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injection moulding - Coggle Diagram
injection moulding
the process;
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3) the screw carries the melted plastic along & when there's a sufficient charge of polymer at the end of the screw a hydraulic ram forces the screw thread forward injecting the polymer at high pressure into the mould
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6) excess polymer is trimmed off - former or jigs may be used to maintain accuracy while it cools & hardens completely
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often used to make; packaging, toys, casing on electrical products such as computers, TVs & vacuums
these have complex parts- such as integral clip fastenings, screw posts, batter housings & circuit board holders
can make complex pieces & pieces with thin walls because the melted polymer is forced into the mould at high pressure
however - undercuts, variable wall thickness, inserts & threads significantly increase the cost of the tooling
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surface finish depends on quality of steel mould - can be glossy - ejector pins need to be considered because that leave small circles indented circles as well as split lines
