PM-11 Conference Report: Trends in PM applications and technologies
Trends in PM applications and technologies
Dr. Cesar Molins, in his keynote presentation “Trends in PM Applications and Technologies”, explained how Powder Metallurgy (PM) is a rapidly evolving industry with both technical evolutions in response to increasing market demands as well as new market applications resulting from improved technical capabilities.
Dr. Molins considered hard metals and tool steels to have increased industrial utilisations, special alloys and forming technologies to break new ground with innovative technological advancements that impact living standards such as aviation, medical technology and even oil exploration. Some of the significant features of his presentation are outlined below.
The growth of markets for Powder Metallurgy
Traditionally PM was used for varied industrial usage. Typically, timing pulleys and chain sprockets were manufactured with thin walls and run out in medium density and hardness. Induction hardening at various levels gave machinability and steam treatments led to oil tightness and hardness. Similarly, synchroniser hubs, pump pulleys/hubs and reduction gear rings had the attributes of medium density with high strength and zoned hardness at several levels. The machinability, elongation, medium strength and the roundness could be achieved and the parts could be case hardened, phosphated, high precision machined and brazed.
Powder forged connecting rods and synchroniser rings exhibited very high density, fatigue resistance and reduced machining costs.
Parts for household appliances such as valve plates, counterweights, connecting rods, pistons etc, had demonstrated wear resistance, air tightness and are manufactured to a high level of precision.
Emerging market bring increased demands
The emerging markets for PM are considered to be diverse and include electric cars, fuel cells, aeronautics, medical devices and prosthesis, and micromechanics with stringent requirements such as reduced prices followed by tighter tolerances, reduced weight, fuel consumption and emissions (in the case of cars).
There is also a demand for increased mechanical properties and quality assurance, improved magnetic properties with shorter time to reach the market. There is a need for customised solutions for complex geometries with high precision, low cost and high performance.
Reduced prices are achieved by using lower alloy steels containing reduced Ni and substitution of Ni by Cr; using better heat insulated furnaces, gas fired furnaces and furnace atmosphere generators. Improvements in efficiency in hydraulics and manufacturing of faster machines at similar costs are being undertaken. There will be increasing focus on shorter processes with higher density compaction and improvements in sinter hardening steels.
Tighter tolerances are achieved by using improved mixes and mixing technologies; fluidised bed powder loaders; tricks in press movements with more sophisticated presses and employing better machine tools for pressing and secondary operations.
Hybrid and electrical vehicles are fast coming into the market and PM is responding with the development of better performing magnetic circuits and medium frequency materials with increased mechanical strength. New powders are appearing with high resistivity, improved permeability and saturation and higher mechanical strength. Additionally, high-density compacting technologies are being used as well for these materials.
“Twenty years ago,” stated Dr. Molins, “a small percentage of defective parts were acceptable. Ten years ago, industry started demanding low ppm level quality. Today, 1 ppm is often considered unacceptable. The increased quality assurance as well as 100% inspection can be achieved by automated techniques such as, computer vision, eddy current crack detection and ultrasonic resonance checking.”
Medical devices, general consumer goods, aeronautics etc., demand increasingly complex parts, with high precision and low cost. MIM is a rapidly developing PM technology which responds to these requirements. Although the high price of raw material limits the size of the applications, complex geometries, high precision and low cost can be achieved.
Dr. Molins surmised that, “PM is continuously evolving, both in the industrial and in the basic research aspects. There is a continued trend for higher technological demand. This means that PM will be driven not only by production costs, but also by technology. In any case, PM continues to show a bright future and technology demand for years to come”.
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