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2.3 MECHANICAL ENGINEERING
Demoulding parts from replication tools is a critical stage of replication processes such as injection moulding and hot embossing. This challenge increases as part size decreases since components and associated replication cores become more fragile and liable to damage. Understanding interfacial characteristics between a polymer and the tool surface is critical to optimise the demoulding of such parts from replication tools. The strength of the polymer-tool interaction is characterised by the adhesion energy and is specific for a particular polymer-tool pair. It’s magnitude depends upon the tool material, the chemical structure of the polymer, the processing conditions and the surface roughness.
Interfacial characteristics of a variety of polymer-tool steel surfaces are being studied by measuring contact angles of polymer droplets on the surfaces to predict the work of adhesion. The experimental set-up, selection of test parameters and main challenges faced to date are described and preliminary experimental results presented. In addition a description of how these results may be used to predict the force needed to demould parts from replication tools is discussed.
Delaney, K., Kennedy, D., Bissacco, G.: Investigating Polymer-Tool Steel Interfaces to Predict the Work of Adhesion for Demoulding Force Optimisation. MTSM 2011. Split, 29-30 September, 2011.