Powder Metal Processing

Powder Metal Powder Metal ProcessingProcessing

Manufacturing Manufacturing ProcessesProcesses

By:By:

Dr.Behzad HeidarshenasDr.Behzad Heidarshenas

OutlineOutline

IntroductionIntroduction

Powder ManufacturingPowder Manufacturing

Powder Metallurgy ProcessPowder Metallurgy Process

SinteringSintering

Other Powder Metal ProcessesOther Powder Metal Processes

Powder Metal ProductsPowder Metal Products

Powder Metallurgy DesignPowder Metallurgy Design

Powder MetallurgyPowder Metallurgy

Powder MetallurgyPowder Metallurgy

MetalMetal

PowderPowder

Metal ProductMetal Product

Examples of Powder Examples of Powder Metal ProductsMetal Products

GearsGears

CamsCams

CranksCranks

BearingsBearings

Roller bearing cagesRoller bearing cages

HousingsHousings

Light bulb filamentsLight bulb filaments

Sprinkler mechanismsSprinkler mechanisms

Powder Metal MaterialsPowder Metal Materials

ElementalElemental

A pure metal, most commonly A pure metal, most commonly iron, aluminum or copperiron, aluminum or copper

PrealloyedPrealloyed

An alloy of the required An alloy of the required composition, most commonly composition, most commonly copper alloys, stainless steel copper alloys, stainless steel or high-speed steelor high-speed steel


Conversion of molten metal to Conversion of molten metal to powderpowder

AtomizationAtomization


Other methods of producing Other methods of producing powder:powder:

- Chemical reduction of Chemical reduction of particulate compoundsparticulate compounds

- Electrolytic depositionElectrolytic deposition- Pulverization or grinding of Pulverization or grinding of

brittle materialsbrittle materials- Thermal decompositionThermal decomposition- Precipitation from solutionsPrecipitation from solutions- Condensation of metal vaporsCondensation of metal vapors

Particle ShapeParticle Shape

Particle SizeParticle Size

The process of separating particles The process of separating particles by size is called classificationby size is called classification


Micrograph of screened powder particles, showing that particles may be longer than the mesh is wide


void

smaller, more numerous voids

voids filled by smaller particles, small voids remain

Mixing particles of different sizes allows decreased porosity and a higher packing ratio

Powder Metallurgy Powder Metallurgy ProcessProcess

Blending and MixingBlending and Mixing

BlendingBlending

Combining powders of the same material Combining powders of the same material but possibly different particle sizesbut possibly different particle sizes

MixingMixing

Combining powders of different materialsCombining powders of different materials

CompactionCompaction

High pressure is applied to squeeze High pressure is applied to squeeze the powder into the desired shapethe powder into the desired shape

Example of a Powder Example of a Powder PressPress

Other Powder Metal Other Powder Metal ProcessesProcesses

Cold Isostatic PressingCold Isostatic Pressing

Hot Isostatic PressingHot Isostatic Pressing

Injection MoldingInjection Molding

Powder RollingPowder Rolling

Powder ExtrusionPowder Extrusion

Plasma SprayingPlasma Spraying

Isostatic PressingIsostatic Pressing

Uses pressurized fluid to compress the Uses pressurized fluid to compress the powder equally in all directionspowder equally in all directions

Cold Isostatic PressingCold Isostatic PressingCompaction performed at room Compaction performed at room temperaturetemperature

Hot Isostatic PressingHot Isostatic PressingPerformed at high temperatures and Performed at high temperatures and pressurespressures

Example of an Isostatic Example of an Isostatic PressPress

Injection MoldingInjection Molding

The powder is mixed with a binder The powder is mixed with a binder and molded, and the binder is and molded, and the binder is removed before sinteringremoved before sintering

Powder RollingPowder Rolling

Powder is compressed in a rolling mill Powder is compressed in a rolling mill to form a stripto form a strip

Powder ExtrusionPowder Extrusion

The powder can be extruded within a The powder can be extruded within a container or after being formed into container or after being formed into billets billets


Uses a plasma arc to propel molten Uses a plasma arc to propel molten droplets at a surface at a high droplets at a surface at a high velocity, forming a high-density velocity, forming a high-density structurestructure

SinteringSintering

Heats the powder below the melting Heats the powder below the melting point to allow solid-state diffusion point to allow solid-state diffusion and bond the particles togetherand bond the particles together

SinteringSintering

Diagram of particles in sintering, showing the possible movements of atoms

SinteringSintering

Sintering Production Sintering Production LinesLines

Examples of Sintering Examples of Sintering Production LinesProduction Lines

SinteringSintering

Strength of sintered structures as related to density, showing that the strength is higher when the density

is higher (less residual porosity)

Powder Metal ProductsPowder Metal Products

1.1. Porous or permeable Porous or permeable productsproducts

2.2. Products of complex shapesProducts of complex shapes3.3. Products made of materials Products made of materials

that are difficult to machine or that are difficult to machine or have high melting pointshave high melting points

4.4. Products which require the Products which require the combined properties of combined properties of multiple materialsmultiple materials

5.5. Products in which powder Products in which powder metallurgy produces superior metallurgy produces superior propertiesproperties

Powder Metallurgy Powder Metallurgy DesignDesign

1.1. The shape must permit removal The shape must permit removal from the diefrom the die

2.2. The shape should not have thin The shape should not have thin walls or sharp cornerswalls or sharp corners

3.3. The shape should permit the The shape should permit the construction of strong toolingconstruction of strong tooling

4.4. The shape of the part should be The shape of the part should be within the thickness range for within the thickness range for which the powder can be properly which the powder can be properly compactedcompacted

5.5. The part should have as few The part should have as few changes in section thickness as changes in section thickness as possiblepossible


6.6. Parts can be designed to take Parts can be designed to take advantage of the capabilities of advantage of the capabilities of the powder metallurgy processthe powder metallurgy process

7.7. The design should be consistent The design should be consistent with available equipmentwith available equipment

8.8. Consideration should be given for Consideration should be given for product tolerancesproduct tolerances

9.9. Design should consider the Design should consider the dimensional changes that occur dimensional changes that occur after pressing, such as shrinkage after pressing, such as shrinkage during sinteringduring sintering

Powder Metallurgy Powder Metallurgy AdvantagesAdvantages

1.1. Elimination/reduction of Elimination/reduction of machiningmachining

2.2. High production ratesHigh production rates

3.3. Complex shapes can be Complex shapes can be producedproduced

4.4. Wide composition variations Wide composition variations are possibleare possible

5.5. Wide property variations are Wide property variations are possiblepossible

6.6. Scrap is eliminated or Scrap is eliminated or reducedreduced

Powder Metallurgy Powder Metallurgy DisadvantagesDisadvantages

1.1. Inferior strength propertiesInferior strength properties

2.2. Relatively high die costRelatively high die cost

3.3. High material costHigh material cost

SummarySummary

Powder metallurgy can create Powder metallurgy can create parts that would otherwise be parts that would otherwise be difficult to form, including those difficult to form, including those with complex shapes or with complex shapes or porosityporosity

Sintering bonds particles Sintering bonds particles together by allowing atoms to together by allowing atoms to move, forming necks and grain move, forming necks and grain boundaries between the boundaries between the particlesparticles

Powder Metal Processing

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