Which of the following is not considered a type of mandrel?

A mandrel is a tool used to shape or support workpieces during machining or forming processes. The types of mandrels are categorized primarily by how they function or interact with the workpiece.

An expanded mandrel is designed to expand against the inside surface of a workpiece, which allows for gripping and stabilization as the workpiece is machined. On the other hand, a taper mandrel provides support by utilizing a tapered shape to fit tightly against a hole or internal surface, which keeps the workpiece securely in place.

An extended mandrel is typically used when a longer reach is necessary, allowing the support or shaping to occur deeper inside a hollow workpiece without obstructing access.

Contrasting with these established types, a contraction mandrel is not recognized as a standard type of mandrel in machining terminology. The term suggests a method of gripping that does not align with the commonly accepted mechanics of expanding, supporting, or tapering. Therefore, identifying contraction as not being a recognized type solidifies the understanding of various mandrel functions in machining processes.