the package  2000 ,  2000 A,  2000 B may comprise two or more heat affected zones (not shown), in which the number of heat affected zones corresponds to the number of heating zones. 
       FIGS.  12  and  14    are photographs of packages formed using conventional processes, and  FIGS.  13  and  15    are photographs of similar packages formed using processes in accordance with the present disclosure. With reference to  FIG.  12   , a package  3000  containing six boxes of facial tissues comprises a display panel  3000 - 1  with graphics  3003  extending over substantially an entirety thereof. The package  3000  is made with a conventional heat sealing process. It can be seen that the display panel  3000 - 1  includes several defects  3005  where the overwrap material is bunched together and ink from the graphics  3003  is collected to form dark, visible lines. In addition, the display panel  3000 - 1  includes defects  3005  in the form of stretching, wrinkling, and distortion, which are believed to be due to uneven shrinking of the overwrap material.  FIG.  13    is a photograph of a substantially similar package  4000  with substantially similar graphics  4003 , in which the package  4000  is formed in accordance with the present disclosure. It can be seen that a display panel  4000 - 1  of the package  4000  contains no visible defects and that the graphics  4003  are clear with no visible distortion or collection of ink. 
       FIGS.  14  and  15    are photographs of packages  5000 ,  6000  containing ten boxes of facial tissue. A display panel  5000 - 1  of the package  5000  of  FIG.  14   , which is formed using a conventional process, has multiple defects  5005 , including bunching of the overwrap material in some areas and overstretching of the overwrap material in other areas. The display panel  5000 - 1  also includes areas where ink from the graphics  5003  is collected, along with overall distortion and misalignment of the graphics  5003  and areas where the overwrap material is overstretched to the point that portions of the graphics  5003  are washed out.  FIG.  15    is a photograph of a substantially similar package  6000  with substantially similar graphics  6003  that is formed in accordance with the present disclosure. It can be seen that a display panel  6000 - 1  of the package  6000  contains no visible defects and that the graphics  6003  are clear, properly aligned, and contain no visible distortion or collection of ink. 
     A configuration of a configurable heat sealing surface in accordance with the present disclosure may be quickly and easily changed to accommodate each package  2000  or stack of packages  2000 A,  2000 B. In a conventional heat sealing apparatus, altering any properties of the heat sealing surface generally requires removing and/or replacing entire heating block assemblies, which can be a difficult and lengthy process. Conducting maintenance likewise requires removing/replacing the entire heating block assembly. In contrast, a configuration of a heat sealing surface in accordance with the present disclosure may be quickly and easily adjusted by altering the insulator and/or conductor segment configuration of one or more heating block assemblies define a different number of heating zones, change a vertical and/or horizontal location of one or more of the heating zones, and/or change a dimension of the one or more heating zones. 
     For example, following sealing of the package  2000  in  FIG.  9   , it may be desirable to change the insulator and/or conductor segment configuration of the heating block assembly  510  to a configuration that permits sealing of a double-stack package configuration as shown in  FIG.  10   . One or more of the insulator and/or conductor segments  530   a ,  530   b ,  532   a  of the heating block assembly  510  may be removed as described herein and replaced with one or more insulator and/or conductor segments of a different length (not labeled; see  FIGS.  2  and  4   ), e.g., the insulator and conductor segments  630   a - c ,  632   a .  632   b  of  FIG.  10   , such that the configuration of the heat sealing surface  560  is altered without the need to remove the heating block assembly  510 . In addition, any damaged insulator and/or conductor segments can easily be removed and replaced without the need to remove the heating block assemblies  510 ,  610 . 
     In other examples, the controller (not shown; see  FIG.  1   ) may selectively control operation of the heating block assemblies within a heat sealing surface, thereby allowing a single heat sealing surface to accommodate packages of differing dimensions and/or different numbers of packages without the need to change the insulator and/or conductor segment configuration between runs. For instance, the controller may selectively provide power to one or more of the heating block assemblies to achieve a desired configuration of the heat sealing surface, e.g., a desired number, dimension, and/or location of heating zones in a vertical and/or horizontal direction. In particular, the controller may be configured to selectively provide power to pairs of heating block assemblies such that heating zone(s) of one pair of heating block assemblies are a first temperature and heating zone(s) of an adjacent pair of heating block assemblies are a second temperature that is different from the first temperature 
     With reference to  FIG.  7   , when a (single-stack) package, e.g., package  1000  in  FIG.  8   , is advanced along the heat sealing surface  360 , the controller (not shown; see  FIG.  1   ) may selectively provide power only to the heating elements  358  of pairs  328   b  of heating block assemblies  310 ′, such that only the appropriate heating zone, e.g., heating zone  362 ′, is active (i.e., at or above a temperature necessary to melt the material of the overwrap) and conducting heat to seal only the one or more sections of the first end surface  1000 - 1  of the package  1000 . The heat sealing surface  360  may then be adapted for two (double-stacked) packages, e.g., packages  2000 A,  2000 B in FIG.  10 , by selectively providing power only to the heating elements  358  of pairs  328   a  of heating block assemblies  310 , such that only the appropriate heating zone, e.g., heating zones  362 ,  364 , are active and conducting heat to seal only the one or more sections of the first end surfaces  2000 A- 1 ,  2000 B- 1  of the first and the second package  2000 A,  2000 B. 
     Alternatively, with continued reference to  FIG.  7   , the controller (not shown) may provide power to all of the heating block assemblies  310 ,  310 ′ simultaneously such that the heating zones  362 ,  364  or  362 ′ of only one of the pairs  328   a  or  328   b  of heating block assemblies  310 ,  310 ′ are at or above the temperature necessary to melt the material of the overwrap and the heating zones  362 ,  364  or  362 ′ of the other one of the pairs  328   a  or  328   b  of heating block assemblies  310 ,  310 ′ are above room temperature but below the temperature necessary to melt the material of the overwrap. In the case of a polyethylene overwrap, when a (single-stack) package (not shown) is advanced along the heat sealing surface  360 , the controller may provide power to the pairs  328   a  of heating block assemblies  310  such that the heating zones  362 ,  364  are at a temperature necessary to melt polyethylene, e.g., 150° C. or higher. The controller may simultaneously provide power to the adjacent pairs  328   b  of heating block assemblies  310 ′ such that the heating zone  362 ′ is at a lower temperature, e.g., 125° C., that does not melt polyethylene. This selective control of the heating block assemblies  310 ,  310 ′ limits the dimensions of the heat-affected zone of the package (see  FIG.  11   ). For double-stacked packages, the controller may provide power such that the heating zones  362 ,  364 ,  362 ′ of all of the heating block assemblies  310 ,  310 ′ are at or above 150° C. Maintaining the inactive pair(s) of heating block assemblies at a minimum temperature that is above room temperature but below the temperature needed to melt the material of the overwrap may minimize the time needed to bring the heating zones of the inactive pairs to the required temperature and may increase the number of runs that may be performed using a single configurable heat sealing surface. 
       FIG.  16    is a flow diagram illustrating an exemplary method  7000  for sealing at least one portion of a package in accordance with the present disclosure. The method  7000  begins providing a configurable heat sealing surface at Step  7002  and selectively adjusting a configuration of the configurable heat sealing surface to define one or more heating zones at Step  7004 . At Step,  7006 , the package is advanced along the configurable heat sealing surface adjacent to the one or more heating zones to seal the at least one portion of the package, after which the method  7000  may conclude. 
     Representative embodiments of the present disclosure described above can be described as follows: 
     A. A heating block assembly comprising:
         one or more configurable insulator segments; and   a heater block comprising a first surface configured to removably receive the one or more configurable insulator segments,   wherein each of the one or more configurable insulator segments covers only a portion of the first surface.       

     B. The heating block assembly according to paragraph A, wherein each of the one or more configurable insulator segments comprises an inner surface positioned adjacent to the first surface of the heater block and an outer surface opposite the inner surface. 
     C. The heating block assembly according to paragraph B, wherein each of the one or more configurable insulator segments comprises a thickness of between 2.9 and 3.1 mm, wherein the thickness is defined between the inner and outer surfaces. 
     D. The heating block assembly according to paragraphs B or C, wherein a temperature of the outer surface of each of the one or more configurable insulator segments is between 20% and 30% less than a temperature of the first surface of the heater block. 
     E. The heating block assembly of according to any of paragraphs A to D, wherein the first surface of the heater block comprises a first extension and a second extension and wherein each of the one or more configurable insulator segments comprises a first corresponding channel and a second corresponding channel configured to receive the respective first and second extensions. 
     F. The heating block assembly according to any of paragraphs A to E, wherein the heater block comprises aluminum and wherein each of the one or more configurable insulator segments comprises polyether ether ketone. 
     G. The heating block assembly according to any of paragraphs A to F, wherein the heater block is configured to receive a heating cartridge and the heater block comprises a thermally conductive material. 
     H. The heating block assembly according to any of paragraphs A to G, further comprising one or more configurable conductor segments each comprising a thermally conductive material. 
     I. The heating block assembly according to paragraph H, wherein the one or more configurable insulator segments comprise a first insulator segment and a second insulator segment, and wherein the first and second insulator segments are spaced apart from each other along a longitudinal length of the heater block by at least one of the one or more configurable conductor segments to define at least one heating zone. 
     J. The heating block assembly according to paragraph I, wherein the first insulator segment comprises a first length and the second insulator segment comprises a second length that is the same as or different from the first length. 
     K. A heat sealing apparatus comprising at least a first heating block assembly and a second heating block assembly, each of which comprises:
         one or more configurable insulator segments; and   a heater block comprising a first surface configured to removably receive the one or more configurable insulator segments,   wherein each of the one or more configurable insulator segments covers only a portion of the first surface.       

     L. The heat sealing apparatus according to paragraph K, wherein the first heating block assembly comprises a first insulator segment and the second heating block assembly comprises a second insulator segment, and wherein when the first and second heating block assemblies are positioned side-by-side, at least one of top edges or bottom edges of the first and second insulator segments are horizontally aligned with each other. 
     M. The heat sealing apparatus according to paragraphs K or L, further comprising a plurality of configurable conductor segments, wherein the first heating block assembly comprises first and second insulator segments spaced apart from each other along a longitudinal length of the heater block of the first heating block assembly by at least one of the plurality of configurable conductor segments, and wherein the second heating block assembly comprises third and fourth insulator segments spaced apart from each other along a longitudinal length of the heater block of the second heating block assembly by at least one of the plurality of configurable conductor segments. 
     N. The heat sealing apparatus according to paragraph M, wherein the first and second heating block assemblies are positioned side-by-side and wherein at least one of: at least one of top edges or bottom edges of the first and third insulator segments are horizontally aligned with each other; or at least one of top edges or bottom edges of the second and fourth insulator segments are horizontally aligned with each other. 
     O. The heat sealing apparatus according to any of paragraphs K to N, wherein the first heating block assembly is positioned to at least partially define a first heat sealing surface configured to seal a portion of a first end surface of a package, and wherein the second heating block assembly is positioned opposite the first heating block assembly to at least partially define a second heat sealing surface configured to seal a portion of a second end surface of the package. 
     P. A heat sealing apparatus comprising: a configurable heat sealing surface comprising one or more heating zones each defined by one or more configurable insulator segments and one or more configurable conductor segments, wherein each of the one or more configurable insulator segments covers only a portion of the configurable heat sealing surface. 
     Q. The heat sealing apparatus according to paragraph P, wherein the configurable heat sealing surface comprises a first configurable heat sealing surface, the heat sealing apparatus further comprising: a second configurable heat sealing surface comprising one or more second heating zones each defined by one or more second configurable insulator segments and one or more second configurable conductor segments, wherein each of the one or more second configurable insulator segments covers only a portion of the second configurable heat sealing surface. 
     R. The heat sealing apparatus according to paragraph Q, wherein the first configurable heat sealing surface comprises a first insulator segment configuration and wherein the second configurable heat sealing surface comprises a second insulator segment configuration that is the same as or different from the first insulator segment configuration. 
     S. The heat sealing apparatus according to paragraphs Q or R, wherein the first configurable heat sealing surface comprises one or more first heating block assemblies, each of the one or more first heating block assemblies comprising a first heater block with a first surface configured to removably receive the one or more configurable insulator and conductor segments, wherein the one or more configurable insulator segments each cover only a portion of the first surface of the first heater block; and the second configurable heat sealing surface comprises one or more second heating block assemblies, each of the one or more second heating block assemblies comprising a second heater block with a first surface configured to removably receive the one or more second configurable insulator and conductor segments, wherein the one or more second configurable insulator segments each cover only a portion of the first surface of the second heater block. 
     T. The heat sealing apparatus according to paragraph S, wherein the one or more first heating block assemblies comprise a first plurality of heating block assemblies, the first plurality of heating block assemblies comprising a first pair of heating block assemblies and a second pair of heating block assemblies positioned side-by-side with the first pair of heating block assemblies, the heat sealing apparatus further comprising: a controller operatively coupled to each of the first plurality of heating block assemblies and configured to selectively operate the first and second pairs of heating block assemblies. 
     U. The heat sealing apparatus according to paragraph T, wherein the first pair of heating block assemblies comprises a first insulator segment configuration and the second pair of heating block assemblies comprises a second insulator segment configuration that is different from the first insulator segment configuration, the controller being configured to selectively provide power to the first and second pair of heating block assemblies such that the one or more heating zones of the first pair of heating block assemblies comprise a first temperature and the one or more second heating zones of the second pair of heating block assemblies comprise a second temperature that is different from the first temperature. 
     V. A method for sealing at least one portion of a package, the method comprising:
         providing a configurable heat sealing surface;   selectively adjusting a configuration of the configurable heat sealing surface to define one or more heating zones; and   advancing the package along the configurable heat sealing surface adjacent to the one or more heating zones to seal the at least one portion of the package.       

     W. The method according to paragraph V, wherein selectively adjusting the configuration of the configurable heat sealing surface comprises adjusting at least one of (i) a number of heating zones, (ii) a vertical location of the one or more heating zones, (iii) a horizontal location of the one or more heating zones, or (iv) a dimension of the one or more heating zones. 
     X. The method according to paragraphs V or W, wherein the configurable heat sealing surface comprises a plurality of heating block assemblies each comprising a heater block with one or more configurable insulator segments and one or more configurable conductor segments that define the one or more heating zones. 
     Y. The method according to paragraph X, wherein selectively adjusting the configuration of the configurable heat sealing surface comprises, for each of the plurality of heating block assemblies, selectively positioning the one or more configurable insulator and conductor segments along a longitudinal length of the heater block to define the one or more heating zones. 
     Z. The method according to paragraphs X or Y, wherein the plurality of heating block assemblies comprise a first pair of heating block assemblies and a second pair of heating block assemblies, the method further comprising: selectively operating the first and second pairs of heating block assemblies to seal the at least one portion of the package. 
     AA. The method according to paragraph Z, wherein the first and second pair of heating block assemblies are positioned side-by-side. 
     BB. The method according to paragraphs Z or AA, wherein the package comprises a first package, the method further comprising: selectively providing power to the first pair of heating block assemblies to seal the at least one portion of the first package; after sealing the at least one portion of the first package, advancing a second package along the configurable heat sealing surface; and selectively providing power to the second pair of heating block assemblies to seal at least one portion of the second package. 
     CC. The method according to paragraph BB, wherein the first pair of heating block assemblies comprises a first insulator segment configuration and the second pair of heating block assemblies comprises a second insulator segment configuration different from the first insulator segment configuration. 
     DD. The method according to any of paragraphs V to CC, wherein the configuration of the configurable heat sealing surface comprises a first configuration, the method further comprising: after sealing the at least one portion of the package, selectively adjusting the configuration of the configurable heat sealing surface to comprise a second configuration defining one or more second heating zones, the second configuration being different from the first configuration. 
     EE. The method according to paragraph DD, further comprising: advancing a second package along the configurable heat sealing surface adjacent to the one or more second zones to seal at least one portion of the second package. 
     FF. The method according to any of paragraphs V to EE, wherein the one or more heating zones comprise a first heating zone and a second heating zone that is positioned above or below the first heating zone, and wherein the package comprises a first package, the method further comprising: positioning a second package above or below the first package; and advancing the second package along the configurable heat sealing surface with the first package, wherein one of the first or the second heating zone seals the at least one portion of the first package and the other of the first or the second heating zone simultaneously seals at least one portion of the second package. 
     GG. The method according to any of paragraphs V to FF, wherein the configurable heat sealing surface comprises a first configurable heat sealing surface, the method further comprising: providing a second configurable heat sealing surface positioned opposite the first configurable heat sealing surface; and selectively adjusting a configuration of the second configurable heat sealing surface to define one or more second heating zones. 
     HH. The method according to paragraph GG, wherein the at least one portion of the package comprises a first end surface and wherein advancing the package along the first configurable heat sealing surface seals at least a section of the first end surface of the package. 
     II. The method according to paragraph HH, wherein the at least one portion of the package further comprises a second end surface positioned opposite the first end surface, the method further comprising: advancing the package along the second configurable heat sealing surface adjacent to the one or more second heating zones to seal at least one section of the second end surface of the package. 
     JJ. The method according to paragraph II, wherein the package is advanced along the first and second configurable heat sealing surfaces such that the at least one sections of the first and second end surfaces of the package are sealed simultaneously. 
     KK. The method according to any of paragraphs V to JJ, further comprising: after advancing the package along the configurable heat sealing surface, subjecting the package to a heat shrinking process. 
     The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.” 
     Every document cited herein, including any cross referenced or related patent or application and any patent application or patent to which this application claims priority or benefit thereof, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern. 
     While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.