What is Transfer Molding?

Transfer molding is the method of creating components in a closed mold using thermosetting materials that are pushed via runners and gates into the closed cavity or cavities while under pressure and in a hot, plastic condition from an auxiliary chamber known as the transfer pot.

Transfer Molding Process

The transfer molding method is exactly like injection molding, with a few key exceptions. The following are the steps:

  • The material is put into a holding chamber known as the transfer pot, which may or may not have been warmed.
  • The material is pushed into the mold cavity by a plunger that is hydraulically propelled through a tube known as the sprue.
  • The substance is kept inside the mold and either heated to cure metal alloys or chilled to harden thermoplastics (thermosets). Any material that is still inside the sprue after the item hardens is linked to it.
  • Once the material has been set, the mold is opened, and the part is ejected.
  • The sprue’s extra material is taken out.

Transfer Molding Advantages

The preheating of the material and injection through a small aperture increases the temperature distribution inside the material and speeds up the crosslinking process, which is one of transfer molding’s benefits.

  • Minimal flash formation at parting lines of molds.
  • Faster setup times.
  • Lower tooling costs.
  • Greater part design flexibility (and capacity for part complexity).

Transfer Molding Disadvantages

Transfer molding has a few drawbacks due to its ease of use and speed:

  • Material Waste: Due to the higher size of the sprues and overflow channels, transfer molding generates additional material waste.
  • Slow Production: Transfer molding’s production pace is slower than injection molding because materials must be heated prior to molding.
  • Low Quantity: Transfer molding machines create fewer pieces per cycle than injection molding machines because they cannot handle many cavities.

Common Polymer Materials Of Transfer Molding

Transfer Molding can apply both thermosetting and thermoplastic materials, the most common polymer materials include:

  • Unsaturated Polyester
  • Epoxy
  • Phenol-formaldehyde Plastics
  • Silicone Rubber

Transfer Molding FAQs

What is transfer molding and why is it used?

One of the many processes used by engineers to create rubber items is transfer molding. The correct quantity of molding material is measured, inserted, and put into the molding pot before the process begins. Pressure forces the material to transfer into the mold cavities as it is heated.

What material is used for transfer moulding?

A thermoset polymer is a substance that is most frequently utilized for transfer molding. This kind of polymer is simple to work with and mold, yet it takes on a permanent shape after curing. The component for straightforward homogeneous transfer molded pieces is comprised solely of this plastic base.

What is cull in transfer Moulding?

The disc of substance that is left in the transfer pot to cure after the cavities have been filled is known as the cull. Cure: The period of time needed for a thermoset material to crosslink when under pressure and heat.


About Frank

With a background as an injection molding engineer at Kaysun, Frank brings unique depth and insight to his role as Business Development Engineer. His ability to synthesize information and pair need with opportunity is a benefit to prospects and customers alike.

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