Powder Manufacturing Process

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1.4 POWDER METALLURGY PART PROCESSING P/M process generally consists of four basic steps: (1) Powder manufacturing (2) Powder mixing and blending (3) Compacting and (4) Sintering. Compacting is generally performed at room temperature and the elevated-temperature process of sintering is usually conducted at atmospheric pressure. According to Narayanasamy et al. (2009), compaction process generates green strength of compacts by two phenomena, namely (i) particle sliding and interlocking (ii) plastic deformation. After sintering, the sintered body was close to the theoretical density, and a lot of remaining pores were present in the matrix. Initially before sintering, the powder particles of solid materials (metal, oxide) were surrounded…show more content…
The advantage of the P/M process offers material utilization, shape complexity, near-net shape parts, dimensional control with an excellent surface finish, lower cost for high volume production of complicated components and great versatility among others. Optional secondary processing often follows to obtain special properties or enhanced precision. 1.4.1 Mixing To achieve the uniformity of the product manufacturing, mixing is carried out. By mixing the two different powders, can obtain a homogeneous mixture. To minimizing the wear of dies and reduce friction between the surfaces of dies and the powder particles during compaction, some lubricants are also mixed with powders. Mixing time depends upon the results desired, and over mixing should be prevented, or otherwise the size of particles will be decreased, and they will be hardened. 1.4.2 Compaction Widanka (2008) explained that increasing applied pressure, the density of the powder mass increases or porosity decreases. Figure 1.3 Relationship of green density and compacting…show more content…
Hot extrusion has been used to fabricate different shapes such as rods, strips and tubes with desirable lengths. Extrusion is usually performed at high temperatures around the recrystallization temperature, in order to achieve more strength and area reduction simultaneously. Extrusion is the process by which the material is reduced in cross-section by forcing it to flow through a die orifice under high pressure. Initially, extrusion is viewed as a processing technique from the perspective of achieving a wide variety of shapes. While extrusion may not be suitable for processing ceramics that are inherently brittle in nature, it is suitable for soft materials to increase the theoretical density. Extrusion makes use of compressive stresses to process the material. So, any possibility of a pore getting transformed into a crack and eventual failure is remote. The process can be used to maximize the densification of the component to be fabricated. Except for initial preheating of the material to be processed, the process takes less operation time especially with sophisticated hydraulic rams available in the market in terms of speed and

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