Page 276 - Mold Bases & Plates 2020

Technical Reference
283

Tables for Determining Metric Tolerances

Table 1: description of preferred fits

Table 1 is pulled from the ANSI metric tolerances section of the machinists’ handbook, which conforms to the ISO and DIN
tolerances for hole basis and shaft basis fits. Table 1 provides an overview of the hole basis and shaft basis fits that make up
clearance fit, transition fit and interference fit combinations.

iso symbol
hole basis shafT basis
h11/c11 c11/h11 lOOse rUnnInG FIt FOr WIDe cOMMercIAl tOlerAnces Or
AllOWAnces On eXternAl MeMbers.
nOt FOr Use Where AccUrAcy Is essentIAl,
h9/d9 D9/h9 Free rUnnInG FIt bUt GOOD FOr lArGe teMperAtUre VArIA-
tIOns, hIGh rUnnInG speeDs, Or heAVy
jOUrnAl pressUres.
cleArAnce FOr rUnnInG On AccUrAte MAchInes
FIts h8/f7 F8/h7 clOse rUnnInG FIt AnD FOr AccUrAte lOcAtIOn At MODerAte
speeDs AnD jOUrnAl pressUres.
nOt IntenDeD tO rUn Freely, bUt tO MOVe
h7/g6 G7/h6 slIDInG FIt AnD tUrn Freely AnD lOcAte AccUrAtely.
prOVIDes snUG FIt FOr lOcAtInG stAtIOn-
h7/h6 h7/h6 lOcAtIOnAl cleArAnce FIt Ary pArts; bUt cAn be Freely AsseMbleD
AnD DIsAsseMbleD.
h7/k6 k7/h6 lOcAtIOnAl trAnsItIOn FIt FOr AccUrAte lOcAtIOn, A cOMprOMIse
trAnsItIOn betWeen cleArAnce AnD InterFerence.
FIts FOr MOre AccUrAte lOcAtIOn Where
h7/n6 n7/h6 lOcAtIOnAl trAnsItIOn FIt
GreAter InterFerence Is perMIssIble.
FOr pArts reqUIrInG rIGIDIty AnD AlIGn- Technical Reference | Tables for Determining Metric Tolerances
Ment WIth prIMe AccUrAcy OF lOcAtIOn
h7/p6* p7/h6 lOcAtIOnAl InterFerence FIt
bUt WIthOUt specIAl bOre pressUre
reqUIreMents.
FOr OrDInAry steel pArts Or shrInk
InterFerence h7/s6 s7/h6 MeDIUM DrIVe FIt FIts On lIGht sectIOns, the tIGhtest FIt
FIts UsAble WIth cAst IrOn.
sUItAble FOr pArts WhIch cAn be hIGhly
stresseD Or FOr shrInk FIts Where the
h7/u6 U7/h6 FOrce FIt heAVy pressInG FOrces reqUIreD Are
IMprActIcAl.
excerpt from Machinists’ Handbook, pg. 661, 25 ed., Industrial press.
*the h7/p6 hole basis fit is a transition fit for basic sizes in ranges from 0 through 3mm.

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