Author: haroonkhan

These are secondary operations intended to provide dimensional tolerances and better surface finish. They are sizing, coining, machining, impregnation, infiltration, heat treatment, and plating. Sizing: It is repressing the sintered component in the die to achieve the required size with accuracy. Coining: It is repressing the sintered components in the die to increase density and to give…

Sintering involves heating of the green compact at high temperatures in a controlled atmosphere to protect from oxidation of metal powders. Sintering increases the bond strength between the particles. Sintering temperature is usually 0.6–0.8 times the melting point of the powder. In case of mixed powders of different melting temperatures, the sintering temperature will usually…

The main purpose of compacting is converting loose powder into a green compact of accurate shape and size. The techniques adopted for compacting are pressing, centrifugal compacting, extrusion, gravity sintering, and rolling. Pressing: The metal powders are placed in a die cavity and compressed to form a component shaped to the contour of the die (Figure…

Blending and mixing of the powders are essential for uniformity of the product. Lubricants (such as graphite) are added to the blending of powders before mixing. The function of lubricant is to minimize the wear and to reduce friction. Different powders in correct proportions are thoroughly mixed either wet or in a ball mill to…

There are various methods available for the production of powders. Some of the important processes are as follows: atomization, machining, crushing and milling, reduction, electrolytic deposition, shotting, and condensation. Atomization: In this method, molten metal is forced through a small orifice and is broken into small particles by a powerful jet of compressed air, inert gas,…

The performance of metal powders during processing and the properties of powder metallurgy depend on the characteristics of the metal powders that are used. Following are the important characteristics of metal powders: particle shape, particle size, particle size distribution, flow rate, compressibility, apparent density, and purity.

Powder metallurgy is a process of making components from metallic powders. Initially, it was used to replace castings for metals which were difficult to melt because of high melting point. The development of technique made it possible to produce a product economically, and today it occupies an important place in the field of metallurgical process.…

Roll forming is a process by which a metal strip is progressively bent as it passes through a series of forming rolls (Figure 21.28). Figure 21.28 Eight-roll Sequence for the Roll Forming of a Box Channel