Effect of textures on machining of carbon steel under dry cutting condition

The effect of cutting performance was investigated using uncoated plain andtextured tungsten carbide tools in dry machining of carbon steel. Texture namely straight line,zigzag and plus profiles was created on flank face of the uncoated tungsten carbide tool. This textured tool was designed and fabricated by Neodymium-doped Yttrium Aluminium Garnet ND-YAG laser machine. Also it was evident with scanning electron microscopy analysis. In further design of experiment was carried by taguchi method by using L9 orthogonal array for varying cutting speed, feed rate, depth of cut to perform the machining experiment. The cutting force,surface roughness and cutting temperature were measured in which it depicts that microscale textured tools improves the machining characteristics to a greater extent when compared with untextured tool. It can be effective in all manufacturing industries provide an eco friendly environment since no coolant is required due to which it becomes pollution free.

ICMECE 2020 IOP Conf. Series: Materials Science and Engineering 993 (2020) 012143 IOP Publishing doi:10.1088/1757-899X/993/1/012143 2 been developed to improve machinability process of cutting.Textures permitted to reduce the friction on tool surfaces, reducing the required cutting force.This effect was largely due to the contact lengthdifference between the tool and the workpiece.Due to difference in adherability in material at enhanced cutting speeds there was observed a reduction in cutting force when machining aluminium alloys.The influence of textures was mainly apparent in better lubrication conditions, when cutting forces were at higher cutting speed of 200m/min were reduced to 21.2-34.7 %. Wu Ze et al., [6] Grooved that acted as a same liquid replenishment micro-reservoir were largely responsible for the beneficial impact of surface texturing.The beneficial effect of extended surface texture cutting tools of the cutting performanceeven in a worst lubrication conditions was small whenever the existence of grooves resulted in lower cutting forces on interface of the tool chip solely2% to 8% aimed at highest speed about 200 m / min. Analysis revealed that wear debris trapping function and secondary lubrication effect generated by the textures was smaller.
From the literature study it was found that very less work is carried out in machining carbon steel as the workpiece with textured tool so there are plenty of scopes for further works.

2.Work material and cutting tool used
For the proposed work the workpiece is chosen as Carbon steel (EN3B) grade which has good machining properties. EN3B Steel is able to withstand higher stress levels, especially at small diameters. Tungsten Carbide Insertwhich has been used as cutting tool is been used inturning applications. Geometric specification are orthogonal rake and inclination at an angle of -6°, Orthogonal clearance at an angle of 6°, auxiliary cutting edge at an angle of 15°, principal cutting edge at an angle of 75°, finally the nose radius is taken as 0.8mm. Compared with other metals Tungsten carbide which has hardness value to be 1600 HV make it a very hard metal due to the equal amount of carbon atomsand tungsten. Therefore generally it isviewed as an appropriate material for the production of turning tools.

3.Design and fabrication of micro textured tools
The design of micro texture is done by using design software Creo as shown from Figure [1][2][3][4][5][6][7][8][9][10][11][12], if we look at the design we can observe that the grooves have a width size of 50µm and the distance between each groove is 100µm, the distance from the cutting edge is 150µm these dimensions. The dimension specification of straight line profile tool is taken with the width of the slot to be 0.05mm(50µ) and the distance between the slots is considered as 0.1 (100µm) and the depth of slots is taken as 0.02mm(20µm), finally the distance from the cutting edge is 0.15m (150µm). The dimension specification of zigzag profile tool is taken with the width of the slot to be 0.05mm(50µ) and the distance between the slots is considered as 0.1 (100µm) and the depth of slots is taken as 0.02mm(20µm) and the distance from the cutting edge is 0.15m (150µm). The angle is set to be 45˚ and finally the length of micro texture from corner is set as 2.4mm (2400µm). The dimension specification of plus profile tool is taken with the width of the slot to be 0.05mm(50µ) and the distance between the centre of slots is set as 0.1 (100µm) and the depth of slots is taken as 0.02mm(20µm) and the distance from the cutting edge is 0.15m (150µm) and finally the length of micro texture from corner is set as 2.64mm(2640µm).Arul et al., [7] have conducted a similar experiment to find out the performance of the tool on the work piece material and most of their experiments have shown positive results. Here we are using WC tool for our experiment to conduct test on the hard Carbon Steel EN3B. Nd-YAG laser machine have been used on cutting inserts to produce of 1064nm wavelength slotshaped structures.The above specified laser system produces 3 kHz repetition rate, 0.001m pulse width and 250mJ/sec pulse energy and energy stability accounted for about ±12% of the average value.Cutting insert were analysed in SEM Scanning electron microscope to check micro texture and also dimensions. There are 3 different types of micro textures were fabricated using this laser machining process with distortion in the dimensions of ±10 μm.

4.SEM analysis of fabricated micro textured tools
The SEM analysis for straight line profile tool are captured at a magnification of 64x/269x to measure the dimensions of the micro texture is shown in Figure 13. The SEM analysis for zigzag profile tool are captured at a magnification of 97x/232x to measure the dimensions of the micro texture is shown in Figure 14. The SEM analysis for zigzag profile tool are captured at a magnification of 102x/247x to measure the dimensions of the micro texture is shown in Figure.15 From the SEM analysis it can be observed that three different textures namely straight line, zig zag and plus profile was fabricated according to the design made in pro e software which is shown on the figures listed below.

Machining of Carbon steel with textured and Untextured tool
For turning operations three primary cutting parametersare cutting speed, feedrate, depth cut. In order to establish non-linearity, cutting parameters across three levels were varied for the simulation trials.Experiments were performed based on L9 design of experimental approach as mentioned in Table 1 by using various textured cutting tools for machining carbon steel material.The output parameters are selected so as they give us an overall idea of the relationship between the quality characteristic and the selected factors. Kirloskar Turn master-35 lathe as shown in Figure 16 was used to carry turning operation. A Kistlermulti-component dynamometer of type 9257B and Surface roughness tester named as Mitutoyo-SJ 210 as shown in Figure 17 were equipments used for measuring cutting force and surface roughness. An optical pyrometer as shown in Figure 18 was used to gauge cutting temperature.These responses were recorded and further analysis by using plain and textured uncoated tungsten carbide tool.  Figure.16Machining Setup Figure.17Mitutoyo tester Figure.18 Optical Pyrometer L9 taguchi design was used for designing the experiment. The workpiece is fixed in the Kirlsloskar made turnmaster-35 lath. The cutting speed (the speed of rotation of chuck) is adjusted using tachometer and the required cutting speed is set by adjusting the nob on the set up. The feed rate in voltage is set in the voltmeter in the experimental setup. Kistler dynamometer is used to measure cutting force and surface roughness tester to measure surface roughness. To measure surface smoothness the instrument was placed on the machined surface. Four average values are taken from the surface to find out surface roughness. Pyrometer was used for measurement of cutting temperature. Cutting force,cutting temperature,surface roughness is given in Table 2 for dry turning of plain tungsten carbide tool, Table 3 for dry turning of straight line profile tool, Table 4 for dry turning of zigzag profile tool and Table 5 for dry turning of plus profile tool. All the measured responses were analysed for this proposed research.

Analysisof responses by using MINITAB
The MINITAB software is used to analyse Taguchi design and generate graphs.From graphical chart as shown in Figure 19 there is a gradual reduction in cutting force, surface roughness and cutting temperature when the cutting speed was 115m/min, feed rate was 0.05 mm/rev and depth of cut was 0.5mm . The cutting force, surface roughness and cutting temperature increases as we decrease the cutting speed and increase the feed rate and depth of cut for plain uncoated tungsten carbide tool.From graphical chart as shown in Figure 20 there is a gradual reduction in cutting force, surface roughness and cutting temperature when the cutting speed was 95m/min, feed rate was 0.075 mm/rev and depth of cut was 0.5mm for straight line textured tool. From graphical chart as shown in Figure 21 there is a gradual reduction in cutting force, surface roughness and cutting temperature when the cutting speed ICMECE 2020 IOP Conf. Series: Materials Science and Engineering 993 (2020) 012143 IOP Publishing doi:10.1088/1757-899X/993/1/012143 8 was 115m/min, feed rate was 0.075 mm/rev and depth of cut was 0.5mm . The cutting force, surface roughness and cutting temperature increases as we decrease the cutting speed and increase in depth of cut and mid range for feed rate incase of zigzag textured tool. From graphical chart as shown in Figure 22 there is a gradual reduction in cutting force, surface roughness and cutting temperature when the cutting speed was 95m/min, feed rate was 0.01mm/rev and depth of cut was 0.5mm . The cutting force, surface roughness and cutting temperature increases as we increase in depth of cut and mid range for cutting speed incase of plus textured tool. Plain tool has an average cutting force of 264N on machining the Carbon Steel as shown in Figure.23.The cutting forces which are generated by micro textured tools (straight line and zigzag) have less cutting force while machining when compared them with the plain tool profile. But the zig zag microtextured tools have made lesser cutting forces when liken with all other profile because of anti adhesive properties and efficient transfer of heat during turning operation.Zigzag profile has better surface roughness value when compared with rest of the profiles as shown in Figure 24.The straight line micro profile has a better surface roughness value when compared with plain profile. This phenomena is because of formation of less build up edge at interface of tool chip.The temperatures generated by the Zigzag profiled tool is less than all other profiled tools as shown in Figure 25.The temperature generated by the straight line profile is better than the plain profile.The temperature generated by the plus profile is quite high compared to plain profile. The reduction in temperature is due to reduced friction in tool and machined surface due to microtexture. When the cutting speed increases there is a great reduction in BUE formation as the chips can be easily detached from the tool chip interface hence the friction reduces and hence there is gradual decrease in cutting force and  [8]. At lower cutting speed the BUE formation is more because the chip will be plastically weld to the tool surface which results in increase of cutting force and cutting temperature. From the graph it can be observed that cutting speed, surface roughness and temperature is less when compared with the machining of plain uncoated tungsten carbide tool.

Conclusions
Three designs of micro texture namely straight line, zigzag and plus were designed and fabricated using Creo software and Nd:YAG laser macine. The effects of machinability parameters such as cutting forces , cutting temperature and surface roughness was analyzed during dry turning of Carbon ICMECE 2020 IOP Conf. Series: Materials Science and Engineering 993 (2020) 012143 IOP Publishing doi:10.1088/1757-899X/993/1/012143 10 steel (EN3B). Cutting forces generated by the Zigzag profile has shown best results and Straight line profile has shown better results than plain tool. TheZig-zag profile tool has given best Surface roughness and straight line has shown better results than plain tool.The temperature generated while machining of Zigzag as well as Straight line profile tool has given better results than plain tool. Textures developed on flank face structured on cutting tool inserts have shown benefits in lowering cutting forces, cutting temperature,surface roughness when compared with plain tool. It can be effective in all manufacturing industries provide an eco friendly environment since no coolant is required due to which it becomes pollution free.