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G S Upadhyaya, Powder Metallurgy Technology R M German, Powder Metallurgy Science 2 Finally, the end part is formed by applying pressure,

Steps in powder metallurgy: Powder production, Compaction, Sintering, Secondary Single powder production method is not sufficient for all applications

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G S Upadhyaya, Powder Metallurgy Technology R M German, Powder Metallurgy Science 2 Finally, the end part is formed by applying pressure,

[PDF] Chapter 18: Powder Metallurgy

Figure 18-3 (Left) Typical press for the compacting of metal powders A removable die set (right) allows the machine to be producing parts with one die set while

[PDF] Powder Metallurgy Methods and Applications - ASM International

and Applications W Brian James, Hoeganaes Corporation, retired Powder metallurgy (PM) is the production and utilization of metal powders Powders are

[PDF] Recent Technology of Powder Metallurgy and Applications

Powder metallurgy (P/M) is a materials processing technology to create new materials and parts by diffusing different metal powders as raw ingredients through

various properties and performance of P/M materials for applying these powder metallurgy route consists of the following processes, namely, (ii) dry 3 1 Electrical resistivity for typical PTCR device and schematic presentation of defect

[PDF] POWDER METALLURGY (P/M) Introduction 1 Characterization of

Powder Metallurgy (PM) (around 1800s) – Pressing Sintering - Heating at a temperature well below melting An alternative application is when parts are

[PDF] POWDER METALLURGY

Powder Metallurgy (PM) Metal processing technology in which parts are produced from metallic powders •In the usual PM production sequence, the powders

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MME 3518

POWDER METALLURGY

COURSE MATERIAL

LectureNotes

G.S. Upadhyaya, PowderMetallurgyTechnology

Suggested

Readings

S.A.Tsukerman, PowderMetallurgy

R.M. German, Powder Metallurgy Science

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Definition of Powder Metallurgy

science of producing metal powders and utilizing them OR technique used to consolidate particulate matter i.e. OR is a process whereby a solid metal, alloy orceramic in the form of a mass of dry particlesis converted into an engineering component of predetermined shape and possessing properties which allow it tobe used in mostcases without further processing.

Powder metallurgy is a forming and fabrication technique consisting of three major processing stages.

First, the primary material is physically powdered, divided into many small individual particles.

Next, the powder is injected into a mold or passed through a die to produce a weakly cohesive structure (via cold welding) very near the dimensions of the object ultimately to be manufactured.

Finally, the end part is formed by applying pressure, high temperature, long setting times during which self-welding occurs.

Powder Metallurgy (PM)

Metal processing technology in which parts are produced from metallic powders powdersareconvertedtoproduct produceporousmetalparts canbeshapedbyPM

TungstenfilamentsforlampbulbsaremadebyPM

Basic steps of the Powder Metallurgy Process.

12A collection of powder metallurgy parts.

PM Parts

Connecting Rods:

Forged on left; P/M on right

Powdered Metal Transmission Gear

Warm compaction method with 1650-ton press

Teeth are molded net shape: No machining

UTS = 155,000 psi

30% cost savings over the original forged part

Industrial Machines Parts

For Electric Motors

PM vs. O ther F abrication M ethods casting , stamping or machining PM is the choice whenrequirements for strength, wear resistance or high operating temperaturesexceed the capabilities of die casting alloys. PM offers greater precision,eliminating most or all of the finish machining operations required forcastings. It avoids casting defects such as blow holes, shrinkage and inclusions. Powder injection molding is coming out as a big challenge forinvestment casting.

Howeverthe PM process is economical only when

production rates are higher, sincethe tooling cost is quite appreciable The powdermetallurgy methodsstartswithpowders and the propertiesof the manufacturedpartsdepend to a large extent on the properties of the initial powders. Amongst powder properties, composition, size, form and structure of particle, specific surface, porosity and volume characteristics, fluidity, strength, hardness, permeability regarding liquids and gases, electric conductivity, compressibility and sinterabilityare of great importance in powder metallurgy. Metal powders consist of separate small bodiesȄthe so- called particlesȄfrom 0.1µup to several millimeters in size. In the majority of powders the size of particle varies from several microns to 0.5 mm. Particles usually have internal pores, cracks and impurities. Particleshapeis widely varied and determined by the methods of production; the desired particle size is obtained by regulating the conditions of manufacture. Particles are divided according to their shape into three basic groups: (1 ) hair or needle-shaped, the lengths of which considerably exceed their other dimensions; (2) flat (flakes or leaves) whose length and breadth are many times greater than their thickness; (3) equiaxed, which are roughly identical in all dimensions. Powders of the same chemical composition, but with different physical characteristics, are sharply distinguished by technological properties, i.e. by their behaviourduring processing. Production methods and the fields of application for powders are determined withpowderproperties(shape,size) Example: copper powder with particles in the form offtakes (flat) up to 1 µthick and up to 50µ in diameter are used only as a pigment since any articles made from it contain cracks after pressing. Copper powder with particles of spherical form (globules) from 100 to 700µ in diameter is pressed only at very high pressures. A powder with irregularly shaped particles, so called dendritic, 40-45µ in size is easily pressed even at low pressures.

POWDER FABRICATION

METHODS

Itis a mechanicalmethodforpowderproduction, wherethe initial material is pulverized without any change in chemical composition.Reductionof particlesize is beneficialforsintering, whichdependson diffusionof atoms.

Mostcommonmillingmethodis ballmilling

-Generallyballsareusedformilling. Hardnessof the ballsmustbe equalor greaterthanthe hardnessof the powderwillbe milled. -Amountand size of the ballsarecriticalforthe final powdersize. -Wetordrymillingcan be applied. -From ballsorbarrelimpuritiesmayaddedtothe powder (millingtime and ballhardness)

Milling

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