Induction heating improves surfaces

(Published November 2007) Kunststoff Institut Lüdenscheid has completed a research project with 20 participating companies exploring the impact of inductive mould heating on the surface quality of injection moulded plastics parts.

The project identified a number of quality improvements, including elimination of visible knit and flow lines in high gloss surface parts with only a marginal increase in the overall cycle time.

Other benefits included better definition of matt, micro and optical surfaces, easier moulding of thin wall and micro parts, and reduction of stress in the moulding.

Two methods of inductive heating were used in the project. One approach placed an external inductor into the open tool on a robotic device to warm the mould surface prior to injection. The second approach integrated the induction heating coils within the mould tool.

Project manager Udo Hinzpeter says the study found that inductive heating provided an effective means to warm the mould tool surfaces, enabling development of very high and locally defined temperature differences on the surface within a short time.

He said the technology offers a good compromise between quality and efficiency, with some of the project partner companies already said to be applying inductive heating in both pre-series and trial tools.

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