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Composite Mould manufacturing. Project 3 sacrificial mold. Concept. When a mold is made with a negative curvature , the lamina can not be removed . A lamina is shrinking when resin curing , this for small mold aspect ratio may lead to clamping of the lamina to the mold .
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Composite Mouldmanufacturing Project 3 sacrificialmold
Concept • When a mold is madewith a negative curvature, the laminacan not be removed. • A lamina is shrinkingwhenresincuring, this for small moldaspectratiomayleadtoclampingof the laminato the mold. • The mold is removed from the laminaratherthanotherwayaround. Materials that mak suchpossible is wax, salts and some special metals.
Example: Winding tube • If the mold is thicker in the center of the laminathan at the endsthe laminacan not be removed from a ridigmold. • Consider and mold for the moldsuchthat the mold (core) is actuallycastedofsome material. The resultingmold (core) is used in a winding process and as the lamina is cured ready removed from the lamina by melting/disolving it.
Material for sacrificialmolds • Lead, rosemetal • Wax and wax on metal • Salt on metal
Semi expandingmolds • Silicon expands 8% at dT=100K. Thiscan be usedtosimplifydemolding
Design task • Design a casting moldthat is 30cm long, and at least 20mm in diameter at the smallest position. • The moldcontains at least ONE thickersection at the center of the moldthatwould make demoldingimposibble • The designed mold is tofunctionsuchthat a metalrod is placed inside the old and thancastedoutusingwax or rosemetal. Afterlamination (winding) the rod is heatedsuchthat the wax och rosemetalmelts and the rodcan be removed from the lamina.