Rubber Injection Molding Process | Rubber Injection Molding Guidelines

A rubber injection mold is a specialized tool used to manufacture rubber products through the injection molding process. Rubber material (such as natural rubber, silione, EPDM, etc.) is injected into the mold cavity under high pressure, then heated and vulcanized to form complex-shaped rubber parts. This technology is suitable for high-precision, mass production and is widely used in indutries such as automotive, medical, electronics, and sealing components. Traditional forming way of silicone products is compression molding, which is one of the cheapest and simplest molding methods and widely used in rubber industries. But with the higher requirements on the quality and production efficiency, rubber injection molding is developed. In addition, rubber injection molding process can realize high level of automation. Rubber injection molding is highly efficient for mass-producing complex rubber components with tight tolerances and consistent quality.

Rubber Injection Molding Process

Rubber Injection Molding by injection machine, feeding material automatically

1. Material Preparation: Rubber compound(granules or strips) is preheated to soften.

2. Injection & Filling: Rubber is pushed by the injection machine screw and injected into the closed mold cavity under high pressure

3. Vulcanization (Curing): The mold is heated (typically 150-200°C), causing the rubber to cross-link and solidify.

4. Cooling & Ejection: After forming, the mold opens, and ejector mechanisms remove the part.

5. Post-Processing: Trimming flash, secondary vulcanization (if required).

Rubber Injection Molding Key Components 

• Injection Unit: Melts and injects rubber material into the mold.

• Mold (Tooling): Custom-designed steel or aluminum mold that shapes the rubber.

• Clamping Unit: Holds the mold tightly closed during injection.

• Heating & Curing System: Vulcanizes (cures) the rubber for optimal elasticity and durability.

• Ejection System: Removes the finished part after cooling.

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Common rubber materials for injection molding

• Natural Rubber (NR) – High elasticity, good wear resistance.

• Silicone Rubber (VMQ) – Heat-resistant, flexible, biocompatible.

• EPDM (Ethylene Propylene Diene Monomer) – Weather & ozone resistant.

• Nitrile Rubber (NBR) – Oil & fuel resistant.

• Fluoroelastomer (FKM/Viton®) – Extreme chemical & heat resistance.

• Advantages of Rubber Injection Molding

• ✔ High Precision – Produces complex geometries with tight tolerances.
  ✔ Fast Production – Shorter cycle times compared to compression molding.
  ✔ Material Efficiency – Minimal waste due to precise injection.
  ✔ Consistency – Uniform part quality in high-volume production.
  ✔ Automation-Friendly – Suitable for large-scale manufacturing.

• Rubber Injection Molding vs. Compression Molding

• Feature	Injection Molding	Compression Molding
  Speed	Faster cycle times	Slower process
  Complexity	Better for intricate designs	Simpler shapes
  Tooling Cost	Higher initial cost	Lower mold cost
  Waste	Minimal flash	More material waste
  Volume	Ideal for mass production	Better for low to medium volumes

Rubber Injection Molded Parts Common Applications

• Automotive: Seals, gaskets, vibration dampers, O-rings.

• Medical: Syringe seals, surgical tubing, medical device components.

• Industrial: Hose connectors, grommets, shock absorbers.

• Consumer Goods: Kitchenware seals, grips, waterproofing components.

• Electronics: Keypads, cable gaskets, protective coatings.

  Our Advantanges on Silicone Compression Molded Parts:

• Good control of rubber flashing, and flashing can be as tiny as possible. For these tiny fashing, we can not see through our eyes, need to amplify to check. Our company have all these complete test equipment and can test and provide test report according to customers' requirements.

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