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Heat Treating
Heat-treating improves a part's strength and wear resistance. The part is heated to a specific temperature according to its Rockwell hardness specification and then quenched (quickly cooled). It is submerged in quenching oil that prevents the part from breaking while cooling.
Oil Impregnation
Oil impregnation minimizes the need to periodically grease the part because the part itself becomes self-lubricating. A small batch of parts is put into a vacuum chamber. Oil replaces air as the vacuum is drawn. The oil fills the porosity of the parts. The density of powder metal parts is adjusted during the compacting process. Dense parts cannot be impregnated with as much oil as less dense parts.
Resin Impregnation
Resin Impregnation fills the porosity of the part with a resin/ plastic to allow for plating. The resin keeps the plating material out of the part's pores. The process of resin impregnation is similar to the process of oil impregnation. Both operations use vacuum chambers. Anaerobic resin, rather than oil, is drawn into the part's pores.
Resin impregnation also strengthens the part and improves machinability.
Coining
Coining is done after sintering to make adjustments to the parts surface configuration. Coining is necessary for parts that may have warped during the sintering process. Material and design factors and not a poor quality process cause the warping.
Infiltration
Infiltration is done after sintering to improve the strength and machinability of a part. The process fills the pores of the part with a metal that has a lower melting point than the part's material. Copper or copper alloy is generally used for infiltrating.
Plating
Plating can be done to high-density parts or to parts that have been impregnated with resin. There are various types of plating that can be done to powder metal parts such as zinc clear chromate and golden iridite.
Steam Oxidizing
Steam oxidizing extends a part's life by making it wear resistant and seals porosity.
Machining
If the part's complete design cannot be created during the compacting process, it must be machined after sintering. Machining includes drilling cross-holes that cannot be created with a core rod.
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