Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

P/M: Basics


Published on

Published in: Education, Business

P/M: Basics

  1. 1. Powdered Metallurgy : The Basics
  2. 2. Basics of P/M <ul><li>Highly developed method of manufacturing precision metal parts </li></ul><ul><li>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. </li></ul><ul><li>Basically a ”chip-less” process, P/M uses roughly 97% of the starting material in the finished part. </li></ul>
  3. 3. Advantages of P/M <ul><li>Versatile in numerous industries </li></ul><ul><li>Eliminates or minimizes machining </li></ul><ul><li>Minimizes scrap </li></ul><ul><li>Maintains close dimensional tolerances </li></ul><ul><li>Permits a wide variety of alloy systems </li></ul><ul><li>Facilitates manufacture of complex shapes which would be impractical with other processes </li></ul><ul><li>Provides excellent part to part repeatability </li></ul><ul><li>Cost Effective </li></ul><ul><li>Energy and environmentally efficient </li></ul>
  4. 4. Basic P/M Steps <ul><li>Raw Material </li></ul><ul><li>Mixing </li></ul><ul><li>Forming </li></ul><ul><li>Sintering </li></ul><ul><li>Optional Operations </li></ul><ul><li>Finished Products </li></ul>
  5. 5. Mixing <ul><li>Elemental, partially alloyed or pre-alloyed metal powders are first blended with lubricants to produce a homogeneous mixture. </li></ul>
  6. 6. Compaction <ul><li>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. </li></ul><ul><li>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. </li></ul><ul><li>Typical compaction techniques use rigid dies, set into mechanical or hydraulic presses. </li></ul>
  7. 7. Conventional Mechanical Press
  8. 8. Compaction Tooling
  9. 9. Compaction Cycle <ul><li>Cycle Start </li></ul><ul><li>Charge die w/powder </li></ul><ul><li>Compaction begins </li></ul><ul><li>Compaction complete </li></ul><ul><li>Ejection of compact </li></ul><ul><li>Recharging of die </li></ul>
  10. 14. Sintering <ul><li>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. </li></ul><ul><li>Typical sintering temperatures for ferrous based metals range from 2050- 2100 degrees F. </li></ul><ul><li>Standard cycle times range from 2-3 hours. </li></ul>
  11. 15. Conventional Furnace Profile
  12. 16. Optional Operations
  13. 17. Optional Operations
  14. 18. Powdered Metallurgy: Design Considerations
  15. 19. Material Selection
  16. 20. Design Considerations <ul><li>Dimensional accuracy depends upon: </li></ul><ul><ul><li>Control of powder composition </li></ul></ul><ul><ul><li>Size of dimension </li></ul></ul><ul><ul><li>Control of powder fed to the tools with each stroke </li></ul></ul><ul><ul><li>Control of press and tooling variables </li></ul></ul><ul><ul><li>Control of sintering variables </li></ul></ul>
  17. 21. MPIF Reference Tolerance Guide <ul><li>Typical tolerances for ferrous P/M components up to 2.00 inches in dimension </li></ul><ul><li>Tolerances, inch/inch </li></ul>±.001 ±.0015 Parallel of Ends ±.001 ±.002 Flatness on Ends .004 .006 Concentricity ±.001 ±.002 Outside Diameter ±.001 ±.002 Inside Diameter ±.003 ±.005 Length Possible Practical Characteristic
  18. 22. Design Details <ul><li>Fillets and Radii </li></ul><ul><ul><li>Tooling with such fillets are more economical, longer lasting </li></ul></ul><ul><ul><li>Parts made with generous fillets are more economical </li></ul></ul><ul><ul><li>Parts made with fillets have greater structural integrity </li></ul></ul>
  19. 23. Design Details <ul><li>Holes in the pressing direction can be round, D-Shaped, keyways or splines </li></ul><ul><li>Wall thickness is all important; walls thinner than .060 inches are avoided. </li></ul><ul><li>Flatness depends on part thickness and surface area. </li></ul><ul><li>Thin parts tend to distort more than thick parts </li></ul><ul><li>Chamfers rather than radii are necessary on part edges </li></ul>
  20. 24. Questions: