D# is for Diameter Offset of a Tool
G40/G41/G42 – Cutter Diameter Compensation (CDC)
CDC is a key to precision CNC machining, allowing the operator to compensate for tool wear and deflection by commanding the machine to veer left (G41) or right (G42) from the programmed path.
The amount of offset is entered in a CNC control D-register. The wear register can be thought of like a table that the control refers to with every move.
Table 1: Diameter Offset Register
|
Tool Diameter Offset |
Value |
|
D1 |
0.0125 |
|
D2 |
0.0000 |
|
D3 |
0.0000 |
|
D4 |
0.0000 |
|
D5 |
0.0000 |
|
D6 |
0.0000 |
The value in the D-register is calculated by the machine tool operator, who monitors the finished size of part features, compares them with the print, and enters the difference in the register as needed to keep the part within specifications. If there is no difference, the register is set to zero.
For example: G01 G41 D1 X1.0 Y.25 F40. Refer to the wear registry above.
In this example, Tool #1 can be identified because of the D#. This means that Tool 1 has an offset (it has wear) of 0.0125.
G40 cancels cutter compensation.
Questions
Adapted from “CNC Language and Structure “ by LamNgeun Virasak, Manufacturing Processes 4-5 is licensed under CC BY-SA 4.0