11/1/2014 Hole And Shaft Basis Limits and Fits,Hole Limits And Fits,Hole And Shaft,Tolerance,

http://www.cobanengineering.com/Tolerances/ISOHoleandShaftBAsisLimitsAndFits.asp 1/2

Hole And Shaft Basis Limits And Fits

Hole basis limits and fits with Shaft basis limits and fits have been given as an example in the chart below.The definitions for descriptions given in the chart explained as follows. The chart below gives simpleunderstanding of Hole Basis Limits and Shaft Basis Limits. Some of the application and some of the selectedPreferred Fits for Hole and Shaft Basis system have been given followed by Fits explanations.

More Clearance (Close to Top of The Chart)

More Interference(Close to Bottom of TheChart)

ClearanceFits

Description HoleBasis

ShaftBasis

Free Running H9/d9 D9/h9Loose Running H11/c11 C11/h11Easy Running H8/f8 F8/h8Sliding H7/g6 G7/h6Close Clearance H8/f7 F8/h7Locational Clearance H7/h6 H6/h7

TransitionFits

Location- slightinterference

H7/k6 K7/h7

Location/Transition H7/n6 N7/h6InterferenceFits

Location/Interference H7/p6 P7/h6Medium Drive Fit H7/s6 S7/h6Force Fit H7/u6 U7/h6

Free Running; This type of tolerance can be usable where any special requirements for accuracy in notessential, but good for wide temperature variation, heavy journal pressures and high running speeds.Some of the applications: Multiple fits of shafts of production and piston machines, parts rotating very rarelyor only swinging.. Some of the selected Preferred fits: H9/d9, D9/h9, H9/C9, H9/d10, D9/h8, H8/d9, H8/d8, D10/h9,

Loose Running; Fits For wide commercial tolerances/clearances or allowances with parts on externalmembers.Some of the applications: Fits of parts exposed to corrosive effects, pivots, latches, contamination with dustand thermal or mechanical deformations.Some of the selected Preferred fits: H11/c11, H11/a11, C11/h11, H11/c9, D11/h11, H11/d11, A11/h11,

Easy Running; This is tuning fits with smaller clearances with general requirements for fit accuracy.Some of the applications: Main fits of machine tools. General fits of shafts, regulator bearings, machine toolspindles, sliding rods. Some of the selected Preferred fits: H8/f8, H9/f8, F8/h6, F8/h7, H8/f7, H7/f7,

Sliding/Running Fit; This fit does not provide freely running. This running/sliding tolerance fits with very smallclearances for accurate guiding of shafts. This kind of tolerance helps the parts to move and turn freely andlocate accurately.Some of the applications: sliding gears and clutch disks, parts of machine tools, pistons of hydraulicmachines, rods sliding in bearings, grinding machine spindles, crankshaft journals.Some of the selected Preferred fits: H7/g6, H8/g7, G7/h6,

Close Clearance ( Spigots and Locations);This fit is for accurate location at moderate speeds and journalpressures, and running on accurate machine parts. Running fits with smaller clearances with generalrequirements for fit accuracy. Some of the applications: General fits of shafts, machine tool spindles, main fits of machine tools, regulatorbearings, sliding rods.Some of the selected Preferred fits: H8/f7, F8/h7, F8/h6, H9/f8, H8/f8, H7/f7,

Locational Clearance; For locating stationary parts, it provides snug fit. It provides freely assemble anddisassemble. This fit helps for precise guiding and centering of parts and mounting by sliding on without useof any great force, after lubrication the parts can be turned and slid by hand. Some of the applications: Roller guides. precise guiding of machines and preparations, exchangeablewheels.

11/1/2014 Hole And Shaft Basis Limits and Fits,Hole Limits And Fits,Hole And Shaft,Tolerance,

http://www.cobanengineering.com/Tolerances/ISOHoleandShaftBAsisLimitsAndFits.asp 2/2

Some of the selected Preferred fits: H7/h6, H8/h7, H8/h9, H8/h8,

Location- slight interference; This type of fit compromise between interference and clearance for accuratelocation. With this fit, the parts can be assemble or disassemble without great force using a rubber mallet.Some of the applications: Clutches, demountable fits of hubs of gears and pulleys, manual wheels, brakedisks.Some of the selected Preferred fits: H7/k6, H8/k7, K7/h6, K8/h7,

Location/Transition; This fit for accurate location where greater interference permissible. It is fixed fits withsmall interferences or negligible clearances. Mounting of fits using pressing and light force.Some of the applications: Armatures of electric motors on shafts, gear rims, fixed plugs, driven bushings,flushed bolts.Some of the selected Preferred fits: H7/n6, H8/n7, H8/p7, H7/m6, H8/m7, M8/h6, N7/h6, N8/h7,

Location/Interference; This type of fit where the assembled parts requiring rigidity and great alignment withprime accuracy of location. Press fit which can be separated, pressed fits with guaranteed interference.Assembly of the parts can be carried out using cold pressing.Some of the applications: Bearing bushings, Hubs of clutch disks.Some of the selected Preferred fits: H7/p6, H7/r6, H8/r7, P7/h6, R7/h6,

Medium Drive Fit This fit for shrink fit on light section or ordinary steel parts. Pressed fits with mediuminterference, assembly of parts using hot pressing, assembly using cold pressing only with use of large forces.the tightest tolerance usable for cast iron.Some of the applications: Permanent coupling of gears with shafts, bearing bushings. Some of the selected Preferred fits: H7/s6, H8/s7, H7/t6, H8/t7, S7/h6, T7/h6,

Force Fit; This fit suitable for parts which can be highly stressed. Pressed fits with big interferences,assembly using pressing and great forces under different temperatures of the parts. This fit for shrink fitswhere the heavy pressing forces required are impractical.Some of the applications: Permanent couplings of gears with shafts, flanges.Some of the selected Preferred fits: H7/u6, H8/u7, H8/u8, H8/x8, U7/h6, U8/h7,