Flank Surface Research Articles

Forecasting the output using ANN models and effect of input factors on machinability of Duplex Steel 2205 in dry-turning operation for high strength and anti-corrosive applications

ABSTRACT The products made of advanced materials are the buzz amid material scientists as they possess enhanced mechanical properties, leading to development of material such as Duplex Steel 2205. The material being hard and having high strength, machinability along with stringent environmental regulations is a challenge keeping in view the wide range of applications that the material caters like pressure vessels, marine equipment and heat exchanger. The current experimental investigation of flank wear and surface roughness was predicted through ANN model and experimentally evaluated under dry-turning conditions using carbide-tipped inserts. Dry turning was performed by selecting the speed levels of 103, 134, and 174 m/min; feed rate (FR) levels of 0.12, 0.15, and 0.18 mm/rev; and depth of cut (DOC) levels of 0.5, 1.0, and 1.5 mm. Experiments were designed using Taguchi-L9 model, optimum cutting speed (134 m/min), feed (0.12 mm/rev), and DOC of (1.0 mm) resulted in least Ra values. The regression model created on the experimental data is in 95% conformance for surface roughness and flank wear. Optimal machining parameters indicate that cutting speed have greatest significance on machining trailed by feed and DOC.

Development of PCBN micro ball-end mill with multi-edge and spherical flank face

Micro mills play an important role in micro-milling applications for precision micro-parts such as optical molds, microsensors, etc. With the wide application of difficult-to-machine materials in such micro-parts, poor machining quality and rapid tool wear have become serious problems restricting the application of micro-milling technology. In order to achieve higher machining quality and longer tool life, a PCBN micro ball-end mill structure with multi-edge and spherical flank face (MSPBM) is designed. This structure enables multiple edges to participate in cutting at the same time, which can share the cutting force to reduce tool wear. In addition, the structure of the spherical flank surface makes the flank surface fully in contact with the machined surface, which enables CBN particles to micro-grind the machined surface to achieve the effect of milling-grinding combined machining, and the better surface quality can be obtained. The grinding experiments are carried out to optimize fabrication process parameters based on grey relational grade theory and the MSPBM with 0.2 mm diameter is fabricated through multi-axis linkage grinding and micro-compensation of motion axes. Then, slot milling experiments are carried out on the martensite stainless steel to investigate the micro-milling performance of the mill, and the surface topography, surface roughness, and the tool wear topography are observed and analyzed. The results show that the surface quality and wear resistance of the MSPBM are improved compared to the standard ball-end mill. The structural design principle of the micro mill can be used to guide the design of mills for high-quality machining of difficult-to-machine materials.

Assessment of textured broach lubricated with carbon fiber and calcium sulfonate composite grease

Due to the heavy load of broaching, a severe shearing effect occurs between the tool material and workpiece material, resulting in tool wear and a decrease in the quality of the workpiece. The groove is introduced into the flank surface of the tool to improve its tribological properties. Moreover, a mixed lubricant (G/CF) containing carbon fiber (CF) and calcium sulfonate composite grease (CSG) is used in the textured tool. The lubricating properties of G/CF are then investigated by broaching steel 1045 (AISI). Cutting force, the surface morphology of the workpiece and tool, and cutting vibration are used to evaluate the cutting performance of the tool under different lubrication conditions. The results show that G/CF reduces the cutting force by 12 % and the surface roughness of the workpiece by 36.7 % compared with dry cutting. The reason is that the carbon fibers attached with grease are taken out of the textures during cutting to re-lubricate the friction pair. In addition, carbon fibers adhering to the workpiece surface prevent debris from damaging the machined surface. Therefore, adding G/CF to the groove improves the cutting performance of the tool and provides a useful reference for the research of self-lubricating tools.

Performance Characteristics of Spur Gears Hobbed under MQL, Flood Lubrication, and Dry Environments

This paper presents the influence of three lubrication environments, namely hobbing with minimum quantity lubrication (HWMQL), hobbing with flood lubrication (HWFL), and hobbing without any lubrication (HWAL), on the wear characteristics, microhardness, functional performance parameters, generation of noise and vibrations, flank surface roughness, and microgeometry deviation parameters of spur gears. Convective heat transfer coefficients in HWMQL and HWFL are evaluated to study the cooling mechanism involved and their heat dissipation capabilities during spur gear manufacturing. It is found that HWMQL-manufactured spur gears exhibited higher microhardness and smaller values of microgeometry deviations, flank surface roughness, functional performance parameters, wear rate, wear volume, and noise and vibrations than the spur gears manufactured by HWFL and HWAL. HWMQL facilitated a significantly higher convective heat transfer coefficient than HWFL, indicating its superior hobbing performance. An examination of the worn flank surfaces of HWMQL-manufactured gears revealed a wear track that resulted in less abrasive wear, wear debris, and subsurface damage, whereas the worn flank surfaces of HWFL-manufactured gears showed deep grooves, feed marks, and surface defects. This study proves that HWMQL is capable of manufacturing gears with better accuracy, enhanced wear resistance, smoother and quieter operational performance, and longer service life due to its better cooling and lubrication action. The results of this study will be very helpful for the manufacturers and users of spur gears.

Study on Low-Damage Cutting of Alfalfa Stalks by Self-Sharpening Blades of Gradient Material with Carbon-Nitron-Boronized Heat-Treatment

The work aims to realize low-damage cutting of Alfalfa stalk. The self-sharpening blades of gradient material were prepared by 40 Cr steel, then heat-treating the flank surface by carbon-nitron-boronized with a rare elements catalysis technique. The biological characteristics of Alfalfa incision self-healing and regeneration process were analyzed in order to compare the cutting effects of different blades. After treatment with carbon-nitron-boronized with rare elements catalysis, the flank surface and tip point of blades were coated by boride layer and carbonitriding layer. The composition, microstructure and properties of the carbon-nitron-boronized layer demonstrated a gradient distribution state, and had good wear resistance. A kinetic model for the formation of the carbon-nitron-boronized layer was proposed. The initial stage of heat-treatment was mainly a carbonitriding process. When continuous and compact boride was formed on the surface, it was mainly boridized. The results of field experiment indicated that compared with the commercial blades, the self-sharpening blades have excellent properties as wear resistance and long service life. In addition, the cut damage caused by the self-sharpening blades was less, the self-healing and regeneration process of Alfalfa stalk was normal, and the regeneration duration was greatly shortened. The blades with carbon-nitron-boronized heat-treatment could form the self-sharpening characteristics, always maintaining the cutting sharpness, and realized the low-damage cutting of Alfalfa stalk.

Assessment of machining performance parameters of nanofluid-based MQL-turning: An experimental analysis and CFD modelling

Nano-cutting fluids as a coolant are often used in modern days manufacturing industry. These nano-cutting fluids have certain advantages over conventional coolants in terms of heat transferability and lubricity. The present focused study investigates the machining performance in Minimum quantity lubrications (MQL) turning operation using MoO3/water nano-cutting fluid. The machining performance parameters (like friction coefficient, cutting forces, surface roughness and wear) are investigated experimentally using MoO3/water nano-cutting fluid. Also, a computational fluid dynamics (CFD) model was developed to investigate the heat dissipation and temperature profile at rake and flank surface of the carbide cutting tool. The experimental outcomes of the present study illustrate the enhancement in machining performance in terms of reduction in friction coefficient, cutting forces, surface roughness and wear. Heat transfer analysis and a numerical model based on the notion of a CFD tool were used to explore the temperature propagation along with the flank and rake surface of tungsten carbide cutting inserts in order to properly measure tool tip temperature while turning. The simulation study demonstrated the reduction in tool tip temperature at rake face from 1031 K to 824.98 K for the cutting fluid velocity of 25 m/s, while for 2 bar cutting fluid pressure the temperature at rake face reduces to 874.37 K.

Generation mechanism of surface micro-texture in axial ultrasonic vibration-assisted milling (AUVAM)

Although axial ultrasonic vibration-assisted milling (AUVAM) is promising for rapid and economical fabrication of 3D micro-texture on various surfaces, it has been a challenge to obtain micro-texture with small feature size and large height simultaneously. The mechanism and major influence factors for the formation of micro-texture by this method were explored in this study. It was found that the generation of micro-texture was mainly caused by cutting and extrusion from the flank face of the milling tool under ultrasonic vibration. Therefore, a novel 3D tool model that considered the relief angle, end cutting edge angle and the blade profile was established in simulation analysis. The good agreement between simulation and experimental results demonstrated that the influence of the flank face on the micro-texture was mainly attributed to the relief angle of the milling tool. It was the first time to report that both the height and the profile shape of the micro-texture unit were affected by the overlap and extrusion between the flank surface and the micro-texture. But this influence diminished with the increase of spindle speed. 3D sinusoid-shaped micro-texture with minimum width of 20 μm and height of 2 μm (fully reproduced the ultrasonic amplitude) was realized with the relief angle of 40° and spindle speed of 4000 rpm. Other typical textures of weave, shell, scale and corrugation were also presented to show the effective regulation of texture patterns in AUVAM. This work provides both theoretical and practical basis for such a low-cost, efficient and controllable 3D micro-texture preparation method.

Machining induced tribological investigations in sustainable milling of Hardox 500 steel: A new approach of measurement science

Hardox 500 is known as hard-to-cut steel possessing supreme abrasive wear resistance that makes it suitable for industrial applications especially for transportation. However, such properties limit the machinability of this low alloy, martensitic material in addition to being sensitive to thermal loading. Therefore, this study purposes to improve the machinability index of Hardox 500 steel by questioning the tribological influence of the various cooling and lubricating environments during milling operation. In this direction, dry, pure-MQL, conventional flooding and LN2 based cryogenic mediums were tested while observing tool wear, surface roughness and topography, cutting temperature and chips morphology. Seemingly, cryogenic environment suppresses the thermal effects while cutting with improving tool wear resistance, surface quality of the part and chips morphology, in comparison with other regimes. A supreme enhancement in the flank wear (114 %), cutting temperature (319 %) and surface roughness (152 %) were achieved by using cryogenic cooling over dry regime. Obtained findings were discussed within the framework of the tribological performance of the sustainable lubri-cooling regimes.

THE ORIENTATION ANGLE OF REINFORCING ELEMENTS INFLUENCE ON TOOL WEAR INTENSITY IN PROCESSING POLYMER COMPOSITES

The relative angle between the direction of the reinforcing fibers and the cutting speed vector, defined as the angle of the reinforcing elements orientation, has a significant impact on the chip formation mode, cutting forces and the final surface quality. During machining of polymer composite materials, high-intensity wear occurs along the flank surface. This paper presents an analysis of the problem of the orientation fibers angle influence in a polymer composite on the cutting tool wear rate. For the previously proposed hereditary-aging model of tool weight loss due to wear, it is proposed to take into account the influence of the reinforcement angle through the dependence of the contact pressure and friction coefficient on this parameter. The article develops a generalizing model for practical consideration of the known in advance angle of reinforcement to predict tool wear and tool life during of polymer composite materials machining.

Open Gear Rolling Contact Fatigue Life Prediction by a Numerical Approach

Abstract In order to characterize the resistance to surface pitting of gears subjected to contact fatigue cycles, test campaigns have been carried out on toothed rings in through hardened wrought steel 42CrMo4, meshing a case-hardened 17CrNiMo6 pinion. It was observed that due to the operating conditions, low speed, and grease lubrication, significant strain hardening developed on the involute tooth flank surface and subsurface. This resulted in enhanced material properties against pitting and consequently much higher allowable stress levels than those given by the ISO 6336 series of standard. The 42CrMo4 load capacity was increased by 38% at surface pressure (+90% in torque) compared to the expected results from the ISO 6336. Similar tests carried out on a through hardened wrought steel 30CrNiMo8 gears lead to results of the same order of magnitude. The purpose of this study is to develop a chain of numerical models and methods fed by material tests, in order to improve the accuracy of the estimation of the load capacity of open gear pair with hybrid material (surface case-hardened pinion against through hardened wrought steel). This new approach shows, explains, and predicts the increase in the capacity to withstand surface pressure by comparing present results with rolling contact fatigue lifetimes obtained during tests on several open gears submitted to different mission profiles. This study made it possible to reproduce how and under what conditions the work hardening during running-in reaches required depth resulting in a beneficial effect on the resistance to pitting.

Comparative performance evaluation between uncoated and TiAlN + AlCrN coated carbide tools in hard turning of AISI H11 steel

Cutting tools, such as ceramic, cubic boron nitride, and polycrystalline diamond, are normally preferred to machine hardened hot work steel materials which are exclusively demanded in mould and die-making industries. However, such tool materials are very costly. If carbide tools with proper coatings will be used within a particular machining range, comparative tool life can be achieved with lesser cost in hard machining. The present experimental work is based on the comparative assessment among new generation TiAlN + AlCrN coated and traditional uncoated carbide tools concerning tool life, tool flank wear, cutting temperature, cutting force, and surface integrity in dry hard turning of AISI H11 steel. The experiments with 16 trials are performed according to the L16orthogonal array by considering various machining parameters that include cutting speed, depth of cut, and feed. At last, with the measured tool life and as per Gilbert's economic approach, distinctive cost analysis has been implemented to demonstrate the cost-effectiveness of coated carbide tools in hard turning. From the experimental results, a promising machining performance is noticed for TiAlN + AlCrN coated carbide inserts in terms of all machining attributes compared to uncoated carbide inserts due to superior wear resistance, and surface hardness as well as strength of coating material. In summary, the multilayer TiAlN + AlCrN coated carbide tool offers significant cost savings (Rs. 12.82 in Indian currency), with a 9% reduction in production costs in comparison with hard turning via. uncoated insert (Rs. 14).

Flank Surface Treatment of Spur Gears Machined by MQL Assisted Hobbing Using Micro-Plasma Transferred Arc

In the present study, feasibility of micro-plasma transferred arc (M-PTA) for flank surface treatment of gears has been explored. 20MnCr5 spur gears manufactured by sustainable technique minimum quantity lubrication assisted hobbing (MQLAH) were subjected to M-PTA-based heat treatment for further improving the surface properties of flank surface and comparisons were made with respect to M-PTA treated gears machined by conventional flood lubrication assisted hobbing (FLAH). The results revealed that M-PTA enhanced flank surface hardness of all the gears without deteriorating the gear accuracy. However, flank hardness increment was observed to be almost 18% in case of MQLAH gears as compared to 15% for FLAH gears. This study proves that M-PTA based heat treatment after MQLAHcan result in superior surface hardness along with better gear accuracy and can improve the sustainability of overall process chain involved in machining-based gear manufacturing.

Sustainable Manufacturing of Asymmetric Miniature-Sized Ratchet Wheels by Wire Electrical Discharge Machining

In this paper, the outcomes of an investigation conducted on the sustainable manufacturing of asymmetric rotary miniature-sized ratchet wheels of stainless steel (SS) 304 by a vertically traveling wire electrical discharge machining (WEDM) process are reported. The consumptions of energy and wire material are the process sustainability indicators considered in this work. Box-Behnken-based seventeen experiments were conducted by varying spark-on-time ‘Ton’, spark-off-time ‘Toff’, and wire rigidity ‘WT’. Desirability function analysis (DFA) based on multi-response optimization was performed to obtain an optimum setting of WEDM parameters to manufacture miniature-sized ratchet wheels with minimum energy and wire consumption. Sustainable manufacturing of ratchet wheels is performed at the optimum parameter combination of Ton-1.5 µs; Toff-40.5 µs; WT-1260 g, for the least values of energy consumption of 0.64 kWh and wire consumption of 20.11 g with no wire breakage and a significant reduction in total idle time. This ratchet wheel, manufactured at optimum parameters of WEDM, was also found to have a good finish (average surface roughness ‘Ra’-1.08 µm and maximum surface roughness ‘Rt’-6.81 µm) and defect-free tooth flank surfaces. Overall, it is concluded that WEDM has the potential to achieve sustainability in the manufacturing of miniature-sized ratchet wheels and other gears. The outcomes of this work will extensively facilitate engineers and researchers in selecting a suitable range of machining parameters for sustainable manufacturing of miniature-sized wheels and gears.

Wear behaviors of cubic boron nitride tools with various binders in high-speed turning of compacted graphite irons

Compacted graphite iron (CGI) is a promising material as diesel engines in automotive industry, but the poor machinability and low machining efficiency have further hindered the employment of CGI in the potential applications. Cubic boron nitride (cBN), possessing extreme hardness and chemical inertness, is the best candidate as tools to machine ferrous metals. In this paper, we attempt to explain the disparities in wear behaviors of cBN tool with different binders by implementing high-speed turning of CGI. The effects of various binders on cBN tool flank wear, cutting force, cutting temperature, and machined surface roughness was systematically investigated. Additionally, the response relationship among flank wear, cutting force, temperature and surface roughness was obtained. Further, the underlying reasons of the wear mechanism of cBN tool were revealed. The results indicated that the cBN tool performances strongly depend on the affinity of binders with CGI. The contributions of binder phases, cBN content, and cBN grain size under the employed machining conditions: the binders are dominated, and followed by cBN grain size or cBN content in the high-speed cutting of CGI. The small cBN grain size, and TiCN, TiC, TiN binders of cBN tools have superior cutting performance than the Co binders.

Geometry modifications of single-lip drills to improve cutting fluid flow

For single-lip drills with small diameters, the cutting fluid is supplied through a kidney-shaped cooling channel inside the tool. In addition to reducing friction, the cutting fluid is also important for the dissipation of heat at the cutting edge and for the chip removal. However, in previous investigations of single-lip drills, it was observed that the fluid remains on the back side of the cutting edge, and accordingly, the cutting edge is insufficiently cooled. In this paper, a simulation-based investigation of an introduced additional drainage flute and flank surface modifications is carried out using smoothed particle hydrodynamics as well as computational fluid dynamics. It is determined that the additionally introduced drainages lead to a slightly changed flow situation, but a significant flow behind the cutting edge and into the drainage flute cannot be achieved due to reasons explained in this paper. Accordingly, not even a much larger drainage flute with unwanted side-effect of a decrease tool strength is able to archive a significant improvement of the flow around the cutting edge. Therefore, major changes to the cooling channel, like the use of two separate channels, the modification of their positions, or modified flank surfaces, are necessary in order to achieve an improvement in lubrication of the cutting edge and heat dissipation.

Analytical Model for Temperature Prediction in Milling AISI D2 with Minimum Quantity Lubrication

Milling with minimum quantity lubrication (MQL) is now a commonly used machining technique in industry. The application of the MQL significantly reduces the temperature on the machined surface, while the cost of the lubricants is limited and the pollution caused by the lubricants is better controlled. However, the fast prediction of the milling temperature during the process has not been well developed. This paper proposes an analytical model for milling temperature prediction at the workpiece flank surface with MQL application. Based on the modified orthogonal cutting model and boundary layer lubrication effect, the proposed model takes in the process parameters and can generate the temperature profile at the workpiece surface within 1 min. The model is validated with experimental data in milling AISI D2 steel. With an average absolute error of 10.38%, the proposed model provides a reasonable temperature prediction compared to the experimental results. Based on the proposed model, this paper also investigates the effect of different cutting parameters on the cutting temperature. It is found that the application of the MQL decreases the temperature at the cutting zone, especially at the flank surface of the workpiece, which is due to the heat loss led by air-oil flow.

Performance comparison of green lubricants in gear hobbing with minimum quantity lubrication

It presents performance comparison of two green lubricants based on fatty alcohol and synthetic ester in hobbing with minimum quantity lubrication of spur gears using temperature generation at teeth hobbing zone (THZ), heat transfer mechanism, hob wear, gear quality, microhardness, and work hardening capacity. It is found that fatty alcohol-based lubricant yielded smaller THZ temperature, minimum hob wear, microgeometry deviations, and flank surface roughness and higher Prandtl number, microhardness, and work hardening capacity than synthetic ester-based lubricant. Higher Prandl number means friction reduction at THZ by forming a stable protective layer and heat dissipation by convection. Synthetic ester reduced THZ temperature by better cooling action. The outcome will aid in selection of better green lubricant to improve sustainability of hobbing.

Novel generation method of tooth surface points for variable transmission ratio gears

Variable transmission ratio gears have shown considerable potential as key components of variable speed transmission steering boxes that balance steering portability and sensitivity. The objective of this study is to develop a novel method for designing variable transmission ratio tooth surfaces to circumvent the shortcomings of the meshing theory method. The involute rack of the variable transmission ratio pinion-and-rack pair is considered as a set of countless and infinitely close transverse sections, each of which is referred to as a gear element. Assuming evenly distributed circles in the physical domain of the variable transmission ratio tooth surfaces of the pinion, the problem of generating a tooth surface point is transformed into solving the specific geometric feature intersection point of each circle and corresponding gear element during variable transmission ratio meshing. Thereafter, a mathematical model and algorithm are developed to generate tooth surface points in an approximately even pattern. The normal deviations of the gear-element–generated tooth surface points and the corresponding tooth surface points calculated using meshing theory show that the proposed design method has a sufficiently high accuracy. Finite element models are employed analyzing the contact pattern, contact stress, bending stress, and transmission ratio error. The results indicate that the layout of approximately even tooth surface points using the gear element method is beneficial for improving the fitting precision of tooth surfaces and reducing the contact stress and transmission ratio error. Further, the same derived law of the flank and fillet tooth surfaces is conducive to the continuity of the tooth surfaces, which contributes toward reducing the bending stress. Finally, a prototype is manufactured via CNC end milling. The major contributions lie in a robust and efficient modeling method for variable transmission ratio tooth surfaces, which combined forms a solid foundation for their application.

Influence of the cutting parameters on the flank surface roughness at thread whirling of low carbon steel worm shafts

Thread whirling is a machining process applied mainly for its high material removal rate, ensuring the thread cutting in one single machining pass. The process presents other advantages as continuous and accurate machining, by tilting the whirling ring to the helix angle, machining long threads of deep thread parts as worm shafts, feed screws, etc. This paper presents experimental research results on the whirling process, respectively the influence of the cutting parameters specific to the whirling process on the roughness of the flank surface, in the case of worm shafts made of low carbon steel. The empirical mathematical models were obtained and discussed.

Investigation of the performance of cermet tools in the turning of Haynes 25 superalloy under gaseous N2 and hybrid nanofluid cutting environments

Co-based superalloys such as Ni-based, Fe-based, and other such superalloys are classified as difficult-to-machine materials. Due to the poor machinability of superalloys, their machining is a big challenge for metal cutting industries. However, the machining of superalloys under ecological cutting environments (e.g., MQL, nanofluids, cryogenic cooling, etc.) has shown promising results. The present study investigated the effects of ecological cutting environments on the performance of cermet cutting tools. To this purpose, Co-based Haynes 25 superalloy was turned under MQL, graphene nanoplatelet (GnP) doped mono nanofluids, multiwalled carbon nanotube (MWCNT) doped mono nanofluids, GnP/MWCNT doped hybrid nanofluids, gaseous N2 based cutting environments, and mono/hybrid nanofluids combined with N2. Viscosity, pH, thermal conductivity, and wettability properties were investigated to determine the characteristics of the nanofluid mixtures. Cutting temperature, tool wear, wear mechanisms, surface roughness, surface topography, and chip formation morphology were chosen as the machining performance criteria. The experimental results showed that the cermet cutting tool and the GnP/MWCNT+N2 hybrid cutting environment contributed significantly to the Haynes 25 machining performance. Compared to the dry cutting environment, the N2 cutting environment showed the best performance improvement (63.57%) for cutting temperature, whereas the GnP/MWCNT+N2 hybrid cutting environment yielded the best performance and the best the improvement in tool flank wear (45.13%) and surface roughness (36.36%).