Thermoforming sandwich heating

Sandwich heating (two-sided heating) n. A method of heating a plastic sheet for thermoforming in which the sheet is positioned between two radiant heaters. 

A variation of thermoforming which does not involve gas pressure or vacuum is matched die forming. The concept is very simple and is illustrated in Fig. 4.53. The plastic sheet is heated as described previously and is then sandwiched between two halves of a mould. Very precise detail can be reproduced using this thermoforming method but the moulds need to be more robust than for the more conventional process involving gas pressure or vacuum. 

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