Quality5 min read
What Does ±0.003 mm Tolerance Mean in CNC Machining?
Tolerances determine both the function and the cost of your components. This guide explains IT grades, fits and when ±0.003 mm is really necessary — for buyers and design engineers.
A
Ana Kovač
Leiterin Qualität / Vodja kakovosti·8 March 2025
A tolerance defines the allowable deviation band from a nominal dimension. In CNC machining, ±0.003 mm means the finished part may be at most 3 micrometres smaller or larger than the drawing dimension. For reference: a human hair is about 70 µm thick — ±0.003 mm is one twentieth of that.
- IT5–IT6: Bearing and precision fits
- IT7–IT8: Standard engineering applications
- ±0.003 mm: Achievable with our 5-axis centres
- 100%: CMM inspection of critical features
