An Index Plate is a precision component used in dividing heads, rotary tables, or other indexing devices to position a workpiece at accurate, repeatable angular intervals during machining, inspection, or assembly.

To divide a circle into equal parts for operations like drilling, milling gear teeth, splines, or slots. To control angular positioning of a workpiece with high accuracy. To enable both simple indexing (equal divisions) and differential indexing (more complex divisions).