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Slip gauges areextremely accurate and
precise steel blocks. Slip
gauges are stored in a
box set, and the slips can
be built, using two or
more, to form a widerange of sizes to check
dimensional accuracy or
accuracy of measuring
instruments.
LIP GUAGES (Guage blocks, Johansson gauges, or Jo blocks)
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2
Gauge blocks
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•Slip gauges are often called Johannsen gauges also, as Johannsen
originated them
•
These are rectangular blocks of steel having a cross-section ofabout 30 b !0 mm
• These are "rst hardened to resist #ear and carefull stabilised so
that the are independent of an subse$uent variation in si%e or
shape&
Rectangular slip gauge
' combining gauges select
ed from a suitabl arrangedcombination, almost an dimension ma be built-up&
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The slip gauges are mae !rom high graesteel" cemente carbies (such as tungsten
carbie or tantalum carbie)
$oe%cient o! thermal e&pansion ('' * ') &'+,- per egree $elsius bet.een '+/$ an 0+/$
These are harene throughout an suitabl1heat,treate in orer to stabilise theirimensions or are pro2ie .ith har measuring!aces like carbie !aces
The harness o! the slip gauges are al.a1smore than 3++ 45 (5icker6s P1rami 7umber)
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' These ma1 be use as re!erence stanars
!or trans!erring the imensions o! the unit o!length !rom the primar1 stanar to gaugeblocks o! lo.er accurac1
8 9or the 2eri:cation an grauation o!
measuring apparatus
0 Length measures !or the regulation ana;ustment o! inicating measuringapparatus
uipment such as
micrometers" gap gauges" sine bars" ialinicators .hen use in an ins ection role
USES ?9 SLIP GUAGES
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Slip gauges are classi:e accoring totheir guarantee accurac1
aster slip gauges, accurate to plus or minus t.o micetre
erence purpose,accurate up to plus or minus !our mi
etre
@ !or .orking slip gauges, accurate toplus or minus eight microns per
metre
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Accoring to graes or classes "slip gauges areesigne in :2e graes as uner
Grae 8 This is the #orkshop grade& Tpical usesinclude setting up machine tools, positioning millingcutters and checking mechanical #idths&
Grae ' (sed for more precise #ork, such as thatcarried out in a good-class tool room& Tpical usesinclude setting up sine bars and sine tables, checkinggap gauges and setting dial test indicators to %ero&
Grae + This is more commonl kno#n as the)nspection grade, and its use is con"ned to tool roomor machine shop inspection&
Grae ++ This grade #ould be kept in the Standard*oom and #ould be ke t for #ork of the hi hest
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Bringing
Wringing is the process o! sliing t.o blockstogether so that their !aces lightl1 bon
@ecause o! their ultraCat sur!aces" .hen .rung" gaugeblocks ahere to each other tightl1
0- Johansson gauge blocks .rungtogether easil1 support their o.n.eight
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This is accomplishe b1 pressing the !aces into contact
(keeping them perpenicular) an then imparting a smallt.isting motion .hilst maintaining the contact pressureThe contact pressure is ;ust su%cient in orer to hol thet.o slip gauges in contact an no aitional intentionalpressure
4?B BRI7GI7G IS =?7ED
Phenomenon o! .ringing occurs ue to molecular ahesion
bet.een a li>ui :lm (.hose thickness ma1 be bet.een - to & '+,- mm) an the mating sur!aces
silicone or :ltere kerosene is use aslubricant Appl1 a thin coat o! same an .ipe it asthin as possible
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In metric units" sets o! '+0" -"
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!!
Measurement Ranges
(mm)
Jump
(mm)
No of gauge
blocks
1.0005 1
From 2.001 to 2.009 0.001 9
From 2.01 to 2.49 0.01 49
From 0.5 to 9.5 0.5 19
From 10 to 100 10 10um! "" block
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@asic 9orms o! Slip Gauges
Slip gauges .ith three basic !orms are
commonl1 !oun
!& *ectangular- less epensive to manufacture,applications #here space is restricted , avoidecess #eight
2& S$uare #ithout centre hole 1 epensive, #earlonger and adhere better to each other #hen#rung to high stacks&
3& S$uare #ith centre hole- to permit the use of tierods as an added assurance against the #rungstocks falling apart #hile handling , #ear longerand adhere better to each other #hen #rung tohigh stacks&
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@asic 9orms o! Slip Gauges
Slip gauges #ith three basic forms are commonlfound& These are rectangular, s$uare #ith centre hole, and s$uare #ithout cen*ectangular form is the more #idel used because rectangular blocks are lessmanufacture, and adapt themselves better to applications #here space is restrecess #eightis to be avoided&or certain applications, s$uare slip gauges, though epensive, are preferred&large surface area, the #ear longer and adhere better to each other #hen #rstacks&S$uare blocks #ith centre holes are used to permit the use of tie rods as an adassuranceagainst the #rung stocks falling apart #hile handling& The greatest emphasis in the slip gauges is laid on the t#o gauging surfaces osides of the blocks& The length bet#een measuring surfaces, 4atness and surfaconditions of measuring surfaces are the most important features of slip gauges #hich havecontrolled
Slip gauges are blocks of steel that have been hardened and stabili%edb heat treatment& The are ground and lapped to si%e to ver highstandards of accurac and surface "nish& The are the most accuratestandards of length available for use in #orkshops&