Electroplating on 3D printed (a.k.a. AM) parts can be done using plating sequences familiar to most production plating on plastics (POP) operations albeit in different proportions and some of the steps must be done differently. Production POP uses a limited number of resin substrates, predominantly platable grade ABS, and cosmetic parts are injection molded in highly polished steel tools. The resin is etched using chromic acid, then an autocatalytic Cu or Ni conductive layer is applied followed by plating sequentially with copper, nickel and then chrome (or other cosmetic top coat). At high volume, the cost of plating is similar to the cost of injection molding.
3D printed parts can be made via photopolymerization, sintering/fusion of thermoplastic powders and extrusion of thermoplastic filaments. Printing rates are an order of magnitude slower, albeit without the investment in tooling. Within the broad printing categories there are a large variety of resins that can be printed. Photopolymer prints are fully dense, can be printed at the highest resolution but have the greatest sensitivity to the strong acids use in many plating processes. Thermoplastic prints contain at least a small amount of residual porosity and can have rough, permeable surfaces. There are printing artifacts on most surfaces of AM parts and these can change depending on printer type, build orientation, layer thickness, printing method and resin chosen.
With such a broad range of print options it is imperative that printers and platers form a close working relationship in order to choose to optimum print method, materials, post processing and plating process sequence to obtain the performance required but the customer. There may even be changes needed on the CAD file to accommodate the coating. Photopolymer marts will likely require more thorough cleaning and curing. Sintered and fused thermoplastic parts may require additional energy on the part surface to make them water tight and extra cleaning to remove all residual powders. Filament prints will have to be built with minimal porosity but the surfaces will still need to be sealed in a way that is compatible with the plastic substrate and the plating processes.
This presentation will review the design through fabrication processes followed for plated 3D printed parts from the various printing technologies in used today. A few examples will also be presented to show the design freedom of AM can be used on conjunction with traditional plating process to make unique functional parts.
Dr. Sean Wise is president of RePliForm Inc. and has been working at making prototyping parts since the early 1980’s, even before “rapid” and layered manufacturing entered the lexicon. His career began in working on new methods to make rapid tooling so parts could be fabricated from production materials by production processes to test designs in development. When rapid prototyping (RP) came along, he used the new RP methods in a novel pattern design approach for quick tooling processes using electroformed metals and mass cast tooling systems. About 18 years ago a customer wanted to make fully functional prototypes with properties similar to injection molded fiber reinforced materials using a 3D printed SLA model and found an electroformed coating was an effective reinforcing layer to stiffen and strengthen the parts. The success of this project let to a new direction for RePliForm where coatings over additive manufactured parts became the focus to make metal clad composites that simulated the properties of reinforced plastics and light weight metals. These methods are sufficiently robust that that they have transitioned prototypes into production methods for low volume manufacturing.
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