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RD Abbott printer helps cut the prototyping process

By: Bruce Meyer
LSR World

12 February 2018

Cerritos, Calif. — R.D. Abbott Co. Inc. is looking to help spread the word in North America about the liquid silicone rubber 3D printing technology developed by German RepRap GmbH and Dow Performance Silicones.
Its laboratory in Cerritos is now equipped with the patent-pending Liquid Additive Manufacturing 3D printer that RepRap designed to be used in conjunction with the Silastic LC 3335 LSR grade from DowDuPont Inc.
The two companies unveiled the technology in late 2016, and now R.D. Abbott, a supplier of elastomer products and technical services, is aiming to help customers cut down the prototype process and potentially produce low-volume parts, according to Rick Ziebell, R.D. Abbott's vice president of technology.
"With this new LAM 3D printer, we can assist our customers with their LSR designs by providing fast turnaround prototype parts," he said. "This provides assuredness in design and streamlines the process of moving from the design phase to production."
The California-based firm first touted the technology at the ACS Rubber Division's International Elastomer Conference last fall in Cleveland. Besides having it available at its lab in Cerritos, the technology is planned for display at the MD&M West Show in Anaheim, Calif., at M.R. Mold & Engineering's booth, with Ziebell also presenting a paper on the innovation during the conference.
German RepRap designed its 3D printer to print successive layers of the Silastic LC-3335 printable LSR in a method comparable to the firm's fused filament fabrication 3D printers. Each layer of silicone is cross-linked through thermal cure to produce parts with properties comparable to molded components. The firms said the 3D printing process can form complex silicone parts that would be difficult or impossible to achieve through conventional injection molding.
Dow Performance Silicones' Silastic LC-3335 grade is formulated specifically for designers seeking to combine the performance benefits of silicone with the design and processing advantages of the additive manufacturing process. The firm said the 50 Shore A hardness LSR allows new design options in areas where traditional LSRs are used, including automotive, consumer care, cookware and lighting.

"More than simply a technological achievement, this material introduces the power and versatility of silicone technology into the realm of 3D printing," said Kris Verschueren, Dow Performance Silicones' global innovation program manager. "Our customers can now combine the uniquely beneficial properties of our silicones with faster prototype development and small series production of highly complex parts."

Exerting control
Ziebell said the specialty LSR material has viscoelastic properties that allow users to inject the material through a small-tip nozzle and lay it down onto the surface of a platform in a controlled matter. He likens it to squeezing toothpaste onto a toothbrush. It can be piled onto the brush, or it can be stretched out and put down in in unique areas.
R.D. Abbott and Dow Performance Silicones have worked the past several years on the material characterization of the LSR material to understand how the dispensing forces the geometry of the rope that's laid down, he said.
"We've done that with this LSR and tuned it very specifically to allow us to utilize these machines and lay down a very intricate pattern in a controlled manner," Ziebell said. "It's a very precise dispensing method that German RepRap helped develop."

Added benefits
A second potential benefit of this LAM 3D printing process is the possibility of having unique parts made for individuals.
"If you have a low-volume application where you need specialized parts where each one is unique, there's a way to do that without building a mold for each part," said Tom Jenkins, R.D. Abbott's executive director of business development. "So low-volume, unique products can also be produced with this in a production setting."
Ziebell said an example of such an application may be along the lines of a health care prosthesis that needs to be custom-fit for an individual. "There is a lot of work in the biomechanical areas of health care where we could develop a design for a specific aspect of the human body — a platform, if you will — in order to grow cells or to construct tissue in a way that allows for interesting outcomes in biomechanical technologies," he said.