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Experiment # 1To measure the diameters of various pins with the help of vernier caliperApparatus:1-Vernier caliper2-Pins of various diameters

THEORY

Line Standard: Process in which a line is taken as the standard in order to take the measurements.

Vernier Calliper: A measuring instrument consisting of an L-shaped frame with a linear scale along its longer arm and an L-shaped sliding attachment with a vernier, used to read directly the dimension of an object represented by the separation between the inner or outer edges of the two shorter arms.

Types :following are the main types of vernier caliper

Analogue Caliper:Instead of using a vernier mechanism, which requires some practice to use, the dial caliper reads the final fraction of a millimeter or inch on a simple dial.In this instrument, a small, precise rack and pinion drives a pointer on a circular dial, allowing direct reading without the need to read a vernier scale. Typically, the pointer rotates once every inch, tenth of an inch, or 1 millimeter. This measurement must be added to the coarse whole inches or centimeters read from the slide

Digital Calliper:

A refinement now popular is the replacement of the analog dial with an electronic digital display on which the reading is displayed as a single value. Rather than a rack and pinion, they have a linear encoder. Some digital calipers can be switched between centimeters or millimeters.

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Procedure:

1-Take the cornier caliper and check its zero error and least count . If there is some zero error then note it down .2-Take the pins one by one and measure their diameters .3- If there is some zero error in the vernier caliper then correct the value .

Observations and calculations :zero error= 0least count of V.C= 0.05 mmSR # .Dia of Pin in mm Dia of Pin in inches

1 15.90 0.626

2 15.85 0.624

3 15.80 0.622

4 15.90 0.626

5 15.85 0.624

6 15.80 0.622

7 15.90 0.626

8 15.80 0.622

9 15.90 0.626

10 15.85 0.624

11 15.80 0.622

12 15.80 0.622

13 15.90 0.626

14 15.85 0.624

15 15.80 0.622

16 15.75 0.62

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17 15.85 0.624

18 15.85 0.624

19 15.85 0.624

20 15.75 0.62

Comments:

1-There is some least count in the vernier caliper , so the readings are always incorrect to some extent.2-Human error may affect the readings while noting down the readings from the scale.3-Zero error should be checked.4-Friction between the jaws and pins cause wear and affect the values.

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EXPERIMENT # 2

To draw the Histogram of the readings of experiment # 1 THEORY

Histogram:In statistics, a histogram is a graphical representation of the distribution of data. It is an estimate of the probability distribution of a continuous variable and was first introduced by Karl Pearson. A histogram is a representation of tabulated frequencies, shown as adjacent rectangles, erected over discrete intervals (bins), with an area proportional to the frequency of the observations in the interval. The height of a rectangle is also equal to the frequency density of the interval, i.e., the frequency divided by the width of the interval. The total area of the histogram is equal to the number of data. A histogram may also be normalized displaying relative frequencies.

Procedure :1-Arrange the data in ascending order .2-Calculate the range of the data and then calculate the class intervals and class boundries.3-Draw a table showing the class limits , class boundries and number of times an event occure in boundry 4- Draw a histogram with the help of the table x-axis represents the class boundries and y-axis shows the frequency in each boundry.

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EXPERIMENT # 3

To measure the given dimensions with the help of the guage blocks/ slip gauges

Apparatus:

1-Guage blocks2-Petroleum jelly3-Petrol3-Tissue roll

THEORYGauge blocks:

Gauge blocks are a system for producing precision lengths. The individual gauge block is a metal or ceramic block that has been precision ground and lapped to a specific thickness. Gauge blocks come in sets of blocks with a range of standard lengths. In use, the blocks are stacked to make up a desired length.

Materials:A gauge block is a block of metal or ceramic with two opposing faces ground precisely flat and parallel, a precise distance apart. Standard grade blocks are made of a hardened steel alloy, while calibration grade blocks are often made of tungsten carbide or chromium carbidebecause it is harder and wears less.

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Wringing:

Wringing is the process of sliding two blocks together so that their faces lightly bond. Because of their ultraflat surfaces, when wrung, gauge blocks adhere to each other tightly. Properly wrung blocks may withstand a 75 lbf (330 N) pull.

The process of wringing involves four steps:

1. Wiping a clean gauge block across an oiled pad .

2. Wiping any extra oil off the gauge block using a dry pad .

3. The block is then slid perpendicularly across the other block while applying moderate

pressure until they form a cruciform.

4. Finally, the block is rotated until it is inline with the other block.

Procedure:

1-Check the dimension of the given object to be measured using gauge blocks.2-Make that dimensions using the sum of the gauge blocks.3-Use wringing process to make the given dimension .4-Complete the process and check the dimensions if it is accurately achieved.

Observations and calculations :

Sr.No Dimensions used Exact Length 1 15.00+1.600+1.050 17.65 2 1.002+1.001+0.500 2.503 3 1.200+1.030+1.000 3.230 4 7.000+1.008+1.007 9.603

Comments:

1-The gauge blocks should be properly cleaned with the help of petroleum jelly.2-Wringing process should be proplerly performed so that gauge blocks remain stick together firmly.3-Use minimum number of gauge blocks.

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EXPERIMENT # 4

To develop the angular dimensions with the help of angle gauges

Apparatus:1-set of angular gauges2-petrol3-Tissue roll

THEORY

Angular Gauges

In the same way the slip gauges are used to measure the linear distance , the angular gauges are used to measure the angles with accuracy.

Materials:They are usually made up of the hardened steel and their faces are quiet polished and lapped.Some are made up of ceramics materials .

Methods of measuring

There are two methods of measuring with the help of the angular gauges 1-Direct method 2-In direct method

Direct method :Direct methods use the tapper gauges , ring gauges and angulr templates .

In Direct Methods :

Indirect type of angular gauges use the adjustable angular gauges.

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Procedure:1-Check out the angle given to you 2-Make that angle mathematically with the help of the given gauges.3-Clean the gauges to perform the wringing process.4-Start wringing the gauges in order to get the desired angle .5-Complete the process and check the angle if it is accurately achieved.

Comments:

1-This is the quick and easy method to measure the angular dimensions.2-Accuracy of thye angular gaugescan change according to the temperature.3-Bevel protector is used for measuring and lying the angles.4-Care should be taken while adjusting the gauges.

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EXPERIMENT # 5To measure the angle of any substance using the sine bar.

Apparatus:1-Sine bar2-Gauge block 3-Surface plate 4-Dial gauge with stand

THEORYSine bar:A sine bar consists of a hardened, precision ground body with two precision ground cylinders fixed at the ends. The distance between the centers of the cylinders is precisely controlled, and the top of the bar is parallel to a line through the centers of the two rollers. The dimension between the two rollers is chosen to be a whole number and forms the hypotenuse of a triangl when in use. 

Principal:Angles are measured using a sine bar with the help of gauge blocks and a dial gauge or a spirit level. The aim of a measurement is to measure the surface on which the dial gauge or spirit level is placed horizontal. For example, to measure the angle of a wedge, the wedge is placed on a horizontal table. The sine bar is placed over the inclined surface of the wedge. At this position, the top surface of the sine bar is inclined the same amount as the wedge. Using gauge blocks, the top surface is made horizontal. The sine of the angle of inclination of the wedge is the ratio of the height of the gauge blocks used and the distance between the centers of the cylinders.

Procedure :1- Sine bar is placed on the surface plate and level of the sine bar is checked.2-Place the object on sine bar such that its lower end should be towards that side of the sine block which will bw raised by placing the gauge blocks underneath it.3-Start wringing the gauge blocks in and try to level the object and check the level every time

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with dial gauge until it is leveled.4- When objects surface is completely leveled, note down the height of the gauge and calculate the angle.

Observations and Calculations :

Sr.n0 Length of the barr(mm) Height of the bar(mm) Angle calculated(deg) 1 254 15.48 3.49 2 254 14.10 3.18 3 254 12.70 2.86

Comments:1-Hypotenuse is a constant dimension.2-Sine tables are used to measure the angles of larger work pieces.3-Height is taken from the bottom of the roller and the table surface.4-special type of the sine bar is sine centre and can not measure the angle more than 45 degrees.

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EXPERIMENT # 6To measure the taper of a bore with the help of depth gauge and standard ball assembly .

Apparatus:1-Standard asembly2-Depth gauge3-Slip gauge

THEORY

Depth Gauge:A depth gauge is an instrument used to measure the depth of a bored hole, drilled hole or cut. Often referred to as a depth micrometer, the depth gauge can be a precision-build measuring tool that is able to give the depth reading in a variety of measurements. It also can be as simple as a length of tape wrapped around a drill bit or similar boring tool to indicate when the proper depth has been reached. Occasionally, a depth gauge is nothing more than a tool that is inserted into a hole. It features an indicator marked in red for "no go" and one in green for "go," which is pushed up and out of the tool's handle when the probe touches the bottom of the hole, thereby

indicating a properly-drilled hole.

Procedure :1-select two balls , one of larger diameter and second of smaller diameter such that two balls should not touch each other when kept in the tapered hole .2-The larger ball should be 1/3 times outside hole3-Make two columns of gauge blocks such that the height equals the level of the larger ball outside the hole.4-Measure the depth from the top of the small ball by removing the large ball from the top by the

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help of depth gauges.5- From these values perform calculations and find the tapper of the hole .

Observations and calculations :

Radius of smaller ball= R1Radius of Larger ball =R2Height up till larger ball in the hole = HHeight up till smaller ball in the hole=H1LM= H-H1+R1-R2NL=R2-R1

SR.NO R1(in) R2(in) H(in) H1(in) H2(in) LM(in) NL(in) 1 13/64 7/16 1.530 0.455 1.075 0.84 15/16 2 1/5 11/32 1.40 0.725 0.675

Comments :1-Zero error is the error when jaws are closed and they are giving some non zero value ./2-A micrometer that has been tested as described and has to be found to be off should be adjusted so that it once again reads the accuraye value.

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EXPERIMENT # 7To measure the profile of a component by using CMM( Co-ordinate measuring machine ) Apparatus1-CMM2-Object to be measured. TheoryC M M :A coordinate measuring machine (CMM) is a device for measuring the physical geometrical characteristics of an object. This machine may be manually controlled by an operator or it may be computer controlled. Measurements are defined by a probe attached to the third moving axis of this machine. Probes may be mechanical, optical, laser, or white light, amongst others. A machine which takes readings in six degrees of freedom and displays these readings in mathematical form is known as a CMM.Parts:Coordinate-measuring machines include three main components:1-Main structure which includes the motion of three axes2-Probing system3-Data collection and reduction system - typically includes a machine controller, desktop computer and application software.

Types:Cantilever type :

The cantilever construction combines easy access and relatively small floor space requirements.

It is typically limited to small and medium sized machines. Parts larger than the machine table

can be inserted into the open side without inhibiting full machine travel.

Bridge type :

The bridge arrangement over the table carries the quill (z-axis) along the x-axis and is sometimes

referred to as a travelling bridge. It is claimed that the bridge construction provides better

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accuracy, although it may be offset by difficulty in making two members track in perfect

alignment. This is by far the most popular CMM construction. figure shows a bridge structure.

Column type :

The column type machine is commonly referred to as a universal measuring machine rather than

a CMM. These machines are usually considered gage room instruments rather than production

floor machine. The direction of movements of the arms are as shown in figure. The

constructional difference in column type with the cantilever type is with x and y-axes

movements.

Applications :

1-They are used for dimensional measurement

2-Profile measurement

3-Orientation measurement

4-Depth Mapping

5-Reverse engineering

Description :

The typical 3 "bridge" CMM is composed of three axes, an X, Y and Z. These axes are

orthogonal to each other in a typical three-dimensional coordinate system. Each axis has a scale

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system that indicates the location of that axis. The machine will read the input from the touch

probe, as directed by the operator or programmer. The machine then uses the X,Y,Z coordinates

of each of these points to determine size and position with micrometre precision typically.

A coordinate measuring machine (CMM) is also a device used in manufacturing and assembly

processes to test a part or assembly against the design intent. By precisely recording the X, Y,

and Z coordinates of the target, points are generated which can then be analyzed via regression

algorithms for the construction of features. These points are collected by using a probe that is

positioned manually by an operator or automatically via Direct Computer Control (DCC). DCC

CMMs can be programmed to repeatedly measure identical parts, thus a CMM is a specialized

form of industrial robot.

Comments :1- The controller is placed carefully on the table to avoide any sort of the damage .

2-The C M M device should be set to the storage mode when it has been used .

3-There should not be any sort of the scratches on the table which may deviate the values.

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EXPERIMENT # 8To trace and measure the profile of a component using profile projector .

Apparatus :

1-Profile projector

2-Component being Measured

TheoryProfile projector :

A profile projector projects a magnified profile image of an area or feature of a workpiece onto a

screen, most commonly using diascopic illumination. Dimensions can be measured directly on

the screen or compared to a standard reference at the correct magnification. For accuracy, it is

important that the magnification does not change with perspective, i.e. its position or the view

point of the operator. Telecentric lenses are, therefore, highly desirable. The screen often has a

grid and this grid can often be rotated through 360 degrees to align with an edge as displayed on

the screen. Point positions, measurements, and calculations may also be performed using a

simple digital read out device. Episcopic lighting is used to measure features such bores, bosses,

pockets, pads etc, which would not be revealed on a profile view. A computer may be added to a

profile projector system for edge determination, thereby eliminating some human error.

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Components :1-Glass table

2-Projection lense and illumination lamp

3-Screen to view the magnified image of work piece

Applications :Profile projectors are robust measuring tools commonly used in machine shops, quality

assurance departments and occasionally on assembly shop floors. They are suitable for

measuring and quality control for a wide range of size and weights of objects. The most basic use

of a profile projector is to identify a point or edge on the shadow and from this point to calculate

a length. By magnifying the image, the operator is less likely to make a mistake when deciding

where the edge or point starts. Profile images can also be used to make simple stop / go decision

by, for example, matching an image against a standard to determine whether a part has been

made correctly

Procedure :The part to be analyzed is kept on the table and is magnified by an optical system and projected on a screen . Readings on the screen gives the dimensions of the part .

Comments:1- The grid on the screen should be properly aligned with the object .2- Table should be clean .

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EXPERIMENT # 9To measure the surface roughness of a component using the surface texture machine .

Apparatus:

1-Surface texture machine

2-Work piece

THEORY

Surface texture:

Surface Texture or Surface Topography is the local deviations of a surface from a

perfectly flat plane. The measure of the surface texture is generally determined in terms of

its roughness,waviness and form .Surface texture is one of the important factors that control

friction and transfer layer formation during sliding . Surface Textures can be isotropic or

anisotropic . Sometimes, stick-slip friction phenomena can be observed during sliding depending

on surface texture .

Roughness:

Surface roughness, often shortened to roughness, is a measure of the texture of a surface. It is

quantified by the vertical deviations of a real surface from its ideal form. If these deviations are

large, the surface is rough; if they are small the surface is smooth

Waviness:Waviness is the measurement of the more widely spaced component of surface texture. It is a

broader view of roughness because it is more strictly defined as "the irregularities whose spacing

is greater than the roughness sampling length". It can occur from machine or work deflections,

chatter, residual stress, vibrations, or heat treatment. Waviness should also be distinguished

fromflatness, both by its shorter spacing and its characteristic of being typically periodic in

nature.

WORKING & PROCEDURE :

It contains a sensitive diamond prob which touches the surface of the work piece and makes a

graph . The most common method is to use diamond profilometer . It runs perpendicular top the

surface . Prob traces along the straight line on the surface or in a circular arc on the curved

surface .The length traced is called measurement length . Measurement length should be almost

seven times greater than the sampling length .

Procedure :As a fully integrated option for the measurement system , users of the surface finish prob will

benefit from a range of powerful features that will boost inspection speed and flexibility . The

prob incorporates a C axis , which combined with finite positioning capability of measuring head

and a choice of style, allows the prob to be automatically oriented to any angle to suite the part ,

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ensuring that the highest quality surface data is acquired .

Comments :

1- The surface texture ws analyzed using the ETALON TCM measuring microscope .

2- The surface to be analyzed should be properly cleaned to have the accurate

measurements.

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