Evaluation of machining performance in cryogenic machining of Inconel 718 and comparison with dry and MQL machining

There has been significant work on establishing relationships between machining performance and the cutting parameters for various work materials. Recent trends in machining research show that major efforts are being made to understand the impact of various cooling/lubrication methods on machining performance and surface integrity characteristics, all aimed at improving process and product performance. This study presents the experimental results of cryogenic machining of Inconel 718, a high-temperature aerospace alloy, and comparison of its performance in dry and minimum quantity lubrication machining. Experimental data on force components, progressive tool wear parameters such as flank wear, notch wear, crater wear, cutting temperature, chip morphology, and surface roughness/topography of machined samples are presented. New findings show that cryogenic machining is a promising research direction for machining of high-temperature aerospace alloy, Inconel 718, as it offers improved machining performance in terms of reduced tool wear, temperature, and improved surface quality. It was also found that the number of nozzles in cryogenic machining plays a vital role in controlling cutting forces and power consumption in cryogenic machining of Inconel 718.     

Performance studies of multilayer hard surface coatings (TiN/TiCN/Al2O3/TiN) of indexable carbide inserts in hard machining: Part-I (An experimental approach)

In recent years, hard machining using CBN and ceramic inserts became an emerging technology than traditional grinding and widely used manufacturing processes. However the relatively high cost factors associated with such tools has left a space to look for relatively low cost cutting tool materials to perform in an acceptable range. Multilayer coated carbide insert is the proposed alternative in the present study due to its low cost. Thus, an attempt has been made to have an extensive study on the machinability aspects such as flank wear, chip morphology, surface roughness in finish hard turning of AISI 4340 steel (HRC 47 ± 1) using multilayer coated carbide (TiN/TiCN/Al₂O₃/TiN) insert under dry environment. Parametric influences on turning forces are also analyzed. From the machinability study, abrasion and chipping are found to be the dominant wear mechanism in hard turning. Multilayer TiN coated carbide inserts produced better surface quality and within recommendable range of 1.6 μm i.e. comparable with cylindrical grinding. At extreme parametric conditions, the growth of tool wear was observed to be rapid thus surface quality affected adversely. The chip morphology study reveals a more favorable machining environment in dry machining using TiN coated carbide inserts. The cutting speed and feed are found to have the significant effect on the tool wear and surface roughness from ANOVA study. It is evident that, thrust force (Fy) is the largest component followed by tangential force (Fz) and the feed force (Fx) in finish hard turning. The observations yield the machining ability of multilayer TiN coated carbide inserts in hard turning of AISI 4340 steel even at higher cutting speeds.     

Investigations of flank wear, cutting force, and surface roughness in the machining of Al-6061�CTiB2 in situ metal matrix composites produced by flux-assisted synthesis

This paper presents the results of an experimental investigation on the machinability of in situ Al-6061?CTiB₂ metal matrix composite (MMC) prepared by flux-assisted synthesis. These composites were characterized by scanning electron microscopy, X-ray diffraction, and micro-hardness analysis. The influence of reinforcement ratio of 0, 3, 6, and 9?wt.% of TiB₂ on machinability was examined. The effect of machinability parameters such as cutting speed, feed rate, and depth of cut on flank wear, cutting force and surface roughness were analyzed during turning operations. From the test results, we observe that higher TiB₂ reinforcement ratio produces higher tool wear, surface roughness and minimizes the cutting forces. When machining the in situ MMC with high speed causes rapid tool wear due to generation of high temperature in the machining interface. The rate of flank wear, cutting force, and surface roughness are high when machining with a higher depth of cut. An increase in feed rate increases the flank wear, cutting force and surface roughness.     

TC4钛合金在低温CO2冷却下的切削性能

TC4钛合金在高速车削时易出现刀具磨损快和缠屑等问题,难以保证表面加工质量。利用自行组建的强压液态CO2供给系统,将低温CO2混合物高速射流作为冷却润滑介质,研究了低温CO2射流下高速切削TC4钛合金时的切削温度、切削力、刀具磨损、表面粗糙度以及切屑的断屑情况,并将其与干切削状况进行了对比分析。结果表明,低温CO2射流可有效降低切削温度,减小切削力,减轻切屑缠绕,抑制刀具磨损并提高已加工表面质量。     

Experimental investigations on machinability aspects in finish hard turning of AISI 4340 steel using uncoated and multilayer coated carbide inserts

The present work deals with some machinability studies on flank wear, surface roughness, chip morphology and cutting forces in finish hard turning of AISI 4340 steel using uncoated and multilayer TiN and ZrCN coated carbide inserts at higher cutting speed range. The process has also been justified economically for its effective application in hard turning. Experimental results revealed that multilayer TiN/TiCN/Al₂O₃/TiN coated insert performed better than uncoated and TiN/TiCN/Al₂O₃/ZrCN coated carbide insert being steady growth of flank wear and surface roughness. The tool life for TiN and ZrCN coated carbide inserts was found to be approximately 19 min and 8 min at the extreme cutting conditions tested. Uncoated carbide insert used to cut hardened steel fractured prematurely. Abrasion, chipping and catastrophic failure are the principal wear mechanisms observed during machining. The turning forces (cutting force, thrust force and feed force) are observed to be lower using multilayer coated carbide insert in hard turning compared to uncoated carbide insert. From 1st and 2nd order regression model, 2nd order model explains about 98.3% and 86.3% of the variability of responses (flank wear and surface roughness) in predicting new observations compared to 1st order model and indicates the better fitting of the model with the data for multilayer TiN coated carbide insert. For ZrCN coated carbide insert, 2nd order flank wear model fits well compared to surface roughness model as observed from ANOVA study. The savings in machining costs using multilayer TiN coated insert is 93.4% compared to uncoated carbide and 40% to ZrCN coated carbide inserts respectively in hard machining taking flank wear criteria of 0.3 mm. This shows the economical feasibility of utilizing multilayer TiN coated carbide insert in finish hard turning.     

Performance studies of deep cryogenic treated tungsten carbide cutting tool inserts on machining steel

Abstract

Machining studies were conducted on a carbon steel workpiece using both untreated and deep cryogenic treated P-20 tungsten carbide cutting tool inserts. The flank wear of deep cryogenic treated carbide tools is lower than that of untreated carbide tools on machining of C45 steel. The cutting force during machining of C45 steel is lower with the deep cryogenic treated carbide tools when compared with the untreated carbide tools. The surface finish produced on machining the C45 steel workpiece is better with the deep cryogenic treated carbide tools when compared with the untreated carbide tools.     

An optimization method of the machining parameters in high-speed machining of stainless steel using coated carbide tool for best surface finish

High-speed machining (HSM) has emerged as a key technology in rapid tooling and manufacturing applications. Compared with traditional machining, the cutting speed, feed rate has been great progress, and the cutting mechanism is not the same. HSM with coated carbide cutting tools used in high-speed, high temperature situations and cutting more efficient and provided a lower surface roughness. However, the demand for high quality focuses extensive attention to the analysis and prediction of surface roughness and cutting force as the level of surface roughness and the cutting force partially determine the quality of the cutting process. This paper presents an optimization method of the machining parameters in high-speed machining of stainless steel using coated carbide tool to achieve minimum cutting forces and better surface roughness. Taguchi optimization method is the most effective method to optimize the machining parameters, in which a response variable can be identified. The standard orthogonal array of L₉ (3⁴) was employed in this research work and the results were analyzed for the optimization process using signal to noise (S/N) ratio response analysis and Pareto analysis of variance (ANOVA) to identify the most significant parameters affecting the cutting forces and surface roughness. For such application, several machining parameters are considered to be significantly affecting cutting forces and surface roughness. These parameters include the lubrication modes, feed rate, cutting speed, and depth of cut. Finally, conformation tests were carried out to investigate the improvement of the optimization. The result showed a reduction of 25.5% in the cutting forces and 41.3% improvement on the surface roughness performance.     

低温微量润滑高速铣削PH13—8Mo刀具磨损试验研究

针对高强度不锈钢材料加工性能差、刀具耐用度低的问题,进行了硬质合金刀具在低温微量润滑条件下高速铣削高强度不锈钢PH13—8Mo的刀具磨损试验,结果表明：WSP45刀片比WXM35适合加工PH13—8Mo,低温微量润滑（cMQL）能有效地抑制刀具磨损,提高刀具耐用度;两种刀具在铣削过程中前、后刀面同时发生磨损,最终因刃口严重崩刃而失效。     

Wear behaviour of alumina based ceramic cutting tools on machining steels

The advanced ceramic cutting tools have very good wear resistance, high refractoriness, good mechanical strength and hot hardness. Alumina based ceramic cutting tools have very high abrasion resistance and hot hardness. Chemically they are more stable than high-speed steels and carbides, thus having less tendency to adhere to metals during machining and less tendency to form built-up edge. This results in good surface finish and dimensional accuracy in machining steels. In this paper wear behaviour of alumina based ceramic cutting tools is investigated. The machining tests were conducted using SiC whisker reinforced alumina ceramic cutting tool and Ti[C,N] mixed alumina ceramic cutting tool on martensitic stainless steel-grade 410 and EN 24 steel work pieces. Flank wear in Ti[C,N] mixed alumina ceramic cutting tool is lower than that of the SiC whisker reinforced alumina cutting tool. SiC whisker reinforced alumina cutting tool exhibits poor crater wear resistance while machining. Notch wear in SiC whisker reinforced alumina cutting tool is lower than that of the Ti[C,N] mixed alumina ceramic cutting tool. The flank wear, crater wear and notch wear are higher on machining martensitic stainless steel than on machining hardened steel. In summary Ti[C,N] mixed alumina cutting tool performs better than SiC whisker reinforced alumina cutting tool on machining martensitic stainless steel.     

Experimental investigation of surface roughness and cutting ratio in a spraying cryogenic turning process

Abstract

Surface roughness is one of the most common criteria indicating the surface finish of the part, which depends on various factors including cutting parameters, geometry of the tool, and cutting fluid. One of the goals of using cutting fluids in machining processes is to achieve improved surface finish. In addition to high costs, commonly used cutting fluids cause dermal and respiratory problems to the operators as well as environmental pollution. The present article aims at investigating the effect of spray cryogenic cooling via liquid nitrogen on surface roughness and cutting ratio in turning process of AISI 304 stainless steel. Through conducting experimental tests, the effects of cutting speed, feed rate, and depth of cut on surface roughness and cutting ratio have been compared in dry and cryogenic turning. A total number of 72 tests have been carried out. Results show that cryogenic turning of AISI 304 stainless steel reduces surface roughness 1%–27% (13% on the average), compared to dry turning. The obtained results showed that the cutting ratio in cryogenic turning is averagely increased by 32% in comparison with dry turning, also that chip breakage is improved in cryogenic turning.     

TURNING STUDIES OF DEEP CRYOGENIC TREATED P-40 TUNGSTEN CARBIDE CUTTING TOOL INSERTS – TECHNICAL COMMUNICATION

In the present work, coated tungsten carbide tool inserts of ISO P-40 grade were subjected to deep cryogenic treatment at ?176°C. Turning studies were conducted on AISI 1040 workpieces using both untreated and deep cryogenic treated tungsten carbide cutting tool inserts. The turning performance was evaluated in terms of flank wear of the cutting tool inserts, main cutting force and surface finish of the machined workpieces. The flank wear of deep cryogenic treated carbide tools was observed to be lower than that of untreated carbide tools in machining of AISI 1040 steel. The cutting force during machining of AISI 1040 steel was lower with the deep cryogenic treated carbide tools when compared with the untreated carbide tools. The surface finish produced on machined AISI 1040 steel workpieces was superior with the deep cryogenic treated carbide tools as compared to the untreated carbide tools.     

低温液氮冷却下高速切削淬硬钢的切屑形成及刀具磨损

针对低温液氮冷却下淬硬钢高速车削过程中切屑形成及刀具磨损机理尚缺乏相关研究的问题,开展了液氮冷却下的淬硬钢高速切削研究,并与干切进行了对比.分析了切削力、切削温度、切屑特征以及刀具磨损特征,讨论了冷却润滑、切屑形成及刀具磨损机理.结果表明:与干切相比,各组实验中低温液氮冷却切削的切削温度降低了6.9％～9.9％,因材料...     

Performance prediction of high-pressure coolant assisted turning of Ti-6Al-4V

The present study focuses on the development of predictive models of average surface roughness, chip-tool interface temperature, chip reduction coefficient, and average tool flank wear in turning of Ti-6Al-4V alloy. The cutting speed, feed rate, cutting conditions (dry and high-pressure coolant), and turning forces (cutting force and feed force) were the input variables in modeling the first three quality parameters, while in modeling tool wear, the machining time was the only variable. Notably, the machining environment influences the machining performance; yet, very few models exist wherein this variable was considered as input. Herein, soft computing-based modeling techniques such as artificial neural network (ANN) and support vector machines (SVM) were explored for roughness, temperature, and chip coefficient. The prediction capability of the formulated models was compared based on the lowest mean absolute percentage error. For surface roughness and cutting temperature, the ANN and, for chip reduction coefficient, the SVM revealed the lowest error, hence recommended. In addition, empirical models were constructed by using the experimental data of tool wear. The adequacy and good fit of tool wear models were justified by a coefficient of determination value greater than 0.99.     

High-speed micromachining characteristics for the NiTi shape memory alloys

The present study includes three parts—design and development of rotary liquid nitrogen applicator, investigation of machining performance under cryogenic application by using the developed applicator, and lastly comparison of the performances with dry and flood cutting. The surface milling of hardened EN 24 steel was performed at different speed-feed combinations corresponding to full factorial design plan (48 exp. runs). The effects of cutting speed, feed rate, and cutting conditions were investigated in respect of surface roughness, cutting force, and tool flank wear. The results of this study revealed the supremacy of cryogenic cooling in respect of all investigated quality characteristics. Lack of cooling and lubrication in dry cutting, and inadequate cooling and lubrication of flood cutting resulted in worse performance. On contrary, the double action cooling effect of cryogenic produces a superior performance, when passes through internal channel, firstly—due to an increased heat transfer rate caused by the primary and secondary flow within cutter, and secondly—because of the creation of a swirl flow at the outlet of the channel but within work surface.     

液氮低温切削钛合金实验研究

针对钛合金难加工特点,将液氮作为冷却介质直接喷向切削区进行钛合金TC4低温车削加工,测量其切削力、表面粗糙度和刀具磨损,并与干切削在相同实验条件下对比,分析低温切削对钛合金的影响。实验结果表明:低温切削钛合金,主切削力有所增大,但进给方向力减小,刀具磨损状况与表面质量得到改善,断屑相对容易。     

高速铣削AF1410高强度钢的实验研究

高强度钢具有优异的机械性能和广阔的应用,但切削加工较为困难,存在加工效率低,加工表面质量差等问题.以AF1410高强度钢为研究对象,应用高速铣削的加工方法,使用涂层硬质合金刀片,对AF1410高强度钢进行了高速铣削实验,研究分析了在高速切削条件下刀具磨损、切削力、切削温度以及已加工表面粗糙度的变化规律.研究发现以TiC...     

An experimental analysis and measurement of process performances in machining of nimonic C-263 super alloy

Nimonic C-263 alloy is extensively used in the fields of aerospace, gas turbine blades, power generators and heat exchangers because of its unique properties. However, the machining of this alloy is difficult due to low thermal conductivity and work hardening characteristics. This paper presents the experimental investigation and analysis of the machining parameters while turning the nimonic C-263 alloy, using whisker reinforced ceramic inserts. The experiments were designed using Taguchi’s experimental design. The parameters considered for the experiments are cutting speed, feed rate and depth of cut. Process performance indicators, viz., the cutting force, tool wear and surface finish were measured. An empirical model has been created for predicting the cutting force, flank wear and surface roughness through response surface methodology (RSM). The desirability function approach has been used for multi response optimization. The influence of the different parameters and their interactions on the cutting force, flank wear and surface roughness are also studied in detail and presented in this study. Based on the cutting force, flank wear and surface roughness, optimized machining conditions were observed in the region of 210 m/min cutting speed and 0.05 mm/rev feed rate and 0.50 mm depth of cut. The results were confirmed by conducting further confirmation tests.     

Suppression of tool damage in ultraprecision diamond machining of stainless steel by applying electron-beam-excited plasma nitriding

Mirror surface machining of stainless steel with single-crystalline diamond tools is proposed in this study by applying a new nitriding method, called electron-beam-excited-plasma (EBEP) nitriding, to workpiece surfaces as pretreatment. It is well known that mirror surface finish of steel workpieces by conventional diamond cutting is unachievable owing to rapid tool wear. Nitriding of steel workpieces has been one of the several attempts to prevent the rapid tool wear of diamond tools. It has been reported that the rapid tool wear is caused by thermochemical interaction between diamond and steel, and that the wear can be greatly reduced by nitriding of steel. However, hard compounds formed on the outmost surfaces of workpieces by the conventional nitriding methods can cause micro-chippings of cutting tools. The authors has recently developed a new nitriding method called EBEP nitriding, in which a high dissociation rate for nitrogen molecules is achieved using the electron-beam-excited-plasma, and iron-compounds-free nitriding has been realized. Therefore, the EBEP nitriding is applied to a typical mold material, modified AISI 420 stainless steel, aiming at suppressing the micro-chippings as well as the thermochemical tool wear during diamond cutting of the stainless steel. The conventional ion nitriding and the gas nitrocarburizing are also applied to the same stainless steel in comparison. Chemical components of the nitrided workpiece surfaces are analyzed by an electron prove micro-analyzer (EPMA) and an X-ray diffraction (XRD) in advance, and turning experiments are conducted with single-crystalline diamond tools. Subsequently, changes in cutting forces and roughness of finished surfaces and tool damages after the turning experiments are evaluated. Finally, mirror surface machining by using the EBEP nitriding is demonstrated, and its advantages and disadvantages in the diamond cutting of stainless steel are summarized in comparison with the conventional nitriding methods.     

TiAlN涂层铣刀铣削9SiCr钢切削性能试验研究

采用TiAlN涂层刀具,对合金工具钢9SiCr的高速铣削加工性能进行试验研究,分析铣削速度对铣削力、表面粗糙 度、表面形貌、切屑变形和刀具的磨损的影响。并获得能够保证对其进行高效高精度加工的合理工艺参数。     

On the machining characteristics of H13 tool steel in different hardness states in ball end milling

This paper investigates and compares the machining characteristics of AISI H13 tool steel in hardness states of 41 and 20 HRC in the ball end milling process. The machining characteristics are illustrated through three types of process outputs from the milling experiments: the milling force, the chip form, and the surface roughness. Characteristic differences in these process outputs are shown to reflect the hardness effect of the tool steel on the ball end milling process. The mechanistic phenomena of the milling process are revealed by the six shearing and ploughing cutting constants extracted from the milling forces. The experimental results show that all the cutting constants of the softer tool steel are greater than those of the hard steel, indicating that higher cutting and frictional energies are required in the chip shearing as well as in the nose ploughing processes of the softer tool steel. The higher cutting energy is also attested by the more severely deformed, shorter, and thicker chips of the softer steel. Surface roughness of the hard steel is shown to be considerably better than that of the soft steel at all cutting speeds and feed rates and is independent of cutting speed, whereas the surface roughness of the softer steel is significantly improved with increasing cutting speed.