Scaling Issues in Miniaturization of Injection Molded Parts

Miniaturization of injection molded parts causes changes in the relative contribution of relevant design and process parameters. As a result, scaling-related size effects occur. Size effects can be either of the first order or of the second order. First-order size effects can be predicted using standard modeling, while second order ones cannot. This paper deals with first-order size effects encountered in injection molding miniaturized parts. Through the scaling analysis of the heat transfer and flow process in injection molding, the size effects on the change of molding characteristics including viscous heating, freezing time, capillary force effect, and moldability were identified. Strategies were consequently proposed to alleviate or eliminate the scaling-related molding difficulties in molding ultrathin-wall parts and microparts. Particularly, a scalable filling process was presented, with experimental verification.

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