Powder Metallurgy
Powder metallurgy (PM) is a popular and cost-effective method of fabricating metal components with precise dimensional characteristics. The process of powder metallurgy comprises of three basic steps, each of which is an integral part of the overall metallurgical process. These steps include powder processing, die compaction and sintering. This method is commonly used for mass production of components which are required for several industrial applications including automotive, aerospace, medical, military and many more.
The basic process of powder metallurgy starts with the production of the base powder material, which is usually a ferrous or non-ferrous alloy or a combination of both. This powder material is then blended with lubricants, binders and other additives as required in order to make a homogeneous powder mixture. This mixture is then loaded into a die, where it is compressed and formed into a desired shape by a device called a die punch. The die compaction step is an important process since it determines the final compact density of the sintered component. The compact is then sintered in an oven either at low or high temperatures depending on the type of powder material used. The sintering process eliminates residual voids present in the compact by way of coalescence and diffusion bonding of the particles to each other.
The powder metallurgy process can also be used to combine two or more different materials with different properties. The most common technique used for material blending is referred to as near-net shape forming. The two materials (or two different alloys) are mixed together in the form of a powder and then the mixed powder is compacted in a die before being sintered. The materials remain separate and in the final component, one material can be found at different layers in the component, one for example inside the component, and one on its outer surface. This process allows for the fabrication of components with specific wear, corrosion and chemical resistance properties.
Powder metallurgy offers a number of advantages over other traditional manufacturing and fabrication methods. One primary advantage is that it eliminates the need for secondary and post processing operations, as the component can be finished at the sintering stage. The technology also offers tremendous cost savings over traditional forming methods such as casting or machining. Additionally, complex shapes, intricate details and tight tolerances can be achieved through powder metallurgy without any difficulty. The process also produces no hazardous by-products which helps reduce environmental pollution.
In conclusion, powder metallurgy is a reliable and cost-efficient method for fabricating metal components for different types of industrial applications. It is a versatile technology with numerous advantages over traditional manufacturing methods. In spite of its advantages, the process is still susceptible to porosity and strength reduction, therefore proper control of the conditions of process variables is necessary for successful fabrication.
