POWDER METALLURGY

Powder Metallurgy (PM)

A metal processing technology in which parts are produced from metallic powders.

Pressing

The process of compressing powders into a desired shape to produce a green compact.

Sintering

The heating of green compacts to bond particles into a hard mass, carried out below the melting point.

Green Compact

The work part after pressing, which is not fully processed.

Porosity

The ratio of the volume of the pores in the powder to the bulk volume.

Packing Factor

The ratio of bulk density to true density, typically ranging from 0.5 to 0.7 for loose powders.

Metallic Powders

Fine particles made from metals used in powder metallurgy.

Interparticle Friction

Friction between particles that affects powder flow and packing density.

True Density

The density of the true volume of the material if the powders were melted into a solid mass.

Bulk Density

The density of powders in the loose state after pouring.

Atomization

A method of producing metallic powders by converting molten metal into fine droplets.

Chemical Method

A way to produce metallic powders using chemical reactions to convert metals into powder form.

Electrolytic Method

A process of producing metallic powders through electrolytic deposition.

Isostatic Pressing

A method that applies hydraulic pressure uniformly to achieve compaction in all directions.

Powder Injection Molding (PIM)

A process that combines a polymer with powder to shape parts before sintering.

Densification

The process of increasing the density of a sintered part through additional pressing or sizing.

Pre-Alloyed Powders

Alloy powders where each particle has a desired chemical composition.

Elemental Powders

Pure metal in particulate form used in powder metallurgy.

High velocity gas stream

Used in gas atomization method to produce metallic powders by cooling and solidifying molten metal.

Water Atomization Method

A technique to produce powders by spraying high-velocity water streams onto molten metal.

Dimensional Control

Precision in the dimensions of parts produced by powder metallurgy compared to casting processes.

Friction Angle

An indicator of interparticle friction, greater angles signify more friction.

Lubricants

Substances added to powders to reduce interparticle friction and facilitate flow during pressing.

CT machining

A secondary operation used when precise geometric features cannot be formed by pressing.

Chemi-mechanical methods

Refers to techniques used occasionally to reduce powder sizes in production.