Braided comingled tow filament for use in 3d printing

Abstract

A feedstock configured for use in an extruder in an additive manufacturing system is configured as a braided comingled tow filament. A method of producing the braided comingled tow filament includes providing a bundle of comingled tow material having a fiber count ranging from about 1,000 fibers to about 25,000 fibers having thermoplastic fibers comingled therewith, wherein the tow material in the filament ranges from about 50 to 75 volume percent and the volume percent of the thermoplastic material ranges from about 25 volume percent to about 50 volume percent. The method includes dividing the length of comingled tow material into sections, twisting each section into a strand to form a plurality of strands of twisted tow material, and braiding together the strands.

1 . A method of producing a feedstock configured for use in an extruder in an additive manufacturing system, the method comprising:
 providing a length of comingled tow material having a fiber density ranging from about 1,000 fibers to about 25,000 fibers having thermoplastic fibers comingled therewith, wherein the tow material in the filament ranges from about 50 to 75 volume percent and the volume percent of the thermoplastic material ranges from about 25 volume percent to about 50 volume percent;   dividing the length of comingled tow material into sections;   twisting each section into a strand to form a plurality of strands of twisted tow material;   braiding together the plurality of strands of tow material to form a braided tow filament having a longitudinal axis for use in the additive manufacturing system.   
     
     
         2 . The method of  claim 1 , and wherein the thermoplastic fibers in the braided tow filament remain unmelted in the braided tow filament prior to being processed in the additive manufacturing system. 
     
     
         3 . The method of  claim 1 , wherein the fiber tow material comprises carbon fiber, glass fiber and combinations thereof. 
     
     
         4 . The method of  claim 1 , wherein the fiber tow material comprises carbon fiber, glass fiber, basalt, cotton, aramid fibers, high density polyethylene (HDPE) and combinations thereof. 
     
     
         5 . The method of  claim 1 , and further comprising treating the unmelted thermoplastic fibers and/or the strands of tow material with sizing treatments to increase bonding with the tow material, when the thermoplastic is melted or heated to a flowable state. 
     
     
         6 . The method of  claim 1 , wherein providing a length of commingled material comprises providing at least two lengths of different materials, and wherein dividing the length of comingled tow material into sections comprises dividing the at least two lengths of different materials into sections, such that the braided tow filament is formed of at least two different materials braided together. 
     
     
         7 . The method of  claim 1 , and further comprising sizing the comingled braided tow to a selected size by processing the braided tow through a sizing die, wherein as the comingled braided tow is processed through the sizing die, the thermoplastic material is melted or heated to a flowable state. 
     
     
         8 . The method of  claim 1 , and further comprising processing the comingled fiber tow material through a calendaring die to form a substantially flat ribbon tape, wherein as the comingled braided tow is processed through the calendaring die, the thermoplastic material is melted or heated to a flowable state. 
     
     
         9 . The method of  claim 1 , wherein the filament has a substantially circular cross-section when taken along a plane substantially normal to the longitudinal axis. 
     
     
         10 . The method of  claim 1 , wherein the filament has a substantially square cross-section, rectangular cross-section, elliptical cross-section or obround cross-section when taken along a plane substantially normal to the longitudinal axis, wherein the filament with the rectangular cross-section, elliptical cross-section or obround cross-section has an aspect ratio ranging from about 2:1 to about 20:1 when taken along a plane substantially normal to the longitudinal axis. 
     
     
         11 . The method of  claim 1 , wherein the comingled tow material in the filament ranges from about 55 to 70 volume percent and the volume percent of the thermoplastic material ranges from about 30 volume percent to about 45 volume percent 
     
     
         12 . The method of  claim 1 , wherein the feedstock is coextruded to form a core/shell configuration wherein the braided tow filament is within the core, wherein the coextrusion process melts the commingled thermoplastic in the braided tow filament. 
     
     
         13 . The method of  claim 12 , wherein the core/shell filament is in a cylindrical form or in a ribbon form with an aspect ratio ranging from about 2:1 to about 20:1. 
     
     
         14 . The method of  claim 1 , and further comprising coextruding the braided tow filament with a thermoplastic to bond layers of thermoplastic material on opposing sides of the braided tow filament. 
     
     
         15 . A method of printing a part with an extrusion based additive manufacturing system, the method comprising:
 providing a filament of braided tow material with a longitudinal axis and having a fiber density ranging from about 1,000 fibers to about 25,000 fibers having thermoplastic fibers comingled therewith, wherein the comingled tow material in the filament ranges from about 50 to 75 volume percent and the volume percent of the thermoplastic material ranges from about 25 volume percent to about 50 volume percent;   heating the thermoplastic material within the filament to a flowing or melted state; and   extruding the filament along a first tool path to form at least a portion of the part wherein the thermoplastic material bonds to the tow material and provides a sufficient amount of thermoplastic material on a surface of the extruded filament such that layers of the filament bond to each other to print at least a portion of the part.   
     
     
         16 . The method of  claim 15 , and further comprising severing the filament proximate an end of the first tool path. 
     
     
         17 . The method of  claim 16 , wherein severing the filament comprises mechanically cutting the filament. 
     
     
         18 . The method of  claim 16 , wherein severing the filament comprises subjecting the filament to electromagnetic energy. 
     
     
         19 . The method of  claim 16 , and further comprising:
 heating the thermoplastic material within the filament to a flowing or melted state;   extruding the filament along a second tool path to print another portion of the part; and   severing the filament proximate an end of the second tool path.   
     
     
         20 . The method of  claim 19 , and further comprising repeating the heating, extruding and severing steps until the part is printed. 
     
     
         21 . The method of  claim 16 , wherein the filament has a substantially circular cross-section when taken along a plane substantially normal to the longitudinal axis. 
     
     
         22 . The method of  claim 16 , wherein the filament has a substantially square cross-section, rectangular cross-section, elliptical cross-section or obround cross-section when taken along a plane substantially normal to the longitudinal axis, wherein the filament with the rectangular cross-section, elliptical cross-section or obround cross-section has an aspect ratio ranging from about 2:1 to about 20:1 when taken along a plane substantially normal to the longitudinal axis. 
     
     
         23 . The method of  claim 15 , wherein the tow material in the filament ranges from about 55 to 70 volume percent and the volume percent of the thermoplastic material ranges from about 30 volume percent to about 45 volume percent. 
     
     
         24 . A filament for use in an extrusion based additive manufacturing system, the filament having a longitudinal axis, the filament comprising:
 a braided comingled tow material comprising at least three twisted strands, the commingled tow material having a fiber density ranging from about 1,000 fibers to about 25,000 fibers having thermoplastic fibers comingled therewith, wherein the tow material in the filament ranges from about 50 to 75 volume percent and the volume percent of the thermoplastic material ranges from about 25 volume percent to about 50 volume percent   
     
     
         25 . The filament of  claim 24 , wherein the filament has a substantially circular cross-section when taken along a plane substantially normal to the longitudinal axis. 
     
     
         26 . The filament of  claim 24 , wherein the filament has a substantially square cross-section, rectangular cross-section, elliptical cross-section or obround cross-section when taken along a plane substantially normal to the longitudinal axis, wherein the filament with the rectangular cross-section, elliptical cross-section or obround cross-section has an aspect ratio ranging from about 2:1 to about 20:1 when taken along a plane substantially normal to the longitudinal axis. 
     
     
         27 . The filament of  claim 24 , wherein the tow material in the filament ranges from about 55 to 70 volume percent and the volume percent of the thermoplastic material ranges from about 30 volume percent to about 45 volume percent. 
     
     
         28 . The filament of  claim 24 , wherein the fiber tow comprises carbon fiber, glass fiber and combinations thereof. 
     
     
         29 . The filament of  claim 24 , wherein the fiber tow comprises carbon fiber, glass fiber, basalt, cotton, aramid fibers, high density polyethylene (HDPE) and combinations thereof. 
     
     
         30 . The filament of  claim 24 , and further comprising a sizing treatment on the thermoplastic fibers and/or the fibers of the tow material, wherein the sizing treatment is configured to bond the thermoplastic material to the tow material when the thermoplastic material is in a flowable state or melted. 
     
     
         31 . The filament of  claim 24 , wherein at least two of the at least three strands are of different materials. 
     
     
         32 . The filament of  claim 24 , wherein the filament comprises a core/shell configuration wherein the braided commingled tow is within the core. 
     
     
         33 . The filament of  claim 32 , wherein the core and shell have the same thermoplastic material. 
     
     
         34 . The filament of  claim 32 , wherein the core and shell are of different thermoplastic materials. 
     
     
         35 . The filament of  claim 32 , wherein the thermoplastic materials of the core and shell are substantially miscible. 
     
     
         36 . The filament of  claim 32 , wherein the thermoplastic materials of the core and shell are substantially immiscible.