Study of ejection forces in the AIM™ process

The AIM™ process has been used to successfully produce short runs of injection moulded parts. One of the main drawbacks of the process is the tendency of the tools to be damaged during part ejection1. At De Montfort University a successful AIM™ moulding cycle has been developed in which simple shapes from polypropylene are produced and the ejection forces required are measured. Two different ejection methods are used; one uses conventional ejector pins and the other uses a conformal ejector pad. The tool surface roughness is measured before and after moulding to observe any changes caused by ejection. Results show that ejector pins require a lower ejection force than a conformal ejector pad and this may contribute to longer tool life for the AIM™ process. Possible reasons for the results are discussed along with recommendations for further work.