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INSPECTION AND

MEASUREMENT OF TOOTH

THICKNESSRAJEEV U Prajeevullatt@gmail.com

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GEAR MEASUREMENT

Gears are the devices meant for powertransmission.or proper wor!ing the gears should "e measuredand inspected in each steps as#

Raw materials. $achining the "lan!s. %eat treatment.&he cutting and 'nishing operations.

&he accurac( depends on#

&he measuring e)uipment availa"le. Errors in the tooth surface 'nish

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GEAR INSPECTION

*nspecting the dimensions and the surfacefor getting a designed thread.

&wo t(pes Anal(tical# slow process which chec! all

individual elements. +ess preferred

unctional# carr(ing out running test

with master and deciding. $uchpreferred

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MEASUREMENT OF TOOTH

THICKNESS ,e'ned as the length of an arc- which is dicult to

measure directl(.

&his is the most important measurement a gear shouldundergo.

&he tooth thic!ness is generall( measured at pitchcircle and is therefore- the pitch line thic!ness of tooth.

Gear tooth thic!ness varies from the tip of the "asecircle of the tooth-

&he instrument must "e capa"le of measuring thetooth thic!ness at a speci'ed position on the tooth.

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METHODS FOR MEASUREMENT

1. GEAR TOOTH VERNIER CALLIPER.

2. CONSTANT CHORD METHOD.

3. BASE TANGENTIAL METHOD.

4. BY DIMENSION OVER PINS.

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MEASUREMENT BY GEAR TOOTH VERNIER

CALLIPER *t/s ver( convenientl( measured "( a gear tooth vernier

caliper.

&he gear tooth vernier has two vernier scales and the( are

set for the width 0w1 of the tooth and the depth 0d1 fromthe top.

Each of which is adjusted independentl( "( adjustingscrew on graduated "ars.

*t measures the tooth thic!ness at the pitch line.

*t can also measure chordal addendum- the distance fromtop to chord.

2nl( used to verif( the theoretical measurements.

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GEAR TOOTH VERNIER CALLIPER

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*n 'g.

w3A435A,

6A2,373 - 8here 9 is the no.of teeth

w35A,35:A2.sin 735R.

$odule m335R;9

&herefore

R39.m;5

w3539.m.

Also d32m309m;51>m

And 2,3R3

&herefore

d3

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&his method is simple and ine7pensive.

%owever it needs di?erent setting for a variation in num"erof teeth for a given pitch.

Accurac( is limited "( the least count of instrument.

&he wear during use is concentrated on the two jaws.

&he calliper has to "e cali"rated at regular intervals tomaintain the accurac( of measurement.

ADVANTAGES AND LIMITATIONS

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CONSTANT CHORD METHOD

,e'ned as &he chord joining those points- on opposite faces of

tooth- which ma!e contact with the mating teeth when thecenterline of the tooth lies on the line of the gear centers.

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ADVANTAGES

or all num"er of teeth value of constant chord issame.

*t readil( lends itself to a form of comparator whichmore sensitive than the gear tooth vernier

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