scope:

This standard covers the American National Standard practice for Die Buttons, Variable, Press Fit, Step Relief, including dimensions, tolerances, nomenclature and sizes. These die buttons are classed as extra precision. Two types are covered; Headless and Head-type, Round Hole only. For Shaped Hole die buttons, refer to ANSI B94.30

Headless die buttons are intended for press fit mounting in the retainer or die block. Head-type die buttons may be press fit or slip fit mounted in which case they are retained in the die block by shoulder action. The head also increases bearing area during piercing.