Plastic resin flows better when heated, but is cooled as it travels past the coolant channels surrounding the mold cavity and core. Therefore, an ideal molding temperature must be maintained by controlling the coolant temperature, pressure and flow rate. If practical, the incoming coolant should pass the hottest molding surfaces first, and then pass the cooler mold surfaces.
The illustration presents a cooling circuit for a narrow, shallow, single cavity mold. Parallel coolant channels are drilled through the mold steel, and a tapered pipe thread is tapped on each end, for quick disconnect water line fittings. Heat is removed as the coolant travels through the channel.
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