Award-winning molded metal parts cover wide range of applications

07/19/2010

Metal Injection Molding (MIM) has been catching on faster over the past decade in applications from medical and dental instruments, to aerospace and automotive parts. Let's see the winners from the Powder Metallurgy Design Excellence Awards Competition.

Winners of the 2010 Powder Metallurgy Design Excellence Awards Competition, sponsored by the Metal Powder Industries Federation (MPIF), were announced at PowderMet 2010, an international conference on Powder Metallurgy and Particulate Materials. The MIM parts that came out on top show the technology's wide applicability.

Megamet Solid Metals Inc., Earth City, MO, won one of two Awards of Distinction in its category for an upswept grip safety used in the 1911-style 45-caliber pistol made by Colt Manufacturing Company, LLC, West Hartford, CT. The complex 1704 PH stainless steel MIM part has a density of 7.6 g/cm3. The upswept design of the grip safety part, which was traditionally investment cast, previously required extensive secondary machining. Switching to the MIM process reduced customer lead times and provided exceptional cost savings, in addition to increasing production rates and producing a more uniform part. The upswept grip safety performs several functions: it blocks the trigger from firing, shields the hammer from impacting or injuring the shooter's hand when the pistol cycles, and interacts with the shooter's palm for comfort. Colt performed a 10,000-cycle test to qualify the part.

"The award best demonstrates the complex detail that is achieved by the MIM process," said Phil McCalla, operations manager for Megamet. "The part also displays the excellent surface finish that is attainable with MIM. Much of the grinding and polishing that was required with other manufacturing processes was virtually eliminated."

FloMet LLC in Deland, Fla., won the Grand Prize in the Aerospace/Military category for a safe and arm rotor used in an explosive device for the Department of Defense. Produced by the MIM process, the 316L stainless steel part is formed to a density of 7.6 g/cm3. Significant properties include ultimate tensile strength of 75,000 psi, yield strength of 25,000 psi, 50% elongation, 140-foot-pound impact strength and 67 HRB hardness.

The complex shape features numerous outside radii and angular surfaces. At least 12 functional features and surfaces are geometrically controlled by concentricity, profile, and true position tolerances. The part is assembled into a housing to provide the two-stage safety for the explosive device. It replaced a zinc die casting whose mechanical properties were not consistent enough to pass validation testing.

"We've won an award every year since 2007 and have been involved in MIM since 1990," says Dan Tasseff, director of sales and marketing for FloMet. "That's a very tough part but there was no other way to make it in large quantities unless you machine it, and that would be very expensive."

Advanced Materials Technologies Pte Ltd, Singapore, won the Grand Prize in the Industrial Motors/Controls & Hydraulics category for four complex 316L stainless steel MIM parts - a lock cover, lock barrel pin, lock barrel boss, and lock barrel square - assembled into a locking device for heavy machinery operating in harsh environments. Choosing the MIM process over die casting, said the company, provided superior surface finish that did not require polishing, enhanced corrosion resistance, as well as helped the company realize a 30% cost savings.

Smith Metal Products, Lindstrom, Minn., received the Grand Prize in the Hand Tools/Recreation category for a 17-4 PH stainless steel hunting arrow tip - called a shuttle T-lock broadhead - for Trophy Taker Inc., Plains, Montana. The hunting arrow tip was made by the MIM process because the unusual shape demanded the design engineering advances of the MIM process. While other processes were considered, they couldn't provide the necessary geometry for commercial production, and the prototypes cost many times more than MIM. Also, the arrow tip required minimal secondary operations, limited to a final grinding of a razor sharp edge on the tip of the ferrule and the leading edge of the blade.

Dan Evans, President of Trophy Taker, said the company uses the MIM process for a few other products including arrow rests. "We decided on the MIM process for the shuttle T because in our industry there's a value - even if it's a perceived value - in stainless steel for these parts," says Evans. "The MIM process allows us to use a stainless steel product that is hard to machine -- to get the contours required and the t-shaped grooves that allow the blades to slide into the ferrule -- those are really difficult to machine."
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