Generally, CNC machine drawings are dimensioned according to the method of machining and assembly precision requirements to find the appropriate level of IT tolerance. Tolerance of CNC machining means the acceptable dimensions range which is determined by the engineer according to the function, fit, and shape. In the context of CNC machines, tolerance is the dimensional accuracy degree a machine can achieve when machining a part. The tolerance depends on the CNC machining parts. There are some services like CNC machining service China offers online parts of CNC machining to enhance accuracy and tolerance. The following are the ways that influence tolerance on CNC machining.


It is very important to determine which material in the CNC machine to use for machining when tolerance requirements are tight. Relatively, aluminum is soft compared to alloys and steel materials. It is not easy to control for tight tolerances. Correspondingly, POM, and nylon materials are also very difficult to control the tight tolerance as compared to metals.

The technique of manufacturing:

Tight tolerance needs the department of production to debug the machine continuously and test the process of production while processing. For instance, a simple hole drilling can be converted to CNC milling as it’s more rigorous than standard tolerances.


The more your effort is required to invest, the more you get an elaborated product. Due to tight tolerance, the trial and error cost, cost of labor and time are increased. If the parts of CNC machining are costly, it means they work efficiently and accurately, which makes the tolerance better. Moreover, when you invest costly programs in CNC machines, to tolerance also increased.

Tips for tolerance:

  • The process of adding tolerance to the dimension of CNC machining, you need to focus on a few tips:
  • Tolerance is important to CNC machining design. To save time and cost of machining, apply only tolerance to some features like mater or interfere with CNC machining other parts.
  • You need to avoid unnecessarily tight tolerances. They often cause increased scrap production, additional fixture, special measurement tools, and longer cycles.