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Powdered Metallurgy : The Basics

Powdered Metallurgy : The Basics. Basics of P/M. Highly developed method of manufacturing precision metal parts

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Powdered Metallurgy : The Basics

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  1. Powdered Metallurgy: The Basics Prepared by MetalKraft Industries

  2. Basics of P/M • Highly developed method of manufacturing precision metal parts • Made by mixing elemental or alloy powders then compacting the mixture in a die. The resulting shape is sintered in an atmosphere controlled furnace to convert mechanical bonds into metallurgical bonds. • Basically a ”chip-less” process, P/M uses roughly 97% of the starting material in the finished part. Prepared by MetalKraft Industries

  3. Advantages of P/M • Versatile in numerous industries • Eliminates or minimizes machining • Minimizes scrap • Maintains close dimensional tolerances • Permits a wide variety of alloy systems • Facilitates manufacture of complex shapes which would be impractical with other processes • Provides excellent part to part repeatability • Cost Effective • Energy and environmentally efficient Prepared by MetalKraft Industries

  4. Basic P/M Steps • Raw Material • Mixing • Forming • Sintering • Optional Operations • Finished Products Prepared by MetalKraft Industries

  5. Mixing • Elemental, partially alloyed or pre-alloyed metal powders are first blended with lubricants to produce a homogeneous mixture. Prepared by MetalKraft Industries

  6. Compaction • A controlled amount of a mixed powder is gravity fed into a precision die and then compacted. Compaction occurs at room temperature, at a pressure range of 25-50 tons per sq. in. • Compacting the loose powder produces a “green compact” which, with conventional pressing techniques, has the size and shape of the finished part when ejected from the press. Green compacts have sufficient strength for in-process handling. • Typical compaction techniques use rigid dies, set into mechanical or hydraulic presses. Prepared by MetalKraft Industries

  7. Conventional Mechanical Press Prepared by MetalKraft Industries

  8. Compaction Tooling Prepared by MetalKraft Industries

  9. Compaction Cycle • Cycle Start • Charge die w/powder • Compaction begins • Compaction complete • Ejection of compact • Recharging of die Prepared by MetalKraft Industries

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  14. Sintering • Typically, the “green compact” is placed on a mesh belt which then moves slowly through a controlled atmosphere furnace. The parts are heated below the melting point of the base metal, held at the sintering temperature, then cooled. Basically a solid state process, sintering transforms compacted mechanical bonds between powder particles into metallurgical bonds. • Typical sintering temperatures for ferrous based metals range from 2050- 2100 degrees F. • Standard cycle times range from 2-3 hours. Prepared by MetalKraft Industries

  15. Conventional Furnace Profile Prepared by MetalKraft Industries

  16. Optional Operations Prepared by MetalKraft Industries

  17. Optional Operations Prepared by MetalKraft Industries

  18. Powdered Metallurgy:Design Considerations Prepared by MetalKraft Industries

  19. Material Selection Prepared by MetalKraft Industries

  20. Design Considerations • Dimensional accuracy depends upon: • Control of powder composition • Size of dimension • Control of powder fed to the tools with each stroke • Control of press and tooling variables • Control of sintering variables Prepared by MetalKraft Industries

  21. MPIFReference Tolerance Guide Typical tolerances for ferrous P/M components up to 2.00 inches in dimension Tolerances, inch/inch Prepared by MetalKraft Industries

  22. Design Details • Fillets and Radii • Tooling with such fillets are more economical, longer lasting • Parts made with generous fillets are more economical • Parts made with fillets have greater structural integrity Prepared by MetalKraft Industries

  23. Design Details • Holes in the pressing direction can be round, D-Shaped, keyways or splines • Wall thickness is all important; walls thinner than .060 inches are avoided. • Flatness depends on part thickness and surface area. • Thin parts tend to distort more than thick parts • Chamfers rather than radii are necessary on part edges Prepared by MetalKraft Industries

  24. Questions: Prepared by MetalKraft Industries

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