Injection Molding Rubber

Injection molding rubber is a combination of injection and transfer molding that Coi Rubber Products uses quite frequently to maximize the number of cavities in a given footprint.  It is commonly used within liquid injection and/or LSR molding.  Some classifications with liquid injection versus transfer injection would further provide subcategory classifications.

Injection Molding

  • Perfect for large volume runs of small-to-medium size parts
  • Good for intricate metal inserts, thin-wall diaphragms and similar components requiring uniform physical properties
  • 300 ton to 1000 ton clamping pressure

Advantages of Injection (LSR) Molding Rubber:

  • Tooling can be more complex and higher precision than compression
  • Material properties created within A/B mix can have superior properties
  • Process is suitable from most elastomers and cure systems
  • Cycle times may be shorter reducing time while increasing efficiency
  • Complete elimination of pre-forms, a labor-intensive step that can introduce variability in pre-form weight and shape resulting in variability of the finished product.

Disadvantages of Injection Molding vs. other rubber molding methods

  • Labor for preforming material can add cost (however offshore manufacturing curtails this problem)
  • Cycle times may be longer (additional shifts counter this problem)
  • Tooling can be more complex and higher cost to construct than compression
  • Higher percentage material runner scrape vs. compression molding