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How the Low-Pressure Molding Process Works

Posted by Rick Regole on February 01, 2021 | Updated on February 1, 2021

low pressure overmolding

When it comes to overmolding delicate electronic equipment, such as printed circuit boards (PCB), nothing beats the benefits of low-pressure molding. Compared to potting, low-pressure molding is faster and simpler to perform, less expensive to produce, environmentally friendly, and offers excellent resistance and protection — all thanks to a unique manufacturing process.


Before the manufacturing process begins, product teams and engineers work together to identify the environmental and mechanical demands of the application for which the overmolded part will be used. With all specifications laid out and design details approved, the overmolding process can begin. Unlike traditional potting, which involves a seven- or eight-step process, the low-pressure molding process only requires three. Here’s how the low-pressure molding process works:

    • Step 1: Melt The Molding Material

In this step, adhesive thermoplastic polyamide materials (aka “hot melts”) derived from the plants’ fatty acids are poured into a large hopper and heated until liquified. Because hot melts are all-natural, no outgassing or toxic fumes are emitted during this step.

    • Step 2: Inject The Mold Set

Next, the wire or electrical part is placed in a mold half. Once in place, the other half of the mold closes, creating a cavity around the electrical component. A machine slowly injects the liquified thermoplastic into the mold cavity until full. Even though the injection rate is slower than high-pressure injection molding, filling the mold cavity can take as little as 30 seconds, depending on the size of the part.

    • Step 3: Cool Down

Lastly, the mold set opens to allow the overmolded part to cool. Unlike potting, which requires a lengthy curing process, hot melts cool quickly at room temperature and can be removed from the mold and tested shortly after the injection molding process is complete.

The resulting product offers protection, strain relief, and water encapsulation for electrical cables of all sizes, including fiber optics and thin flex cables. Since low-pressure molding is so precise and uses bio-based materials, the process produces near-zero waste and significantly cuts labor and materials costs. If material is leftover, it can be recycled into new material. In addition to various sizes and designs, the low-pressure molds themselves can be customized to include special features, such as grommets and logos. Ultimately, the entire low-pressure molding process allows design teams to get products to market faster without compromising cost or quality.

To learn more about overmolding electronics, download our free guide.

Overmolding Guide

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