Compression Molding

Compression molding is a well established process having been thoroughly admired for its simplicity and low cost production paired with a strong, high quality part. While not on everyone’s radar as a modern technique, compression molding is indeed a set of processes that are being used by industries such as automotive, aerospace, electronics and consumer goods. 

Compression molding involves filling the heated mold cavity with a preheated (or at times, room temperature) material, such as a charge, slug or sheet. That’s because when the mold closes, an astounding pressure and heat causes the material to flow and form to the contours of the mold. The newly formed part is ejected after opening the mold after a set curing time. Because of its ability to produce durable and dimensionally stable components with relatively low tooling costs, this technique is particularly valued.

Step-by-Step: How It Works

1. Preparation: The chosen material (polymer or composite) is measured and prepared for loading.
2. Loading: This material, often in a moldable state, is placed into the lower half of the heated mold.
3. Compression & Curing: The mold closes, applying pressure and heat, causing the material to spread and fill the cavity. It is held under these conditions until it cures.
4. Cooling & Ejection: Once cured, the mold opens, and the formed component is removed—ready for any post-processing steps like trimming or finishing.

Typical Materials for Compression Molding

This table gives a clear breakdown of the various materials used in compression molding, their advantages, and typical use cases for each.

Key Advantages of Compression Molding

Cost-Effective Tooling

As with injection or transfer molding, compression molds could be simpler, i.e. lower cost tooling.

High Strength & Structural Integrity

Compression molded parts, when working with fiber reinforced materials, are especially strong and stiff.

Low Material Wastage

As the exact amount of material is squashed into the mold cavity, the scrap rate can be reduced.

Complex Geometries & Large Parts

The compression molding process is perfectly suited for large products that require structural stability.

Consistency & Reliability

Both pressure and temperature of the curing are consistent across runs to ensure equal part quality.

Partner with Gree-Ge for Compression Molding

Gree-Ge’s engineers have decades of collective experience in the compression molding process: material selection, process optimization, etc. Our unique facilities are ready for both prototypes or high volume manufacturing.

The quality of each project is checked thoroughly. Our operations are centered around dimensional accuracy, material consistency and performance testing.

Gree-Ge knows that there is never one way to do things. But, we work really closely with clients to channel materials to suit their needs, mold designs, and production methods.