Plastics Processing II test 1

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  1. Compression Molding:
    • Charge Mold 
    • Close Mold
    • Fill the mold with plasticized paterial 
    • Cure by addition of heat
    • Open the mold 
    • Eject using ejector pins 
    • Clean the mold of flash
  2. Pressure range extremes:
    15 --> 1,000,000 PSI
  3. Material physical forms:
    • Granular 
    • Nodular 
    • Pellets
    • Flakes 
    • Liquid
  4. Stages of material:
    • A: liquid, solids, high flow
    • B: Partially polymerized 
    • C: Cured, polymerized 
  5. Describe additives used in molding compounds:
    • UV Stabilizers 
    • Fillers 
    • Plasticizes 
  6. First Molding Compounds:
    • Urea:
    • A cellulose filler is normally used in formulating the molding compound, Excellent colorability and compounds are produced using wet process.
    • Applications:
    • Decorative housings 
    • Closures for drug/cosmetic products 
    • Wiring devices
  7. Second molding compound:
    • Melamine-Phenolic:
    • Combining of one-stage phenolic with melamine resin, not used in large volume applications and produced in black or dark colors.
    • Applications:
    • Appliance parts where color may be needed 
    • Electrical 
    • Electrical switch gear parts
  8. Why use preforms
    • Bulky material is reduced 
    • Easier to handle 
    • Reduces mold cost
    • Cleaner 
    • Pre-weighed 
    • Heat Faster 
  9. Automatic Methods of mold loading
    • Weigh feeding system
    • Volumetric feeding system
    •    -Loading borards 
    •    -Hand Cups 
    •    -Tube 
    • Preforms of any of the material types used in compression molding 
  10. Bulk factor problem 
    Ratio of loose material volume divided by the molding part volume. 
  11. When to use low and high flow materials
    • High: Delicate parts, molding inserts 
    • Low: Thicker, more durable parts 
  12. Name of procedure to futher complete cure 
    Post cure or Normalizing 
  13. Reasons for deflashing 
    • Aesthetics 
    • Safety 
    • Fit/Function
  14. Methods for deflashing
    • Tumbling
    • Tumbling with media 
    • Wheelabrasion  
  15. Minimum/Maximum thickness of C.M. parts
    • Min: 0.040
    • Max:.0250
  16. Terms used for main mold sections 
    • Male: Core, Ram
    • Female: Cavity 
  17. Mold component hardening 
    Final hardening should be done after finalizing part
  18. Complexity of producing T.S. vs. T.P. molds
    More steps involved in making the molds
  19. Types of molds
    • Flash:10%
    • Semi-positive:Most common, little flash 
    • Positive: A lot of money, High accuracy
  20. Basic mold heating methods 
    • Steam 
    • Oil 
    • Electric cartage heater 
  21. Use and placement of vents 
    • Eliminates the gasses 
    • On parting line 
    • Corner of the mold 
    • Last place to fill across the face of the mold 
  22. Safety Factor- Molding pressure 
  23. Mold pressure problem
     Image Upload 1
  24. How are presses rated
    • Number of tons of Clamp pressure 
    • Size of platen
  25. How does our "Hull" press actuate/develop pressure
    Pneumatic Toggle 
  26. Define Double Shrinkage
    • Use melamine 
    • Shrink Faster 
  27. Why use Shrink fixtures 
    Reduce shrinkage and warping 
  28. Use of drafts on molds and amount 
    Makes it easier to remove parts over 1/4" 
  29. Minimum number of K.O. pins
  30. Placement of K.O. pins
    On the back of the part
  31. Max L/D for pins under 1/4" diameter 
  32. What factors affect mold filling 
    • Amount % of fillers 
    • Type of thermoset polymer 
    • Use of bulk material vs. preform 
    • Temperature of mold 
    • Pre-heating 
    • Part size/mold 
    • Mold pressure 
  33. Hot Strength 
    Material has cured enough that it can be removed from mold without damaging it 
  34. Holds parts to one side of the mold 
    Undercut or hooker 
  35. Use of bump cycle 
    Momentary opening after heating material to relieve gasses 
  36. Advantages of Compression Molding
    • Minimum amount of material used 
    • No erosion of gates and runners 
    • Internal stresses and warpage is less 
    • Automatic material handling equipment available
    • Shrinkage is less than transfer molding
  37. Disadvantages of Compression Molding 
    • Cant use inserts 
    • Problem occur with cleaning of the mold insert sections 
    • Uneven parting line can happen 
    • Flash is thicker than transfer molding 
  38. Hardening of mold components
    • Heat treatment to increase hardens 
    • Only the surfaces are heated 
    • Partially heat treated material
Card Set:
Plastics Processing II test 1
2013-01-31 22:41:38
PP2 Test

Questions for test one in processing II
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