Tribological behavior of Clutch Plate Material in Laboratory Simulated Conditions

A Clutch is a machine member used to connect the driving shaft to a driven shaft, so that the driven shaft may be started or stopped at will, without stopping the driving shaft. While riding the clutch, it simply means keeping the clutch pedal, fully, or partially pressed down. Hence, the pressure on the pad is creating a huge amount of friction which will very quickly produces the wearing in Clutch plate material. The concept is to understand material behavior and wear and friction criteria. The clutch plate is made of material usually of Grey Cast Iron with Asbestos used as Friction Lining Material. In this research, an attempt is made to try out Composite material clutch plate. Composite are of polymer, ceramic and metal matrix type. The use of composites is motivated because of good friction co-efficient and wear resistant properties. The aim of this present work is to identify a heat resistant clutch material for optimum friction coefficient (μ) and to decide a perfect composite material which has low wear rate at different temperature, load and velocity conditions. The Clutch Plate is modelled and analyzed using Creo and FEA software. The Experimental investigation of plate is done by Pin on Disc Apparatus for validation of wear rate and Friction Co-efficient.


I. INTRODUCTION
Wear is damage to a surface as a result of relative motion with respect to another substance. One key point is that wear is damage and it is not limited to loss of material from the surface. However, loss of material is definitely one way in which apart can experience wear. In the older definitions of wear there used to be a greater stress on the "loss of material" Wear causes an enormous annual expenditure by industry and consumers. For some industries such as agriculture, as many as 40% of the components replaced on equipment's have failed by wear. Estimates of direct cost of wear to industrial nations vary from 1% to 4 % of GNP and it is estimated that 10% of all energy generated by man is dissipated in various friction processes. Thus the magnitude of losses caused to mankind (which can be expressed in percentage points of GDP) makes it absolutely necessary to study ways to minimize it. Thus minimizing wear, affects the economics of production in a major way A clutch mainly consists of two parts, i.e. friction plates and separator plates. These plates engage and disengage to transmit speed and torque. The transmitted torque is proportional to the overall friction coefficient of the clutch plates. The friction behavior of clutch plates is critical for overall performance of the transmission and it depends on the sliding velocity, the normal pressure, the lubrication, the temperature and the surface topography of the clutch plates. It is necessary to investigate the effect of surface topography on the friction behavior of the clutch plates. Study of various research paper, the surface characteristics of clutch plate materials have been investigated since it is closely related to friction [1]. describes Engagement characteristics of a friction pad for commercial vehicle clutch system [2]. analyze the effect of different material composition on friction & wear of Clutch Plate material [3]. the effect of load, Velocity of sliding and sliding distance on friction and wear of materials made of Polytetrafluoroethylele (PTFE) and PTFE composites [11].
In the present work the wear behavior of various clutch materials at different operating conditions is carried out using pin on disc apparatus. Additionally, the wear volume is calculated and hardness was carried out. Further finite element analysis of clutch plate was carried out.

II. EXPERIMENTAL DETAILS
Wear is a process of removal of material from one or both of two solid surfaces in solid state contact. As the wear is a surface removal phenomenon and occurs mostly at outer surfaces, it is more appropriate and economical to make surface modification of existing alloys than using the wear resistant alloys. [1] Pin on disk wear testing is a method of characterizing the coefficient of friction, frictional force and rate of wear between two materials. As a particularly versatile method for testing wear resistance, pin on disk can be configured in multiple scenarios depending on the goals of your project. Pin on disk testing can simulate multiple wear modes, including unidirectional, bidirectional, omnidirectional and quasi-rotational wear. Our equipment allows us to test virtually any combination of materials to determine the effect of wear on a medical device. [3] In this experiment, the test was conducted with the following parameters: 1. Load 2. Speed 3. Distance   • S-GlassFiber: S-Glass is generally used for polymer matrix composites include, High production rates, improved mechanical properties compared to E-glass., High strength, High stiffness. Relatively low density, Non-flammable, Resistant to heat. • CarbonFiber : The use of this as the reinforcement material in polymer matrix composites is extremely common. Optimal strength properties are gained when straight, continuous fibers are aligned parallel in a single direction.  1. Volume loss (V): The volume loss is actually the remaining material of pin which is left after the worn out of the pin. The Volume is the loss material of the pin which can be mathematically given as, [7] Volume loss = Cross sectional Area x Height loss V= A/H2 mm 3 2. Wear rate: The wear rate per unit sliding distance in the transient wear regime decreases until it has reached a constant value in the steady-state wear regime. Hence the standard wear coefficient value obtained from a volume loss versus distance curve is a function of the sliding distance. [7] Wear rate = Volume loss / Sliding distance mm 3 /Nm (2) 3. Wear resistance: When material generally offer good resistance to sliding and impact abrasion, increases the hardness and toughness of the steel, making it an ideal material for applications that require high impact or high abrasion resistance. [7] Wear resistance = 1/ Wear rate (3) 4. Specific wear rate: At each loading condition, the wear rate is different. Hence the wear rate at particular loading condition is called as the Specific Wear rate. In can be defined as the ratio of wear rate to acting load. It can be given as, [7] Specific wear rate = Wear rate/load (4) Clean and dry specimen and disc using solvent. Weight Specimen and disc individually on weighing scale having accuracy 0.1 mg .Insert disc on fixture and tightens screws from sides to clamp, ensure the perpendicularity within +1 dig to the axis of rotation. Insert Specimen to jaw holder,insure it is sitting properly and tighten two jaws to hold ball and tighten jaws to specimen holder .Switch on controller, allow 5 min for normalizing the display on controller. Press test start push button on controller after setting 10 min time on timer display, rotate speed knob till 60 rpm is displayed, ensure the speed is constant at 60, then press stop button.Press zero button of normal load, frictional force and wear on controller.Open software on pc, select a new file, enter test parameters and sample id on screen and click on start icon to activate screen to receive data. Add 2 kg dead weight on loading pan to apply normal load .Set timer to 30min to achieve 1000mt sliding distance. Begin test by pressing on start push button, record the room temperature and relative humidity. Test stop after completion of test duration. Remove specimens , clean off loose wear debris , note the existence of feature on or near thee wear scar such as ;protrusions , displaced metal , discolorations, microcracking or spotting Weight the specimen and record the loss in weight .The loss in weight is negligible , alternately volume loss may be measured On the bottom disc no wear is observed

Wear Volume :
Wear Volume is the volume which is lost by the material after rubbing of pin. This is actual weight lost by the material. [14] Wear Volume canbe determined as by, Vw= (W1-W2)/Density Hence for all the materials, wear can be determined as, So as to determine the volume rate in mm 3 , the densities of materials are converted to g/mm 3 . Hence forth the wear volume can be seen as follows, The wear Volume for Carbon Fiber and S-Glass Fiber are comparatively low. Due their low density and good wear resistant property, the gives less wear out during the experimental test.

Co-Efficient of Friction
: The Graph 05, shows the behavior of co-efficient of friction for different materials under different interval of time. The Carbon fiber which shows the lower wear rate possess the coefficient of friction which slightly varies with respect to deeper wear testing. The Friction coefficient for S-Glass Fiber remains constant throughout the test, which shows that the wear behavior will remain constant after a certain period of time. The aluminum composites of 6061 shows the lowest amount of friction rate whereas the friction co-efficient of 7075 decreases with respect to time. After an interval of time, the Friction co-efficient of 7075 continuous to be constant. [14] Graph 06 Time Vs. Co-Efficient of Friction From the experimentation results, it is clear that the polymer matrix composites shows better results as that of Aluminum Composites. The Aluminum Composites, also show better results. The Aluminum and polymer composites can be used as replacement for other friction lining materials so as to reduce the wear rate and also to increase the life of friction pads in case of clutch plates.

Hardness Analysis
The wear system is very important; the presence of corrosion or impact can have large influence on the relation between hardness and wear resistance. The relation between hardness and wear is actually inversely proportional. The Harder the material goes, the less the wear volume. [14]

V CONCLUSIONS
In the present work the investigations of wear and friction characteristics of aluminum matrix and polymer matrix material for clutch plate is carried out on pin on disk apparatus under different testing conditions. It is observed that AL6061 shows very less coefficient of friction but wear volume is very high. As per requirement of clutch plate material S glass fiber shows significantly higher coefficient of friction i.e. about 0.2 and also it shows very less wear volume ie. 45 mm 3 compared to aluminum matrix. So it can be concluded that S Glass fiber can be used for clutch plate material.

ACKNOWLEDGMENT
The report is outcome of guidance, moral support and devotion bestowed on me throughout my work. For this I acknowledge and express my profound sense of gratitude and thanks to everybody who have been a source of inspiration during the experimentation. The consistent guidance and support provided by Dr A.B Kakade thankfully acknowledged and appreciated for the key role played by him in providing me with his precious ideas, suggestions, help and moral support that enabled me in shaping the experimental work.