metrology laboratory manualoss.nri.edu.in/...3-1/...3-1-metrology-lab-manual.pdf · metrology...

DEPARTMENT OF MECHANICAL ENGINEERING NRIH

S PRAVEEN KUMAR Assistant Professor

METROLOGY LABORATORY

MANUAL

iii-b.tECh i-sem-mechanical &

iv-b.tech i-sem-automobile

Prepared By:

S PRAVEEN KUMAR

Assistant Professor

DEPARTMENT OF MECHANICAL

ENGINEERING



SYLLABUS

(55604) MACHINE TOOLS AND METROLOGY LAB

Section A : METROLOGY LAB

S.NO: NAME OF THE EXPERIMENT NAME OF THE EQUIPMENT

1 Use Of Gear Teeth Vernier Calipers For

Checking The Chordal Addendum And

Chordal Height The Of Spur Gear

Gear Teeth Vernier Calipers

2 Machine Tool Alignment Of Test On

The Lathe

Lathe Machine and Dial Guage

3 Tool Makers Microscope And Its

Application

Tool Makers Microscope

4 (a) Angle And Taper Measurements By

Bevel Protractor

Bevel Protractor and Dial Guage

4 (b) Angle And Taper Measurements By

Sine Bars

Sine Bar and Slip Gauges

5 Use Of Spirit Level And Optical Flats In

Finding The Flatness Of Surface Plate

Spirit Level and Surface Plate

6 Thread Measurement By 2-Wire And 3-

Wire Methods

Micrometer and 2-Wire And 3-

Wire Threads



Experiment No. 1

GEAR TOOTH MEASUREMENTUSING GEAR TOOTH CALIPER

AIM :-

Inspection of gear tooth using gear tooth caliper and

measurement of gear tooth thicknes

INTRODUCTION :-

Gears are mainly used for transmission of power and motion. For close

control over the accuracy of manufacture, precision measurement of gears plays

a vital role.

Various types of gears commonly used are:

Spur Gear :- It is cylindrical gear whose tooth traces are straight line.

Helical Gear:-It is cylindrical gear whose tooth traces are straight helical



Spiral Gear :-A gear whose tooth traces are curved lines

Straight Bevel :-

A gear whose tooth traces are straight line generator of cone. It is conical in

form operating on intersecting axes usually at angles.

Worm Gear :- The worm and mating worm wheel have their axes nonintersecting.



Terminology Of Gear Tooth :-

Base Circle:- It is circle from which involutes form is generated. Only the hare on a gear is

fixed and unalterance.

Pitch Circle:-It is an imaginary

Pitch Circle Diameter:- It is the diameter of a circle which by pure rolling action would produce the

same motion as the tooth gear wheel. This is more important diameter of gear.

Module:- It is defined as length of pith circle diameter per tooth.



Addendum: This the radial distance from the pitch circles to the tooth.

Clearance :-

This is the radial distance from the tip of tooth to the bottom of a mating tooth

space, when the teeth are symmetrically engaged. Its STD value is 0.157 M .

Duodenum:-

This is radial distance from the pith circle to the bottom of tooth space.

Blank Diameter: - This is the diameter of blank from which gear is out

Blank Diameter = P.C.D + 2M

Tooth Thickness :-

This is the arc distance measured along the pitch circle from it’s intercept with

one flank to it’s intercept with the flank of same tooth.

The teeth thickness measurement is the more important measurement. Most of

gear manufacturer may not undergo checking of all other parameter but

thicknessmeasurement is must.

Gear tooth thickness is measured by using gear tooth vernier caliper. It is

applicable for gears where tooth traces are straight line.

Procedure: -

The gear tooth vernier has two vernier scales and they are set for width ‘W’ of

the tooth and depth‘d’ from the top at which ‘W’ occurs.

* Consider one gear tooth, the values of ‘W’ and‘d’ can be found by using

caliper.

It may be noted that ‘w’ is chord length but tooth thickness is specified by arc

distance. Also‘d’ found out by using caliper is slight greater than addendum.

Therefore ‘W’ and‘d’are called chordal thickness and chordal addendum

respectively.

* Take five readings of ‘W’ and‘d’ and calculate ‘Wavg’ and ‘davg’.

* With the help of ‘Wavg’ calculate the experimental value of module.

* Calculate theoretical value of the module.

* Finally find out % error in module.



Observation Table:-



Experiment No. 2

LATHE MACHINE ALIGNMENT

AIM :-

To perform the alignment test on the lathe machine

APPARATUS:

Dial gauge with stand

PROCEDURE:

1) Clamp the job in universal chuck.

2) Place the dial gauge stand on the compound slide and turn on magnetic

lock

3) Adjust the stylus of the dial gauge so that it touches the surface of the job

with pressure.

4) Rotate the chuck by ha

5) nd.

6) If there is change in the reading of the dial gauge adjust the job to

compensate the deflection

7) Rotate the chuck by hand

8) See if there is any deflections do the same as in step number 5

9) Repeat the procedure till there is no deflection in the reading of the dial

gauge during complete revolution.

RESULT:

Using the above procedure the alignment of the chuck is done.



Experiment No. 03

TOOL MAKERS MICROSCOPE AND ITS APPPLICATION

AIM:- Measurement of threads parameters using tool maker's microscope.

APPARATUS :- Tool maker's microscope, threading job.

TOOL MAKER'S MICROSCOPE :-

Tool maker's microscope is versatile instrument that measures by optical means

with no pressure being involved it is thus a very useful instrument for making

measurements on small and delicates parts. The tool maker's microscope is

designed for the following measurements; measurements on parts of complex

form for example, the profile of external thread as well as for the tools,

templates and gauges, measuring centre to centre distance of holes in any plane

and other wide variety of linear measurements and accurate angular

measurements A tool maker's microscope is as shown in fig. The optical head can be moved up or

down the vertical column and can e clamped at any height by means of a clamping

screws. The table which is mounted n the base of the instrument can be moved in two

mutually perpendicular horizontal directions (longitudinal and lateral) by means of

accurate micromeres screws having thimble scale and venires.

A ray of light from light source is reflected by mirror through 90. It is then passes

through a transparent glass plate (on which flat parts may be placed). A shadow image

of the outline or contour of the work piece passes through the objective of the optical

head and is projected by a system of three prisms to ground glass screen. Observations

are made through an eyepiece. Measurements are made by means of crosslines

engraved on the ground glass screen. The screen can be rotated trough 360 the angle

of rotation is read through an auxiliary eyepiece.



TOOL MAKERS MICROSCOPE

PROCEDURE:-

The use of - tool maker's microscope for the taking the various measurements is

explained below-

1) For taking linear measurements, the work piece is placed over the table. The

microscope is focused and one end of the work piece is made to coincide

with cross line in the microscope (by operating micrometers screws). The

table is again moved until the other end of the work piece coincide with the

cross line on the screen and the final reading taken. From the final reading,

the desired measurement can be taken.

2) To measure the screw pitch, the screw is mounted on the table. The

microscope is focused (by adjusting the height of the optical head) until a

sharp image of the projected contour of the screw is seen of the ground glass

screen. The contour is set so that some point on the contour coincides with

the cross line on the screen. The reading on the thimble of the longitudinal

micrometer screw is noted. Then the table is moved by then same screw until

a corresponding point on the contour (profile) of the next thread coincides

with the cross line. The reading is again noted and the difference in two

reading gives the screw pitch.



3) To determine pitch diameter the lateral movement to the table is given

4) To determine the thread handle, the screen is rotated until a line on the angle

of screen rotation is noted. The screen is further rotated until the same line

coincides with the other flank of the threads. The angle of thread on the

screen will be difference in two angular readings.

Different types of gradated and engraved screens and corresponding eye piece

are used for measuring different elements.

RESULTS:- 1) External diameter = R2 - R1 = -------------- mm.

2) Internal diameter = R2 - R1 = -------------- mm.

3) Pitch of threads = R2 - R1 = --------------- mm.

4) Threads angle = R2 - R1 = --------------- mm.

PRECAUTION:-

1) Obtain clean picture of cross line and the cross thread seen through the eye

piece.

2) For angular measurements lines must remain parallel to flank edge to the

tooth.



Experiment No. 04[a]

MEASUREMENT OF ANGLE USING VERNIER BEVEL PROTRACTOR

AIM:- To measure the angles o f given specimen using bevel protractor

APPARATUS REQUIR ED

1. Surface P late,

2. Dial Gauge,

3. Slip Gauge,

4. Bevel protractor,

5. Specimen

FORMULA

×100

BEVEL PROTRACTOR

A bevel protractor is a graduated circular protractor with one pivoted

arm; used for measuring or marking off angles. It is attached with an acute

angle attachment. The body is designed such that its back is flat and no

projection is beyond its back. The base plate is attached to the main body

and an adjustable blade is attached to the circular plate containing vernier

scale. The main scale is graduated in degrees from 0o-90o in both the

direction. The adjustable blade can be made to rotate freely about the centre.

The base plate is made flat for measuring angles and can be moved

throughtout it‘s length.

Uses:-

It has wide application in architectural and mechanical drawing, although its use is decreasing with the availability of modern drawing software or CAD.

http://en.wikipedia.org/wiki/CAD



PROCEDURE

1. Initially bevel protractor is adjusted as per requirements.

2. Specimen is placed between the blades.

3. Reading noted directly from main scale and Vernier scale

4. For measuring, taper angle of sine bar, protractor is fixed to height gauge

5. The protractor is corresponding adjusted.

6. Noted reading is tabulated



TABULATIONS

RESULT:

Thus angle of the given specimens was determined by using bevel protractor

Angle of the given specimen 1 =

Angle of the given specimen 2=



Experiment No. 04[b]

MEASUREMENT OF TAPER ANGLE USING SINE BAR

AIM:-

To determine unknown angle using sine bar.

APPARATUS:- Sine bar, surface plate, dial indicator, slip gauges.

INTRODUCTION:-

Sine bar is used in conjunction with slip gauges for precise angular

measurement. Sine bar is used either to measure angle very accurately or face

locating any work to a given angle. Sine bars are made from high chromium,

corrosion resistant steel, hardened, ground and stabilized.

Two cylinders of equal dia. are attached at ends. The axes of these two cylinders

are mutually parallel to each other and also parallel to and at equal distance

from the upper surfaces of the sine bar. Accuracy up to 0.01mm /m length of

sine bar can be obtain.



Application of sine bar :-

A] Checking of unknown angles of small workpiece

B] Checking of unknown angles of heavy component.

Figure. Checking of unknown angles of heavy component.



SLIP GAUGES:-

Introduction:- Slip gauges are rectangular blocks of steel having a cross-section of about 30 by

10mm. These gauges are used to provide end standard of specific length by

temporarily combining a number of individual gauge by ‘wringing’, each

representing a dimension (standard) into a single gauge bar. Here the basic

requirements are formation of a bar in reasonable cohesion between individual

element and its dimension truly within specific limits representing the desired

nominal dimensions.

Accuracy:-

Accuracy up to 10 millionth of an inch for flatness and parallelism can be

obtained in slip gauges

Grading:-

Grading according to accuracy and application.

AA - for master slip gauges.

A - for reference purpose.

B - for working slip gauges.

Grade 2 - Workshop grade

Grade 1 - Tool-room grade (More precise work)

Grade 0 - Inspection grade

Grade 00 - Standard-room grade

Calibration grade - Special grade (Prepared on chart)



Precaution in use of sine bar :- 1) The sine bar should not be used for angle greater than 60

0.

2) A compound angle should not be formed by mis-aligning the component

with sine bar.

3) Accuracy of sine bar should be ensured.

4) As far as possible longer sine bar should be used since many errors are

reduced by using longer sine bars.

Wringing:-

The term ‘wringing’ refers to condition of intimate and complete contact and of

permanent adhesion between measuring faces. Wringing is done by hand

though sliding and twisting motions. One gauge is placed perpendicular to other

using standard gauging pressure and rotary motion is then applied until the

blocks are lined up. In this way air is expelled from between the gauge faces

causing the blocks to adhere. This adherence is caused partly by molecular

attraction and partly by atmospheric pressure. Similarly, for separating two

wring slip gauges, combined sliding and twisting motion should be used.



PROCEDURE:- 1) Surface plate is placed on a horizontal surface.

2) Build up slip gauges of a proper height by wringing.

3) Place one of the cylinders of sine bar on surface plate and other on slip

gauges.

4) Dial indicator is set at one end of the component and moved to the other

end.

5) Note the deviation in dial reading.

6) Again slip gauges are so adjusted that dial indicator reads zero deviation

across the

7) work surface if deviation is ‘δh’ over length ‘l1’, change slip gauge height

by (δh x L / l1)

8) Where L is standard sine bar length

9) Again take dial indicator reading to assure zero deviation.

Read slip gauge height and perform calculation

RESULT:-

The unknown angle of component is



Experiment No.05[a]

USE OF SPIRIT LEVEL FINDING THE FLATNESS OF SURFACE

PLATES

SPIRIT LEVEL:

Spirit level is one of the most commonly used instruments for inspecting

the horizontal position of surfaces and for evaluating the direction and

magnitude of minor deviation from that nominal condition. It essentially

consists of a close glass tube of accurate form. It is called as the vial. It is filled

almost entirely with a liquid, leaving a small space for the formation of an air or

gas bubble. Generally, low viscosity fluids, such as ether, alcohol or benzol, are

preferred for filling the vial. The liquid due to its greater specific weight tends

to fill the lower portion of the closed space.

Upper side of the vial is graduated in linear units. Inclination of a surface

can be known from the deviation of the bubble from its position when the spirit

level is kept in a horizontal plane. Temperature variations in the ambient

condition cause both liquid and vial to expand or contract. Therefore, selection

of proper liquid and material for the spirit level is very important for accurate

result. To reduce the effect of heat transfer in handling spirit levels are made of

a relatively stable casting and are equipped with thermally insulated handles.

Figure shows a schematic diagram of a spirit level.

Spirit Level

Sensitivity of the vial used in spirit level is commonly expressed in the

following two ways.



Each graduation line representing a specific slope is defined by a tangent

relationship, e.g. 0.01 cm per meter.

An angular value is assigned to the vial length covered by the distance of two

adjacent graduation lines, i.e. the distance moved by the bubble from the zero

will correspond the angle directly.



Experiment No.05 [b]

USE OF OPTICAL FLATS FINDING THE FLATNESS OF SURFACE

PLATES

AIM :- Use Of Optical Flat And Monochromatic Light

APPRATUS :- Optical Flat And Monochromatic Light Source

OPTICAL FLAT

Optical flats are cylindrical in form with the working surfaces flat and are of

two types: Type A-It has only one surface flat. The working surface of this

type of flat is indecently by an arrow head on the cylindrical surface pointing

towards the working surfaces. Type B-It has both the surfaces flat and parallel

to each other. Type A are used for testing the flatness of precision measuring

surface of flats, slip gauges, measuring tables, etc.

Type B are used for testing measuring surfaces of micrometers,

measuring anvils and simila length measuring devices for testing flatness and

parallelism These are generally made of either fused quartz or borosilicate

glass. This glass is clear and colorless and free from inclusions and defect like

bubbles, internal strains and extraneous matter. The cylindrical surface of

the optical flat are finished by grinding and the working surfaces are

finished by lapping and the polishing process. The finishing is done to such

an extent that straight and parallel interference b fringes are produced when

the optical flat is viewed under a monochromatic source of light by

placing it in contact with reference flat surface. Their edges are

generally beveled to45 degree by a suitable grinding or polishing process

so that the edges are free from any chips.

Out measurement of length variation when reference plane of the

measurement is established and both indicator and object are located in a

definite relation to the common reference plane. These are achieved by means



of appropriate gauging set-ups.when dial indicator united with member which

serve

PROCEDURE :-

1. Start the optical flat m/c and place w/p on platform whose curvature is

to be measured.

2. Now the Optical flat is placed on it and observed the types of fringes

appear on the optical flat.

3. To take a current reading applying the finger tip at a center of optical

flat and observed the behavior of fringes made on optical flat.

4. By comparing behavior on the fringes with std-one & decided whether the

surface is convex concave or flat etc.

RESULT: - Thus we are studying the different types of flat or curvature

of surface.



Experiment No.06

THREAD MEASUREMENT BY 3-WIRE AND 2-WIRE METHODS

AIM:- Measurement Of Thread By 3-Wire Method

The pitch diameter of a threaded object can’t be measured directly except

with specialized thread micrometers. But using three wires of the same known

diameter, the thread pitch can be measured with a standard micrometer.

PROCEDURE:

metrology laboratory manualoss.nri.edu.in/...3-1/...3-1-metrology-lab-manual.pdf · metrology...

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