Rubber Transfer Molding

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Rubber Transfer Molding2018-10-29T17:04:51+00:00

Rubber Transfer Molding

The rubber transfer molding process is ideal to produce both solid rubber parts, rubber part with inserts and parts that require bonding rubber to metal. Rubber transfer molding combines the advantages of injection molding with the ease of compression molding. Transfer molding is the ideal process for forming rubber products that require:

  • Exact positioning
  • Bonding rubber to fragile metal parts – such as wire
  • Mold designs that contain multiple cavities and can trap air
  • Intricate parts with lower volume requirements

The Rubber Transfer Molding Process

The process of transfer molding involves pushing unvulcanized rubber through sprues into a heated mold. Similar to compression molding, transfer molding requires raw material preparation into pellets and/or pre-forms.

Rather than placing the preform in the mold cavity, the rubber pre-form is placed in a chamber “pot” at the top of the mold then placed in a press. In the pot, the material is compressed by a heated plunger and transferred through sprues into the cavity below.  The plunger is kept in place until the preform takes on the shape of the mold and the rubber is vulcanized.  The part cures, hardens, cools, then is ejected. Excess cured rubber left in the pot, is removed, mold cavities are cleaned and the next molding cycle begins.

When transfer molding is used for rubber to metal bonding or over molding, the components are loaded into a heated mold either by hand or using a loading fixture.  Material is loaded into the well pot of the transfer mold.  The mold closes and the heated rubber is then transferred through the runner and gate sprues into the mold cavities and around the metal insert.  Under pressure and elevated temperatures, the rubber cures/vulcanizes and parts are removed.

The rubber transfer mold consists of a piston, well pot, sprue plate, cavity plate, and a base plate with a knock-out system used to eject the parts after molding.

Advantages of the Rubber Transfer Molding Process

Transfer molding offers several advantages over other methods by providing:

  • Shorter production cycles
  • Maintains closer dimensional tolerances than compression molding
  • Provides uniformity
  • Fast mold setup
  • Economical process with high cavity count per mold per cycle
  • Cost effective tooling
  • Allows for rubber to metal bonding
  • Allows for rubber overmolding
  • Allows for  design flexibility, sharp edges and intricate parts

Disadvantages of Rubber Transfer Molding

  • Complex molds that are more expensive than compression molding
  • Longer cycle times
  • Labor intensive
  • Increased mold maintenance
  • Increased flash and waste

Transfer molding is an ideal process to not only produce precision molded rubber products, but also products that require rubber bonded to metal surfaces.

Rubber Transfer Molding combines the advantages of injection molding with the ease of compression molding. Rubber transfer molding is the ideal process for forming parts that require:

  • Exact positioning
  • Bonding rubber to fragile metal parts – such as wire
  • Mold designs that contain multiple cavities and can trap air
  • Intricate parts with lower volume requirements

Qualiform molds both natural rubber and synthetic rubber which include:

  • Butyl
  • Colored Compounds
  • EPDM
  • Natural Rubber
  • Neoprene
  • Nitrile
  • SBR
  • Silicone
  • Viton™
  • Fiber Molding

Transfer Molding Design and Material Consultation

Our technical staff is available to answer any questions call (330) 336-6777, or submit a question through our Contact Form or Send Us a PDF.

Transfer Molding
Our technical staff is ready to assist you with all your custom rubber molding needs.

Transfer molded EPDM latches.

Neoprene transfer molded eye protection product used on top of antenna.

Feet for application use on bottom of Red Box DVD machines.

Custom dental grips with numerous color options available.

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