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INJECTION MOLDING OF THERMOSET PLASTICS

INJECTION MOLDING OF THERMOSET PLASTICS. BY ALOK KUMAR. THERMOSET INJECTION MOLDING MACHINE. PHOTO OF PLASTICIZING THE RESIN. PHOTO OF INJECTION OFTHE RESIN. PHOTO OF CROSSLINKING. PHOTO OF EJECTION. How injection molding works?.

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INJECTION MOLDING OF THERMOSET PLASTICS

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  1. INJECTION MOLDING OF THERMOSET PLASTICS BY ALOK KUMAR

  2. THERMOSET INJECTION MOLDING MACHINE

  3. PHOTO OF PLASTICIZING THE RESIN

  4. PHOTO OF INJECTION OFTHE RESIN

  5. PHOTO OF CROSSLINKING

  6. PHOTO OF EJECTION

  7. How injection molding works?

  8. Difference between injection molding of thermoset and thermoplastics •  Barrel • Screw • Mold temperature

  9. BARREL

  10. Processcharacteristics • Production Rate - high • Can produce intricate parts • Can produce a wide range of part sizes with different press sizes. • Tooling cost - high

  11. What is thermoset material? • A material, such as an epoxy or polyester resin, which has the property of undergoing a chemical reaction by the action of heat, catalyst, ultraviolet light, etc., to become a relatively insoluble and infusible substance. They develop a well-bonded three-dimensional structure upon curing. Once hardened or cross-linked, they will decompose rather than melt.

  12. Phenolics Urea Melamine Unsaturated polyester Some of the thermoset materials

  13. Specialty of the thermoset polymers for injection molding • Delayed curing even at higher temperature • Good flow properties • Fast reaction at tool temperature • Improved wear characteristics

  14. MATERIAL NOZZLE CYLINDER MOLD MATERIAL PHENOLIC 80-100 55-75 170-190 110-130 UREA 85-115 65-80 130-150 120-140 MELAMINE 90-110 65-80 160-170 115-135 UN-SATURATED POLYESTERS 70-100  50-70 170-200 70-100 TEMPERATURE IN degree C

  15. THERMAL PROFILE OF IM

  16. Rheology •    HEAT EXPOSURE TIME •    TEMPERATURE •     SHEARING

  17. Rheology of Thermoplastics and Thermosets

  18. Advantages of Injection Molding • Material handling is reduced

  19. Advantages of Injection Molding • Longer and smaller diameter core pins may be used

  20. Advantages of Injection Molding • Parting line flash can be held to minimal thickness if the mold is designed properly and well maintained

  21. Advantages of Injection Molding • Injection molding of thermoset materials lends itself to automating the process which can result in lower piece costs.

  22. Disadvantages of Injection Molding • The total amount of scrap produced during injection molding will usually be higher than that for compression molding

  23. Disadvantages of Injection Molding • Warpage can be a problem in injection

  24. Disadvantages of Injection Molding • The filling of the parts through one or two gates produces parts that have knit lines.

  25. Applications Phenolics: • Electrical plug and sockets • circuit board • cutlery handles

  26. Applications Melamine-formaldehyde: • Dinnerware • Kitchen utensils • Bathroom accessories

  27. THANK YOU

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