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A methodology for setting the injection moulding process parameters for polymer rapid tooling inserts

Anurag Bagalkot (Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand)
Dirk Pons (Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand)
Don Clucas (Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand)
Digby Symons (Department of Mechanical Engineering, University of Canterbury, Christchurch, New Zealand)

Rapid Prototyping Journal

ISSN: 1355-2546

Article publication date: 15 January 2019

Issue publication date: 17 October 2019

618

Abstract

Purpose

Polymer rapid tooling (PRT) inserts can be used as injection moulding (IM) cavities for prototyping and low volume production but lack the robustness of metal inserts. Metal inserts can withstand high injection pressure and temperature required, whereas PRT inserts may fail under similar parameters. The current method of parameter setting starts with using the highest pressure setting on the machine and then fine-tuning to optimize the process parameters. This method needs modification, as high injection pressures and temperatures can damage the PRT inserts. There is a need for a methodical process to determine the upper limits of moulding parameters that can be used without damaging the PRT inserts.

Design/methodology/approach

A case study analysis was performed to investigate the causes of failure in a PRT insert. From this, a candidate set-up process was developed to avoid start-up failure and possibly prolong tool life. This was then tested on a second mould, which successfully avoided start-up failure and moulded 54 parts before becoming unusable due to safety issues.

Findings

Process parameters that are critical for tool life are identified as mould temperature, injection pressure, injection speed, hold pressure and cooling time.

Originality/value

This paper presents a novel method for setting IM process parameters for PRT inserts. This has the potential to prevent failure at start up when using PRT inserts and possibly extend the operating life of the PRT inserts.

Keywords

Acknowledgements

The authors thank Talbot Technologies Ltd. and Callaghan Innovation (grant number TALB 1501/PROP-47676-FELLOW TALBOT) for the opportunity to pursue this research. Special thanks to Steve W, Steve O, Lance F and Ben A at Talbot Technologies for continued guidance through the project.

Conflict of interest: The authors declare no financial conflict of interest in this project. The funding agency and industry partners did not control the research nor influence the content of the paper.

Contribution statement: This work was conducted by AB and supervised by DP, DC and DS. The idea for parameter setting was developed by AB and DP. All authors contributed to the writing of the paper.

Citation

Bagalkot, A., Pons, D., Clucas, D. and Symons, D. (2019), "A methodology for setting the injection moulding process parameters for polymer rapid tooling inserts", Rapid Prototyping Journal, Vol. 25 No. 9, pp. 1493-1505. https://doi.org/10.1108/RPJ-10-2017-0217

Publisher

:

Emerald Publishing Limited

Copyright © 2019, Emerald Publishing Limited

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