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New Medical Designs Power Metal Injection Molding
Parmatech gear cuts costs 70 percent compared to machined metal
Doug Smock, Contributing Editor -- Design News, August 25, 2008
New designs for medical and automotive applications will drive growth of powder metal and ceramic injection molding (PIM), says Randall M. German, mechanical engineering professor at Mississippi State University and author of "Powder Injection Molding: Design & Applications."
"Asian PIM will grow nearly 11 percent per year, while Europe and much of the rest of the world will grow at a more modest 8 percent per year," German said in a presentation at the PIM World Congress held recently in Washington, D.C.
One example of new
medical products is a 17-4 PH stainless steel articulation gear used in a
surgical stapling unit made by metal injection molding to a density of more
than 7.65 g/cm3. Parmatech
Corp., Petaluma, California, won the grand prize in the
medical/dental category at the World Congress for the part. The MIM part has an
ultimate tensile strength of 130,000 psi, yield strength of 106,000 psi and a
25 HRC hardness.
MIM is gaining ground because it combines functions in complex, net shapes that
require no finishing operations. The Parmatech part has tight tolerances and
provided a 70 percent cost savings compared to machining the gear from bar
stock.
Parts Get Smaller
There's a trend toward increasingly smaller parts in MIM, partly due to high powder costs. Most parts weigh between 5 and 10 gm, says German, although parts range from 0.002 gm to 1.3 kg. The North American PIM companies sometimes trend toward higher mass parts for medical applications, according to German. There's also significant interest in microminiaturized medical parts.
More than one-third of sales by North American PIM producers go to medical and dental applications.
"For continued growth, MIM needs to focus on competitive advantages that help defend the high component cost when compared to forging, machining, casting and related technologies," says German. "One goal is to improve dimensional control, second is to reduce process costs and a third is to shorten the time to production."
German says the total PIM industry consists of 360 firms, of which less than four-fifths practice metal injection molding. The U.S., Germany and Japan account for 57 percent of global PIM sales. Global PIM sales in 2007 reached 1.07 billion, says German.
Steel-based materials dominate metal injection molding, although there is tremendous interest in new materials' systems such as tungsten alloys and titanium. Tungsten alloys are particularly attractive as lead replacements.
