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  • 1. Ravinder Pal Singh, Pankaj Sharma Attri, Upinder Kumar Yadav, Sandeep Kumar / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 3, Issue 1, January-February 2013, pp.308-311 Development of self lubricating Cutting tool material for machining polymer matrix materialRavinder Pal Singh, Pankaj Sharma Attri, Upinder Kumar Yadav, Sandeep Kumar (Department of Mechanical Engineering, M.M.University, Mullana - Ambala, Haryana (India))ABSTRACT Dry machining i.e. without use of cutting spacecraft bearings. Evans and Senior [3] reportedfluid has been accepted as most preferred option the performance in plain bearing applications offor clean manufacturing environment and commercially available self-lubricating materials,precision machining in space, electronics and including PTFE and other plastics and metalsmedical applications. In dry machining, there will containing solid lubricants. Todd [4] reported thebe more friction and adhesion between the tool performance of three specific lubricants, whichand work piece. In this work, an attempt has account for the majority of applications: PTFE-been made to develop self lubricating cutting tool composite, RF-sputtered MoS2 and ion plated leadmaterial for machining polymeric composites. film, and then compared in terms of durability andPowder metallurgy technique is chosen for torque characteristics.manufacturing the self lubricating cutting toolmaterial. With the tungsten carbide as base Paxton [5] investigated the operating limits,material and cobalt as binder material, solid physical properties of carbon, graphite and metal-lubricant material, molybdenum di-sulphide bonded molybdenum disulphide solid lubricant(MoS2) material is added during milling. Milling bearings and recommended design practices and lifeas well as compaction characterization is carried expectancy. He et at. [6] developedout to understand the influence of material and polyoxymethylene/molybdenum disulphideamount of solid lubricant material. Addition of composite and investigated tribological behaviour tosolid lubricant material found to improve the utilize as self lubricating bearing material. Self-compaction characteristics. Load deflection curve lubrication bearing materials with MoS2 nano-ballsof compaction and powder morphology showed better tribological properties under selectedconfirmed this behavior. Compacted specimens testing conditions than those with micro-MoS2were sintered at controlled atmosphere and platelets. Du et al. [7] developed a coating ofsintering characterization is done. When the tungsten carbide, cobalt and molybdenum disulphideamount of cobalt is less than a particular amount mixture and investigated the friction and wearvisible cracks were found. Micro structure of behaviour under sliding condition. It is found thatsintered part confirmed the improvement of theMoS2 composition disperses homogeneously insintering due to the presence of solid lubricant the coating, which results in the decreasing hardnessmaterial. and fracture toughness for the coating. Dhanasekaran and Gnanamoorthy attempted toKeywords: Cutting fluid, Dry machining, Milling, develop sintered steel with self lubricatingPolymeric composite, Powder metallurgy, Self characteristics [8-10]. Iron-copper-carbon sinteredlubrication, Solid lubricants. steels with MoS2 are prepared through powder metallurgy route, wherein microstructure,I. INTRODUCTION: mechanical strength is reported. Addition of MoS2 In the recent years, many works has been found to improve compressibility and part densityattempted to develop self lubricating material for the [8]. Sintered steel containing 3 % MoS2 exhibitedvarious applications such as bearings, gears, cutting reduction in coefficient of friction whereas attool and coating [1-10]. sintered steel containing 5 % MoS2 material causes severe three body contact due to the excessive Agostino et al. [1] reported the tribological formation of brittle phases [9]. The abrasive wearproperties of sintered iron bearings self-lubricated behavior of sintered steel with MoS2 at differentwith perfluoropolyethers under severe operating normal loads is reported [10]. MoS2 added materialconditions [1] .The performance of the PFPE- exhibited high coefficient of friction and good wearlubricated bearings was found to be superior to that resistance compared to the base composition.bearings lubricated with mineral oil. Hopple andLoewenthal [2] reviewed the development and In the present work, attempt has been madeproblems encountered in applying recently to develop tungsten carbide cutting tool materialdeveloped sputtered MoS2 films to precision with self lubrication characteristics by powder 308 | P a g e
  • 2. Ravinder Pal Singh, Pankaj Sharma Attri, Upinder Kumar Yadav, Sandeep Kumar / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 3, Issue 1, January-February 2013, pp.308-311metallurgy technique, wherein compaction andsintering characteristics of the proposed mixture isreported 40 0 % MoS2II. MATERIALS AND PROCESSING: 3 % MoS2 Tungsten carbide (WC) of 1-6µm size with 30 Load (kN)99.8% purity (Rapicut carbides) as base material,Cobalt (Co) of 1-6µm of size with 99.5% purity 5 % MoS2(Loba Chemie) as binder material , molybdenum 20disulphide(MoS2 ) of 10µm with 98% of purity 7 % MoS2(Loba Chemie), as lubricant materials are chosen forthe proposed cutting tool material. To understand the 10effect of binder and solid lubricant on the proposed 10 % MoS2material over mechanical properties of the proposedcutting tool material, three different proportion of 0cobalt and five different proportions of molybdenum 0 1 2 3 4 5 6disulphide mixtures are chosen. Weight percentage Ram displacement(mm)of cobalt is chosen as 5 and 10 and weightpercentage of molybdenum di sulphide is chosen as Figure 1: Load and displacement plot of0, 3, 5, 7 and 10 %. compaction test compacted at 40 KN Process control agent, stearic acid of 4gms The presence of MoS2 in the test materialis added to the mixture to avoid cold welding during alters the compaction behaviour, from the slope ofmilling. The proposed powders are milled in the the second and third stage of load deflection curve, itplanetary ball mill (Insmart system) under nitrogen is apparent that presence of MoS2 found to improve(0.5kg/cm²) atmosphere, with plate and bowl speed compaction, higher amount of MoS2 contribute to90 and 207 rpm for 40 hrs and the powder to ball improve compaction further. Presence of MoS2 inratio is fixed as 1:5.Plate speed and powder ball ratio the mixture found to reduce the particle size andis decided to avoid iron pickup during milling reported elsewhere (PFAM Conference Ref).(PFAM Conference Ref). Effect of milling time and Rigidity of compacted specimen also confirms thatdistribution of powder is investigated and reported test material without MoS2 and test material withwith the aid of powder morphology, XRD and SEM small amount of MoS2 (3%) is found to be poor.and reported elsewhere (PFAM Conference Ref)..After completion of milling the powder is heated to Hence there is a need to mill these materials beyondremove the PCA agent stearic acid in the powder in 40 hours so that they can be compacted into rigidthe in house dewaxing unit up to 300°C in a vacuum specimens.atmosphere with a holding time of 30 min. IV. SINTERING CHARACTERISTICS:III. COMPACTION CHARACTERISTICS: The compacted rigid test specimens are Dewaxed test powders are uniaxially sintered (Okay, Bysakh) in the controlledcompressed (UTE 20) into rectangular transverse environment. The heating and cooling cycle of testrupture strength specimen of 40 X 16 X 5mm size as specimen is shown in figure 2. Heating rate isper the ASTM B331-95 at different loads, 40, 44, maintained at 3.2°C/min and sintering is carried outand 48 kN with displacement rate of 1mm/min. in the nitrogen (0.5kg/cm²) atmosphere to avoid theFigure 1 shows the load displacement curve of test oxidation. Test specimens with 5 % cobalt exhibitsspecimen compaction. From the figure it is infer that mild to severe cracks whereas specimens with 10 %the compaction take place in three stages. In the first cobalt doesn’t show any cracks as shown in figure 3stage, particle arrangement, take place which issignificantly influenced by the particle size andshape. In the second stage, elastic and plasticdeformation takes place which is influenced by thenature and purity of particles. In the third stage coldworking of the bulk material take place and issignificantly affected by deformation and workhardening of the particles. 309 | P a g e
  • 3. Ravinder Pal Singh, Pankaj Sharma Attri, Upinder Kumar Yadav, Sandeep Kumar / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 3, Issue 1, January-February 2013, pp.308-311 800 5 % MoS2 600 7 % MoS2 Load (N) 400 200 3 % MoS2 0 0 0.1 0.2 0.3 0.4 Deflection (mm)Figure 2: View of sintered specimens (a) 5 % Co, Figure 3: Transverse rupture strength of test5 % MoS2, (b) 5 % Co, 7 % MoS2, (c, d) 10 material%Co, 5 and 7% MoS2 Green and sintered density of test specimens wasTRANSVERSE RUPTURE STRENGTH, measured by the Archimedean principle. From theHARDNESS AND MICROSTRUCTURE OF results it is further confirmed that amount of MoS2SINTERED SPECIMENS significantly contributes to the compaction as well as density. When the amount of MoS2 increases in the Transverse rupture strength (TRS) of the test mixture, density as well as hardness is found totest material is evaluated as per the ASTM B406-96, be increased. At lower percentage of MoS2 thesince the proposed material is meant for the cutting formation of agglomerates is more by which thetool application using following equation bonding of particles are not even as with fine powders. As the percentage of MoS2 increase the 3 P  L compaction of powders is good with fine density by TRS  2t2  w which the liquid phase sintering of specimen is also performed well. Hardness of the sintered specimens was measured with the micro hardness tester where P is the force requires to rupture the (Micromet 2101. Buehler) with indented load of 50specimen (N), L is the length of the specimen spanof fixture (mm), W is width of the specimen (mm), gms as per the ASTM 3384T is thickness of specimen (mm) and TRS is 14transverse rupture strength (MPa).The sintered testspecimens of 3, 5and 7 % MoS2, were tested for 12transverse rupture strength (TRS) with loading rate Density( g/mm)-of 0.25mm/min. Test specimen with 7% MoS2 10 3exhibited superior strength 85.7MPa; followed by75.3MPa by 5% MoS2and 10MPa by 83%MoS2.These magnitude of strength reflects the Greenrole of MoS2in sintering. Figure 5 shows the 6 Sinteredmicrostructure of fractured sintered specimens,wherein the role of MoS2 is clearly exhibited 4 2 0 5 6 7 8 9 10 11 Amount of MoS2( %) 310 | P a g e
  • 4. Ravinder Pal Singh, Pankaj Sharma Attri, Upinder Kumar Yadav, Sandeep Kumar / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 3, Issue 1, January-February 2013, pp.308-311 The addition of solid lubricant MoS2 in the tungsten 100 carbide material for the self lubrication purpose is found to improve compaction as well as sinteringVickers Hardness (HV)- characteristics of the proposed material. 80 REFERENCES 60 [1] Agostino, V.D. Niola, V. and Caporiccio G.,” Tribological behaviour of sintered 40 iron bearings self-lubricated with PFPE under severe operating conditions,” Tribology International, 1998, 21 (2),105- 20 108. [2] Hopple, G. B. and Loewenthal, S.H., 0 “Development, testing and characterization 3 4 5 6 7 8 of MoS2 thin film bearings”, Surface and Amount of MoS2( %) Coatings Technology, 1994, 68-69, 398- 406. Figure 4: Influence of MoS2 (a) Green and [3] Evans, D.C. and Senior, G.S., “Self- Sintered density of test specimen and (b) lubricating materials for plain bearings”, Hardness of test specimens Tribology International, 1982, 15(5), 243- 248. [4] Todd, M.J., “Solid lubrication of ball bearings for spacecraft mechanisms”, Tribology International, 1982, 15 (6), 331- 337. [5] Paxton, R.R., “Carbon, graphite and metal- bonded molybdenum disulphide solid lubricant bearings”, Tribology International, 1982, 15(5), 285-292. [6] Hu, K.H. Wang, J. Schraube, S. Xu, Y.F. Hu, X.G. and Stengler, R., “Tribological properties of MoS2 nano-balls as filler in polyoxymethylene-based composite layer of three-layer self-lubrication bearing materials”, Wear, Volume 266, Issues 11- 12, 30 May 2009,1198-1207. [7] Du, H. Sun, C. Hua, W. Wang, T. Gong, J. Jiang, X. and Lee, S. W., “Structure, mechanical and sliding wear properties of WC–Co/MoS2–Ni coatings by detonation gun spray”, Materials Science and Engineering, 2007, A 445–446, 122–134 [8] Dhanasekaran, S. and Gnamoorthy, R., “Microstructure, strength and tribological behavior of Fe-C-Cu-Ni sintered steels prepared with MoS2 addition”, Journal of Material Science 2007, 42, 4659-4666. [9] Dhanasekaran, S. and Gnamoorthy, R., “Dry sliding friction and wear characteristics of Fe-C-Cu alloy containing molybdenum di sulphide”, Figure 5: Microstructure of sintered test Materials and Design, 2007, 28,1135-1141. specimens (a) 10 % Co, 5 % MoS2 and (b) 10 % [10] Dhanasekaran, S. and Gnamoorthy, R., Co, 7 % MoS2 “Abrasive wear behavior of sintered steels prepared with MoS2 addition”, Wear, 262 V. CONCLUSIONS: 2007, 617-623. Development of self lubricating cutting tool material for dry machining of polymer matrix material is attempted. 311 | P a g e