Development of A New Bio-degradable Friction Material for Brake Pads from Palm Kernel Shell

Transcription

1 International Journal of Mechanical Engineering and Materials Sciences, 4(1) January-June 2011, pp. 1-6 Development of A New Bio-degradable Friction Material for Brake Pads from Palm Kernel Shell DAREDDY RAMANA REDDY 1, SWADESH KUMAR SINGH 2 AND BALU NAIK BANOTH 3 1 Deptt. of Mechanical Engineering, NRIIT, Kandukuru, Hyderabad, AP, India Deptt. of Mechanical Engineering, GRIET, Bachupally, Hyderabad, AP, India Deptt. of Mechanical Engineering, JNTUH, Kukatpally, Hyderabad, AP, India ABSTRACT Friction materials have their significant role for braking and transmission in various machines and equipment. Their composition keeps on changing to keep pace with technological development and environmental/legal requirements. Earlier asbestos has been used as a friction material because of its good physical and chemical properties. But later researches eyed that there are many health hazards associated with asbestos handling. The average disk temperature and average stopping time for pass is increased and it has poor dimensional stability. Hence it has lost favor and several alternative materials are being replaced these days. In this work a non-asbestos bio-friction material is enlighten which is developed using an Agro-waste material palm kernel shell (PKS) along with other Ingredients. The developed friction material is used to produce automobile disk brake pads. The developed brake pads were tested for wear and effectiveness on a specially designed experimental test rig. When compared with premium asbestos based commercial brake pad PKS pads were found to have performed satisfactorily in terms of amount of wear and stopping time. Keywords: Bio friction material; material substitution; brake pads. 1. INTRODUCTION The development of modern friction materials has a history spanning over the past 110 years. Herbert Frood is credited with inventing the first brake lining material in His invention led foundation to the Ferodo Company, a firm that still supplies brake lining materials today. In 1901, Herbert patented a block made from layers of textile material impregnated with rubber, if the block was to be used against steel, or wax, if it were to be used against rubber. As the duty of the brakes increased, the cotton tended to char, so in 1908, Herbert replaced it with asbestos. The asbestos was woven into a loose fabric and impregnated with resins and varnishes of high melting point. By 1914, the use of Ferodo brake linings was widespread. In 1920s all friction materials were Corresponding author: ramana4u.iitm@gmail.com of the Ferodo type. In 1925, the British Belting and Asbestos (BBA) Limited which is known as BBA Group that produced famous friction material brands name do Mintex, Don, Textar. In the 1930s, Ferodo turned towards thermosetting resins and later introduced molded instead of woven linings. The molded linings were made by mixing fiber and resin together and by polymerizing the resin under pressure and temperature. Fillers such as mineral and metal particles, which modify the wear properties of the lining, can be introduced in these linings and polymers which were impracticable with woven linings. Non-asbestos organic based friction materials are mostly multi ingredient systems (containing more than 10 ingredients, in general) in order to achieve the desired amalgam of performance properties. Though pad manufacturers know by experience how formulations must be changed in order to achieve certain properties, there is a lack of fundamental knowledge about the influence of pad materials on friction and wear properties. Development of innovative friction materials by adopting sustainable approaches via utilization of agro wastes such as PKS by-products would be a solution not only to control the health hazards but also to reduce the extent of dependence on depleting resources and to save the environment from the end products. From the foregoing, asbestos has been used as base material in the manufacture of brake lining materials for close to 100 years. It is still being used by some manufacturers who do not possess the necessary technology or who are not willing change to other materials. Though asbestos has been referred to as a God given material for inclusion in friction linings due to its good physical and chemical properties that remain stable over the temperature range experienced by friction materials it has been reported that asbestos has serious health risks. Diseases associated with it include asbestosis, Mesothelioma, lung cancer and other cancers. Efforts

2 2 International Journal of Mechanical Engineering and Materials Sciences have been geared to replace asbestos fibers in friction linings. This is exemplified by the work of Nakagawa in 1986, used metal fibers for inclusion in brake pads to overcome environmental pollution. They developed semi-metallic pad material using chatter machined short metal fibers because it exhibited excellent properties in view of brake characteristics and resistance to wear. The brake pad contained about 60% by weight of steel fibers with 60µm in diameter and 3mm long [1]. Blau (2001) reported the additive effects of various non-asbestos materials on friction linings. Asbestos free organic, semi-metallic and metallic friction lining materials are now increasingly being used [2]. Thus to reduce or to completely eliminate the health risks posed by the asbestos in friction lining manufacture and to reduce the cost of friction linings, this work presents the development of an asbestos free friction lining material in which an agro based palm kernel shell [PKS] is used as base material. Thus to reduce or to completely eliminate the health risks posed by the asbestos in friction lining manufacture and to reduce the cost of friction linings, it is proposed by Ibhadode et al to develop an asbestos - free friction lining material in which an agro based material is going to be used as base material[3]. Chand et al. had carried out investigations to find an alternative to the Asbestos. They suggested that it can be replaced with suitable reinforcement and suitable formulation. Abrasive wear volume decreases with the decrease in ratio of filler and glass fibre in the non asbestos formulation. These also proved that asbestos free friction lining can be used for brakes and other friction lining applications [4]. Gbadam et al are done extensive investigations on the palm kernel shell to evaluate the properties of the PKS. The cracking of palm nut shell mostly depends on the moisture content in it. The PKS shell is completely dried out, then it is easy to crush into fine powder. Apart from this other physical and mechanical properties are also evaluated [5]. Dagwa, I.M et al developed an experimental setup for testing the performance of the brake pad material [6]. Sivarao et al designed and developed brake pad wear monitoring system for successful testing and validation. In this the embedding of sensor at the manufacturing level into the brake pad is suggested. A method for manufacturing a brake pad comprised of casting back plate in the mould. The plate is formed with at least one integral projection which overhangs an adjacent surface of the plate [7]. As mentioned in [8], Bunker et al had opted patents for the adhesive used in the manufacturing process. Thus this paper presents the development of a new friction material and testing of it in order to achieve better functionality as a friction material by doing investigation on the selection of ingredients and their composition levels. 2. EXPERIMENTATION Palm kernel shells are derived from the oil palm tree (elaeis guineensis), an economically valuable tree. Palm kernel shells have been used as aggregates in light and dense concretes for structural and nonstructural purposes. The palm kernel shells were obtained from the local market and crushed to remove the seeds. The base raw material, PKS, was collected and cleaned thoroughly to remove impurities. It was crushed and ground to a fine powder, and sieved using sieve. Physical and mechanical properties like particle size distribution, are then determined in the laboratory. The physical properties of palm kernel shell are shown in table 1. The base material for formulation is palm kernel shell which is an agro waste. Apart from PKS, the other materials used are Sulphur, Quartz, Iron Ore, and Ceramics. The design of brake lining and deign of brake shoe are shown in Fig. 1 and Fig. 2. In Fig. 1, the actual drawing with dimensional tolerances of the brake lining material which is going to be manufactured is shown. The brake shoe on which the manufactured friction lining is going to be attached is shown in Fig. 2. About eight trial formulations were initially made for preliminary test. After trial formulations, a fairly good composition was arrived at, which was used for determining the manufacturing parameters. The dies required for pressing of composite material are manufactured which are shown in Fig.3. Four brake pads based on this formulation were made using four different sets of manufacturing parameters. Property Table 1 Physical Properties of Palm kernel shell Value Bulk density Mg/m Dry density Mg/m Void ratio (%) 0.40 Porosity (%) 28 Water content (%) 9 Water absorption (%) 14 Specific gravity 1.62 The composition used for making of brake pad is shown in table 2. After composition of the brake pads they were mixed and sent for hydraulic pressing. The pressing is performed by using Universal Testing Machine (UTM) as shown in Fig. 4. The UTM used is of 40T capacity and is hydraulically operated. They

3 Development of a New Bio-Degradable Friction Material for Brake Pads from Palm Kernel Shell 3 were pressed hard at molding temperatures and then were sent for heat treatment. The structure of the brake pad after pressing is shown in Fig. 5. Once the pressing is over in UTM, it is allowed to dry out over a duration of 6-8hrs.The various factor levels for manufacturing parameters are shown in Table.3. The fixture developed for applying pressure during heat treatment is shown in Fig. 6. The specimen is heated to the required temperature in an electrical furnace as shown in Fig. 7. The heating temperature range is C. After the heating is over it is allowed to cure. The final brake pad is shown in Fig. 8. Then further tests were conducted on them using a test rig as in Fig. 9 which led to identification of optimum formulation for friction lining. Figure 1: Design of Brake Lining Table 2 Composition of the Brake Pad Material S. No. Material Quantity(%) 1 PKS J+1 2 CACO 3 i-1 3 Ceramics B 4 Quartz D 5 Carbon black A Table 3 Factor Levels for the Manufacturing Parameters S. No. Factors Brake pad 1 Brake pad 2 Figure 2: Design of Brake Shoe 1 Molding pressure 41KPa 48KPa 2 Molding Temperature C C 3 Heat treatment time 23 min 21 min 4 Curing Time 5 hrs 7 hrs Figure 3: Dies Used to Make the Friction Pad Figure 4: Universal Testing Machine

4 4 International Journal of Mechanical Engineering and Materials Sciences Figure 5: The Brake Pad (Before Heat Treatment) Figure 8: Final Brake Pad Developed from Palm Kernel Figure 6: The Fixture used to Apply Pressure during Heat Treatment Figure 9: The Experimental Test Rig used for Performance Testing performance was compared with that of the premium asbestos-based commercial brand of brake pads. Figure 7: The Electric Furnace used for Heat Treatment 3. RESULTS AND DISCUSSION Brake pad specimens were formulated according to the experimental design layout. Tribological tests like determination of coefficient of friction and wear rate on each specimen were carried out. The optimum level settings for the ingredients were determined. Actual values of ingredients were used for the optimum formulation of the brake pad. Its 3.1. Brake Pad Test Setup The major laboratory equipment used was a brake pad test rig [refer Fig. 9], which was manufactured for determining the brake pad wear and braking time under different braking conditions. The functional characteristic values of laboratory brake pad and commercial brake pad were evaluated under similar working conditions. The test rig was used to determine the performance of the brake pads produced with the optimum manufacturing parameters and optimum composition. The pads were tested for wear and disc stopping time. The brake pad test rig has a one horse power (1 H. P.) motor. The motor provides the energy required to set the flywheel weights and the brake disc in angular motion. When a set of brake pad is

5 Development of a New Bio-Degradable Friction Material for Brake Pads from Palm Kernel Shell 5 fixed into the brake caliper assembly of the test rig, the system is switched-on and the drive shaft begins to rotate, it is then allowed to attain a desired speed. Thereafter, a manual force is applied on the brake pedal which is similar to that of a motor car. Subsequently the stopping time and brake pad material lost are recorded and reported Vehicle Braking Test Actual braking tests with the laboratory and commercial, brake pads were carried out at different vehicle speeds of 20, 30, 40, 50, 60, 70, 80, 90 and 100km/hour. Pad wear, disc temperature rise and stopping time were measured at the above speeds. Constant brake pressure was assured by using a fixed brake pedal travel during the tests Stopping Time Vs Vehicle Speed The test rig was used to perform static tests at a constant speed of 676 rpm of the drive shaft and a brake line pressure of 0.3MPa. Four braking applications were performed to obtain each set of measurements for pad wear, stopping time. The Figure.10 compares the effects of vehicle speed on brake pad wear and stopping time for the laboratory and commercial brake pads. The average material loss per application of the laboratory pad (4.4mg) compared well with that of the commercial pad (4.1mg). The deviations of the laboratory and the commercial pads tested from the quoted value are 46.7% and 36.7% respectively. values of the ingredients indicated and were used for the optimum formulation of the brake pad. Its performance was compared with that of the premium asbestos-based commercial brake pad which is shown in Fig. 10. The values obtained are tabulated in Table.4. The figure shows that the laboratory pad had greater wear than the commercial pad at relatively high speeds especially at speeds higher than 80 km/ hour. Table 4 Comparison of Functional Characteristics of Developed and Commercial Brake Pad S. Functional characteristic Developed Commercial No. brake pad brake pad 1 Wear (Amount of material) 4.2 mg 4.1 mg 2 Coefficient of friction Average disk temperature rise C C 4 Average stopping time 4.1sec 4.2 sec (at80kmph) 4. CONCLUSIONS This work presents the manufacturing of an asbestosfree friction lining material in which an Agro-waste (palm kernel shell) was used as the base material. Palm kernel shells can be used as partial replacement for asbestos in friction material formulation which will be helpful in reducing or controlling the environmental pollution to some extent. A friction lining material based on PKS as a substitute for Asbestos has been developed. The mechanical and physical properties compare well with Commercial asbestos-based friction lining material. Its performance under static and dynamic conditions is compared well with the asbestos-based lining material. PKS has a coefficient of friction (0.41), which falls within that expected for friction materials. However, further refinement of the PKS lining formulation is recommended in order to have a comparable wear rate at higher vehicular speed. Figure 10: Vehicle Speed Vs Stopping Time Graph for Developed Friction Material 3.4. Comparisons between Laboratory Brake Pad & Commercial Brake Pad Brake pad specimens were formulated according to the experimental design layout in Tribological tests (determination of coefficient of friction and wear rate) on each specimen was carried out. The optimum level settings for the ingredients were determined. Actual REFERENCES [1] Nakagawa, T., Suzuki, K., Ito, K., Ishi, M. and Yanada, M., Development of Technology for Producing Short- Length Metal Fiber by Chatter Machining, Research and Development in Japan, The Okochi memorialprize, 1986, pp [2] Blau, P. J., Compositions, Functions and Testing of Friction Brake Materials and their Additives. Being a report by Oak Ridge National Laboratory for U.S. Dept of Energy, [3] A. O. A Ibhadode, I. M. Dagwa, Development of Asbestos Free Friction Lining Material from Palm Kernel Shell, Journal of Brazilian Society of Mechanical Science and Engineering, 2008, Vol. XXX, No. 2, pp

6 6 International Journal of Mechanical Engineering and Materials Sciences [4] Dr N. Chand, Dr. S. A. R. Hashmi, S. Lomash, A. Naik, Development of Asbestos Free Brake Pad CSIR, Vol. 85, [5] Eric Kofi Gbadam, Simons Anthony, Elias Kwasi Asiam, The Determination of Some Design Parameters for Palm Nut Crackers European Journal of Scientific Research, 2009, 38(2), [6] Dagwa, I. M., Ibhadode, A. O. A., Design and Manufacture of Automobile Disk Brake Pad Test Rig, Nigerian Journal of Engineering Research and Development, [7] Sivarao, M. Amarnath, M. S. Rizal, A. Kamily, An Investigation Toward Development Economical Brake lining Alert System, IJET, 9(9). [8] Kenneth James Bunker, John David Holme, Manufacture of Brake Pads United States Patent, 2001.