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Economics of powder metallurgy

Powder metallurgy is the process by which materials are formed from constituent powdered metals. There are two major areas where powder metallurgy has advantages over other metal forming and shaping processes:

Effective usage of raw materials

The near net-shape capability of powder metallurgy gives it a significant advantage over other manufacturing processes. The net-shape components produced by powder metallurgy have dimensional tolerances that do not require further machining and leaves a negligible amount of scrap. As a result, the process of powder metallurgy makes use of over 97 percent of its starting raw materials in the mold during die formation . This ranks powder metallurgy as the most efficient of the most common manufacturing processes in terms of raw material usage compared to processes such as casting at 90 percent, cold or warm extruding at 85 percent, and machining processes between 40 and 50 percent .

The capability to make efficient use of materials makes powder metallurgy a sustainable form of processing in that is also recycles and conserves natural resources . This is why technological developments have begun to boom in the powder metallurgy industry over the past decade. It is crucial that Sintering wastes such a small amount of material especially since powder feed stock is usually expensive . Considering the cost of the stock, powder metallurgy is usually economical when manufacturing small or lightweight parts where raw material costs account for approximately 20 percent or less of the total manufacturing cost .

The most available forms of metal powder include iron and steel, tin, nickel, copper, aluminum, and titanium and have the advantages of being able to control the shape and size of powder particles, which range from 0.1 to 1,000 micrometers . Iron and steel is, as expected, the most consumed stock with 416,373 tons shipped in North America in 2014 followed by aluminum by a large margin at an estimated 40,000 tons . Another detail to account for when planning to use PM is the amount of pressure required to compact the materials and energy costs which will be discussed later in Energy Savings.

Energy costs and Raw Material Utilization for different manufacturing processes

Energy savings

The energy sustainability of powder metallurgy also results from its net-shape capability. While other manufacturing processes demand multiple heating steps to reach the final shape, powder metallurgy only requires heating in the atomization step . The rest of the thermal processes are undertaken below melting temperature, which conserves huge amount of energy while achieving the final form . Additionally, the net-shape components require no further machining which saves energy in another way . Consequently, the energy requirement per kilogram of completed components for powder metallurgy is only 29 megajoules, compared to 41 megajoules of cold/warm extrusion and 46-49 megajoules of forging . Only casting is in the comparable range of PM's energy costs, but it still requires 1-9 more megajoules of energy per kilogram than does PM.

Economic drawbacks

While powder metallurgy is associated with significant energy savings and a reduction in waste material, there are several economic factors that should be considered that reduce this manufacturing process' value. The first is the cost of the powder itself. The powder used in powder metallurgy can be significantly more expensive to manufacture than metal in the form of a bar that would then be machined down to its desired form . The tools used in powder metallurgy are also more expensive than those used in traditional machining, and the machines used in sintering are expensive to purchase. Both of these factors mean that it is not economically advantageous to use this method of manufacturing unless you anticipate large scale production .