Transfer Molding

C-Frame Transfer Molding Press
C-Frame Transfer Molding Press for Molding Neoprene Rubber Products

In concept, the transfer molding process is a simplified version of injection molding. It provides many of the benefits of both injection and compression press molding. Transfer molding presses allows the molding of intricate parts while providing highly accurate dimensional control for low to medium production volume requirements. The cycle times are generally longer than injection molding, however they can be very cost competitive.

A transfer molding press can also reduce cure time by heating the material before it reaches the mold. The material can be and is forced into a closed mold by means of a hydraulically operated plunger, or by using the compressive force of the press in combination with a tooling with an internal transfer pot.

The transfer molding press was developed to facilitate the molding of intricate products with small deep holes or numerous metal inserts. It is ideal for insert molding because the tool is closed prior to the material being transfer, which limits the amount of shift with the insert parts.

Request a Quote or Contact French engineers with any questions about our Transfer Molding Presses. Read about our 250 ton Automatic Hydraulic Vacuum Press custom designed for cold pot transfer molding.

A Transfer Molding Press is best suited for:

• Mid range dimensional tolerances
• Low to medium volume production
• Small to medium sized parts
• Delicately shaped parts
• Low to medium durometer materials
• Insert molding
• Colored and translucent compounds

Transfer Molding Press Advantages:

• Shorter production cycles than compression molding
• Ability to maintain closer dimensional tolerances than compression molding
• Excellent uniformity from mold cavity to mold cavity
• Rapid mold setups
• Typically less flash than compression because the cavity plates are closed
• For multi-cavity tools, labor cost is lower than compression since only a single pre-form is necessary.

Processing Applications:

• Low to medium durometer materials
• Low to medium production volumes – flexibility with part sizes
• Small delicate parts

Disadvantages:

• Higher Investment Cost than compression (press, tooling and auxiliary equipment)
• Requires a preform (a pre-measured slug of material)
• Not well suited for filled materials
• Generates some amount of material degradation
• Cannot process high durometer materials
• Tool maintenance costs are typically higher than compression
• Wear of cavities is less than injection, but gates and runners erode
• Labor content typically higher than injection
• Flash Pad or Pot Pad is excess scrap material

Resin Transfer Molding (RTM) is a low pressure (typically under 100 psi), closed molding process, which offers a dimensionally accurate, and high quality surface finish composite molding, using liquid thermoset polymers reinforced with various forms of fiber reinforcements.

Typical Materials:

  • Epoxy
  • Vinyl Ester
  • Methyl Methacrylate
  • Polyester
  • Phenolic
  • Filled Materials such as with Glass, Arimid, Carbon and Synthetic fibers