Page 190 - Threading_Handbook

3.9 Entering the Workpiece
THREAD MILLING A sudden load is applied to the cutter when it enters the workpiece and as a result the

cutter may be broken, or a mark will remain. If entering is smooth, then the load on the tool
will increase gradually and the surface will remain “clean”. There are three ways to initially
enter the workpiece: radial entering, tangential entering by arc, tangential entering by line.

Radial Entering
The cutter enters the workpiece in a straight line to the center workpiece axis.
This is the simplest method, but also the least recommended, because the angle of the
hugging is too large.

Internal Threading

DW DC 1 2
4 3

External Threading

DW 2 1
3 4
DC

DW - Workpiece diameter
DC - Cutter Diameter
1-2: Straight line entry
2-3: Helical movement during one full orbit (360°)
3-4: Straight line exit

190 ISCAR