Overview
FrançaisABSTRACT
Powder metallurgy (PM) technology is favorable in facilitating the production of metals or alloys, possessing particular mechanical or physical properties, such as tungsten, copper or graphite. The principle behind PM is the process of blending powdered materials consequently consolidated by a heat treatment. In contrast to a large number of shaping processes, the forms and dimensions are defined prior to the mechanical characteristics. Numerous processes exist, but the one that covers the largest number of applications is uniaxial oedometric compression at room temperature. This process makes it possible to envisage the significant reduction in transformation operations; the forms and the physical characteristics that may be generated upon compression.
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Read the articleAUTHORS
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Gérard PUENTE: Mechanical Process Consultant - Former Powder Metallurgy Technical Manager
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Philippe FRANÇOIS: Europe-India Technical Service Manager Rio Tinto Metal Powders (QMP)
INTRODUCTION
Powder metallurgy (PM) technology uses powdered materials consolidated by a thermal process. Powder preparation, shaping and thermal conditions vary according to the products involved.
It is used either because it is :
a convenient means of producing certain metals or alloys with special physical or mechanical properties (e.g. refractory metals such as tungsten, alloys or pseudo-alloys of two immiscible materials in the liquid state, such as copper and graphite, or porous parts throughout their mass);
a relatively economical manufacturing method when a large number of parts are required.
The high moldability of powders will be exploited to obtain complex shapes, or the possibilities of diversifying the constituent elements to obtain very specific structures. In this way, processes can be designed to obtain special materials with specific physico-chemical properties, or to produce components whose shape and geometry meet specific functional requirements.
What sets this technology apart is that, unlike many other shaping processes, the shapes and dimensions are generated before the mechanical characteristics. As a result, there are some distinct differences.
Main processes :
uniaxial oedometric compression (cold or hot) ;
isostatic compression (cold or hot (HIP) ;
MIM (metal injection moulder) or PIM (powder injection moulding);
compression-free forming.
Main markets :
mechanical parts (automotive, jet engine, watchmaking, armaments, portable electrical equipment, etc.) ;
self-lubricating ;
braking ;
electrical components (connectors, magnetic components) ;
medical (prostheses, stapler tips, brackets) ;
tool steels ;
filter parts ;
nuclear fuel.
This presentation focuses on the oedometer compression process, which covers the most important markets in powder metallurgy. These markets are characterized by :
volumes justifying the production of molds (tooling);
complexity and precision of shapes ;
surface quality ;
high mechanical properties ;
severe...
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Powder metallurgy
Bibliography
Websites
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MPIF – Metal Powder Industries Federation : Princeton (New Jersey USA)
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EPMA – European Powder Metallurgy Association
Standards and norms
- Metal powders – Determination of bulk density – Part 1: funnel method. - ISO 3923-1 - Mai 2008
- Metal powders excluding hard metal powders – Determination of compressibility under uniaxial compression. - EN ISO 3927 - Avril 2011
- Metal powders – Determining the strength of rectangular raw tablets. - DIN ISO 3995 - Mai 1991
- Metal powders – Determination of flow time using a calibrated funnel. - EN ISO 4490...
Directories
Main producers of iron and steel powders
Höganäs (Sweden)
Hoeganaes Corporation – GKN (USA)
Rio Tinto Metal Powders – QMP (Canada)
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