# ISO Hole and Shaft tolerances & limits

### Index of ISO Hole and Shaft tolerances/limits pages

Relevant Standards
BS EN 20286-1:1993(ISO 286-1:1988 )...... ISO system of limits and fits. Bases of tolerances, deviations and fits
BS EN 20286-2 : 1993(ISO 286-2:1988 ).... ISO system of limits and fits. Tables of standard tolerance grades and limit deviations for holes and shafts

Notes

The tolerance of size is normally defined as the difference between the upper and lower dimensions.

The need for tolerances to be identified on drawings is vital to allow assembly of parts in the desired way and interchangeability of parts as required in modern manufacturing methods.

ISO 286 implements 20 grades of accuracy to satisfy the requirements of different industries.

• IT01,   IT0,   IT1,   IT2,   IT3,   IT4,  IT5,  IT6.. Production of gauges and instruments.
• IT 5,   IT6,   IT7,  IT8,  IT9,  IT10,  IT11,  IT12...Precision and general Industry.
• IT11,   IT14,   IT15,   IT16..Semi finished products
• IT16,   IT17,  IT18 ..Structural Engineering
Hole and Shaft tolerance tables- Using Fundamental Deviations and Tolerance Band T

Examples in using above tables..

Note: The tolerance band T is an absolute length value it does not have a negative value.

Hole Dia 110mm H11,...
Nearest zero ( El )= 110mm + 0mm = 110,000mm ...
Furthest from zero ( ES )= 110mm + (0+ T=0,220)=110,220mm
Resulting limits 110,000/110,220

Shaft 110mm e9...
Nearest zero ( es ) = 110mm - 0,072=109,928mm...
Furthest from zero ( ei ) = 110mm - (0,072 + T=0,087) = 109,841mm
Resulting limits 109,928/109,841

Note for the tolerance bands which can be either side of zero, (J,K,N,j )
The diagrams provided with the table clearly show calculation needed.e.g. consider Hole 300K7.

T= 52 micrometres (0,052mm). Limit nearest zero ( K ) ES = 16 micrometres = (0,016mm)
Limit furthest from zero ( K ) El = (0,016- 0,052)= -0,036
Limits therefore (300 -0,036) = 299,964..and ...300+0,016= 300,016
limits 299,964/300,016

Hole and Shaft Tolerances to ISO 286-2

Example limits and fits using hole basis
 Description Hole Shaft Loose Running H11 c11 Free Running H9 d9 Loose Running H11 c11 Easy Running - Good quality easy to do- H8 f8 Sliding H7 g6 Close Clearance - Spigots and locations H8 f7 Location/Clearance H7 h6 Location- slight interference H7 k6 Location/Transition H7 n6 Location/Interference- Press fit which can be separated H7 p6 Medium Drive H7 s6 Force H7 u6

Machining Process associated with ISO IT Tolerance Grade..

 IT Grade 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Lapping Honing Superfinishing Cylinderical grinding Diamond turning Plan grinding Broaching Reaming Boring, Turning Sawing Milling Planing, Shaping Extruding Cold Rolling, Drawing Drilling Die Casting Forging Sand Casting Hot rolling, Flame cutting