Example designation
STI M2 x 0.4-4H5H
- STI
- Internal thread prepared to receive a screw-thread insert.
- M2 x 0.4
- Nominal screw diameter of 2 mm and pitch of 0.4 mm.
- 4H5H
- Selected internal insert-tapping tolerance designation.
Prepare the housing thread
Use the STI pitch- and minor-diameter limits for the hole before installing the insert. The nominal M size identifies the screw the insert accepts; it is not the tapped housing diameter.
Two catalog fit choices
The supported metric catalog offers 5H and 4H5H insert-tapping fits. Choose the one required by the insert specification. The internal major-diameter upper value is shown as a reference.
Keep the process with the drill size
Select cut or form tapping before choosing a drill. The target depends on that process and the selected thread percentage, so retain both when recording the hole preparation.