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Introduction to Manufacturing

Introduction to Manufacturing. Chapter 14: Forging. Forging. Metal-forming process in which the workpiece is shaped by compressive forces applied through various dies and tools. Example – Blacksmith Hammer and anvil. Forging. Forgeability

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Introduction to Manufacturing

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  1. Introduction to Manufacturing Chapter 14: Forging

  2. Forging • Metal-forming process in which the workpiece is shaped by compressive forces applied through various dies and tools. Engr 241-R1

  3. Example – Blacksmith Hammer and anvil Engr 241-R1

  4. Forging • Forgeability • Capability of a material to undergo deformation without cracking. • Forging is a discrete (individual) parts process • Forging is a near net shape process Engr 241-R1

  5. Metal flow and grain structure controlled – parts have good strength • Landing gear • Jet engine shafts • Bolts • Connecting rods • Hand tools Engr 241-R1

  6. Forging classified cold or hot Engr 241-R1

  7. Cold Forging • Requires greater forces and workpiece materials must have sufficient ductility at room temperature; good surface finish and dimensional accuracy. Engr 241-R1

  8. Hot Forging • Requires smaller forces, not as good finish or dimensional accuracy; usually require additional machining. Engr 241-R1

  9. Open-Die Forging • Upsetting or flat-die forging • Simplest forging process. • Solid workpiece is set between two flat dies and reduced (height) through compression. Engr 241-R1

  10. Barreling • outward bowing of material • Two causes • 1.) by friction at die-work piece interface • minimized by use of lubricants. Engr 241-R1

  11. Barreling • (2) by hot work piece between cold dies • Material cools at die interface and resists deformation Engr 241-R1

  12. Cogging: • Drawing out • Operation where the thickness of a bar is reduced by successive forging steps at certain intervals. • Typical for parts such as I-beams which must be pre-shaped before rolling Engr 241-R1

  13. Fullering • Distribute material away from die Engr 241-R1

  14. Edging • Gather material into die Engr 241-R1

  15. Impression-Die Forging • Work piece takes shape of die cavities (impressions). • Flash: material which flows out from dies (frictional resistance from cooling flash causes material to fill the inside of the die cavity). Engr 241-R1

  16. Closed-Die Forging • Also called precision forging • flashless forging (flash does not form). • workpiece completely fills the die cavity. Volume of material is precise. • Economical - eliminates trimming flash Engr 241-R1

  17. Closed die forging (cont.) • Greater forces to obtain fine detail • Al and magnesium good because malleable • Less material wasted • Gears, connecting rods, etc. Engr 241-R1

  18. Coining: • Another closed die process • Produces fine details • No lubricants used – can be trapped in die cavities – don’t compress • pressures five to six times the strength of material. Engr 241-R1

  19. Related Forging Operations Engr 241-R1

  20. (1) Heading • upsetting operation, usually performed at the end of a round rod or wire to produce a large cross section • heads of bolts, screws nails, rivets, etc. Engr 241-R1

  21. (2) Piercing • indenting, without breaking, the surface of a workpiece with a punch to produce a cavity or an impression Engr 241-R1

  22. (4) Roll Forging • the cross section of a bar is reduced or shaped by passing it through a pair of rolls with shaped grooves • leaf springs, hand tools, discrete parts Engr 241-R1

  23. (5) Skew Rolling • similar to roll forging • Ball bearing production Engr 241-R1

  24. (6) Orbital Forging • upper die moves along an orbital path above the part which is also spinning. Engr 241-R1

  25. (7) Incremental Forging • process where a blank is forged into a shape in several small steps (the die penetrates the blank at different depths across the surface). Similar to cogging. Engr 241-R1

  26. (8) Isothermal Forging • Hot die forging • Dies heated to same temp as workpiece • Good for complex parts with dimensional accuracy Engr 241-R1

  27. Forging die design • Most important rule in die design • Work piece material must flow in direction of least resistance • Machining allowance used Engr 241-R1

  28. Die inserts • Separate sections • Reduce cost of making dies Engr 241-R1

  29. Die lubricants • Slow rate of cooling • Improve metal flow • Serve as parting agent • Not for coining – precision forging Engr 241-R1

  30. Forging Machines Engr 241-R1

  31. Presses • Hydraulic • Mechanical • Screw Engr 241-R1

  32. Hammers • Gravity drop – free falling ram • Power drop – stroke accelerated by steam, air, or hydraulic Engr 241-R1

  33. Hammers (cont.) • Counterblow (two hammers simultaneously approach each other • High-energy-rate machines - ram accelerated by high pressure – part forged in one blow Engr 241-R1

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