Ovaj članak je usredotočen na eksperimentalno određivanje trajnosti alata za indeksiranje keramičkih reznih uložaka. Postavljen je kriterij trošenja alata VBBmax = 0,6 mm (sukladno ISO 3685) ili 30 komada obrađenih tuljaka. Kada je postignut barem jedan od ovih parametara, ispitivanje je zaustavljeno i procijenjeno. Ispitivane su dvije vrste reznog materijala uz pomoć tvrtke Saint Gobain Advanced Ceramics s.r.o. – ZTA 7 NI i D 250. Pratili smo njihovu trajnost kod istih parametara obrade. Eksperimenti su izvedeni na alatnom stroju – CHEMNITZ NILES N22. Obrađivani materijal bio je lijevano željeza 25P koje se koristi za motore automobila. Trošenje alata praćeno je za svaki peti obrađeni tuljak. Mjerena je mikrogeometrija nakon ispitivanja trošenja alata na svakom petom tuljku. Cilj je bio odrediti aritmetičku toleranciju Ra profila, najveću visinu Rz profila i vanjski promjer D. Mjerenje je provedeno četiri puta, aritmetička sredina je izvedena naknadno i prikazana je u tablicama.This article is focused on the experimental determination of tool life tests for indexable ceramic cutting inserts. The set criterion of tool wear was VBBmax = 0,6 mm (in accordance with ISO 3685) or 30 pieces of machined sleeves. After at least one of the mentioned parameters was achieved, the tests were stopped and evaluated. Two types of cutting material by Saint Gobain Advanced Ceramics s.r.o. Company – ZTA 7 NI and D 250 were tested. We monitored their tool life at the same cutting parameters. The experiments were performed on machine tool – CHEMNITZ NILES N22. The machined material was the cast iron 25P mainly used for car engines. Tool wear was monitored on every fifth machined sleeve. Microgeometry was measured after tool wear test on each fifth sleeve. The aim was to determine the arithmetic tolerance of Ra profile, the greatest height of Rz profile and the external diameter D. The measurement was carried out four times; arithmetic average was performed subsequently as it is shown in the tables

Adam Janásek

Branislav Martinický

Marek Sadílek

Robert Čep

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1Introduction2Experimental part2.1Machine toolUvodEksperimentalni dioAlatni strojTool wear tests belong to one of the basic parameters ofmachining technology. The results of successfulapplication, which were obtained in practice, remarkableincrease of the quality of production and indirect affect onthe position of the enterprise in the sharp competition [3, 4].That experimental determination of tool life can provideadditional information about cutting process in next tests[5].Roughness is a sum of surface imperfections with asmall distance. These phenomena arise from the productionor effect of production effect [6]. Surface defects notassumed as the roughness are: random irregular geometry(lines, crevices, etc.) and defects which arise by materialproduction [2].The machine tool CHEMNITZ NILLES N22(Fig. 1) was used for test sample machining. The machinetool has rigid structure and it provides a sufficient clampingcondition. Jaws have recessed cone with the same apicalangle as the cast iron sleeves.203R. Čep, A. Janásek, B. Martinický, M. SadílekISSN 1330-3651UDC/UDK 621.9.025:620.169.1CUTTING TOOL LIFE TESTS OF CERAMIC INSERTS FOR CAR ENGINE SLEEVESRobert Čep, Adam Janásek, Branislav Martinický, Marek SadílekThis article is focused on the experimental determination of tool life tests for indexable ceramic cutting inserts. The set criterion of tool wear was = 0,6mm (in accordance with ISO 3685) or 30 pieces of machined sleeves. After at least one of the mentioned parameters was achieved, the tests were stopped andevaluated. Two types of cutting material by Saint GobainAdvanced Ceramics s.r.o. Company – ZTA7 NI and D 250 were tested. We monitored their tool life atthe same cutting parameters. The experiments were performed on machine tool – CHEMNITZ NILES N22. The machined material was the cast iron 25Pmainly used for car engines. Tool wear was monitored on every fifth machined sleeve. Microgeometry was measured after tool wear test on each fifth sleeve.The aim was to determine the arithmetic tolerance of profile, the greatest height of profile and the external diameter . The measurement was carried outfour times; arithmetic average was performed subsequently as it is shown in the tables.:VBRa Rz Dcutting tool tests, machining, surface roughness, tool wearBmaxKeywordsOriginal scientific paperOvaj na eksperimentalno trajnosti alata za indeksiranje reznih uložaka. Postavljen je kriterij trošenja alata= 0,6 mm (sukladno ISO 3685) ili 30 komada tuljaka. Kada je postignut barem jedan od ovih parametara, ispitivanje je zaustavljeno i procijenjeno.Ispitivane su dvije vrste reznog materijala tvrtke Saint Gobain Advanced Ceramics s.r.o. – ZTA 7 NI i D 250. Pratili smo njihovu trajnost kod istihparametara obrade. Eksperimenti su izvedeni na alatnom stroju – CHEMNITZ NILES N22 lijevano željeza 25P koje se koristi zamotore automobila. Trošenje alata je za svaki peti tuljak. Mjerena je mikrogeometrija nakon ispitivanja trošenja alata na svakom petom tuljku.Cilj je bio odrediti toleranciju profila, visinu profila i vanjski promjer . Mjerenje je provedeno puta, jeizvedena naknadno i prikazana je u tablicama.članak je usredotočen određivanje keramičkihobrađenihuz pomoć. Obrađivani materijal bio jepraćeno obrađeniaritmetičku najveću četiri aritmetička sredinaVBRa Rz Dispitivanje reznog alata, hrapavost površine, obrada rezanjem, trošenje alataBmaxKljučne riječi:Izvorni znanstveni članakIspitivanje trajnosti reznog alata keramičkih uložaka za tuljke automobilskih motoraIspitivanje trajnosti reznog alata keramičkih uložaka za tuljke automobilskih motoraTechnical Gazette 18, (2011),2 203-2092.2Measuring machines2.3Machined materialMjerni strojeviRa Rzand values were evaluated on portable surfaceroughness tester - Mitutoyo Surftest SJ-400. A wide range,high-resolution detector and an ultra-straight drive unitprovide a class-leading accuracy. Cylinder surfaceroughness is possible to be evaluated by the skid lessmeasurement and R-surface compensation functions.An external diameter was determined by SOMETmicrometer ( ).As the machining material were used sleeves for carČSN 25 1420; 50÷75 mmObrađeni materijalFigure 1Slika 1.Machine tool CHEMNITZ NILES N22Alatni stroj CHEMNITZ NILES N22204Cutting tool life tests of ceramic inserts for car engine sleevesTehni ki vjesnikč ,18, 2(2011)  203-209engines (Fig. 3), which were supplied by the contractingauthority. The class of material was 25P. Due to conicalshape of sleeves it was necessary to machine a cylindricalsurface and the same diameter. Supposing we had not doneit, a constant depth of cut would not have been maintainedduring testsap.2.4Used toolsKorišteni alati.A tool-holder CSSNR 2525 M12-K (Fig 4) was used inaccordance with ISO 3685, with defined by an angle =45°. Machining system is shown in (Fig. 5).κrR. Čep, A. Janásek, B. Martinický, M. Sadílek2.5Indexable cutting inserts2.6Cutting parameters3Experiments' evaluationRezne pločiceTwo types of ceramic cutting inserts were tested in total(the first type – 2 pieces and the second type – 4 pieces).Only one cutting edge was tested on the plate of each type.The cutting plates had the following marks:D 250_1ZTA_7_NI_2ZTA_7_NI_1D 250_2D 250_3D 250_4Cutting parameters were selected on the basis ofexperience and consultations of the research team with acontracting authority. The aim was to get as near as possibleto real operation conditions.cutting speed = 500 m/minfeed = 0,4 mmcutting depth = 2 mmnumber of chips per one sleeve 4machining length 1 chip 61 mm, 2 chip 60 mm, 3chip 59 mm, 4 chip 58 mmtotal machining length 238 mmdry machining.The contracting authority supplied a semi-product of------Parametri rezanjaProcjena eksperimenata:::vfacpst nd rdthFigure 2Slika 2.Portable Surface Roughness TesterMitutoyo Surftest SJ-400PrijenosniMitutoyo Surftest SJ-400mjerač hrapavosti površine[1][1]a)                                                    b)Figure 3Slika 3.Clamped sleeves:before machining (a) and after machining (b)Stegnuti tuljci: prije obrade (a) i nakon obrade (b)Table 1Tablica 1.Chemical composition of the materialKemijski sastav materijalaC / % Si / % Mn / % P / % S / % Ti / % Cu / %2,8÷3,3 1,8÷2,5 0,6÷0,8 0,5÷0,8 < 0,1 0,03÷0,1  0,8Figure 4Slika 4.The tool-holder with clamped ceramic cutting insertDržač alata s pričvršćenim keramičkim uloškomFigure 5Slika 5.Machining system: 1 tool-holder, 2 chuck, 3 workpiece- - -Obradni sustav: 1 - držač alata, 2 - glava, 3 - izradak205Technical Gazette ,18, 2(2011)  203-209machined materials and two kinds of ceramic cuttinginserts. The criterion of tool wear was chosen = 0,6mm. If the 30 sleeve was machined and the critical value oftool wear was not reached, the tests were stopped. The toollife was determined as follows:VBBmaxthR. Čep, A. Janásek, B. Martinický, M. Sadílek Ispitivanje trajnosti reznog alata keramičkih uložaka za tuljke automobilskih motora3.1Tool life and tool wear – individual cutting insertsVijek i trošenje alata – pojedinačni rezni ulošciThe number of machined pieces by individual ceramiccutting inserts is shown in the following graph (Fig. 7). D250 series of cutting inserts machined the maximumnumber of 30 pieces except for D 250_1 insert. The D 250_1insert probably reached this maximum as well. There was acrack of sleeve (at machining the 27 sleeve) and it resultedin cutting edge destruction. ZTA_7_NI inserts reached thecriteria of tool wear at 26 , respectively at 15 machinedsleeves. Fig. 8 shows the tool life of plates calculatedaccording to formula (1) and (2) in minutes.thth th(1)ptT ,4fnlt (  )2where:– tool life, min– machining time, min– number of machined pieces, –– machining length, mm– spindle speed, 1/min– feed, mm.Microgeometry was measured after the tool wear test -on each 5 , 10 , 15 , 20 , 25 and 30 machined sleeve. Theaim of this experiment was to determine the arithmetictolerance of profile, the greatest height of profile andthe external diameter .Arithmetic tolerance of profile, the greatest height ofprofile and the external diameter are shown in thefollowing tables. Measurements were evaluated four times– as shown in (Fig. 6). The arithmetic average wascalculated from these measurements.TtplnfRa RzDRaRz Dth th th th th thFigure 6Slika 6.Measured surface – machined insertMjerena površina – obrađen uložakTable 2Tablica 2.The number of machined pieces for individual cutting insertsBroj obrađenih komada za pojedinačne rezne uloškeD250_1ZTA_7_NI_2ZTA_7_NI_1D250_2D250_3D250_4Machinedpieces27 26 15 30 30 30Figure 7Slika 7.The number of machined pieces for individual indexablecutting insertsBroj obrađenih komada za indeksirane rezne uloškeTable 3Tablica 3.Tool life for individual indexable cutting insertsPostojanost alata za pojedine rezne pločiceD250_1ZTA_7_NI_2ZTA_7_NI_1D250_2D250_3D250_4Tool life,min 8,03 7,74 4,46 8,93 8,93 8,93Figure 8Slika 8.Tool life for individual indexable cutting insertsVijek alata za indeksirane rezne uloške206 Tehni ki vjesnikč ,18, 2(2011)  203-209Cutting tool life tests of ceramic inserts for car engine sleeves R. Čep, A. Janásek, B. Martinický, M. Sadíleka) tool flankb) tool facec) tipFigure 9Slika 9.Tool wear – indexable cutting insert type D 250_1Trošenje alata – rezna pločica tipa D 250_1a) tool flankb) tool facec) tipFigure 10Slika 10.Tool wear – indexable cutting insert type ZTA_7_NI_2Trošenje alata – rezna pločica tipa ZTA_7_NI_2a) tool flankb) tool facec) tipFigure 11Slika 11.Tool wear – indexable cutting insert type ZTA_7_NI_1Trošenje alata – rezna pločica tipa ZTA_7_NI_1a) tool flankb) tool facec) tipFigure 12Slika 12.Tool wear – indexable cutting insert type D 250_2Trošenje alata – rezna pločica tipa D 250_2207Technical Gazette ,18, 2(2011)  203-209Comment :Tool face chipped from 17 piece;28 piece – workpiece snapped and destroyed insertComment :25 piece – tool wear on lateral tool flank;Tool wear increases very slowlyComment :Insert sparks almost from the beginning;14 piece - significant deterioration of the surface andsignificant sparks;15 piece - unsatisfactory roughness - terminatedComment :Calm cut without sparking;Tool wear is very small and almost not growing;Chipped tool face – at the end of testsComment :16 piece - inserts begin to sparkle slightly;28 piece - spark ceased;Small tool wearComment :8 piece - inserts begin to sparkle;24 piece - spark is of low intensity;Small tool wear(Fig. 9).(Fig. 10).(Fig. 11).(Fig. 12).(Fig. 13).(Fig. 14).----------------ththththththththth3.2Surface roughnessHrapavost površineR. Čep, A. Janásek, B. Martinický, M. Sadílek Ispitivanje trajnosti reznog alata keramičkih uložaka za tuljke automobilskih motoraa) tool flankb) tool facec) tipFigure 13Slika 13.Tool wear – indexable cutting insert type D 250_3Trošenje alata – rezna pločica tipa D 250_3a) tool flankb) tool facec) tipFigure 14Slika 14.Tool wear – indexable cutting insert type D 250_4Trošenje alata – rezna pločica tipa D 250_4Table 4Tablica 4.Values of arithmetic tolerance of Ra profileVrijednosti aritemetičke tolerancije Rz profilaRa / μmNumberworkpieceD250_1ZTA_7_NI_2ZTA_7_NI_1D250_2D250_3D250_45 3,17 6,09 4,22 5,68 6,58 5,9410 4,07 5,7 2,76 4,72 2,33 5,7715 2,39 5,23 10,61 5,06 1,69 4,7020 1,82 4,26notmeasured4,15 1,78 4,0325 1,61 3,03notmeasured3,54 2,28 3,7027 1,98 - - - - -30 -notmeasurednotmeasured4,37 1,97 2,02The value of surface roughness ( ) decreases with thenumber of machined pieces of almost all sleeves. It is acharacteristic for the ceramic cutting tools. If we want toachieve maximum performance, we have to "wear down"lightly these inserts. If the plate achieved the maximum toollife, roughness would begin to rise slightly. This could becaused by increasing tool wear.ZTA 7 NI_1 inserts caused sparking that increased withthe number of machined sleeves. This test was finished forunsatisfactory roughness at the 15 piece as shown in thegraph.Rath208 Tehni ki vjesnikč ,18, 2(2011)  203-209Cutting tool life tests of ceramic inserts for car engine sleeves R. Čep, A. Janásek, B. Martinický, M. SadílekThe value of external diameter growths withincreasing number of machined sleeves. This process iscaused by the tool wear. The tool wear was createdespecially on lateral tool flank (edge) and on the tip whichwas "burned". It changed a decrease in dimensionalaccuracy (first and last piece did not have the samediameter). The difference was in several tenths ofDRoughness is the most correlated with the value.This parameter is the most common in engineering practicein the Czech Republic. Unfortunately, it is influenced byunique extreme surface roughness.Parameter of roughness of profile decreases withthe number of machined pieces of almost all inserts withslight deviations, as shown in the previous measurement.parameter nearly replicates parameter.RaRzRzRa3.3External diameterVanjski promjerFigure 15Slika 15.Arithmetic tolerance of Ra profileAritemetička tolerancija Ra profilaTable 5Tablica 5.Values of the greatest height of Rz profileVrijednosti najveće visine Rz profilaRz / μmNumberworkpieceD250_1ZTA_7_NI_2ZTA_7_NI_1D250_2D250_3D250_45 20,33 28,50 19,80 29,33 36,90 28,2310 20,20 26,50 19,80 22,45 15,35 26,5015 17,60 25,10 53,95 26,58 11,25 23,8320 12,80 19,85notmeasured22,70 11,48 20,1525 10,20 16,75notmeasured21,68 15,73 18,6327 14,50 - - - - -30 -notmeasurednotmeasured27,53 14,20 14,43Figure 16Slika 16.The greatest height of Rz profileNajveća visina Rz profilaTable 6Tablica 6.Values of the external diameter DVrijednosti vanjskog promjera DØ D / mmNumberworkpieceD250_1ZTA_7_NI_2ZTA_7_NI_1D250_2D250_3D250_45 73,56 73,51 73,49 73,50 73,58 73,4710 73,56 73,55 73,64 73,60 73,64 73,5115 73,72 73,59 74,03 73,70 73,69 73,6320 73,75 73,62notmeasured73,83 73,72 73,6425 73,81 73,71notmeasured73,86 73,79 73,9027 73,81 - - - - -30 -notmeasurednotmeasured73,88 73,89 73,96Δ 0,25 0,20 0,534 0,38 0,31 0,49Figure 17Slika 17.External diameter DVanjski promjer D209Technical Gazette ,18, 2(2011)  203-209R. Čep, A. Janásek, B. Martinický, M. Sadílek Ispitivanje trajnosti reznog alata keramičkih uložaka za tuljke automobilskih motoramillimetres (see in Tab. 6). Abrasion and peeling off werecreated at the tool face of inserts. This phenomenon shouldnot have any significant effect on dimensional accuracy.Tool wear is caused by high thermal and mechanical load.The tool is not able to perform its function (after a period) asa result of this process. Tool wear arises from abrasive wear,plastic deformation and brittle fracture.The requirements are very high on the parameters ofsurface integrity in engineering practice. Cutting speed isbeing constantly increased. This leads to the CNCmachining; these machines can secure the optimal workingconditions so it is possible to produce products with thefinest precision.ZTA 7 NI inserts did not reach the maximum number of30 machined inserts. The reason was impaired surfaceroughness in both cases. Tests were finished forunsatisfactory surface. The cutting inserts reached theprescribed criterion of tool wear ( ).D 250 inserts had significantly better results.Almost allplates machined the maximum number of inserts at toolwear ( ) about 0,2 mm, except the first. The D 250_1insert could reach this maximum as well. The sleevecracked (hollow in the casting) – the result was thedestruction of the cutting edge. We will need to focus moreon these parameters in other experiments – secondary edge,tool tip and tool face. The tool wear arises on the secondaryedge and the tip. There is reduction of dimensional accuracyas a consequence (first and last piece have not the samediameter). The difference is in several tenths of millimetres.Figures 15 and 16 show that the value of both roughnessparameters is lower after 30 pieces machined. Roughness( ) is below 6,3. Roughness ( ) gets even under 3,2 withan increasing number of machined inserts – D 250 series.This can be attributed to the properties of ceramics materialwhich must be "abrade" first and then its potential can befully realized.D 250 inserts are suitable for cutting inserts made from25P material at given cutting parameters and cuttinggeometry. The whole machining was carried out in dry(without using the liquid process) and it is environmentallyfriendly.4Conclusion5ReferencesZaključakVBVBRa RaBmaxBmaxLiteratura[1] www.mitutoyo-czech.cz [online]. 2009 [cit. 2011-01-08].Mitutoyo SJ-400. <http://www.mitutoyo-czech.cz/cz/pdf/SJ%20400-CZ.pdf>.[2] Orlovsky, I.; Hatala, M. Sprinkle Drying Kiln CeramicGranulate Drying Characteristic and ExperimentalMeasurements of the Drying Process Parameters. // TehnickiVjestnik - Technical Gazette, 16, 2(2009), 27-30. ISSN 1330-3651.887.[3] Čep, R.; Neslušan, M.; Barišič, B. Chip Formation AnalysisDuring Hard Turning. // Strojarstvo, 50, 6(2008), 337 – 345.ISSN 0562-1[4] Neslušan, M.; Turek, S.; Brychta, J.; Čep, R.; Tabaček, M.Experimentálne metódy v trieskovom obrábaní. Žilina : EDISŽilina, 2007. 343 p. ISBN 978–80–8070–711–8.[5] Cep, R.; Ocenasova, L.; Novakova, J., Kouril, K.; Valicek, J.;Barisic, B. Influence of Thermal and Mechanical Shocks toCutting Edge Tool Life. // Proceedings of World Academy ofScience, Engineering and Technology, 56, (2009) (August),pp. 754-757. ISSN 2070-3740.nd surface by diamond roller dressing. // Tehnicalgazzete. 9, 3-4 (2003), pp 3-8, ISSN 1330-3651.[7] Jurkovic, Z.; Cukor, G.; Andrejcak, I. Improving the surfaceroughness at longitudinal turning using the differentoptimization methods // Tehnical Gazette. 17, 4 (2010), pp397-402, ISSN 1330-3651.[6] Cebalo, R.; Stoić, A. Optimisation of the roughness of thegrouAuthors' addressesAdrese autoraRobert Čep,Assoc. prof. Ing. PhD.Adam Janásek, Ing.Marek Sadílek, Ing., Ph.D.Branislav Martinický, Ing., PhD.VŠB - Technical University of OstravaFaculty of Mechanical Engineering346 - Department of Machining and Assembly17. listopadu 15/2172708 33 Ostrava - PorubaCzech Republic+420 597323193robert.cep@vsb.czUniversity of ŽilinaFaculty of Mechanical EngineeringDepartment of Machining and Manufacturing TechnologyUniverzitna 1010 26 ZilinaSlovakia

Cutting tool life tests of ceramic inserts for car engine sleeves

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