Compression molding method: advantages, applications
Compression molding is one of the oldest and most reliable rubber-processing methods. Here a pre-measured rubber compound is placed inside a heated mold, the mold is closed and compressed, and the material takes the shape of the cavity under pressure. Despite its simplicity, this method still remains the most economical solution for many applications.
How does compression molding work?
The process consists of several basic steps:
1. Preparation (preform)
The rubber compound is cut to the required weight. The correct amount is important — too little material does not fully fill the mold, while too much creates excess flash.
2. Placement and compression
The preform is placed in the lower half of the heated mold. When the mold closes, the upper half compresses the material and it fills the cavity. The temperature is usually kept in the range of 150–180 °C.
3. Vulcanization
The material is kept in the mold in a heated state and vulcanized. During this, cross-links form between the polymer chains and the part gains its final strength. The mold is then opened and the product is removed.
Advantages of compression molding
- Low mold cost: molds are simpler and cheaper than injection molds.
- Large parts: ideal for thick-walled and large-sized products.
- Low and medium series: economically advantageous for small batches.
- Material variety: works well with stiff compounds and highly filled materials.
Which products is it suitable for?
Compression molding is widely used in the production of flat seals, flange gaskets, plugs, rubber sheets, large O-rings and protective pads. Material selection depends on the application environment — EPDM is often chosen for heat and weather conditions. For the right product, a seal selection guide will be helpful.
Comparison with injection molding
For complex, fine-detailed and high-volume parts, injection molding is faster and more precise. For simple-shaped, large or low-volume parts, compression molding is more economical. For long profiles, extrusion is used. To choose the right method, our manufacturing team can help you.
Do you want to choose the most suitable molding method for your project? Take a look at our products and contact us for technical advice.