Induction Heating in Plastic Processing

Introduction

In thermosetting plastic processing, methods such as compression molding, injection molding, and extrusion are commonly used. During the polymerization (curing) process, both heat and pressure play essential roles. While molds, injection cavities, and extrusion barrels can be heated using gas, steam, or resistance heating, induction heating offers higher thermal efficiency, faster heating speed, and more precise temperature control.

How Induction Heating Works in Plastic Processing

Induction coils are installed directly onto the mold body. When alternating current flows through the coil at the power supply frequency, heat is generated within the mold. These coils can also be mounted on appropriate components of injection molding machines and extrusion lines, enabling localized heating in the same manner. This prevents excessive temperature fluctuations and reduces power loss, while achieving rapid thermal response and significantly lower heat dissipation.

For mold sizes of 750 mm square and above, three-phase power is used. For smaller molds, both single-phase and three-phase induction heaters can be applied, depending on the equipment design and heating requirements.

Induction Heating for Extrusion Barrel Heating

Induction heating is also well-suited for heating extrusion barrels. Traditional heating methods such as gas, steam, or resistance heaters typically result in low production rates. By contrast, induction heating dramatically improves throughput due to its fast heating speed and its ability to produce a uniform polymerization reaction.

Advantages of Induction Heating in Plastic Processing

1. Uniform and Deep Internal Heating

Heat is generated within the metal component itself, providing deep and uniform heating without steep temperature gradients. The mold’s surface temperature remains stable with minimal variation, enabling precise thermal control and a more consistent polymerization process.

2. High Thermal Efficiency and Localized Heating

Induction systems deliver high thermal efficiency and allow heat to be concentrated exactly where it is needed. This flexibility broadens process control options and makes it possible to meet production requirements that are difficult to achieve with other heating methods.

3. Improved Material Quality and Higher Productivity

The improved heating uniformity enhances the condition of the processed material. As a result, high-quality products can be produced more quickly with lower energy consumption and minimal maintenance costs.

Conclusion

Induction heating significantly enhances the efficiency, consistency, and productivity of thermoset plastic molding and extrusion processes. With precise temperature control, reduced heat loss, and superior heating uniformity, induction systems offer a strong technological advantage over traditional heating methods in modern plastic processing applications.