Terms Of Tool Wear Research Articles

Tool wear analysis on coated and uncoated carbide tools in inconel machining

The aerospace industry has increasingly been using materials that have outstanding mechanical properties such as high strength, thermal and chemical resistance. Inconel 718 has been considered ideal material for hot and corrosive environments like aircraft jetengines. However, Inconel is difficult to machine due to its high toughness, low thermal conductivity and work-hardening during cutting. In this regard, the cutting speed for Inconel cannot be higher because tool chipping, notching and excessive wear occur at high cutting speeds. In this study, machining methods such as minimum quantity lubrication (MQL) with and without nano-particles, and cryogenic treated cutting tools have been applied for Inconel machining. Tool wear in these conditions are analyzed and compared with that of traditional machining methods, dry and wet machining. Coated and uncoated carbide tools are used to evaluate the coating effect associated with the machining methods. From the experimental results, surprisingly, the dry and wet machining outperformed both MQL and MQL with nano-particles in terms of tool wear. The cryogenic treated tool showed stable tool wear without severe edge fracture due to cryogenic hardening of the cutting tool while the MQL and Nano-MQL fractured severely, and the uncoated carbide tool performed better than the coated one.

Effect of PCBN tool grade on joint strength and tool life in friction stir spot welded DP 980 steel

Friction stir spot welding of advanced high strength steel, like dual phase (DP) 980, is a very demanding application in terms of tool wear. The best candidate material currently being tested is polycrystalline cubic boron nitride (PCBN). The purpose of the current work is to study the effect of PCBN material grade, as specified primarily by CBN grain size, on weld quality and tool life, for the spot welding of DP 980 steel. With a nominal composition of 90% CBN, three tool grades were tested. Grade A had CBN grain sizes of 3–6μm, grade B had grain sizes of 12–15μm, and grade C had a multimodal distribution, with grain sizes ranging from 4 to 40μm. The best performance in terms of joint strength and tool life was achieved with grade A. The effect of fine CBN grain size was less adhesion of DP 980 on the tool surface over time, less abrasive wear, and higher lap shear failure loads of the welds that were produced, compared to the other grades. A-type tools were the most consistent in both the number of welds per tool, and the number of welds that reached acceptable lap shear failure loads. B-type tools, performed slightly better than C-type tools in terms of wear, but neither of them was able to achieve consistent, acceptable lap shear failure load values after the first 200 welds. In fact only one out of five C-type tools was able to produce acceptable lap shear failure loads after the first 100 welds. Based on the experimental evidence, tool wear was likely dominated by grain pullout. This is consistent with the correlation showing that larger CBN grain size was related to shorter tool life.

Influences of Micro Mechanical Property and Microstructure on Performance of Machining High Chromium White Cast Iron with cBN Tools

The variation of the micro mechanical properties, such as hardness and modulus, of the material is important potential factor influencing the machinability of the material. The presented paper is to study the influence of variation in micro hardness and microstructure of the materials on machining performance in terms of tool wear and tool life, cutting forces and surface quality. The work material is high chromium white cast iron and material of cutting tool is cBN. The variation of micro hardness were measured and analyzed by grid nano indentation approach. Volume fraction phases of the material were identified through Weibull mixture distribution from result of grid nano indentation. High chromium white cast irons were prepared with two groups of composition, lower carbon silicon and higher carbon silicon, in the state of as-cast and hardened condition. Results from the machining test indicate that the variation of micro hardness of the work materials show significant impacts on cutting tool wear, tool life, cutting forces and surface quality in the machining of these materials. The effect of micro mechanical properties needs to be taken into account in the modelling and predicting tool life and surface quality. In addition, the mechanism of interaction between the cBN tool and the high chromium white cast iron under the range of machining parameters was also addressed. Lastly, surface roughness measurements complemented the results and a qualitative relationship between the surface roughness generated during the machining and the materials is also laid out.

Flank Wear Mechanism of WC-5TiC-10Co Cemented Carbides Inserts when Machining HT250 Gray Cast Iron

WC–5TiC–10Co cemented carbides inserts were prepared and used for the cutting tool for HT250 gray cast iron. The objective was to investigate the wear mechanism when machining HT250 gray cast iron with WC–5TiC–10Co cemented carbides inserts. WC–10Co cemented carbides with the same sintering technology and grain size were prepared for comparison. wear mechanism was examined at the same cutting parameters. The cutting tests were performed at a speed of 120 m/min with feed rate of 0.2 mm/rev and a constant depth of cut of 0.2 mm under dry conditions. Tool wear mechanism is analyzed by SEM and EDS. Adhesive and built-up-edge were found to be the predominant tool wear for WC–5TiC–10Co cemented carbides inserts. However, Attrition was the main wear mechanisms observed in WC–10Co cutting tools. The results obtained indicated that WC–5TiC–10Co cutting tools performed better than WC–10Co cutting tools, in terms of tool wear with current parameters.

High Speed Machining of Difficult-to-Machine Materials under Different Lubrication Conditions

This paper describes the applicability of air jet assisted (AJA) machining to stainless steel and titanium alloy at high cutting speeds in terms of tool wear and tool life. A specially designed tool holder with an air nozzle very close to the tool tip was prepared for turning stainless steel. From the experimental results, it was found that the application of flood coolant from the side of the end flank face leads to better result in tool life in AJA machining of stainless steel than that from the side of the side flank face. The assistance of air jet can improve the tool life of the M35 CVD coated insert in machining of the stainless steel by 36 to 100% under the optimal conditions in comparison with wet machining. It was also found that the air jet assistance extended the tool life of the S10 PVD coated insert by 48% in turning titanium alloy. The tool life extension of the coated insert in AJA machining titanium alloy is much longer than that of an uncoated carbide insert.

Experimental Effect of Cryogenic MQL Cutting 304 Stainless Steel

Cryogenic MQL is a kind of green machining technology of the combination of cryogenic air and minimal quantity lubrication (MQL). The aim of this research is to determine if the cryogenic MQL technique in turning with Cutting tool with internal cooling structure gives some advantages in terms of tool life, surface roughness and cutting chip breaking. This paper reports the results obtained from turning tests, at one feed rates (0.12mm/r) and one depth of cut (0.4mm) and different cutting speeds (43m/min, 108m/min, 217m/min), and the results obtained show that using cryogenic MQL had some advantages in terms of tool wear, surface roughness and cutting chip breaking compared to using dry cutting and cryogenic air cutting. And the results obtained show that when cryogenic MQL and cryogenic air cutting were applied to high speed cutting, they had more advantages.

Eco-friendly face milling of titanium alloy

Recently, a use of difficult to cut materials including titanium alloy has been substantially increasing in aerospace and automotive industries. Eco-friendly machining technology, which eliminates or minimizes cutting fluids in machining fields, has been emerged in compliance with green manufacturing trend. In this regard, machining technologies, such as hard milling, laser assisted machining (LAM), and enhanced lubrication/cooling method, have been adapted by the industries. Among the technologies, cryogenic machining has been considered for a viable solution for the materials without any environmental problems. LAM and minimum quantity lubrication (MQL) can be useful method to cut these materials with an appropriate use. In this study, machining performance of ecofriendly machining techniques was compared experimentally for the titanium alloy (Ti-6Al-4V). The machining performance was evaluated in terms of tool wear and cutting force. From experimental results, coated cutting tool with flood cooling condition was not recommended in titanium machining. The cryogenic, MQL, LAM showed outstanding machining performance than dry and flood cooling. Especially MQL machining was superior with relatively simple system setup. In addition, lubrication and cooling mechanism by combination of MQL and cryogenic reduced cutting force and tool wear. For energy consumption, MQL and cryogenic methods can be a sustainable solution.

Performance of Brazed Carbide End Mill Tool for Machining of Ti6Al4V

Titanium alloys are attractive materials for aerospace industry due to their exceptional strength to weight ratio that is maintained at elevated temperatures and their good corrosion resistance. Major applications of Titanium alloys were military aerospace industry, but since last decade the trend has now shifted towards commercial industry. On the other hand Titanium alloys are notorious for being poor thermal conductor that leads to them being difficult materials for machining. In this experimental study brazed carbide end mill of grade 5 is used for rough down milling of Ti6Al4V for large depth of cut under different combinations of parameters and application of high pressure coolant. The machining performance was evaluated in terms of tool wear, tool life, thermal crack and tool breaking. The tool wear was mostly observed at the tool tip and at bottom part of tool thermal cracks were observed which propagated with respect to time. Flank wear due to scratching of the cutting chips and diffusion wear because of high thermal stresses were observed specially at the bottom of the cutting tool. At cutting speed of 38m/min tool wear couldnt be observed due to tool failure because of fracture under high thermal stresses. It was found that maximum tool life is obtained at the speed of 25m/min, feed rate of 150mm/min and depth of cut of 10mm. In the end it was concluded that machining of Ti6Al4V is a thermally dominant process which leads to high thermal stresses in machining zone that results in increasing tool wear rate and fracture propagation.

Investigation on Wear Behavior and Chip Formation During Up-Milling and Down-Milling Operations for Inconel 718

A comprehensive study and FEM simulation of ball nose end milling on tool wear behavior and chip formation had been performed on Inconel 718 (nickle-based superalloy) under minimum quantity lubricant (MQL) condition. In this paper, the investigation was focusing on the comparison of up-milling and down-milling operations using a multi-layer TiAlN/AlCrN-coated carbide inserts. A various cutting parameters; depth of cut, feed rate and cutting speed were considered during the evaluation. The experimental results showed that down-milling operation has better results in terms of tool wear compared to up-milling operation. Chipping on cutting tool edge responsible to notch wear with prolong machining. It was observed that the chips formed in up-milling operation were segmented and continuous, meanwhile down-milling operation produced discontinuous type of chips.

Tool Wear Analyses in Low Frequency Vibration Assisted Drilling of CFRP/Ti6Al4V Stack Material

Drilling of fiber-metal compound materials is one of the most challenging machining operations. Besides frequently occurring damages of the borehole surface tool wear is a major concern when drilling compound stacks. The significantly divergent cutting conditions of fiber reinforced plastics and metallic alloys require compromises in the tool geometry as well as the cutting materials and coatings. Excessive cutting edge rounding due to the brittle and abrasive fibers leads to increasing cutting forces and temperatures in the metallic alloy. This usually results in a catastrophic failure of the tools. In the present study low frequency vibration assisted drilling (LFVAD) of CFRP/Ti6Al4V [10/10mm] was investigated in terms of tool wear and compared to conventional drilling. Solid carbide drills with a diameter of 4.8mm and different CVD and PVD coatings have been tested. The flank wear as well as the adhesions at the cutting edges have found to be significantly lower when using LFVAD. The tool life could be increased by more than 300% compared to conventional drilling. This is based on considerably lower process temperatures and an improvement of the process stability which could be proved by cutting force measurements. Additionally the chip extraction was found to be more efficient due to the generation of small chip segments which is a consequence of the interrupted cut. Best results in terms of tool wear and borehole quality have been achieved with an AlCrN coating.

Experimental Investigations on Micro Milling of Stavax Stainless Steel

Micro mechanical milling of Stavax (modified AISI 420) stainless steel which is commonly used in the plastic injection molding industry due to its high corrosion resistance, machinability and wear resistance is studied in this paper. The goal of this study is to investigate the influence of process input parameters such as cutting speed, depth of cut, feed per tooth, radial immersion percentage, and plunging method on process outputs during circular pocketing operation. Tool wear, machining forces and surface roughness measurements are considered to identify the relationships between process inputs and outputs. It is observed that plunging method has a significant influence on tool wear which in turn affects micro milling forces and surface quality. The positive impact of micro milling with a pre-drilled hole is demonstrated. The relationship between radial immersion and feed per tooth is shown to be important in terms of tool wear and surface roughness.

Performance of Coated and Uncoated Inserts during Intermittent Cut Milling of AISI 1030 Steel

Knowledge of tool behaviour during intermittent cut machining of various work material is much required in order to improve the efficiency of the machining process. The tool-work impact and related effects of tool wear and surface roughness are often the subjects of interest. Even though, more work has been done to establish the relationship between cutting speed, tool wear and surface roughness during intermittent milling, there is no significant data available for AISI 1030 steel. To fill the gap, the machining of AISI 1030 steel using both coated and uncoated inserts were performed. Results were used to develop a linear regression model by which the relation between the machining parameters and the response were established. Results on tool wear patterns and wear mechanisms were compared between coated and uncoated inserts. Cyclic load on inserts and unstable temperature at cutting zone leads to flank wear and progressive chipping, which were the dominant failure modes observed. Coated inserts out performed uncoated inserts in terms of tool wear and surface roughness. The results also revealed that the feed rate was the dominant factor affecting surface roughness, whereas the cutting speed significantly contributes to the tool wear.

Investigation of Tool Wear, Tool Life and Surface Roughness when Machining AISI D2 Hardened Steel Using PVD TiAlN Coated Carbide Tools

This paper discussed the behavior of cutting tool in terms of tool wear, tool life and surface roughness when machining an AISI D2 hardened steel. An experimental test was conducted at different cutting speeds (Vc) and radial depth of cut (ae) using PVD TiAlN coated carbide tool under dry condition. Tool failure modes and tool wear mechanism for all cutting tools were examined at various cutting parameters. Flank wear was found to be the predominant tool failure for cutting tools. The highest volume material removal (VMR) attained was 3750 mm3 meanwhile the highest tool life (TL) was 9.69 min. The surface roughness (Ra) values from 0.09 to 0.24 μm can be attained in the workpiece with a high material removal. The relationship of tool wear performance and surface integrity was established to lead an optimum parameter in order to have high material removal, maximum tool life as well as acceptable surface finish.

A productive and cost-effective CBN hard milling-based fabrication method of hardened sliding guideways made of refined cast iron

Sliding guideways have received renewed interest in recent years as machine tool linear motion guides, due to a demand for machine tools to have good dynamic performance, which is of vital importance when machining difficult-to-cut materials. While the traditional fabrication approach of the sliding surface is grinding, this paper investigated the possibility of an alternative cubic boron nitride (CBN) milling-based manufacturing approach while utilizing Al and Mg additives in the cast iron material for better machinability and productivity. Machining results have shown a dramatic improvement in machinability especially in terms of tool wear at certain cutting conditions with the refined hardened cast iron and a CBN tool. It was found by the post experimental analysis that oxide films of the Al and Mg additives were generated at the cutting edge of the CBN tool to protect the tool from wear. Because of suppression of tool wear, a very constant surface roughness can also be achieved. A case study has also demonstrated the effectiveness of the CBN milling-based manufacturing approach with the refined cast iron and the found high-speed cutting conditions.

Effects of vegetable-based cutting fluids on the wear in drilling

This study focuses on both formulation of vegetable-based cutting fluids (VBCFs) and machining with these cutting fluids. For this purpose, characterizations of chemical and physical analyses of these formulated cutting fluids are carried out. In this study, performances of three VBCFs developed from crude sunflower oil, refined sunflower oil, refined canola oil and commercial semi-synthetic cutting fluid are compared in terms of tool wear, thrust force and surface roughness during drilling of AISI 304 austenitic stainless steel with HSSE tool. Experimental results show that canola-based cutting fluid gives the best performance due to its higher lubricant properties with respect to other cutting fluids at the constant cutting conditions (spindle speed of 750 rpm and feed rate of 0.1 mm/rev).

Effect of the Process Parameters on the Machinability Characteristics of a CoCrMo Alloy

The paper investigates the machinability characteristics of the CoCrMo alloy ASTM F1537, usually utilized for the production of joint replacements and fixation devices thanks to its high strength, good wear and corrosion resistance, and excellent biocompatibility. This research work intends to overcome the lack of literature data about this alloy machinability, even if its use in the biomedical sector is intensive and it is usually subjected to various machining operations for the implants production. Orthogonal cutting tests were carried out under both dry and lubricated conditions at different cutting speeds and feeds typical of finishing operations. The alloy machinability was analysed in terms of tool wear, cut surface integrity, and chip morphology. In particular, the cut surface integrity was evaluated through its mechanical properties, metallurgical state and topological parameters, highlighting the influence of the process parameters.

Drilling experiments on a gamma titanium aluminide obtained via electron beam melting

Gamma titanium aluminides are intermetallic structural alloys with many advantages like high temperature and oxidation resistance, low density, high specific strength, rigidity, etc. This makes them promising candidates for critical applications where both mechanical and thermal properties are required. Unfortunately, their machinability is demanding, generating low cutting life and poor surface conditions. A deeper knowledge on the machining parameters is essential for a wider application of these heat-resistant light-weight alloys in aircraft and automotive industry. In this paper, the performance of uncoated carbide drills in drilling a gamma titanium aluminide was analysed. The workpiece material was obtained via electron beam melting (EBM) process, a versatile technology for additive manufacturing of complex metal parts from metal powders. EBM is highly appealing in the field of aeroengine components, and it is particularly interesting in processing gamma titanium aluminides. Cutting performances were measured in terms of tool wear, surface roughness, dimensional and geometric errors. The experimental results show strong dependence of tool wear and part quality on cutting parameters, with poor tool life compared with other work materials.

Review of diamond-cutting ferrous metals

Machining of ferrous metals using diamond tools is one of the most important areas in ultra-precision machining as it is not possible to achieve a nanometric surface if one simply uses diamond tools to do the cutting. A review on the wear mechanism and existing approaches for the tool wear reduction discussed in literatures is conducted. By comparing the existing solutions in terms of tool wear and surface finish, publications have shown that ultrasonic vibration cutting and workpiece surface modification have better effects in improving tool life in diamond cutting of ferrous metals. However, the combination of the two solutions does not show a further improvement of either the surface finish or the tool wear reduction compared with that of ultrasonic vibration cutting alone. Studies show that substitutions of tools made of diamond with nano-grained CBN and development of novel suitable-for-diamond-cutting materials are potentials in prolonging the tool life.

IMPROVING MACHINABILITY OF HIGH CHROMIUM WEAR-RESISTANT MATERIALS VIA LASER–ASSISTED MACHINING

The machinability of high chromium wear resistant materials is poor due to their high hardness with a large amount of hard chromium carbides. This study is focused on improving the machinability of high chromium wear resistant materials with different microstructures and hardness levels via laser-assisted machining (LAM). A laser pre-scan process is designed to preheat the workpiece before LAM to overcome the laser power constraint. A transient, three-dimensional LAM thermal model is expanded to include the laser pre-scan process, and is validated through experiments using an infrared camera. The machinability of highly alloyed wear resistant materials of 27% and 35% chromium content is evaluated in terms of tool wear, cutting forces, and surface integrity through LAM experiments using cubic boron nitride (CBN) tools. With increasing material removal temperature from room temperature to 400°C, the benefit of LAM is demonstrated by 28% decrease in specific cutting energy, 50% improvement in surface roughness and a 100% increase in CBN tool life over conventional machining.

Diamond tool wear during ultra-high precision machining of rapidly solidified aluminium RSA 905

Aluminium alloys such as AA 6061-T6 are used to create forming optical surfaces in mould cavities for the injection of plastic optical components. However, 6061-T6 aluminium is characterised by its coarse microstructure which results in inconsistent performance of the cutting tool in terms of tool wear. In this study, a modified grade of 6061 aluminium, called RSA 905, is diamond machined. RSA 905, which enjoys a finer microstructure achieved using a rapid solidification melting process, is diamond turned at different feed rates and a constant cutting speed and depth of cut. This paper reports on the tool wear mechanisms encountered when turning the rapidly solidified aluminium grade using mono-crystalline diamond inserts on an ultra-high precision machining centre. The cutting speed and depth of cut were set at 2000rpm and 25μm, respectively. The tool wear on the flank and crater surfaces was observed using scanning electron microscopy. In addition, acoustic signals emitted during machining were acquired to monitor the tool wear. Although the RSA 905 alloy possesses an increased ultimate strength, its diamond-machinability is found to be high and tool wear is absolutely low even after relatively high cutting distances. However, the tool wear measurement results show that the tool wear tends to be more intensive at the middle value of the feed rate.