Compression Molding

Maximum Dimensional Control in Thermoforming

Compression molding is a type of thermoforming process that typically uses composite thermoplastic laminates during part formation. During the compression molding process, the preheated thermoplastic is placed in a heated mold cavity. The mold is then closed when a second matched mold applies pressure and causes the material to form around every detail in the mold. Once the molding material cures and cools, the molds are separated.

Ideal for creating large and intricate parts, compression molding is more economical compared to the generally high operating costs of transfer molding or injection molding. Compression molding is material-efficient, an important attribute when working with expensive or difficult-to-create composite thermoplastics.

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Compression Molding

Here are a few key terms associated with compression molding:


Thermoforming is a type of manufacturing process in which a plastic sheet is heated and then formed over a mold. There are different types of thermoforming, depending on the needs of a project including vacuum forming (which utilizes vacuum pressure), pressure forming (which utilizes forced air pressure), and compression molding (which utilizes matched metal mold sets).

Composite Thermoplastics:

Composite thermoplastics are standard thermoplastics (such as styrene polymers and copolymers, vinyls, nylons, fluorocarbon materials, polyethylenes and acrylics) that have been combined with reinforcement materials such as carbon, aramid, or E-glass. These materials allow the composite material to maintain a low density while increasing the strength and durability of the material. Composites are also highly customizable and can be optimized for a wide range of environmental conditions and applications.

Matched Aluminum Mold Sets:

For the compression molding process, two close-fitting aluminum molds are designed and created. When a heated thermoplastic is pressurized between those two molds, the desired part will be formed. Aluminum molds are much more durable than ceramic or wood alternatives and provide a high level of design flexibility.