A NEW GENERATION OF PVD COATINGS FOR HIGH-PERFORMANCE GEAR HOBBING

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1 Preprint from Conference, hessaloniki, Greece, Oct., 04 A NEW GENERATION OF PVD COATINGS FOR HIGH-PERFORMANCE GEAR HOBBING A. Lümkemann², M. Beutner, M. Morstein², M. Köchig, M. Wengler T. Cselle², B. Karpuschewski. Institute of Manufacturing Technology and Quality Management (IFQ), Otto von Guericke University, D-906 Magdeburg, Germany. PLATIT AG, CH-545 Selzach, Switzerland ABSTRACT The aim of the paper was the development of a new high-performance coating tailored for hobs in dry cutting of gears. A range of AlCrN-based coatings was deposited in an industrial rotating arc cathodes PVD unit. These coatings were varied both in terms of their nanostructure and the chemical composition of their top layer. To examine the performance of the different coatings, cutting trials were carried out using the well-established fly cutter analogy test. Significant performance differences between the chemically and structurally modified coatings were found. Doping the coating top layer with titanium in combination with an optimized nanolayer structure lead to a substantial increase of tool life by about 50 % compared to AlCrN. KEYWORDS: gear hobbing, fly cutting test, coating development, PVD, AlCrSiN, AlCr INTRODUCTION In the current globalized trading situation it is mandatory for production companies to stay competitive. Advantages can be realized by reducing costs or delivery times, which requires an optimized manufacturing process. One example for this mechanism is the gear manufacturing industry. In 005, the German turnover concerning gears amounted to 4 billion US-$ //. According to the Freedonia Group, there was a worldwide demand for gears of about 70 billion US-$ in 0, 80% of which are accounted for by the automotive industry //. This demonstrates the enormous potential which can be harvested by gear manufacturing companies. To manufacture automotive gears, the applied standard process chain consists of hobbing the steel blanks, followed by heat treatment and finish grinding. Generally, hobbing is the dominating green manufacturing technique for external spur gears. This manufacturing technique is characterized by an interrupted cut. This kind of cutting process is demanding special tool resistance against impacts and rapid changes in temperature. The performance of the hobbing process benefits both from an increased tool life and more productive cutting parameters. This can be achieved by using improved substrate materials and coatings. Starting in the 970ies, a continuous development of coatings took place, starting from the early and TiCN thin films, followed by the successful broadband of TiAlN coatings (late eighties) towards recent AlCr-based coatings. Connected to the development there is a trend towards application tailored tool micro geometry and coating composition and structure /, 4,5/. Today, more than 00 different coating systems are available /6/ which is an evidence for the importance of coatings. Depending on the coating elements and its structure, different properties regarding wear resistance can be achieved. Due to the type of substrate material mainly used for hobbing (HSS) and the required tool geometry, Physical Vapor Deposition (PVD) coatings dominate this field. For the experimental trials a fly cutting analogy test, which is well established in research, was utilised at the IFQ. The fly cutter generation, measuring and the test execution was performed at IFQ test facilities. The pre-treatment of the tools, the coating development and the post-

2 Preprint from Conference, hessaloniki, Greece, Oct., 04 treatment of the coatings was accomplished by PLATIT R&D. The tests are based on a tool geometry and on cutting parameters that largely correspond to production settings of a major Japanese transmission manufacturer. FLY CUTTING AN ANALOGY TEST FOR GEAR HOBBING The fly cutting analogy test was developed in the 970ies by the WZL of the RWTH Aachen /7/. Increasing research in gear hobbing prompted this improvement because it would be very time and material consuming to perform research using complete hobs. By using a single tooth of a hob, the newly introduced fly cutting analogy test is able to generate gears, equal to those machined by a real hobbing process. Figure : Principle of the fly cutting test. The kinematics of the analogy test (Figure ) reproduces the wear behaviour of a shifted tooth of a hob. The fly cutter continuously moves with the tangential feed rate f t, following the shift axis of a real hob. After one full tangential motion, the fly cutter is discretely moved towards the next axial position with an offset corresponding to the axial feed f a (Figure b). This procedure repeats until the whole width of the wheel has been geared. Even though the machining time for a single gear is increased compared to the real hobbing process (5 to 60 times longer) a statement concerning wear behaviour is already possible after a few milled gears. Moreover, fly teeth can be examined much easier than a full hob tool by methods such as SEM/EDX analysis or optical profilometry. MOUNTING DEVICE BLASTING AND COATING A real hob serves as source to gain the trial tools (fly cutters). These fly cutters are cut out from the hob by wire erosion machining. Extracting rows of teeth is the first step in this procedure, Figure b,c. The fragmentation of these rows into single fly cutter teeth is again done by wire erosion, Figure d. Figure : Generation of teeth for fly cutting test.

3 Preprint from Conference, hessaloniki, Greece, Oct., 04 A mounting device like the mentioned one is essential for coating and post-treatment, due to the specific behaviour of a real hob during such processes. While the hob is rotating inside the PVD coating chamber the teeth of one flute are covering the teeth of the following flute, which is comparable to shadowing, Figure. This shadow induces a reduction of the local coating thickness, which has an enormous influence on the tool life, as described in 4.4. Stand-alone fly cutting teeth do not reproduce this important characteristic, which results in a severe difference in both wear mechanism and tool life, compared to a real hob. Figure : Shadowing effect during hob coating. Similar effects can be suppressed in the pre- and post-treatment. During micro blasting, the cutting edges of free-standing single teeth would be exposed to increased erosion. Therefore, the mounting device is inevitable to carry out the analogy test as close to the real process as possible. 4 IMPROVING THE HOBBING PERFORMANCE The schematic in Figure 4 shows the main factors influencing the tool performance. In this article we are focussing on the surface quality of the tools, the coating composition and structure. All other parameters influencing the performance were kept constant. Hobbing Conditions Hob Geometry (Makro) Hob Geometry (Micro) Dedicated Coating Gear Geometry Modulus Surface Quality Coating Type & Structure Cutting Parameter Number of Starts Pre- & Post- Treatment Coating Thickness Figure 4: Project plan illustrating the investigated performance parameters. 4. TEST SETUP A Liebherr LC80 hobbing machine has been used for the wear studies. Maintaining constant settings (cutting parameters, gear geometry) and gear blanks taken from a single batch, comparable trial conditions can be preserved. Table is summarizing these settings.

4 Preprint from Conference, hessaloniki, Greece, Oct., 04 workpiece process m n :, mm v c : 50 m/min z : 48 f a :,69 mm/rev d a : 0 mm h cu,max : 0,40 mm β : 4,5 T : 7,0 mm b : 9 mm dry 0MnCr5 (47HB) climb hobbing Table : Parameters used in fly cutting test. As implied by the title of this paper, a high-performance approach in hobbing is aimed at. In this case high performance refers to high productivity, where a the minimized cutting time can be achieved by using either high cutting speeds, axial feeds, numbers of starts or small tool diameters, respectively. In the actual industrial gear production case, the number of starts was used as the main variable to gain a higher productivity. The advantages of an increase in the number of starts and the comparison to the other control variables will be discussed in the next chapter. 4. HOB GEOMETRY (MACRO GEOMETRY) The tests were carried out using a tool actually used in industrial production of a Japanese transmission manufacturer. Table shows the major facts regarding tool profile and hob geometry. Two of them diverge from the norm: On one hand that is the small pressure angle to create an integer overlap ration and on the other hand that is the large number of starts. TOOL m n d a :, mm : 90 mm z 0 : 5 α : 4,5 p : 4 PM-HSS Table : Test tool geometry. As mentioned in the previous chapter an increase in productivity can be achieved by using hobs with a large number of starts. When increasing this number from one to five, also the revolution speed of the workpiece increases fivefold. That way the tools axial speed increases keeping the revolution speed of the hob (cutting speed) at the same level. One effect of larger numbers of starts is a decrease of generating positions, causing an increase in chip thickness (h cu,max ) and in generating cut deviations (δ y ). Despite having five starts in the applied case, the deviations in the generating cut do not exceed δ y = 4,0 µm, thus still maintaining a surface quality matching well with the following production steps. The maximum chip thickness is of more importance, because it represents the load on the fly cutter. Using a CAD-based interpenetration calculation, a duplication of h cu,max altering the number of starts from two to five could be noticed, Figure 5a. To illustrate the benefit in productivity, the cutting speed and the maximum chip thickness depending on the number of starts while having a constant machining time are plotted in Figure 5b. To achieve the same productivity as a hob with five starts, a hob with only two starts needs to be used with a cutting speed of v c = 75 m/min. Especially for old hobbing machines or for PM- 4

5 Preprint from Conference, hessaloniki, Greece, Oct., 04 HSS-hobs this cutting speed is exceedingly high. For those applications, an increase of the number of starts is a more feasible solution. Figure 5: Increasing number of starts and its effect on selected cutting parameters. 4. HOB GEOMETRY (MICRO GEOMETRY) A ground, sharp cutting edge exhibits a series of micro-defects that can negatively impact the tool life. The idea of edge preparation is to stabilize the cutting edge, in other words to reduce the failure probability and to prolong the tool life. Edge pre-treatment technologies reduce edge chipping... flatten out surface defects and grinding grooves... produce a "defined" micro geometry (edge radius, symmetry of rounding) In the same way as the right choice of the hard coating, the edge treatment method must be adapted to its application. Rech et al. /8/ did show the important role of edge rounding on the tool life for gear hobbing tools. For comparison reasons all tested tools in that contribution had the same way of edge preparation and post polishing. So the influence of different micro geometries on the fly hobbing performance could be minimized in this study. For edge preparation, all teeth were wet blasted using the above introduced fly teeth holder, again in order to have the same shadowing effects as for a real hob. The cutting edge radius for all tested teeth was kept in the range of 7 µm to 0 µm, measured before coating at the head of the teeth. The symmetry of rounding /9/ was kept in the range of k = for all teeth being tested. However, the optimization of the micro geometry does already start even before edge rounding, when performing the final grinding step. The following images give an impression of the cutting Measured with a GFM Mikrocad Premium Sensor using standard fit routine. 5

6 Preprint from Conference, hessaloniki, Greece, Oct., 04 face of two gear hobbing fly teeth. They were taken at the end of tool tests. Outside the wear region, one can easily identify different kinds of grinding traces on the cutting faces, indicating different grinding qualities. The "original" tooth has big grinding grooves, while the other one shows a nicely ground, much smoother cutting face. Even though the differences in surface quality can easily be seen on the images, the measured surface roughness differs only on a small scale (Figure 6). Figure 6: Influence of fly tooth grinding quality on tool life. The graph on the left side in Figure 6 shows average R z roughness values measured at the cutting face of original and resharpened fly teeth. On average, the resharpened cutting faces do have a roughness R z =.9 µm, compared with R z =.5 µm for the initial cutting faces showing the grinding traces. However, the relatively small difference in R z does have a quite big impact on tool performance. The graph on the right in Figure 6 is correspondingly showing the tool life for original and resharpened tools, all coated in the same cycle by a nanostructured AlCrN PVD coating. In our fly hobbing tests, we found a noticeable gain of total tool life for the precisely resharpened teeth, and even more important, a much lower tool life variation. Therefore only very precisely reground teeth with excellent surface finish were used for the coating development described below. 4.4 DEDICATED COATING DEVELOPMENT The preparation of the hard coatings took place in an industrial PLATIT π 4 Arc PVD coating unit. Due to the simultaneous use of four cylindrical rotating arc cathodes /0/, a very high deposition rate (= short cycle times) together with a very high flexibility of coating composition and structure can be achieved. The aim of these new multilayer high-performance QuadCoatings 4 // is to combine several different coating properties in one high-performance coating system for hobs, i.e.: Starting with CrN for best coating adhesion Followed by multilayered tough layers such as AlCrN or AlTiCrN Ending with an hard nanocrystalline wear resistant skin on top To achieve the full potential of coated high performance tools, the hard coatings need to be adapted for specific applications. A basic requirement when comparing different coatings is the reduction of other potentially overlapping influences. One important parameter to be kept constant for all tested fly cutters is the coating thickness. The following graph gives an impression of how much the tool life might depend on the coating thickness in the case of gear hobbing. A sample test revealed that an increase in coating thickness of 0% (0,7 µm) doubles the tool life. Further investigations on how the coating thickness is influencing the wear behavior were not carried out within this study. 6

7 Preprint from Conference, hessaloniki, Greece, Oct., 04 Figure 7: Influence of coating thickness on gear hobbing tool life. If not otherwise specified all investigated coatings (including the refererence market coating) have a coating thickness in the range of (4.0 ±0.) µm, measured at the tooth head. Gerth et al. // reported having much lower coating thickness around the cutting edge than on the cutting and flank face. The reason for their observation is likely to be caused by too sharp cutting edges, that locally concentrate compressive coating stresses, resulting in coating cracking and edge chipping to relax the stress, leaving the cutting edge unprotected //. In contrast, the multilayered AlCr-based coatings show a relatively low range of internal stress (- 4.0 GPa to -4.5 GPa on HSS). Together with the beneficial effect of rounding the cutting edge to R>5µm, the result is the typical coating thickness distribution seen in Figure 8. The decrease in cutting face coating thickness (Figure 8) is caused by the effects explained in chapter (shadowing effect). The highest coating thickness is generally observed directly on the cutting edge as the SEM cross section image below proves. Figure 8: Cross-sectional SEM image of the head region of a AlCrN-ML coated fly tooth. 4.5 FLY HOB CUTTING TEST RESULTS Based on the above-described settings for tool micro geometry preparation and coating thickness, a set of fly cutter teeth was coated by different AlCrN-based coatings. All coatings follow the general structure described in section 4.4, where generally AlCrN was selected as the main center part of the coating and the composition of the microcrystalline toplayer was varied in between AlCrN, AlCr and an AlCrN/SiN x nanocomposite. In part, the thickness and type of the coatings internal nanolayer structure was additionally varied. Usually three fly cutter teeth were tested per each coating type and the test results averaged TESTED COATING PARAMETERS In this project we focused on aluminium chromium nitride (AlCrN) based coatings. TiAlN or Al coatings were not taken into account, since in comparison with these coatings it is 7

8 Preprint from Conference, hessaloniki, Greece, Oct., 04 reported that AlCrN shows a superior wear resistance, higher oxidation resistance and lower thermal conductivity at high temperatures /4/. Therefore AlCrN-based coatings can be considered the optimum choice to protect the underlying HSS against oxidation and softening during dry hobbing even at very high cutting speeds leading to crater wear for TiAlN-coated tools /5/. For highly productive cutting conditions as reported in chapter 4., the high chip thickness is leading to crater wear, even using moderate cutting speeds. Massive chips apply more load on the cutting face, causing higher thermal and abrasive impact. Indeed, crater wear was observed during both the analogy test as well as the gear hobbing production in Japan using identical machining parameters. In order to prolong the tool life following coating parameters were varied: Nanolayer Structure: Generate coatings with different nanolayer thickness by changing the tool rotation speed Composition: Doping the AlCrN top layer with Si (respectively Ti) to influence the coating nanostructure and hardness 4.5. NANOLAYER STRUCTURE Even for chemically identical coatings, their micro- and nanostructure can significantly influence the hob performance. With the help of a multilayer structure, simply controllable by periodic target power adjustments, PVD coatings can be optimized in terms of toughness and hardness by changing the composition of the individual sublayers /6/. Furthermore multilayering seems to significantly delay the occurrence of indentation induced large cracks as can be deduced from higher values of the fracture toughness and the critical load for cracking /7/. It is also reported that in nanostructured (Cr -x Al x )N, alternating CrN/AlN does prevent crack propagation /8/. The composition and thickness of the single layers inside the multilayer is determined by the evaporation rate of the metallic targets /6/, the carousel rotation speed and the dimensions of the coating chamber. Particularly the use of elemental Cr and Al arc targets, as opposed to alloyed Al-Cr targets, has the potential to create a powerful nanolayered substructure (Figure 9). Figure 9: Formation of the nanolayered multilayer structure. To test the influence of the nanolayered substructure on the wear behaviour we varied the substrate carousel rotation speed, thus the nanolayer thickness for two otherwise identical sample coatings. Two different carousel rotation speeds were chosen: 6 rpm and 9 rpm. The resulting thickness distribution including nanolayer structure was simulated for a "dummy load" of Ø = 00 mm cylinders placed in the coating device. The result is a nanolayer thickness for the two rotation speeds in the range of 0 nm for 6 rpm compared with 7 nm for 9 rpm. On real tools the nanolayer thicknesses might be a bit different due to antenna effects resulting in an higher coating thickness on the cutting edges. The principle of that simulation is shown elsewhere /9/. 8

9 Preprint from Conference, hessaloniki, Greece, Oct., 04 The following two SEM images were taken at the end of tool life for "standard" AlCrN-ML and secondly for AlCrN-ML with optimized nanolayer structure. The wear on the fly hobbing teeth with cutting conditions described above (0) typically starts on the trailing flank, followed by wear on the leading flank and crater wear on the cutting face. The crater wear appearing on the cutting faces close to the edge does influences the flank wear. This may limit the total life time. It can be clearly seen that with optimized nanolayer structure (Figure 0) the crater wear is reduced even after a longer cutting distance. Figure 0: SEM of cutting faces, left: AlCrN-ML-coated tooth at 7 m life time right: optimized AlCrN-ML coated tooth at m life time. As dry cutting is performed, the area where the chips rub on the cutting face heats up considerably. Thereby the martensitic microstructure of the underlying HSS starts to decompose above 550 C //. Stein et. al /0/ measured a reduction of tool hardness in the range of 00 HV next to the crater wear, supporting the theory of friction-induced surface softening. It is assumed that a better thermal insulation, commonly found for high-al AlCrNbased coatings, protects the steel and thus delays crack formation and consequent layer damage. An optimized nanostructure would add to that, by retarding coating crack formation COATING COMPOSITION As already outlined, two versions of AlCrN-ML were tested alongside two new QuadCoatings 4, featuring toplayers doped with titanium and silicon, respectively. Figure is illustrating the calotest images to show the architecture of both QuadCoatings 4. Figure : Optical mircographs of calotests two QuadCoatings 4, nacro 4 and AlCr 4. The graph below, Figure, is showing the flank wear VB on the trailing flank cutting edge. The tool life criterion was a maximum acceptable flank wear of VB = 0 µm. As reference coating, 9

10 Preprint from Conference, hessaloniki, Greece, Oct., 04 we tested an AlCr-based coating from the Japanese market coated by a local hob manufacturer. Evidently, all newly developed coatings exceeded the life time of the reference. The graph furthermore shows that for AlCrN-ML with a slight addition of silicon, the tool life did increase in comparison with the undoped base layer. As shown in 4.5., the optimization of the nanolayered structure for AlCrN-ML enhances the wear resistance, too. Furthermore, by doping the optimized AlCrN-ML with a slight amount of Ti, an even further increase of tool life was achievable. In comparison with the initial AlCrN-ML the AlCr 4 (= opt. AlCrN-ML + AlCr) increases the tool life by more than 50 %. Figure : Wear curves of the trailing flank. The three images on the very left in Figure show the wear on cutting faces after the same cutting length of about 6 m/tooth. The Ti-doped version shows an impressive life time enhancement: In comparison to an equally thick market reference coating, this fly cutter can work twice as long (>46 m/tooth) until a flank wear comparable to the reference tooth ( 4 m/tooth) is reached. All in all, using an optimized micro-/nanostructure and Ti- respectively Si-doped top layers the crater wear that occurs for dry hobbing with HSS single teeth is significantly reduced. Figure : Optical measurement (GFM) of crater wear depth on the cutting face. 5 CONCLUSIONS In this study a sophisticated fly cutting analogy test for the optimization of gear hobbing tools was presented. The special mounting device for the fly teeth during edge preparation and coating ensured the important characteristic of shadowing effects and coating thickness distribution. 0

11 Preprint from Conference, hessaloniki, Greece, Oct., 04 It is shown, that the grinding / polishing quality significantly affects the process stability in gear hobbing. In order to achieve low tool life variation, one has to pay attention to a precise grinding process with excellent surface finish. By using a hob with a high number of starts it is possible to achieve high productivity. A drawback of this cutting strategy especially in dry cutting is that it creates a major increase in chip thickness, which induces crater wear. This effect could however be counteracted by using dedicated PVD coatings with tailored nanolayer structure and thickness. Different structures and compositions of coatings were tested. The Ti-doped QuadCoating4 AlCr4 (CrN + AlCrN-ML + AlCr), with optimized nanolayer, protects the cutting face best. Much higher hob tool life can be achieved maintaining the same or even less crater wear in comparison to the reference coating or undoped AlCrN-ML. 6 REFERENCES. Karpuschewski B., Knoche H.-J., Hipke M.: Gear finishing by abrasive processes, Annals of the CIRP 57 (008), (Keynote paper). McGuinn J., The global gear industry, Gear technology 05/0, -8. Kohlscheen J., Das Prinzip Lamelierung, Werkstatt und Betrieb, WB 05/00, Peyerl G., Kroh R., AlCrN-Schicht erhöht Standzeit von Wälzfräsern bei Zahnradfertigung, Lümkemann A., Cselle T., Büchel C. Morstein M.: Schneidkantenpräparation und Beschichtung: Schlüsselrollen beim Optimieren von Hochleistungswerkzeugen, XIII Internationales Oberflächenkolloquium - IMSAS / Kanten und Radien (0) Cselle T.: Dedication Integration Open Source New Rules in the Coating Industry, Werkzeug Technik 8 (0) 7. Sulzer G.: Leistungssteigerung bei der Zylinderradherstellung durch systematische Erfassung der Zerspankinematik, Dr.-Ing. Diss., RWTH Aachen, Rech J., Schaff M.-J., Hamdi H.: Influence of cutting edge preparation on the wear resistance in high speed dry gear hobbing, Wear 6 (006) Holsten S.: Mikroprozesse an der Schneidkante, Schneidkantenpräparation: Ziele, Verfahren und Messmethoden (009) - 0. Jilek M., Cselle T., Holubar P., Blösch P., Morstein M.: Arc-coating process with rotating cathodes, European Patent EP57577A8 (00). Cselle T., Morstein M., Lümkemann A.: 0 The Year of QuadCoatings, Werkzeug und Technik 0 (0).. Gerth J., Larsson M.,Wiklund U., Riddar, F., Hogmark, S.: On the wear of PVD-coated HSS hobs in dry gear cutting. Wear 66 (009) Gerth J., Werner M., Larsson M., Wiklund U.: Reproducing wear mechanisms in gear hobbing - Evaluation of a single insert milling test. Wear 67 (009) Kalss W,. Reiter A., Derflinger V., Gey C., Endrino J.L.: Modern coatings in high performance cutting applications, International Journal of Refractory Metals & Hard Materials 4 (006) Kohlscheen J., Knoche H.-J., Hipke M., Lümkemann A.: Coating development for gear cutting tools. Key Engineering Mat. Vol. 48 (00) Morstein M., Cselle T., Lümkemann A., Kohlscheen J.: Wälzfräswerkzeug mit einer Beschichtung und Verfahren zur Neubeschichtung eines Wälzfräswerkzeuges. European Patent EP6 66A (00) 7. Karimi A., Wang Y., Cselle T., Morstein M.: Fracture mechanisms in nanoscale layered hard thin films. Thin Solid Films 40-4 (00) Bobzin K., Lugscheider E., Nickel R., Immich P.: (Cr -x Al x )N ein Review über ein vielseitig einsetzbares Schichtsystem. Mat.wiss. u. Werkstofftech. 7, Nr. 0 (006) Cselle T., Coddet O., Galamand C., Holubar P., Jilek M., Jilek J., Lümkemann A., Morstein M.: TripleCoatings - New Generation of PVD-Coatings for Cutting Tools. Journal of Machine Manufacturing Vol. XLIX Issue E (009) Stein S., Lechthaler M., Krassnitzer S., Albrecht K., Schindler A., Arndt M.: Gear Hobbing: a contribution to analogy testing and its wear mechanism. Procedia CIRP (0) - 6

12 Standard Coatings The "parent" coatings determine the application fields of all "children" coatings in the same row. The "children" coatings specify PLATIT's x standard coatings, which can be deposited by the machine of the columns. The exponent x (coating ) describes the generation of the coating. Nitride TiCN-grey TiAlN 4 Al 5 CrN 6 Cr 7 ZrN 8 AlCrN 9 AlTiCrN 0 naco nacro TiXCo Oxi-Nitride nacox DLC 4 VIc 5 cvic 6 CROMVIc 7 CROMTIVIc 8 nacvic Nitride TiCN-grey TiAlN 4 Al 5 CrN 6 Cr 7 ZrN 8 AlCrN 9 AlTiCrN 0 naco nacro TiXCo Oxi-Nitride nacox DLC 4 VIc 5 cvic 6 CROMVIc 7 CROMTIVIc 8 nacvic SCiL 9 -SCiL 0 TiCN-SCiL Al CrN ZrN PL70 cvic : TiCN +CBC TiAlN -ML Al CrN Cr -ML ZrN AlCrN -NL AlTiCrN naco nacro TiXCo TiAlN -ML Al CrN Cr -ML ZrN AlCrN -NL naco nacro p80 p p cvic : TiCN +CBC CROMVIc : CrN +DLC CROMTIVIc : Cr +DLC nacvic : nacro +DLC TiAlN -ML Al CrN Cr -ML ZrN AlCrN -NL naco nacro TiXCo p-eco p p4 VIc : DLC cvic : TiCN +CBC CROMVIc : CrN +DLC CROMTIVIc : Cr +DLC nacvic : nacro +DLC TiAlN -ML Al CrN Cr -ML ZrN AlCrN -NL AlTiCrN naco nacro TiXCo 4 nacox VIc : DLC cvic : TiCN +CBC CROMVIc : CrN +DLC CROMTIVIc : Cr +DLC nacvic : nacro +DLC VIc : DLC cvic : TiCN +CBC CROMVIc : CrN +DLC CROMTIVIc : Cr +DLC nacvic : nacro +DLC TiAlN -ML Al Cr -ML AlCrN -NL 4 4: AlCr = ALL 4 naco 4 nacro 4 TiXCo 4 nacox -SCiL TiCN -SCiL VIc : DLC cvic : TiC+DLC CROMVIc : CrC+DLC TiAlN -ML Al CrN Cr -ML ZrN AlCrN AlTiCrN PL00 cvic : TiCN +CBC CROMVIc : CrN +DLC CROMTIVIc : Cr +DLC