Inch Tolerances
ANSI Standard Limits and Fits
The following fit types and classes are in accordance with the ANSI B4.1-1967 (R1994) standard.
RC: Running or Sliding Clearance fit.
- Intended to provide running performance with suitable lubrication.
- RC9 (loosest) – RC1 (tightest)
Locational fits (LC, LT, LN).
- Locational fits are intended to determine only the location of the mating parts.
- LC = Locational clearance fits
- LT = Locational transition fits
- LN = Locational interference fits
FN: Force Fits.
- Force fits provide a constant bore pressure throughout the range of sizes.
- FN1 – FN5 (tightest)