AiVibeDimensional Tolerance
A dimensional tolerance is the permitted variation of a size, the difference between its upper and lower limits. It tells manufacturing and inspection how far a dimension may deviate from nominal and still be acceptable.
Tolerances can be bilateral, such as 25.00 plus or minus 0.05 mm, unilateral, with all variation on one side, or given as limit dimensions. ISO 286-1 defines standard tolerance grades from IT01 to IT18, with tolerance width depending on grade and nominal size, and general tolerance standards such as ISO 2768-1 apply default limits to dimensions without an individual tolerance.
Tolerances are set to ensure function and interchangeability, for example so that a shaft fits a bearing or parts from different suppliers assemble. Tighter tolerances usually require more capable machines, slower processes, controlled environments and more inspection, so designers balance function against cost. Tolerance stack-up analysis checks how individual tolerances combine in an assembly.
Conformance must account for measurement uncertainty; ISO 14253-1 sets decision rules for proving conformity or nonconformity with specifications. Dimensions are defined at the standard reference temperature of 20 degrees Celsius set in ISO 1, so thermal expansion matters for tight tolerances. Size tolerances alone do not control form, orientation or location, which is why geometric tolerancing is used alongside them.
Key points
- The permitted range between upper and lower limits of a size
- ISO 286-1 defines tolerance grades IT01 to IT18
- ISO 2768-1 provides general tolerances for untoleranced dimensions
- Measurement uncertainty and the 20 degrees Celsius reference temperature matter
Where AiVibe comes in
AiVibe designs and manufactures the AiAmbA AI Factory: edge devices plus AI agents that let people talk to CNC, PLC and robot controllers in plain language. Agents only propose changes, and a trained operator confirms each one.
Related terms
- Limits and Fits (ISO 286)CNC & Precision Machining
- Geometric Dimensioning and Tolerancing (GD&T)CNC & Precision Machining
- Coordinate Measuring Machine (CMM)CNC & Precision Machining
- Surface Roughness (Ra, Rz)CNC & Precision Machining
- Statistical Process Control (SPC)Industry 4.0 & Manufacturing Operations