Glossary · CNC and machine tools
Tool offset
Also known as: Tool compensation, Tool length offset, Tool radius compensation
German: Werkzeugkorrektur
In CNC machining, a tool offset is a stored correction value for the dimensions of a tool, such as its length, radius or wear, that the control applies so the programmed path yields the correct part dimensions.
- CNC
In one sentence
A tool offset stores a tool's length, radius or wear correction so the CNC can machine correct dimensions with different or worn tools.
Example
After measuring the new drill with the tool presetter, the setter enters its length of 142.35 mm in tool offset register 7.
How it applies
- Setup: Tool lengths and radii are measured on a presetter or in the machine with a probe and entered in the offset table. The program calls the tool and its offset register.
- Operation: Operators adjust wear offsets to compensate Tool wear or small dimensional deviations without editing the program. Wrong entries can cause collisions or scrap, so offset changes need care.
- Quality: The measuring devices used to determine offsets should be calibrated, which supports Measurement traceability.
- Documentation: Setup instructions should state the offset register, sign convention and units, and where operators may adjust wear offsets within defined limits. Describe these limits as values, not as 'small corrections'.
Tool offset vs. work offset
A tool offset corrects for the tool's dimensions. A Work offset shifts the zero point to the workpiece. Both are needed for correct dimensions, and confusing their registers is a common setup error.