Hinge

Since many different plastics are flexible (Chapter 1) they are used to manufacture hinges. They can operate in different environments. Based on the plastic used they can meet a variety of load performance requirements. Land length to thickness ratio is usually at least 3 to 1.

Hinges can be fabricated by using different processes such as injection molding, blow molding, compression molding, and cold worked. So called "living hinges" use the TP's molecular orientation to provide the bending action in the plastic hinge. With proper mold design (proper melt flow direction, eliminate weld line, etc.) and process control fabricating procedures these integral hinge moldings operate efficiendy.

Otherwise problems in service immediately or shordy after initial use delamination occurs. Immediate post-mold flexing while it is still hot is usually required to ensure its proper operation.

Hinges depend not only on processing technique but using the proper dimensions based on the type plastic used. Dimensions can differ if the hinge is to move 45° to 180°. If the web land length is too short for the 180° it will self-destruct due to excessive loads on the plastic's land.

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