Rapid Fabrication of an Electrically Insulating, Fiberglass Composite Wrench Using 3D-Printed Dissolvable Molds

Author(s):

Derek J. Bischoff, Michael J. DeGrange, John P. Reynolds, and Eric D. Wetzel

Abstract:

The use of 3D-printed tooling is demonstrated in the fabrication of an electrically insulating wrench for use on electrical lugs for Army generators. The tooling is used in a compression molding process to create a fiberglass composite wrench using high dielectric strength materials. A water-soluble thermoplastic filament, butenediol vinyl alcohol copolymer, is 3D printed using a standard desktop fused filament fabrication machine to produce the tooling. The use of a dissolvable filament simplifies the design by eliminating typical tool design considerations such as draft angles and undercuts. Part release is attained upon the dissolution of the mold in water, further simplifying the molding and de-molding processes while eliminating the need for mold release or ejector pins. A cost analysis is performed indicating that for part runs of less than 10 parts, the 3D-printed mold approach is approximately 10 times cheaper than conventional transfer molding and continues to show reduced cost for production runs of up to 144 parts. Furthermore, part lead times are dramatically reduced because a 3D-printed mold can be designed and produced in a few days, compared with lead times of months for conventionally machined metal transfer molds. This fabrication method is amenable to point-of-need manufacturing with relatively simple and low-cost equipment and materials.