Rubber Molding Processes: Compression, Transfer, Extrusion, and Injection

Rubber manufacturing offers several molding processes designed to meet the technical, geometric, and production requirements of each application. Choosing the right molding method not only affects part performance, but also tooling cost, production efficiency, and long-term reliability.

In this article, we explain the main rubber molding processes—compression molding, transfer molding, extrusion, and injection molding—how they work, their key advantages, common applications, and how to select the most suitable process for your project.

What Is Rubber Compression Molding?

Rubber compression molding is one of the most widely used rubber manufacturing processes. It consists of placing a pre-measured amount of rubber compound directly into the mold cavity. The mold is then closed, and heat and pressure are applied so the material flows, fills the cavity, and cures into its final shape.

Advantages of Compression Molding

• Lower tooling cost
  
• Simple and robust process
  
• Ideal for large or thick rubber parts
  
• Good control of mechanical properties
  
• Minimal material waste
  
  

Typical Applications

Compression molding is commonly used to manufacture:

• Industrial seals and gaskets
• Flat rubber joints
  
• Bushings
  
• Rubber stops
  
• Anti-vibration components
  
  

This process works particularly well with elastomers such as EPDM, natural rubber, NBR, and silicone, especially when parts do not require complex geometries or tight tolerances.

Rubber Transfer Molding: Improved Detail and Precision

Rubber transfer molding is an evolution of compression molding that allows for greater precision and improved surface finish. In this process, the rubber compound is placed into a separate chamber called a transfer pot. When the mold closes, a piston pushes the material through runners into the mold cavities, where it flows and cures under heat and pressure.

When to Use Transfer Molding

Transfer molding is ideal when applications require:

• Better dimensional accuracy
• Improved surface finish
• More complex geometries
  
• Rubber parts with metal inserts
  
  

Common Applications

• Rubber-to-metal bonded bushings
  
• Technical rubber components
  
• Small parts requiring consistent detail
  
  

Transfer molding offers better mold filling than compression molding while keeping tooling costs lower than injection molding.

Rubber Extrusion: Continuous Profile Manufacturing

Rubber extrusion is a continuous manufacturing process in which rubber compound is forced through a shaped die rather than molded in a closed cavity. The material exits the die as a continuous profile and is then vulcanized in-line using hot air ovens, microwave systems, or salt baths.

Advantages of Rubber Extrusion

• Continuous, high-efficiency production
  
• Ideal for long-length products
  
• Excellent dimensional control
  
• Low cost per meter
  
  

Products Commonly Made by Extrusion

• Rubber hoses
  
• Tubes
  
• Continuous gaskets
  
• Sealing profiles
  
• Weatherstripping
  
  

Extrusion is widely used in industries such as automotive, construction, appliances, and industrial sealing applications where consistent cross-sections are required.

Rubber Injection Molding: Precision and High-Volume Production

Rubber injection molding is one of the most advanced rubber and plastic manufacturing processes. In this method, material—either thermoplastic elastomers or rigid plastics—is melted and injected at high pressure into a closed mold, delivering excellent repeatability and tight dimensional tolerances.

This process is especially suitable for small, complex parts and high-volume production, where cycle time and consistency are critical.

Injection Molding Capabilities at Rubber Mexico

At Rubber Mexico, we offer extensive injection molding capabilities, with machine sizes ranging from 50 to 500 tons. This allows us to produce anything from single-cavity molds to large multi-cavity tools.

We work with a wide variety of materials, including:

• Elastomers: TPV, TPU, TPO, FKM, silicone, EPDM, and more
  
• Rigid plastics: Nylon (PA), Polypropylene (PP), Polycarbonate (PC), Polyethylene (PE), among others
  
  

With over 1,000 injection molds and commonly used mold bases, we are often able to develop family tools and MUD tools, helping customers reduce tooling costs and accelerate production timelines.

When Is Injection Molding the Best Option?

Injection molding is the preferred manufacturing method when:

• Thermoplastics (elastomeric or rigid) are required
  
• High production volumes are expected
  
• Tight tolerances and excellent surface finish are critical
  
  

However, for many industrial applications, compression molding or transfer molding remains more efficient, as these processes:

• Handle a wide range of production volumes
  
• Require lower tooling investment
  
• Deliver output comparable to injection molding for small, high-volume thermoset parts (especially with transfer molding)
  
  

Having multiple molding processes available ensures that each project uses the most efficient and cost-effective solution, rather than forcing a single technology.

Key differences between Compression molding, transfer molding, extrusion, and injection molding

Rubber Molding Processes at Rubber Mexico

At Rubber Mexico, we offer compression molding, transfer molding, rubber extrusion, and injection molding, manufacturing components using rubber compounds developed in-house from raw materials. This vertical integration allows us to maintain full control over material performance, consistency, and quality for industrial applications.

 

 

Need help selecting the right rubber molding process for your project?

Let us guide you through the best options for your application via email: sales2@rubber-mexico.com