Post-processing of powder metallurgy


PM post-processing: sintered compacts after further processing according to specific requirements determine of products. Common treatment methods include pressing, maceration, after heat treatment, surface treatment , machining and so on.

1.Repressing
For the purpose of improving the physical and mechanical properties of sintered body pressure, including finishing and shaping. Finishing is carried out in order to achieve the desired size of repressing, through the finishing die-pressure sintered to increase accuracy. Plastic surgery is to achieve specific surface shape of repressing, through pressure sizing die for products to correct distortion and reduced surface roughness .

2.Impregnation

Non-metallic materials (such as oils, waxes and resins) fill the pores of sintered. Commonly used impregnation method including plastic oil impregnation, dipping, dipping the molten metal.Dip dipping oil is on the sintering body oil, improve its self-lubricating properties and rust-proof, often used in iron, copper base oil-impregnated bearings.Leaching of plastic is PTFE dispersion, cured, oil-free lubrication, commonly used in metal-plastic anti-friction spare parts. Molten metal leaching can improve strength and wear resistance, iron-based material, often by dipping copper or lead.

3.Heat treatment

Sintered body is heated to a certain temperature, and then treated by controlling the cooling method to improve product performance. Commonly used methods are heat hardening, chemical treatment, thermal-mechanical treatment, the general process for the dense materials similar.For the requirements of the impact from the iron-based wear-resistant parts may be the overall quenching due to the presence of pores can reduce the internal stress, generally not tempered. hard and tough and requirements within the iron-based parts can be hardened or carburized quenching.
Hot forging is dense parts commonly used method, hot forged products, grains and a high strength and toughness.

4.Surface treatment
Common methods of surface treatment steam treatment, plating, galvanizing, etc.Steam treatment are artifacts in 500~560℃ steam heating and maintaining a certain time to the surface and pores form a dense layer of oxide film surface, the demand for iron rust, abrasion or pressure-proof penetration of workpieces. Plating, electrochemical principle products deposited on the surface of a solid layer, the process method with the dense material.Plating used for rust-proof, wear-resistant and decorative parts.

In addition, also by forging, welding, machining and special processing method to change the shape of sintered or improve the accuracy to satisfy part of the final requirements. Electrical discharge machining, machining methods such as electron beam machining, laser machining and ion nitriding, ionic implantation, CVD, thermal spray and surface engineering technologies have been used for postprocessing of powder metallurgy products, improve production efficiency and product quality.

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