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Experimental objective

Ascertain the validity of laws of friction

Wear characteristics of the givenspecimen

Determination of Wear Constant

Understand the effect of parameters

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Test Set up/unit

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TECHNICAL DATA & SPECIFICATION

BASIC SPECIFICATIONS: Details Description Remarks

Top specimen Pin Dia 3,4,6,8,10 & 12mm Material: as per test needBottom specimen-Disc Standard Disc:165mm x 8mm thick

Material: En 31 hardened to 62HRc Sensor specification Disc Speed Range : 200 to 2000 rpm

Infinitely variable in steps of 1 rpm Sensor: Proximity sensor, model APS-8, PNP Type, make: TAP

Least count 1 rpmDisplay accuracy (11% of measured speed)

Normal load Range 1N to 200 In steps of 5N,

(exact dead weights of size 0.1,0.5,1,2 & 5kg are provided to vary the load)

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Frictional force Range 0 to 200NSpecification 20 kg beam type load cell, make: IPALeast count 0.1NAccuracy (0.1 2% measured frictional force) in N

Wear Range 2mm

Sensor spec LVDT, make: SysconLeast count 1 micronAccuracy (11% of measured wear) in micron

Wear track diameter: Min 50mm to max 100mm

Sliding speed Min 0.5 m/s to max 10m/s Timer Max 99hrs, 59min, 59 sec

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Experimental Procedure in Sequential

steps:

Prepare equipment for test:

Thoroughly clean specimen pin, remove burns formcircumference using fine grade emery paper.

Determine the weight of the specimen very accurately

using highly accurate weighing balance having leastcountof 0.01 mg (Need?)

Clean wear disc thoroughly with solvent and allow it todry

Clamping of specimen pin Specimen pin is clamped to loading lever tip by

hardened jaws. Use the relevant size (4,5,6,8,&12 mm)clamp to hold cylindrical specimenpins

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Set wear track radius The path generated is circle, so the specimen

pin can be positioned over wear disc between50 & 100 mmdia. By this the wear disc between

each grind can used be used for many test bypositioning the specimen pins at differentdiameter (Wear track diameter) on wear disc.

Procedure

Unscrew to loosen the sliding plate, move it tothe desired position (say at 60 mm) by looking atthe graduated scale and tighten the clampscrew at this position

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Setting disc Speed

Set3 or 5 min time on controller

Press teststartpush button 7

Rotate SET rpm knob on controller in clockwisedirection till required testspeed displayed

Continue to run for the remaining time to

observe for any fluctuation. Press stop button on controlled to switch off

rotation

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Calculating the sliding velocity andsliding distance:

Sliding speed in m/sec =

Sliding speed in m = D = Dia of wear track in mm

N = Disc speed in rpm

T = Test duration in secs Based on the wear track set, determine

the motor speed to be set on controller to

achieve the desired sliding velocity

000,60/DN

000,60/DNT

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Applying Normal load Place required weights on loading pan slowly with out

shaking Conduct the test and note the observations Press START push button on the controller front panel to

commence the test; (simultaneously data is transmitted to PC). On controller the acquired test parameters like wear,

frictional force, speeds are displayed, (same values are also displayed on PC screen and

graph is plotted simultaneously) Note the necessary readings and record your data Repeat the procedure from a suitable stage to the next

test condition and till you complete the test

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Friction Force measurement

The friction force between the pin and disc is measuredby a load cell mounted on bracket at a distance equal tothe distance between specimen and pivot. A beam typeload cell with a maximum capacity of of 20kg (200 N) isused.

The load cell is strain gauge type load cell constructedon high strength corrosion resistant steel using foil typestrain gauge with high stability.

The tangential force on the specimen holding beam istransmitted to the load cell beam and (even minute)

deformation of the beam is sensed by the strain gauge The strain gauge is connected to a wheat stone bridge

circuit. Strain conditioning and balancing is automatedand calibrated such that values are direct displayed

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Wear Measurement

Linear wear rate is monitored using a LVDT( Linearvariable differential transducer)

LVDT measures wear of the specimen directly as thesensor is mounted atexactly same distance of specimenfrompivotpoint to get equal (1:1) lever ratio.

The plunger of sensor rests on a hardened pin projectionfrom the lever and as wear occurs the loading lever liftsin upward direction, moving the plunger. This movementis displayed as wear on the controller. The leastcount ofthe LVDT is 0.1 mand thus the wear rate also

The initial position is set on the mid point so that both +and ve wear can be monitored and the maximumrange is 2 mm

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Format of Report

NameBatch

Dept. of Mech. Engg., IIT MadrasME 3280-Mechanical Engg. Laboratory

Roll NoDate

Title of Experiment

Objective

Underlying theory Annexure A (Attach separately)

Test Set up used Shot description. Schematic sketch and basic specifications

Test procedureadopted

Describe the steps in sequential order

Observations Record the data appropriately (tabular form) andsystematically

Inference Do the necessary calculations, Generate the required graphical

plots etc

Conclusion Draw and describe the conclusion arrived at

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Setting of computer for data acquisition

Click START button in PC windows

Post evaluation of test data

On PC the data acquired during test is stored. Openview file to display graph of single test with all testparameters. On the wear graph a line equation isprovided to fit any slope, the slope position is entered asstarting time & ending time, click REFERESH button togive slop equation and graph.

Use compare graph to compare test parameters ofdifferent test files, at a time 4 files test parameters canbe compared.

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S.No

NormalLoad

Frictionforce

Slidingspeed/velocity

Linearwear

Contactpressure

p.V factor Co.eff offriction

Re-marks

Test Specimen Pin Disc

Material

Diameter

Harness

Roughness

Initial Weight Final Weight

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Suggested References

Rabinowicz.E., (1995), Friction and wear of materials,J ohn Wiley & Sons, New York

Gwidon W. Stachowiak and Andrew W. Batchelor(2001) Engineering Tribology Butterworth-Heinemann,

Boston. Bhushan.B., (1999), Principles and Applications of

Tribology, J ohn Wiley & Sons, New York

B.C. Majumdar (1986), Introduction to Tribology ofBearings, A.H. Wheeler and & Company Ltd.

I.M.Hutchings(1992) Friction, Wear and LubricationEdward Arnold-London UK.