Title: Optimum ejector system design for plastic injection mould

Authors: Z. Wang, K.S. Lee, J.Y.H. Fuh, Z. Li, Y.F. Zhang, A.Y.C. Nee, D.C.H. Yang

Addresses: Department of Mechanical and Production Engineering, National University of Singapore, 10 Kent Ridge Crescent, 119260 Singapore. ' Department of Mechanical and Production Engineering, National University of Singapore, 10 Kent Ridge Crescent, 119260 Singapore. ' Department of Mechanical and Production Engineering, National University of Singapore, 10 Kent Ridge Crescent, 119260 Singapore. ' Department of Mechanical and Production Engineering, National University of Singapore, 10 Kent Ridge Crescent, 119260 Singapore. ' Department of Mechanical and Production Engineering, National University of Singapore, 10 Kent Ridge Crescent, 119260 Singapore. ' Department of Mechanical and Production Engineering, National University of Singapore, 10 Kent Ridge Crescent, 119260 Singapore. ' Department of Mechanical and Production Engineering, National University of Singapore, 10 Kent Ridge Crescent, 119260 Singapore

Abstract: Injection moulding is a technology predominantly used for processing thermoplastic polymers. The injection moulding cycle for thermoplastics consists of several major stages. At the end of the injection cycle the plastic moulded part has to be ejected when the injection mould opens. Since the ejection force from ejector plate is usually large enough for the required releasing force, mould designers usually neglect the balance of the ejection force which is exerted on the sticking surface. Part deformation or damage might occur due to the unbalance ejection force. This paper describes an efficient algorithm for optimising the arrangement and the selection of ejectors. The required releasing/ejection force should be proportional to the area of the sticking surface. Furthermore, a CAD environment has been developed to facilitate the ejector system design. The processes for optimisation and implementation of the algorithm are described in detail, and a case study is presented to illustrate the procedure.

Keywords: ejection force; ejector system design; plastic injection moulding; release force; sticking force; thermoplastics; mould design; CAD.

DOI: 10.1504/IJMPT.1996.036339

International Journal of Materials and Product Technology, 1996 Vol.11 No.5/6, pp.371 - 385

Published online: 02 Nov 2010 *

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