The Main Plastic Injection Molding Steps

Plastic injection molding is integral in modern manufacturing, producing various products for different industries. From electrical switches and medical equipment to children’s toys and plastic utensils, this versatile process shapes and produces in bulk small to large items that shape consumer goods, packaging, and more with precision.

To end up with high-quality products, experts craft the dimensions and mold their form before starting the manufacturing process. This precise, meticulous process is completed in four steps: clamping, injection, cooling, and ejection.

Clamping

Clamping, the forming stage, is the first step in the injection molding process. In this stage, the item is made in two metal halves that come together with the help of a machine press. This machine ensures that the objects stay together during the process and that the plastic remains within the molds.

Injection

The injection step consists of filling the clamped mold from the first step. The granulated or pelleted plastic is melted down into liquid before it’s inserted into the cavity, taking the shape of the designed mold. For best results, the temperature must remain constant throughout this stage.

Cooling

The cooling process consists of lowering the heat so that the mold solidifies. The hot plastic inside could take up to 30 days to finalize; however, around 95% of the cooling happens in the mold, and 5% takes place outside.

Ejection

The injection molding process is completed with the ejection of the product. Once solidified, the fabricators separate the mold halves to reveal the final product and eliminate plastic imperfections. This waste material is often recycled and used in other parts.