Fluid injection technique – a comparison between gas-assisted injection moulding (GAIM) and water injection technique (WIT)

摘要

Increasing cost pressure and the steadily growing demands on plastics products lead to the use of innovative production technologies such as the fluid injection technique (FIT). Amongst others, the FIT comprises the wellknown and established gas-assisted injection moulding (GAIM) and the innovative water injection technique (WIT). WIT has been developed at the IKV in Aachen since late 1998. The main objective of the research work was the reduction of cooling times in the production of hollow elongated articles (handles, armrests, media ducts etc.) and moulded parts with integrated thick-walled sections respectively. The hollow space inside the plastics melt is produced by means of water (inexpensive, available everywhere, re-usable, good cooling effect), without the process medium vaporising during melt displacement. The considerably more efficient cooling effect of water means that cooling times can be reduced by up to 70 % compared to gas-assisted injection moulding. By applying WIT, it is generally possible to achieve larger part dimensions. Compared to GAIM, lower residual wall thicknesses, better concentricity of the hollow section and smoother inner surfaces can be achieved when suitable materials are processed.