Before automation.
Before injection.
There was compression.

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Compression molding is the oldest method of shaping rubber.

And even today, it remains one of the most reliable.

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The process is simple:

A heated mold opens.

A preform is placed inside the mold, usually a die-cut blank or slab of uncured rubber.

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The mold closes. Heat and pressure combine.

The rubber compresses, flows into shape and cures.

As crosslinks form, the material hardens into its final geometry.

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When the cycle ends, the mold opens and the part is removed.

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Compression molding shines with large or thick parts, stiff compounds or low-volume production. Because flow is slower and more controlled than in injection, it delivers excellent dimensional stability and uniform cure.

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Tooling is simpler and cost-effective, making it ideal for oversized gaskets, heavy-duty isolators, blocks and prototypes.

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It remains common in critical sectors, from automotive mounts and dampers to HVAC seals and bushings and heavy construction equipment where durability outweighs speed.

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But there are trade-offs.

Cycle times are longer.
Flash is more common.

And manual loading means operator skill plays a role.

Even so, modern presses, digital temperature control and advanced flow simulation have brought new precision to an old method.

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Compression molding isn’t obsolete.

It’s a proven, precise and enduring technique, still chosen when strength, simplicity and control matter most.