Powder Metal Potential Reaches Critical Mass

Diesel Progress North American Edition, Feb, 2001 by Rob Wilson

The use of cold and hot isostatic pressing (CIP and HIP) and metal injection molding are not as widely applied. CIP and HIP are capable of much larger part sizes and are applicable to costly materials such as superalloys, titanium, tool steels and beryllium and provide fully dense material with mechanical properties as good or better than cast or wrought materials. But the tolerance requirements are greater, processing is slower and more costly than other P/M processes. Still they do find many applications for products such as cutting tools, cylinder liners, gas turbine components, petrochemical equipment and medical implants.

Metal injection molding is more limited to small complex parts, generally less than 2 oz. But MIM parts do offer excellent surface quality, fine-grained material structure, outstanding mechanical properties, high dimensional accuracy and material flexibility. MIM is applied to complex automotive parts, fuel system components, computers and electronic devices, medical equipment and precision instruments.

In the overall, P/M processes work successfully with a broad range of material systems including: iron and carbon steel, iron-copper and copper steel, iron-nickel and nickel steel, low alloy steel, sinter hardened steel, diffusion alloyed steel, copper infiltrated iron and steel, 300 and 400 series stainless steel, copper and copper alloys, and soft magnetic alloys.

Designers have plenty of help these days in identifying prospective P/M parts and developing altogether new ones. Ample information is available on secondary machining, green machining, coining and stamping, joining and heat treating technology. Material standards have been codified by the Metal Powder Industry Federation and specialist standards for P/M gear specifications are available from MPIF in conjunction with the American Gear Manufacturers Association (AGMA). All in all, the stage seems set for considerable gains in P/M applications.

"We will see accelerating use of P/M technology," predicts GKN's Ghasemi, "because we are challenged by accelerating competitive pressures in all manufacturing industries, but particularly the automotive sector. The status quo will yield to more innovative approaches. Conventional processes can always be optimized further, but the incremental gains will be smaller and smaller.

"Due in large measure to the fragmented structure of our industry, the application of P/M technology has not been optimized at all while the technology itself is well in hand. That's why we are putting together a new kind of company with comprehensive, global P/M capability that can bring sinter metals into the mainstream of manufacturing technologies. We have the people, the design base, the production facilities, the level of integration and the financial stability to see any project through. Our customer focus is keen and together we can answer any challenge."