RESEARCHES TO IMPROVING TOOL LIFE OF THE CUTTING INSERTS COATED WITH TITANIUM THIN LAYERS

Transcription

1 RESEARCHES TO IMPROVING TOOL LIFE OF THE CUTTING INSERTS COATED WITH TITANIUM THIN LAYERS An BĂDĂNAC 1, Octvin LUPESCU 1, Vsile MANOLE 1 nd Ovidiu Toder RUSU 2 ABSTRACT: It is known tht the cutting tools wer more or less ccentuted in cutting processes my occur, due to the unevenness of the cutting depth, to the mchining prmeters vrition, s well s due to the existence or nonexistence of the coolnt oiling. The cutting tools lives eing influenced y ll these fctors in dominnt nd negtive mode, one cn impose ctions nd decisions to reduce the wer processes of the tools or/nd of the cutting inserts. For incresing the durility of the cutting inserts, there re known numerous reserches concerning their coting with mteril (ions) y vcuum deposition, using methods s therml evportion, ionic plting, pulveriztion or chemicl vpor deposition. The uthors propose to improve the cutting tools lives using the deposition method y ionic plting in vcuum (PVD) with thin titnium lyers, following the cutting tools ehvior in opertion treted in this wy. KEY WORDS: cride cutting inserts, tool life, titnium thin lyers, ionic plting, mchining test. 1 INTRODUCTION During the cutting process, the cutting tool wers out due to the high contct pressures, to the high tempertures, to the reltive high velocities nd shocks etween the contct surfces tool - workpiece, ut lso due to the mechnicl nd therml stresses which pper on the tool ctive fces, hving s effect the cutting cpcity loss nd the processing qulity diminishing. This is continuous nd evolutionry process, leding to grdully diminishing of the qulity prmeters performnce for the cutting tools, when wers out simultneously oth the side flnk nd tool fce (Dulău & Şoită, 2007; Mteescu, 1998). Tking into ccount these spects, in order to increse the durility of the cutting tools or of the metl cride inserts, respectively, in view of their reconditioning fter wer processes, one cn impose mesures of preventive mintennce, respectively corrective mintennce (Sărăriu, 2014). In this direction, the deposition of some mterils such re luminum, tungsten, titnium, chromium etc. my constitute method of mintennce tht provides the chievement of the pursued ojectives, the method eing of current interest in the reserches t the glol 1 Universitte Tehnică Gheorghe Aschi din Işi, Fcultte de Construcţii de Mşini şi Mngement Industril, Deprtmentul TCM, Blvd. D. Mgeron 59A, , Işi, Români 2 Universitte Stefn cel Mre din Sucev, Fcultte de Inginerie Mecnică, Deprtmentul Mecnică Aplictă şi Tehnologii, str. Universităţii 8-9 Corp B, , Sucev, Români E-mil:dnc_n@yhoo.com; olupescu@tcm.tuisi.ro, vsile.mnole01@yhoo.com, rusu.o@fim.usv.ro level (Pop et l., 2010; Serro et l., 2009), nd one cn e interested lso in the results otined in the cse of different technicl pplictions such s: improving wer resistnce, developing nd using some lyers with opticl properties nd/or outstnding electricl, nno composite lyers with protective role or io-lyers used in medicine etc. In the lst decde, the generl trend consisted minly in the development nd deposition of some mterils in the form of multifunction thin lyers, hving to simultneously respond to severl requirements imposed y the conditions in which they re used (Purde, 2014). The coting lyers cn ct s chemicl nd therml rrier etween the tool nd the workpiece, incresing the tool wer resistnce, improving the chemicl inerti of the cutting mteril, reducing the volume of the cutting edge deposition, decresing the friction etween tool nd chips, contriuting in this wy to the cutting forces reduction. The thin lyers deposition using the vcuum s environment of developing the deposition process hd ig scension in the lst period. The first cotings used t industril scle in order to increse the wer resistnce of tools were mde, fter (Dulău & Şoită, 2007), of thin lyers of titnium nitride, minly used s triologicl cotings for cutting tools, ut lso s resistnt lyers t corrosion nd erosion. Currently, there re severl methods of pplying these lyers, their generl clssifiction grouping them (Sărăriu, 2014; Mteescu, 1998) in: chemicl vpor deposition processes (CVD) nd, respectively, physicl vpor deposition processes (PVD) (Sărăriu, 2014; Mteescu, 1998), ionic plting in vcuum eing prt of the second ctegory. 6 ACADEMIC JOURNAL OF MANUFACTURING ENGINEERING, VOL. 12, ISSUE 2/2014

2 2 METHOD AND EQUIPMENT USED In order to increse the durility of the cutting tools, for incresing the wer resistnce of the inserts used for mchining of the ering rings nd ers, the uthors proposed the deposition on these cutting inserts of some thin lyers of titnium, y the PVD method (ion plting method), following the ehvior improvement in the exploittion of the tools thus treted. The ion plting method is the process of deposition of thin lyers in which the sustrte is sujected to omrdment with ions of work gs, efore deposition nd, with ions of mteril of deposition nd of the work gs, during deposition (Mteescu, 1998). This method ws used due to its dvntges compring with other known nd possile methods to e pplied, dvntges etween which one cn enumerte: the reltively low costs of the equipment, the simplicity in opertion, the possiility to e used lso to relize reserch nd industril instlltions. For the deposition of titnium lyer, it ws used the equipment DREVA 400, presented in figure 1, which includes: rotry tle, vcuum chmer, supports of supply (ir, wter, gs), components for completing the instlltion nd the electricl equipments. The deposition of the titnium lyer tkes plce inside the recipient in which certin vcuum is generted, where the mteril tht must e deposited on the sustrte (work piece to e covered, mening the cutting insert), eing in solid stte, is rought in vpor stte s result of its heting, up to evportion of the trget (Ti) nd re-condenstion on the sustrte, when its temperture is lower thn tht of the vpors. The principle scheme of the instlltion is presented in figure 2. Figure 2. The principle generl scheme of the instlltion used in the ppliction of the ionic plting method Figure 1. Generl view of the equipment DREVA 400. The support rc evportion source AS 65 M;. Hollow cthode plsm; c. The support rc evportion source; d. Bthyscphe; e. Device; f. Rotry tle; g. Support ensemle for rotry tle for vcuum chmer The recipient is cylindricl one, hving doule wlls cooled with wter nd three rc evportion sources type AS 65 M, mounted long the thyscphe wlls, used to generte the metl titnium vpors. In the recipient shft, there is mounted rotry port-tool support (figure 2) equipped with the specil devices designed for the settlement of the cutting inserts. The symmetricl positioning of the cylindricl recipient to the xis mkes s the inserts suject to the coting, locted in tch, to e in identicl deposition conditions for ensuring uniform thickness of the deposition. Clening of the cutting inserts efore the titnium deposition is crried out lso inside the vcuum chmer, y sprying with conted strem of rgon. Titnium prticles resulting from the evportion process of the trget, on their wy to the sustrte (the cutting inserts), collide with regent gs ions (nitrogen) nd with the electrons of glow dischrge plsm. Thus, the mteril prticles positive ionized nd excited ACADEMIC JOURNAL OF MANUFACTURING ENGINEERING, VOL. 12, ISSUE 2/2014 7

3 prtilly re ccelerted in cthodic drk spce of the sustrte nd, hitting it with incresed energy, performs the deposition on it. 3 RESEARCHES AND OBTAINED RESULTS For the experimentl reserches, four types of cride cutting inserts were used: - type A, used for turning two chnnels inside the outer ring (figure 3) of ering ll; the profile shpe inserts (cutting inserts), mde y wire electricl dischrge mchining on the equipment ULTRA CUT F1, is evidenced in figure 4 nd is identicl in oth cses: for the titnted cutting insert (figure 4.) nd, respectively, for the cutting inserts without titnium deposition (figure 4.), res of wer fter the turning opertion crried out on equipment SHM 120 re indicted, in oth cses, in figure 5. - type A, used in turning interior rdius nd chmfers of the cr from figure 6, opertion performed on equipment KTSP 80A; cutting inserts shped y wire electricl dischrge mchining on equipment ULTRA CUT F1, oth titnted nd titnium uncoted, re highlighted y figure 7 nd in figure 8 there re shown the cutting inserts fter the turning opertion, hving their wer res mrked. Figure 6.Cr er Figure 7.Pill A. Without titnium deposition;. Titnted Figure 3. of the ll ering Figure 8.Pill A. Without titnium deposition nd used;. Titnted nd used B Figure 4. Insert A. Without titnium deposition;. Coted - cutting inserts type B, uncoted nd coted with titnium, used for turning two chnnels to the outside of the outer ring (figure 9) of cylindricl er ering, highlighted in figure 10., respectively in figure 10., show res of wer of the inserts fter the turning opertion. B 8 Figure 5. Insert A. Without titnium deposition nd used;. Titnted nd used Figure 9. Outer ring of the cylindricl ering Figure 10. Insert B;. Uncoted nd used;. Coted nd used ACADEMIC JOURNAL OF MANUFACTURING ENGINEERING, VOL. 12, ISSUE 2/2014

4 - type B, used in turning of exterior rdius nd chmfers of the cr from figure 11, opertion performed on equipment KTSP 80A; cutting inserts shped y wire electricl dischrge mchining on equipment ULTRA CUT F1, oth uncoted nd coted with titnium, re highlighted y figure 12 nd in figure 13 the cutting inserts fter the turning opertion, hving their wer res mrked re shown. cutting inserts, till their wer nd loss of cutting qulity. Mesurements mde llowed lso elortion of grphicl representtions out how the vrition in time of the cutting inserts wer is, s well s the volume of mchined prts, during their norml operting time, in the cse of inserts type A (figure 14 nd figure 15), respectively in the cse of inserts type A (figure 16 nd figure 17) nd, lso, in the cse of inserts type B (figure 18 nd figure 19), respectively the inserts B (figure 20 nd in figure 21). Figure 11. Cr Figure 12. Insert B. Without titnium deposition;. Titnted.. Figure 13. Insert B. Without titnium deposition nd used;. Titnted nd used Tle.1 Specific conditions of the turning process of ll four cutting inserts uncoted nd coted with Ti Cutting inserts type Depth t [mm] Spee d v [m/m in] Spindle speed ω [rpm] Feed f [mm/ rot] A A B B During the use of the four types of metllic cride cutting inserts in the turning process of the rings nd erings er, it ws determined their tool lives, oth for the uncoted with titnium nd lso in cse of their titnium coting nd the numer of the mchined prts without these cotings nd, lso, in cse of their titnium coting nd the numer of the mchined prts with these Figure 14.Vrition in time of the wer with the cutting inserts type A t outer rings of n rdil ll ering 1- profiled uncoted with titnium; 2- profiled coted with titnium. Figure 15. Vrition in time of the volume of processed prts with the cutting inserts type A t outer rings of n rdil ll ering 1- profiled uncoted with titnium; 2- profiled coted with titnium. ACADEMIC JOURNAL OF MANUFACTURING ENGINEERING, VOL. 12, ISSUE 2/2014 9

5 Figure 16. Vrition in time of the wer of the cutting inserts type A t cutting of cr er: 1- uncoted with titnium; 2- coted with titnium Figure 19. Vrition in time of the volume of processed prts t use of the inserts type B t cutting of outer rings of cylindricl er ering: 1- uncoted with titnium; 2- coted with titnium Figure 17. Vrition in time of volume of processed prts mchined with the inserts type B t cutting of cr er: 1- uncoted with titnium; 2- coted with titnium Figure 20. Vrition in time of the wer t the inserts type B t cutting of cr er: 1- uncoted with titnium; 2- coted with titnium Figure 18. Vrition in time of wer t the inserts type B t cutting of outer rings of cylindricl er ering: 1- uncoted with titnium; 2- coted with titnium Figure 21. Vrition in time of volume of mchined prts t the use of inserts type B t cutting of the cr er: 1- uncoted with titnium; 2- coted with titnium 10 ACADEMIC JOURNAL OF MANUFACTURING ENGINEERING, VOL. 12, ISSUE 2/2014

6 Vlues otined y mchining re shown in tle 2, they showing sustinility remrkle growth of the metllic inserts undergo the process of thin Ti coting y PVD process, for ll four types of cutting inserts used, in reltion to those non-ffected y titnium deposition. Tle 2. The durility of the cride cutting inserts used The type of insert Nr. tested insert Dur. tested [min] Nr. Smples mde A U chnnels (160 rings) A C chnnels (910 rings) A U Rdii nd chmfers A C rdii nd chmfers B B B B U 1 4 C U C chnnels (160 rings) 1820 chnnels (910 rings) 500 rdius nd chmfers 1000 rdius nd chmfers Smples type of ll ering of ll ering Cr Cr of ll ering of ll ering Cr Cr 4 CONCLUSIONS AND FUTURE RESEARCHES Following the nlysis of the otined results presented efore, the titnium deposition in thin lyers leds to n improvement out times of the used cutting inserts life, in the cutting process of outer ering rings nd ers, compred to the cse of those metl crides cutting inserts uncoted with titnium. This fct lrgely confirms indicted results from literture. Use in the process of turning the outer rings of erings of the cutting inserts type A nd type B led, following their coting with thin lyer of Ti y PVD method, to n increse of lmost 6 times of their tool life; with them could e processed 6 times mny pieces until the cutting qulities re lost through wer of the cutting tool. In the cse of the use of the cutting insert type A nd type B, durility of the covered one hs douled towrds to the uncoted one with lyer of Ti. Increse of the durility is lower however thn in the first sitution possile, due to lrger surfce of contct etween cutting insert nd er surfce of the workpiece in this second cse, this when the numer of pieces mnufctured is doule. There is logicl growth, directly proportionl to the working piece volume, possile to e processed with those cutting inserts, simultneously with the increse of durility, fct tht justifies the increse of the processing productivity y highlighting the cutting inserts verge time for proper functioning. The positive otined results open new opportunities to continue the reserches in the field of deposition of thin lyers, were resistnt, following in the future: determining the lyer depth or the successive lyers depth deposited, its optiml vlues estlished so tht they cn rech some high vlues for the durility, determintion of thickness of deposited lyers nd determining their optimum thickness (depending on the lyer structure), study of their ehvior in the processes of turning, the possiility to use some other filler mterils not included in the performed study, using the sme PVD process, s well s the cutting inserts types diversifiction, which will e the suject to filler mteril deposition nd their ehvior in the cutting processes. 5 REFERENCES Dulău, M., Şoită, D. (2007). Electrotehnologii, Editur Universittii Petru Mior, Tg-Mureş. Mteescu, G. (1998). Tehnologii vnste. Strturi suţiri depuse în vid, Editur Dorote, Bucureşti. Pop, S.R., Lupescu, O., Pop, I., Sv, O., Holostencu, G., (2010). Reserches upon the technologicl equipment predictive mintennce through determinist models. Proceedings of the 14 th Interntionl Conference ModTech-New Fce of TMCR, ISSN , My, Romni Purde B., The wer nd durility of the cutting tool, ville t: doc/ /14. Accessed: Sărăriu, V., The remers shrpening, ville t: Accessed: Serro, C., Completo, R., Colço, F., Dos Sntos, C., Loto d Silv, J. M. S., Crl, H., Arújo Pires, E., nd Srmgo, B. (2009). Surfce nd Cotings Technology, 203, pp Accessed: ACADEMIC JOURNAL OF MANUFACTURING ENGINEERING, VOL. 12, ISSUE 2/