Materials Engineering

Strong resins for fast prototypes
Prototal built several iterations of the camera with the stereolithography (SL) photopolymer from Huntsman Advanced Materials, The Woodlands, Tex., taking just two days for each functional prototype. RenShape SL 7810 is a white, ABS-like resin that yields accurate, durable parts with high-quality surface finishes.

According to Prototal project manager Jonas Sandwall, “The time-to-market schedule set by Swedish cameramaker Flir Systems AB, was so tight that SL technology was the only option for building the highly detailed, functional models on time.”

The antimony-free RenShape SL 7810 combines good impact strength with long-term dimensional stability, even at temperatures of up to 104°F (40°C) and 90% humidity. The photopolymer easily processes in Prototal’s SLA 5000 equipment thanks to its low viscosity and high green strength. Cured and painted SL prototypes could be ready in one week.

Sandwall says, “RenShape SL 7810 resin delivers good physical properties and models are stable for a long period. It also processes faster than some other photopolymers, so it is more economical than competitive materials. The models we produced for Flir successfully completed several internal assembly and function tests as well as final customer approval procedures.”

These heels are made for walking
High heels made from Terblend N, an ABS/PA polymer from BASF Corp., Florham Park, N.J., are now hitting the streets in China. The ABS/PA resists impacts at freezing temperatures, has good dimensional stability under heat, and sports a high-quality surface finish so spiked heels up to 10-cm (4-in.) tall continue to look good even after covering miles of city sidewalks and clumping over steel gratings in the dead of winter.

“The higher the heel, the greater the demands on the material,” says BASF Taiwan’s Alfeda Cho. “High heels that are injection molded using Terblend N are robust to dents and fractures. And compared to high heels made from standard styrene plastics, the Terblend N heels have considerably better mechanical properties and cost less to produce.” The ABS/PA blend is easy to coat and molds with good surface quality. The heels reportedly feel good to the touch and have a pleasant sound as they strike the floor.

Coming: Powdered metal titanium armor
Titanium is the material of choice for stopping bullets and lightening up component weight, but it has always been too expensive for all but the most specialized applications. That could soon change, say researchers at Oak Ridge National Lab. The team from ORNL along with industry partners BAE Systems Inc., Rockville, Md, International Titanium Powders LLC, Woodridge, Ill., and Ametek, Paoli, Pa., have developed a nonmelt consolidation process that could halve the energy needed and the cost of making titanium parts from powdered metal. The process makes feasible titanium brake rotors, artificial joints, and armor for military vehicles.

ORNL recently exhibited a new low-cost titanium alloy door for the Joint Light Tactical Vehicle. Titanium-alloy doors let BAE Systems Inc. cut the weight of a next-generation combat vehicle while protecting against armor-piercing rounds. The lightweight titanium alloy also makes it easier to open doors so soldiers have better mobility. The nonmelt approach offers many advantages over traditional melt processing, says Bill Peter, a researcher in ORNL’s Materials Science and Technology Div.

“Instead of using conventional melt processing to produce products from titanium powder the ORNL technique uses roll compaction to directly fabricate sheets from powder, pressand- sinter techniques to produce net-shape components, and extrusion. Powders remain in their solid form during the entire procedure,” says Peter. “This saves a tremendous amount of energy for processing, greatly reduces scrap, and lets us create new alloys and engineered composites.”

Powder metallurgy has been used to produce components for many years but those made from titanium haven’t been widely produced because conventional titanium powders were too expensive.

The titanium-alloy door was produced through a collaboration among the DOE’s Office of Energy Efficiency and Renewable Energy, Darpa, and BAE Systems Inc.