Gas Assisted Injection Moulding: Process Setup and Optimisation Using A Rule Based Expert System
Leigh Mulvaney-Johnson, Phil Coates, Russell Speight, Paul Brincat
IRC in Polymer Science & Technology
UK
Keywords: injection, optimisation, gas
The benefits of the gas assisted injection moulding process are widely accepted by users. As with the conventional injection moulding process, attaining a set of process conditions that consistently produce acceptable quality products can be difficult and generally requires experience and skill from the machine setter. An expert system has been developed here to assist the machine setter eliminate common defects from the product. The system allows part defects to be entered, prompting changes to the process setup by the expert system, via a data link to the machine controller, in order to eliminate the defect.
The system is aimed at any configuration of the gas assisted injection moulding process and strategically breaks down the range of possible configurations into four modes of operation. A process initialisation phase provides a starting point for the setup routines to eliminate the common defects associated with gas assist products; moving the process to a position where good products are manufactured. A process optimisation routine aims to ensure process stability and accuracy. The optimisation routine looks at the natural variation in the process and attempts to relocate the process envelope to avoid intermittent movement outside of the moulding window.
The reasoning behind the system is presented here along with evidence of validation using a multicavity inserted mould tool.