LIMITS, FITS AND TOLERANCES

LIMITS, FITS AND TOLERANCES

Preferred tolerances and fits for hole and shaft basis systems which are given in ISO 286-1 (2010) and ANSI B4.2-1978

standards are summarized in the following tables. The usage of these tolerances is advised for economic reasons.

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Preferred fits table (ANSI B4.2-1978)

ISO SYMBOL
HOLE BASIS SHAFT BASIS DESCRIPTION
CLEARANCE FITS H11/c11 C11/h11 Loose running fit for wide commercial tolerances or allowances on external members.
H9/d9 D9/h9 Free running fit not for use where accuracy is essential, but good for large
temperature variations, high running speeds, or heavy journal pressures.
H8/f7 F8/h7 Close running fit for running on accurate machines and for accurate location at
moderate speeds and journal pressures.
H7/g6 G7/h6 Sliding fit not intended to run freely, but to move and turn freely and locate
accurately.
H7/h6 H7/h6 Locational clearance fit provides snug fit for locating stationary parts; but can
be freely assembled and disassembled.
TRANSITION FITS H7/k6 K7/h6 Locational transition fit for accurate location, a comprimise between clearance
and interference.
H7/n6 N7/h6 Locational transition fit for more accurate location where greater interference
is permissible.
INTERFERENCE FITS H7/p6 P7/h6 Locational interference fit for parts requiring rigidity and allignment with prime
accuracy of location but without special bore pressure requirements.
H7/s6 S7/h6 Medium drive fit for ordinary steel parts or shrink fits on light sections, the
tightest fit usable with cast iron.
H7/u6 U7/h6 Force fit suitable for parts which can be highly stressed or for shrink fits where
the heavy pressing forces required are impractical.
PRACTICAL USE OF INTERNATIONAL TOLERANCE GRADES
  FOR MEASURING TOOLS FOR MATERIAL    
IT GRADES 01 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
    FOR FITS FOR LARGE MANUFACTURING TOLERANCES

Preferable fits of the hole-basis system (ISO 286-1:2010)

BASIC
HOLE
TOLERANCE CLASSES FOR SHAFTS
CLEARANCE FITS TRANSITION FITS INTERFERENCE FITS
H6           g5 h5 js5 k5 m5   n5 p5          
H7         f6 g6 h6 js6 k6 m6 n6 p6 r6 s6 t6 u6 x6
H8 e7 f7 h7 js7 k7 m7 s7 u7
d8 e8 f8 h8
H9 d8 e8 f8 h8
H10 b9 c9 d9 e9 h9
H11 b11 c11 d10 h10

Preferable fits of the shaft-basis system (ISO 286-1:2010)

BASIC
SHAFT
TOLERANCE CLASSES FOR HOLES
CLEARANCE FITS TRANSITION FITS INTERFERENCE FITS
h5 G6 H6 JS6 K6 M6 N6 P6
h6 F7 G7 H7 JS7 K7 M7 N7 P7 R7 S7 T7 U7 X7
h7 E8 F8 H8
h8 D9 E9 F9 H9
h9 E8 F8 H8
D9 E9 F9 H9
B11 C10 D10 H10

 

Note: For economic reasons, the first choice for a fit should, whenever possible, be made from the tolerance classes shown with grey color.