Design Freedoms of Polyurethane Reaction Injection Molding Process Create Fusion of Design, Ergonomics in Laser Micro-Welding Workstation.

Thanks to the design freedom provided by Reaction Injection Molding technology, a next-generation series of micro-welding workstations offers not only improved technology for producing jewelry, dental devices, medical devices, and electronic components, but also creates a fusion of better ergonomics and contemporary design. The new 7000 Series LaserStar Workstation features improved electronics, software, and product functions. A New England product design firm and a custom molder sharpened the aesthetic appeal and ergonomics of the equipment's facade by switching from sheet metal to polyurethane Reaction Injection Molding systems from Exothermic Molding Inc. for five housing panels.

LaserStar Technologies, Riverside, R.I., offers an alternative to soldering or microplasma welding for precious metal jewlery production, fabrication and repair of dental prosthetics, and micro assembly of medical devices and electronic components. The company's laser welding workstations eliminate the need for solder by using a sharp, focused laser beam to weld together any two metal parts.

"For the next generation series of LaserStar Workstations, we wanted to soften the look of the product and improve its ergonomics," said David P. Braman, Vice President of Engineering and Operations for LaserStar Technologies. "We hired a product design firm to help us achieve this. Based on the design firm's advice and articles that our own engineers had read in the trade press, we decided that Reaction Injection Molding (RIM Molding) was the right choice to replace the sheet metal panels that form the workstation's facade."

Item New Product Development, Providence, R.I., and Exothermic Molding, Inc., Kenilworth, N.J., recommended the PRISM® CM-200 solid polyurethane Reaction Injection Molding system from Bayer's Polyurethanes Division.

With UL94 flammability rating of V-O and 5VA, the PRISM® Reaction Injection Molding system is well suited for applications in medical, electronic, and other markets. The material is excellent for thin-wall molding and offers improved strength, surface finish, and large-part capability.

Reaction Injection Molding Creates Softer Look

"The polyurethane Reaction Injection Molding material gave a softer look to the workstation and it allowed us to create curved surfaces and flowing lines that sheet metal could not achieve," said Braman. "The surface quality of the painted parts is very good." An important material requirement was the ability for the molded panels to transition well into the sheet metal panels that still enclose the anterior portion of the workstation, Braman explained. "Bayer's polyurethane Reaction Injection Molding material has no difficulty achieving this. It also helped to better blend in the cuff boxes, which are the areas where users insert their hands to perform micro-welding when using the workstation," he said.

The PRISM® Reaction Injection Molding system's UL flammability rating made the material selection easier too, saving manfacturing time and money otherwise required to establish a flammability rating, said Braman.

The Designer's Perspective

"We thought polyurethane Reaction Injection Molding was the appropriate material for this application due to the production volume and part costs as well as the design freedoms we could achieve to accomplish the client's goals for a more appealing appearance," said Justin Sirotin, Designer with Item New Product Development. "Our firm has worked with the RIM process before, so we knew that it would give us a good platform to take the product's styling to the next level."

The Reaction Injection Molding process served functional purposes, too. "It allowed us to improve the ergonomics of the workstation by utilizing more curved and contoured shapes," he said.

According to Sirotin, it is relatively simple to design using the Reaction Injection Molding process: "The design process went very smoothly. You enjoy a lot of freedom with the design of the part and the tooling that will form it." For example, he said Item New Product Development incorporated large ribs under the surface of such parts as the access door for reinforcement, as well as molded-in bosses and inserts for assembling the parts.

Sirotin said the molded parts look "beautiful" after they are finished and painted. "When the appropriate oppurtunity arises again, we would not hesitate to consider the Reaction Injection Molding process for a product," he said.

Five Parts, Four Color Options

"I recommended the PRISM® Reaction Injection Molding system because it met the OEM's requirements for costing appearance while also providing the highest impact properties," said Paul Steck, President of Exothermic Molding. "The PRISM® system allowed us to mold the parts with thinner walls than a structural foam material. From a molder's perspective, it's an excellent material that helps us to produce outstanding parts."

Four machined aluminum molds designed by Exothermic Molding produce the five parts of the LaserSar Workstation's facade. Exothermic Molding was able to go from the design firm's CAD files directly to cutting tooling without producing drawings, which saved time and money on the project.

The five parts molded with the PRISM® Reaction Injection Molding system are a left cuff box and right cuff box, a bezel assembly that covers the top of the workstation and surrounds the stereo-microscope and electronic controls, and a foot rest cover at the base of the workstation.

A splash of color enhances and complements the workstation's new design. Buyers can order their workstation with the PRISM® Reaction Injection Molding system parts painted in sapphire blue, emerald green, ruby red, or pearl white two-component polyurethane paint. The sheet metal skin of the other panels is painted pearl white.

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