ISO Hole and Shaft tolerances/limits

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

ISO Tolerance Band T (3-315mm size)	ISO Shaft limit nearest Zero (3-500mm shaft size)	ISO Hole Nearest limit nearest Zero (0-500mm hole size)
ISO Tolerance Band T (315-3150mm size)	ISO Shaft limit nearest Zero (500-3150mm shaft size)	ISO Hole Nearest limit nearest Zero (500-3150mm hole size)

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

ISO Hole Limits (3-400mm Hole Size)	ISO Shaft Tolerance(3-400mm Hole Size)
ISO Hole Limits (400-3150mm Hole Size)	ISO Shaft Tolerance(400-3150 mm Hole Size)

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

ISO Hole and Shaft tolerances/limits

Relevant Standards

Notes

Hole and Shaft tolerance tables- Using Fundamental Deviations and Tolerance Band T

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