Powder Metal ProcessingPowder Metal ProcessingManufacturing ProcessesManufacturing Processes

Gudgeon pinGudgeon pin

Gudgeon pinGudgeon pin

• Gudgeon pin connection at connecting rod. Gudgeon pin fits into gudgeon inside piston.

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Process to produce Gudgeon Process to produce Gudgeon pinpin

Flow Chart Of Powder Metallurgy ProcessFlow Chart Of Powder Metallurgy Process

Alloy Metal Powder Additives ( binders)

Blending

Die Compaction

Sintering

Optional Secondary finishing

Optional secondary manufacturing

Finished P/M product

1. Powder Production1. Powder Production• Many methods: extraction from compounds, deposition, atomization,

fiber production, mechanical powder production, etc.• Atomization is the dominant process

(a) Water or gas atomization; (b) Centrifugal atomization; (c) Rotating electrode

(a) (b) (c)

Characterization of PowdersCharacterization of Powders

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2. Blending or Mixing2. Blending or Mixing BlendingBlending• Combining powders of the same material but possibly Combining powders of the same material but possibly

different particle sizes.different particle sizes.

MixingMixing• Combining powders of different materialsCombining powders of different materials

3. Powder Consolidation3. Powder Consolidation

• Cold compaction with 100 – 900 MPa to produce a “Green body”.Cold compaction with 100 – 900 MPa to produce a “Green body”.– Die pressing Die pressing

– Cold isostatic pressingCold isostatic pressing

– RollingRolling

– GravityGravity

• Injection Molding small, complex Injection Molding small, complex

parts.parts.

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4. Sintering4. Sintering

• Parts are heated to 0.7~0.9 Parts are heated to 0.7~0.9 TTmm..

• Transforms compacted mechanical bonds to much Transforms compacted mechanical bonds to much • stronger metallic bonds. stronger metallic bonds.

• Shrinkage always occurs:

Examples of Sintering Examples of Sintering Production LinesProduction Lines

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5. Finishing5. Finishing

• The porosity of a fully sintered part is still significant The porosity of a fully sintered part is still significant (4-15%). (4-15%).

• Density is often kept intentionally low to preserve Density is often kept intentionally low to preserve interconnected porosity for bearings, filters, interconnected porosity for bearings, filters, acoustic barriers, and battery electrodes.acoustic barriers, and battery electrodes.

• However, to improve properties, finishing processes are However, to improve properties, finishing processes are needed:needed:– Cold restriking, resintering, and heat treatment.Cold restriking, resintering, and heat treatment.– Impregnation of heated oil. Impregnation of heated oil. – Infiltration with metal (e.g., Cu for ferrous parts).Infiltration with metal (e.g., Cu for ferrous parts).– Machining to tighter tolerance.Machining to tighter tolerance.

Special Process: Hot compactionSpecial Process: Hot compaction

• Advantages can be gained by combining Advantages can be gained by combining

consolidation and sinteringconsolidation and sintering, , • High pressure is applied at the sintering temperature High pressure is applied at the sintering temperature

to bring the particles together and thus accelerate to bring the particles together and thus accelerate sintering. sintering.

• Methods includeMethods include– Hot pressingHot pressing– Spark sinteringSpark sintering– Hot isostatic pressing (HIP)Hot isostatic pressing (HIP)– Hot rolling and extrusionHot rolling and extrusion– Hot forging of powder preformHot forging of powder preform– Spray depositionSpray deposition

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