4M Knowledge base - papers

W. Michaeli, T. Kamps
Institute of Plastics Processing at RWTH Aachen University, 52056 Aachen, Germany

Abstract

Micro injection moulding is established as one of the most common manufacturing processes for thermoplastic polymers due to its high degree of automation and the short cycle times. With micro assembly injection moulding, offline joining process steps can be avoided by overmoulding components of the micro system directly in the injection mould. Overmoulding can be used to generate movable or fixed combinations of different materials. One of the materials combined in a hybrid micro system is thermoplastic polymers, whereas the other one can be selected from a wide range of materials, e.g. technical ceramics, glass, or metals. Micro assembly injection moulding provides several advantages compared to other joining processes. However, functional integrity of the micro system is an end requirement. In the case of a joint micro structure, the bonding strength between two components affects the stability of the whole micro system and is thus important for the part’s quality. As tests conducted at IKV show, a plasma treatment (plasma activation) of the insert parts significantly increases the bonding strength. Inserts of metal and glass have been overmoulded with several polymers, and the influence of different plasma gases and duration of the treatment on the feasible bonding strength is shown.