Which mechanism is commonly used for indexing in machine tools?

The dividing head is a commonly used mechanism for indexing in machine tools because it allows precise positioning of a workpiece for operations such as milling, drilling, or shaping. It is specifically designed to divide a circle into equal parts, which is a crucial requirement in machining processes where accurate angular movement is needed.

A dividing head typically features a set of gears that facilitate the controlled rotation of the workpiece. By selecting the proper gear ratios, operators can achieve the desired division of angles, enabling them to create features like slots, holes, or notches at precise intervals. This functionality is paramount in applications where uniform spacing is essential, such as in creating gears or circular patterns.

The other mechanisms, such as a universal chuck, are primarily intended for holding and rotating the workpiece but do not provide the same level of indexing precision. A slotter is a machine tool used for producing slots or grooves, and while it may involve indexing, it does not serve as the dedicated indexing mechanism that a dividing head does. The term "indexing" simply refers to the process and is not a specific mechanism. Thus, the dividing head stands out as the most suitable choice for indexing tasks in machine tools.