investigation of wear behavior on coated … · carbide inserts subjected to ... india abstract:...

Investigation of Wear Behaviour on Coated and Non-coated Carbide ...F F

Journal of Metallurgical Engineering, 1(1-2) January-December 2011 1

INVESTIGATION OF WEAR BEHAVIORON COATED AND NON-COATEDCARBIDE INSERTS SUBJECTED TOLOW TEMPRATURE TREATMENT

Sandeep Gandotra1, Jagdev Singh2 and Simranpreet Singh Gill3

1,2,3Department of Mechanical Engineering, Beant College of Engineeringand Technology, Gurdaspur-143521, Punjab, India

Abstract: Cryogenic treatment has shown significant resultssince many decades. It is an effective method for improving lifeof various cutting tools by cooling below room temperatures.In this investigation, an attempt has been made to evaluate theeffect of deep cryogenic treatment (DT) at –196°C and shallowcryogenic treatment (ST) at –110°C on tool life of uncoated (UC),Al2O3 coated and TiCN coated carbide tools by studying flankwear. To evaluate the cutting life of tools, high carbon highchrome (HCHCr) steel was turned on conventional lathe usingthe different tools. The study of the tool life was as per ISO3685-1993. The DT tools showed more favorable results thanST tools at all the selected cutting speeds in case of UC toolswhere as it is interesting to note that the coated tools performedbetter when subjected to ST as compared to UT and DT.

Keywords: Deep Cryogenic Treatment, Shallow CryogenicTreatment, Flank Wear

1. INTRODUCTIONMetal cutting industries essentially try for high material removalrate (MRR) and best products quality. The major problems inachieving high productivity and best quality are short life span oftool. To enhance the tool life many new materials are developed soas to meet market demand and competitive price. For this there

Sandeep Gandotra, Jagdev Singh and Simranpreet Singh GillF F

2 Journal of Metallurgical Engineering, 1(1-2) January-December 2011

should be proper control over various costs involved in themachining named as material cost, labour cost and tooling cost.Material cost can be controlled by using special materials whichmeet all required properties with reduced price. New technologieslike automation and CNC technology reduces the labour cost.Tooling cost involved the cost of new tool, tool changing cost,regrinding cost and depreciation cost. So tooling cost can beminimized by improving tool life and wear resistance. The toolmaterial commonly used in industry is high speed steel, ceramics,carbides, cast cobalt, diamond etc.

To increase productivity and to machine difficult materialtungsten carbide is most acceptable material available which wasfirstly used in 1926. Tungsten carbide is hard refractory materialused for metal cutting, metal forming, rock drilling and miningoperation the cutting tool life has a major role for productivityimprovement and is an important economic factor. In order toincrease the tool life generally heat treatment and coating is doneon cutting tools. A very recent approach to improve the tool life isthe application of cryogenic treatment in the deep stage andshallow stage.

The word cryogenics is derived from the word “kryos”(means cold) and “Genes” (means born). It is an effective method toenhance mechanical as well as physical properties of the materialby cooling down the tool to temperature about-196°C at a gradualrate and maintained at that temperature for long time about 24 hrsand then brings back to room temperature by heating as shown inFig. (1).

Fig. 1: Cryogenic Cycle



Cryogenic temperatures are defined by cryogenics society ofAmerica as the temperature below 120°K the cryogenic treatmentimproves the tool wear resistance, toughness and reduces the costof production [1].

Cryogenic treatment, the discipline upon which the presentstudy is based, can be considered a recent development [2–6].Tungsten carbide inserts respond significantly well to the cryogenictreatment. Reddy et al. [7] observed the improvement in life ofnormal and deep cryogenically treated carbide inserts by an amountto 9.58% and 21.8%, respectively. They studied the improvement intool life of cryogenically treated P-30 tungsten carbide inserts andconcluded that precipitation and distributions of the η phase aftercryogenic treatment have improved the flank wear resistance. Alsothey observed a slight increasing grain size which increases thetoughness. In another study, Yong et al. [8] cryogenically treatedtungsten carbide milling inserts and found 28.9–38.6% increase intool life. They confirmed that, in contrary to steels, there is nomartensite phase in tungsten carbide, as such; any improvement intool life or wear resistance would be due to other mechanisms. Yonget al. [9] showed that cryogenic treatment no doubt improves theresistance to chipping of tools and to a less significant extent,improves flank wear resistance. They stated that tools under mildcutting conditions stand to gain from cryogenic treatment, but heavyduty cutting operations with long periods of heating of the cuttingtool will not benefit from it. Seah et al. [10] implemented thecryogenic treatment on cobalt-bonded tungsten carbide (Co-WC)and found that the treated tools were superior to those of theuntreated as-received inserts at high cutting speeds. From this study,they concluded that cryogenic treatment of tungsten carbide insertsincreased the number of η phase particles, a theory which theysupported with photo-graphs taken using a scanning electronmicroscope. They assigned this as a reason for reducing transverserupture strength hence greater resistance to chipping, improvedresistance to plastic deformation during cutting, and lowertoughness. After experimental evaluation of comparative



performance of cryogenically treated TiCN-coated carbide insertsand Kennametal Grade KC 990 inserts by gas in fusion process(dry process); Bonilla et al. [11] also succeeded in enhancing thetool life. Work by Quek [12] also agreed with the findings of theseauthors. Kao [13] also reported increase in abrasion wear resistanceof sintered tungsten carbides after cryogenic treatment. Bryson [14]attributed the wear resistance, and hence the increase in tool life, ofcarbide tools to the improvement in the holding strength of thebinder after cryogenic treatment. He believes that cryogenictreatment also acts to relieve the stresses introduced during thesintering process under which carbide tools are produced. However,Bryson also warned that under certain conditions, cryogenictreatment would have little or no effect on carbide tools, such aswhen reprocessed carbides are used. Stewart [15] applied cryogenictreatment to C2 tungsten carbide (6%Co) and compared withuntreated carbide to determine if tool wear could be reduced duringturning tests with medium density fiber board. Both the tool forcedata and observation of the cutting edges indicate that tool wearwas reduced. He postulated that the cryogenic treatment appearedto have an effect upon the cobalt binder by changing phase or crystalstructure so that more cobalt binder was retained during cutting.Gallagher et al. [16] analyzed the micro structural alterations of α(tungsten carbide), β (cobalt binder), γ (carbide of cubic lattice) andη (multiple carbides of tungsten and at least on metal of the binder)phases within the tungsten carbide tools caused by the cryogenictreatment, and links these changes to the corresponding enhancedtool life. Nikhil R. et al. [17] done Cryogenic cooling by liquidnitrogen jets on uncoated carbide inserts of different geometricconfigurations results in substantial reduction in tool wear, whichenhanced the tool life, dimensional accuracy and surface finish. Thismay be mainly attributed to reduction in cutting zone temperatureand changes in the chip-tool interaction K.A. Venugopal et al. [18]performed the Cryogenic machining with liquid nitrogen as coolantto reduce the cutting zone temperatures and enhance the tool life.Cryogenic cooling by liquid nitrogen jets enabled substantial



improvement in tool life through reduction in adhesion-dissolution-diffusion tool wear through control of machining temperaturedesirably at the cutting zone. Ali Khan, et al. [19] explained thathigh material removal rate, good work surface finish and low toolwear can be achieved by reducing tool wear using proper coolingsystem of the tool during machining. In the present work a tool hasbeen modified to apply liquid nitrogen as coolant through a holemade in the tool so that liquid nitrogen can be directly applied tothe machining zone. It was found that the tool life increases morethan four times by applying liquid nitrogen using the modified tool.Vadivel et al. [20]. Analyses of the various performances ofCryotreated coated carbide inserts and untreated coated carbideinserts in turning of nodular cast iron shows that Cryotreated coatedcarbide inserts exhibit better performance based on the surfaceroughness of the work specimen, power consumption, and flankwear than the Untreated ones. D. Das et al. [21]. The wearexperiments on AISI D2 steel samples subjected to cryotreatment at77K for different durations shows that there is a ‘critical timeduration’ for achieving the best wear resistance. Sreerama Reddy,T. et al. [22]. When coated tungsten carbide ISO P-30 turning toolinserts were subjected to deep cryogenic treatment at –176°C andmachining of the C45 steel work piece is evaluated by using bothuntreated and deep cryogenic treated tungsten carbide cutting toolinserts in terms of flank wear of the cutting tool inserts. The flankwear of deep cryogenic treated carbide tools is lower than that ofuntreated carbide tools on machining of C45 steel. Gill S.S, et al.[23] showed that the cryogenically treated tungsten carbide insertsperforms significantly better in wet turning conditions under bothcontinuous and interrupted machining modes especially at highercutting speeds and interrupted machining mode exhibit increasedtool than continuous machining mode. From the review of theliterature it is difficult to compile the existing results to achieve anyunified picture. Thus, the major aims of this investigation is toaddress this problem through organized and systematic comparativewear experiments in accordance with Internal Organization of



Standards(ISO) 3685 on Deep-treated, Shallow and untreated singlepoint tungsten carbide Uncoated, Al2O3 Coated and TiCN Coatedcutting tool.

2. EXPERIMENTATIONThe material considered for the study was high carbon high chromesteel which is used for high strength column and shafts of highhardness. The cutting tool material used for machining is tungstencarbide in coated and uncoated form to check the influence ofcryogenic treatment on coated and uncoated carbide inserts. Toolshave been subjected to two different computerized controlledcryogenic treatment conditions, Such as, shallow cryogenic treatment(ST) and deep cryogenic treatment (DT) by cooling down to –110°Cand –196°C with soaking period of 18 hrs and 38 hrs respectively,then brought back to room temperature by heating, followed bytwo tempering cycles consisting of heating to 150°C then bring backto room temperature. In order to avoid thermal shocks from rapidcooling and heating, the specimens were cooled down and heatedup slowly, to and from the cryogenic temperature (–110°C and –196°C) at the rate of 0.5°C/min and the tools were not exposed toliquid nitrogen. The high carbon and high chrome material issubjected to single point carbide cutting tools in coated, uncoated(UT), shallow treated (ST), deep treated (DT) as per standard ISO3685. The tool inserts used for this experiment are given in Table 1

Table 1Tungsten Carbide Tool Inserts Used in Experimentation

S. No. Tool Inserts Used Cryogenic Treatments1. Uncoated tungsten carbide insert UT ST DT2. AL2O3 coated tungsten carbide insert UT ST DT3. TICN Coated Tungsten Carbide Insert UT ST DT

The experimentation was done on high speed conventional lathewith square shaped carbide Insert with tool signature as shown inTable 2, and machining conditions are as shown in Table 3.



A stop watch was used to register the machining time for eachrun. After every 3 min the flank wear was measured in tool maker'smicroscope after stopping the machine. The above procedure isrepeated until the flank wear comes to 0.4 mm. The total machiningtime to reach 0.4 mm flank wear was considered to be average toollife of insert.

3. RESULTS AND DISCUSSIONSDuring machining the flank wear of cryotreated (DT and ST) anduntreated (UT) tools was examined at fixed intervals, i.e. after3 min for interrupted machining mode, and between duration ofcutting, there was a 10 min break to allow the tool to cool. Theobjective of introducing breaks was not to postpone the machiningprocess rather than studying the impact of repeated breaks on theoverall service life of tools by deliberately allowing the tool to cool.Here, it is important to be noted that the time consumed by thebreaks has not been included in calculating the service life of toolsand the results were obtained at each selected cutting speed.

Table 2Tool Signature

S. No. Tool Signature Range

1. Inclination angle –10°2. Orthogonal rake angle –6°3. Orthogonal clearance angle 6°4. Auxiliary cutting edge angle 5°5. Principal cutting edge angle 95°6. Nose radius 0.8 mm

Table 3Machining Conditions

S.No. Cutting Parameter Values

1. Cutting velocity 110 – 180 m/min2. Feed 0.1 mm3. Depth of Cut 1 mm4. Cutting method Dry cutting



Following curves have been plotted for average flank wear atselected cutting speed one each for UT, ST and DT of uncoated,Al2O3 coated and TiCN coated tungsten carbide inserts as shownin Figs. 2-13

Fig. 3: Average Flank Wear Behavior of Al2O3 coated Inserts at 110m/min

Fig. 2: Average Flank Wear Behavior of Uncoated Inserts at 110m/min



Fig. 4: Average Flank Wear Behavior of TiCN Coated Inserts at 110m/min

Fig. 5: Average Flank Wear Behavior of Uncoated Inserts at 130m/min

Fig. 6: Average Flank Wear Behavior of Al2O3 Coated Inserts at 130m/min



Fig. 7: Average Flank Wear Behavior of TiCN Coated Inserts at 130 m/min

Fig. 8: Average Flank Wear Behavior of Al2O3 Coated Inserts at 150 m/min

Fig. 9: Average Flank Wear Behavior of Uncoated Inserts at 150 m/min



Fig. 10: Average Flank Wear Behavior of TiCN Coated Inserts at 150 m/min

Fig. 11: Average Flank Wear Behavior of Uncoated Inserts at 180 m/min

Fig. 12: Average Flank Wear Behavior of Al2O3 Coated Inserts at 180 m/min



It has been observed that the shallow cryogenic treatment (ST)and deep cryogenically treated (DT) on uncoated tools exhibitsremarkable high tool life of 46.57% and 52.15% respectively. TheDT has shown improved results by 24.14% as compared to ST. It isquite evident from this investigation that the cryotreated (DT & ST)tools experience longer tool life, however the maximum improve-ment was observed in the deep cryogenically treated (DT) tools asin Fig. 14.

Fig. 13: Average Flank Wear Behavior of TiCN Coated Inserts at 180m/min

Fig. 14: Tool Life Comparison of Uncoated (UT, ST, and DT)Tungsten Carbide Inserts

In this part of the investigation on Al2O3 coated tools, ST of thecutting tool has shown improved tool life of 123.77 % higher than



untreated one, whereas DT has shown negative results of about53.32 % lesser life than untreated ones and 73.33% lesser than STtools as shown in Fig. 15. It is very clear from this investigation thatthe ST tools experience longer tool life than untreated ones and DTexhibit poor tool life even than untreated carbide inserts. This iscontrary to the findings of Bonilla et al. [11].

Fig. 15: Tool Life Comparison of Al2O3 Coated(UT, ST, DT)Tungsten Carbide Inserts

In the investigation on TiCN coated cutting tools, ST tool hasshown improved tool life of 23.20% higher than untreated one,whereas DT has also shown negative results of about 52.36% lesserlife than untreated ones and 65.09% lesser than ST tools as shown inFig. 16. ST of TiCN tools also experienced longer tool life thanuntreated ones and DT exhibit poor tool life even than untreatedcarbide inserts.

Fig. 16: Tool Life Comparison of TiCN Coated (UT, ST, DT)Tungsten Carbide Inserts



It is very obvious that low temperature treatment is very effectivefor the materials but poor performance of coated tools seems due tocrack generation in the thin layer of coating, when these are kept atvery low temperature for a longer period of time as in case of DTwhereas ST do not develop such cracks, as temperature and timefor which it is kept is less as compared to DT.

3. CONCLUSIONS1. The cryogenic treated uncoated inserts have shown higher

tool life than untreated inserts as deep treated shows ahigher improvement upto 52.15% and shallow treated showsupto 46.56% in terms of tool life.

2. The ST of Al2O3 coated inserts have shown higher tool lifethan untreated inserts as ST shows a highly significantimprovement of 123.77% in tool life, DT has shown lessertool life upto 53.32 than untreated ones.

3. The ST of TiCN coated inserts have also shown higher valuein tool life of 23.20% as compare to untreated insertswhereas DT tools have shown lesser tool life to 52.36% thanuntreated ones.

4. It can be concluded that ST is quite effective in case of coatedtools whereas DT shows better results on uncoated tools.

5. Al2O3 coated inserts seems to be more effective with ST ascompared to TiCN coated inserts.

REFERENCES[1] Alexandru G., Baciu Ailincai C: “Influence de Traitements Thermiques a Basse

temperature sur la Duree de vie des Aciers a Outils a Coupe Reapide Tries”,Memoires Etudes Scientifiques Revue de Metallurgie, (1990), 283-388.

[2] Barron R.F., “Low Temperature Properties of Engineering Materials inCryogenic Systems”, McGraw-Hill, New York, (1996), 15-23.

[3] Albert M., “Cutting Tools in the Deep Freeze”, Mod. Mach. Shop 64 (8) (1992),55-61.

[4] Sweeny T.P., “Deep Cryogenics: The Great Cold Debate”, Heat Treat. 18 (2)(1986) 28-32.



[5] Kosmowski M., “The Promise of Cryogenics”, Carbide Tools (1981), 26-30.[6] Collins D.N., “Deep Cryogenic Treatment of Tool Steels”, A Review, Heat

Treat. Met. 2 (1996), 40-42.[7] Reddy T.V.S., Ajay Kumar, B.S. Reddy, M.V., Venkataram R., “Improvement

of Tool Life of Cryogenically Treated P-30 Tools”, Proceedings of the InternationalConference on Advanced Materials and Compositees (ICAMC-2007) at NationalInstitute for Interdisciplinary Science and Technology, CSIR, Trivandrum, India,(2007), 457-460.

[8] Yong A.Y.L., Seah K.H.W., Rahman M., “Performance of CryogenicallyTreated Tungsten Carbide Tools in Milling Operations”, International Journalof Advance Manufacturing Technology, 32 (2007) 638-643.

[9] YongA.Y.L., Seah K.H.W., Rahman M., “Performance Evaluation ofCryogenically Treated Tungsten Carbide Tools in Turning”, InternationalJournal of Machine Tools Manufacturing, 46 (2006) 2051-2056.

[10] Seah K.H.W., Rahman M., Yong K.H., “Performance Evaluation ofCryogenically Treated Tungsten Carbide Cutting Tool Inserts”, Proc. Inst.Mech. Eng. Part B: Journal of Engg. Manufacturing, 217 (2003) 29-43.

[11] Bonilla C., Meara R.O., Perry L., “Evaluation of the Comparative Performanceof Cryogenically Treated Cutting Inserts as a Capstone Design Project”, ASEEAnnual Conference and Exposition, Conference Proceedings, (2007) 9.

[12] Quek T.W., “Machining of Steel Using Cryogenically Treated Cutting ToolInserts”, Ph.D. Thesis, National University of Singapore, Singapore, (2004).

[13] Kao M., Z. Palmai, “The Effect of Cryogenic Treatment on Sintered TungstenCarbide”, Master Thesis, Arizona State University, USA, Cutting Temperature inIntermittent Cutting, International Journal of Machine Tools Manufacturing, 27(2),(1987), 261-274.

[14] Bryson W.E., “Cryogenics”, Hanser Gardner Publications, Cincinnati, OH,(1999), 81-107.

[15] Stewart H.A: “Cryogenic Treatment of Tungsten Carbide Reduces Tool WearWhen Machining Medium Density Fiberboard”, Prod. J. 54(2) (2004) 53-56.

[16] Gallagher A.H., Agosti C.D., Roth J.T., “Effect of Cryogenic Treatments onTungsten Carbide Tool Life: Microstructural Analysis”, Trans. North Am.Manuf. Res. Inst. SME 33 (2005) 153-160.

[17] Nikhil R., Dhar Islam, Sumaiya Kamruzzaman, M.D., Paul Soumitra, “WearBehavior of Uncoated Carbide Inserts under Dry, Wet and Cryogenic CoolingConditions in Turning”, C-60 Steel Technical Editor: Anselmo E. Diniz , Vol.XXVIII, No. 2, (June 2006), 146-152.

[18] Venugopal A.S., Chattopadhyay Paul A.B., “India Tool Wear in CryogenicTurning of Ti-6Al-4V Alloy Cryogenics”, 47 (2007), 12-18.

[19] Ahsan Ali Khan, Mirghani I. Ahmed, “Improving Tool Life Using CryogenicCooling”, Journal of Materials Processing Technology, 196 (2008) 149-154.



[20] Vadivel Rudramoorthy R., “Improvement of Tool Life of CryogenicallyTreated P-30 Tools International Conference on Advanced Materials andComposites (ICAMC-2007), Performance Analysis of Cryogenically TreatedCoated Carbide Inserts”, International Journal Advanced ManufacturingTechnology, (2008), 222-232.

[21] Das D., Dutta A.K., Ray K.K., Influence of Varied Cryotreatment on the WearBehavior of AISI D2 Steel Wear 266 (2009) pp. 297-309.

[22] Sreerama Reddy T., Sornakumar M., Reddy Venkatarama, and VenkatramR., “Machinability of C45 Steel with Deep Cryogenic Treated TungstanCarbide Cutting Tool Inserts”, International Journal of Refractory Metals andHard Materials, Vol. 27, (2009), 181-185.

[23] Gill S.S., Singh R.S., Singh Harpreet, Singh Jagdev., “Wear Behaviour ofCryogenically Treated Tungsten Carbide Inserts Under Dry and Wet TurningConditions”, International Journal of Machine Tools and Manufacturing, 49(3-4),(2009), 256-260.

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