Terms Of Tool Life Research Articles

Performance of green machining: a comparative study of turning ductile cast iron FCD700

A safe and healthy workplace is important for sustainable manufacturing. Green machining is a metal cutting process that does not use a cutting fluid and, because it is less detrimental to the environment, it is fast being adopted by metal cutting industries. In conventional machining, Metal Working Fluids (MWFs) are widely used to obtain a smoother machining process, a longer tool life, and a better surface finish. Unfortunately, metalworking fluids also have several negative health, production cost, and environmental impacts. This paper focuses on an experimental investigation into the role of green or dry machining on tool life and surface finish, in the machining of ductile cast iron FCD700. A comparative study of turning experiments, under dry and wet cutting conditions, using commercial oil and palm oil-based MWFs, was conducted using the same machining parameter set-up. The results show that dry machining performance is comparable to that of wet machining. It was found that the performance of wet machining, in terms of tool life, was better than dry machining; however, the surface quality of dry machining was almost similar to that of wet machining. Furthermore, it was evident that green machining can be conducted at high cutting speeds, low feed rates, and depths of cut, and using suitable coated tools.

The applicability of Taylor's model to the drilling of CFRP using uncoated WC-Co tools: the influence of cutting speed on tool wear

This work investigates the applicability of Taylor’s model on the drilling of CFRP using uncoated WC-Co tools, by assessing the influence of cutting speed (Vc) on tool wear. Two different resins, possessing low and high glass transition temperatures (Tg), and two different reinforcements, high strength and high modulus woven fabrics, were combined into three different systems. Flank wear rate gradient exhibited to be more reinforcement dependent, while the actual flank wear rate showed to be sensible also to the type of resin. In terms of tool life, all CFRP systems adjusted into a power-type tool life vs. cutting speed curve through the full range of cutting speeds (1,000 RPM to 18,000 RPM). Therefore, Taylor’s model can be applied to estimate the tool life in the drilling of CFRP using uncoated WC-Co tools with good accuracy.

EFFECTS OF CUTTING SPEED WHEN TURNING AGE HARDENED INCONEL 718 WITH PCBN TOOLS OF BINDERLESS AND LOW-CBN GRADES

Application of polycrystalline cubic boron nitride (PCBN) tools as an alternative for ceramic and cemented carbide tools in machining superalloys has been frequently identified as a solution for enhancing process efficiency but only a limited number of studies has been done in this area. The current study explores the effect of the cutting speed, which was varied in a wide range (2–14 m/s), on machinability of age hardened Inconel 718 with PCBN tools. Performance of binderless PCBN grade and grade with low-cBN content was evaluated in terms of tool life, tool wear, cutting forces and surface quality. Chip formation and process dynamics were analyzed as well. It was found that low-cBN grade provided 70–90% better surface finish and tool life than the binderless at moderate speeds (5–8 m/s). Performance of both grades at low and high speed ranges was non-satisfactory due to notching and flaking respectively. At low cutting speed adhesive wear plays a major role while as the speed increases a chemical wear becomes dominant.

Effect of Tool Wear on Tool Life and Surface Finish when Machining DF-3 Hardened Tool Steel

Hard turning is a dominant machining operation performed on hardened materials using single-point cutting tools. In recent years, hard turning operation has become more and more capable with respect to various machinability criteria. This work deals with machinability of hardened DF-3 tool steel with 55 ±1 HRC hardness at various cutting conditions in terms of tool life, tool wear mechanism and surface roughness. Continuous dry turning tests were carried out using coated, mixed ceramic insert with honed edge geometry. Two different cutting speeds, 100 and 210 m/min, and feed rate values of 0.05, 0.125 and 0.2 mm/rev were used with a 0.2 mm constant depth of cut for all tests. Additionally scanning electron microscope (SEM) was employed to clarify the different types of wear. As far as tool life was concerned, best result was achieved at lowest cutting condition whereas surface roughness values decreased when operating at higher cutting speed and lower feed rate. Additionally maximum volume of material removed is obtained at low cutting speed and high feed rate. Dominant wear mechanism observed during the experiments were flank and crater wear which is mainly caused by abrasive action of the hard workpiece material with the ceramic cutting tools.

Effect of the gray cast iron microstructure on milling tool life and cutting force

Gray cast irons are frequently used in machine tool beds due to low cost, high vibration damping capacity, and easiness of manufacturing. The guiding standards for production of these alloys determine their classes based on the range of tensile strength and shape of graphites. This research project aims at investigating the differences in machinability between two gray cast irons belonging to the same class (GG25), i.e., within the same standard tolerance, but with different pearlitic/ferritic concentrations. Machinability was evaluated in terms of tool life and cutting forces in milling operations using carbide and ceramic tools and two different cutting speeds. Two different materials were used as samples, one containing 100 % pearlite and another with 50 % pearlite + 50 % ferrite. The results showed that milling of the 100 % pearlitic alloy led to faster tool wear and higher cutting forces than in the 50 % ferritic alloy. Ceramic tools exhibited longer life than carbide tools. The observed wear mechanisms were diffusion, attrition, and thermal cracks. However, material microstructure was observed to be far more significant for tool life and cutting force than the other input variables (cutting speed and tool material).

An Experimental Investigation of the Influence of Cutting-Edge Geometry on the Machinability of Compacted Graphite Iron

Compacted graphite iron (CGI) is considered as the potential replacement of flake graphite iron (FGI) for the manufacturing of new generation high power diesel engines. Use of CGI, that have higher strength and stiffness as compared to FGI, allows engine to perform at higher peak pressure with higher fuel efficiency and lower emission rate. However, not only for its potential, CGI is of an area of interest in metal cutting research because of its poor machinability as compared to that of FGI. The higher strength of CGI causes a faster tool wear rate in continuous machining operation even in low cutting speed as compared to that for FGI. This study investigated the influence of cutting edge geometry at different cutting parameters on the machinability of CGI in terms of tool life, cutting force and surface roughness and integrity in internal turning operation under wet condition. It has been seen that the cutting edge radius has significant effect on tool life and cutting forces. The results can be used to select optimum cutting tool geometry for continuous machining of CGI.

Machining of Difficult-to-Cut-Alloys Using Rotary Turning Tools

The importance and use of high temperature metals, such as titanium and nickel alloys, in aerospace industries have been continuously increasing due to their high strength-to-weight properties. These superior mechanical properties, however, reduce the machinability of these alloys. Rotary turning tools offer remedy to these problems. Rotary motion of the insert provides cool- down time outside of the cut resulting reduced cutting temperatures with longer tool life and higher productivity. In this article, rotary and stationary turning tools are compared in terms of tool life, cutting forces, surface and dimensional quality.

CBN Grinding Performance Improvement in Aircraft Engine Components Manufacture

Cubic Boron Nitride (CBN) grinding is extensively employed in the aerospace industry as it allows to effectively grind high performance aerospace metal alloys such as nickel base superalloys. With reference to a real industrial case of CBN grinding for the manufacture of aircraft engine components, the aim of this paper is to improve the CBN wheel tool life and optimize the grinding process while taking into account economic, environmental and social sustainability issues. Different types of CBN grinding wheels fabricated using diverse deposition procedures are tested to compare their behavior during grinding of Ni base superalloys and assess their tool life in terms of number of parts successfully ground by a single wheel. Tests are also performed to investigate alternative coolant type applicability as well as grain size influence on surface integrity as these factors can significantly affect process performance, final workpiece quality and grinding wheel life.

Experimental Analysis of Wear Mechanism and Tool Life in Dry Drilling of Al2024

Aluminum alloy is widely used in industry and various researches has been done on machiability of this material mainly due to its low weight and other superior properties. Dry machining is still interesting topic to reduce the cost of manufacturing and environmental contaminations. In present study dry machining of Al 2024 investigated on tool life, tool wear mechanisms, hole quality, thrust force and torque. Different types of high speed steel (HSS) tools utilized at constant feed rate of 0.04 mm/rev and cutting speeds within the range of 28 and 94 m/min. Experimental results revealed that HSCo drills, performed better than HSS drills in terms of tool life and hole quality. The main wear mechanisms which analyzed by scanning electron microscope found abrasive and adhesion wear on flank face, besides, BUE observed at chisel and cutting edges. However tool wear and BUE formation found more significant at high cutting speed. In terms of thrust force, two facet HSCo tools, recorded higher thrust force than four facet HSS drills.

Effect of Total Oxygen Content on the Machinability of Low Carbon Resulfurized Free Cutting Steel

AbstractThe effect of total oxygen content on the machinability of low carbon resulfurized free cutting steel was studied by means of machinability tests, metallographic, and scanning electron microscopy observation. The results showed that the total oxygen content had a notable effect on the machinability of SAE 1215 steel. The best machinability of the steel in terms of tool life and surface roughness could be obtained by controlling the total oxygen content at 0.0105 and 0.0125 wt%. When total oxygen content in the steel was less than 0.0105 wt%, the machinability of the steel was increased with the increase of total oxygen content because of the significant reduction of the aspect ratio of MnS inclusions. However, when total oxygen content in the steel was more than 0.0125 wt%, the machinability of the steel was deteriorated dramatically with the increase of total oxygen content, which was attributed to that the amount and the size of oxide inclusions (MnO–Al2O3, MnO–SiO2, and 2MnO–SiO2) with high hardness and high melting point both had a significant increase, and some MnS inclusions were also wrapped by the MnO–SiO2 and 2MnO–SiO2 hard oxides. Furthermore, the tool wear would reach the maximum when total oxygen in the steel rose to 0.0150 wt%.

The Performances of Different Coated Carbide Drills when Drilling a Cast Nickel-Based Alloy

The performances of different coated carbide drills when drilling cast GH625 nickel-based alloy were evaluated in terms of tool wear and cutting force. Wear pattern observation and cutting force measurement were conducted under different cutting conditions. It was found that the drill coated with TiAlN/TiN showed the best overall performance among all the drill types tested. This drill type gave the longest tool life in terms of number of holes partly due to the excellent wear resistance of TiAlN/TiN multilayer. Besides, the thrust force and torque produced with this drill type were lower, which could be attributed to its good adhesion resistance and chip-ejection ability.

Improvement of Machinability of Mild Steel during Turning Operation by Magnetic Cutting

This paper presents the details of improvement of machinability of mild steel using magnetic cutting during turning operation. Improvement of machinability was evaluated in terms of tool life, surface roughness and chip morphology. Machine tool chatter is a type of intensive self-excited vibrations of individual components of Machine-Tool-Fixture-Work (MTFW) system. Chatter causes unwanted excessive vibratory motion in between the tool and the work-piece causing adverse effects on the product quality and machine-tool and tool life. In addition to the damage of the work-piece surface due to chatter marks, the occurrence of severe chatter results in many adverse effects, which include poor dimensional accuracy of the work-piece, reduction of tool life, and damage to the machine. Chatter is formed as resonance phenomena during machining because of the instability of the closed-loop system formed by machine tool structure and metal-cutting process. In this study, magnets were used to avoid the chatter formation zone and its effect on machinability was investigated. Improvements in tool life and surface finish were observed during magnetic cutting of the mild steel. An obvious change in the chip behaviour was also present. These observations further enhance the possibility of using this magnetic cutting to eliminate the chatter formation zones and hence eliminate the adverse effect of chatter on machinability.

Evaluation of parametric models in predicting the machining performance

The performance of the machining (turning) process is evaluated in terms of tool life, surface roughness, tool–shim interface temperature developed and metal removal rate during the process. It is very important for the manufacturing engineers to know the performance of the turning process for a set of cutting (input) parameters. In this paper, parametric models based on multiple regression analysis (MRA), neural networks (NNs) and case-based reasoning (CBR) are developed for predicting the machining performance, i.e. the output parameters. An experimental database containing 114 data sets are used for developing the three models. Each data set contains nine input and four output parameters. About 20 machining trials are exclusively conducted with various combinations of input parameters, and their corresponding output values are compared with the predicted values of the developed models. Descriptive statistics of the errors are calculated for the three models and it was found that the CBR model provided better prediction capability than MRA and NN models.

Improvement of machinability in end milling of Nimonic C-263 by application of high pressure coolant

This paper investigates the effect of machining environments, conventional wet, liquid nitrogen (LN2) and high pressure (HP) cooling on tool performance when machining nickel-based, Nimonic C-263, alloy with dual layer coated (TiN/TiAlN) carbide insert under different cutting speed and feed conditions. Tool life, tool failure modes, surface integrity and surface finish generated during end milling were recorded and analysed. Analysis of the test results shows that high pressure (50 bar) cooling gave the best result compared to other two machining environments in terms of tool life. Tool life improvement of as high as 133% was recorded under high pressure cooling compared to conventional wet. LN2 cooling gave worst results among all three cutting environments, due to increased thermal fluctuation during machining. Chipping was found to be the dominating tool failure mode in all the cases. Plastic deformation of the machined surface was evident with increase in tool wear.

Enhancement of Machinability of Inconel 718 in End Milling through Online Induction Heating of Workpiece

Abstract. This paper presents the outcome of a study on heat assisted end milling of Inconel 718 using inducting heating technique conducted to enhance the machinability of the material. The heating temperature maintained below the phase transformation temperature was aimed at softening the top removable material layers. The experimental results of both conventional and heat assisted machining were compared. The machinability of Inconel 718 under these conditions was evaluated in terms of tool life, tool wear morphology and chatter. The advantages of Induction heating is demonstrated by an longer tool life and lower chatter. The study showed that preheated machining facilitates up to 80% increase of tool life over conventional machining conducted using TiAlN coated carbide inserts.

Parameter-Design and Experimental Study on Small-Diameter Solid Carbide Deep-Hole Twist Drill

Base on the conventional twist drill, the new type of solid carbide twist drill which the length-to-diameter radio (L/D) is about 12 was developed with improved parameters of drill point and flute geometry. Study of intensity and rigidity of drill was performed by using analysis software ANSYS Workbench for the theoretical support and technical guidance for the design of twist drill. Tests were carried out to compare the new drills with the competitive drills in terms of tool life, chip breaking, and chip disposal. The results obtained from tests indicated that the new type twist drills have similar cutting capability compare to the competitor’s drills.

Development of a new theory of thermal cutting processes 21. Determining optimal cutting conditions to extend tool life

The calculation of cutting conditions that are optimal in terms of tool life is illustrated by examples. The calculations are shown to be highly accurate.

Performance evaluation of CBN, coated carbide, cryogenically treated uncoated/coated carbide inserts in finish-turning of hardened steel

In the present work, the performance of cubic boron nitride (CBN) inserts was compared with coated carbide and cryogenically treated coated/uncoated carbide inserts in terms of flank wear, surface roughness, white layer formation, and microhardness variation under dry cutting conditions for finish turning of hardened AISI H11 steel (48–49 HRC). The flank wear of CBN tools was observed to be lower than that of other inserts, but the accumulated machining time for all the four edges of carbide inserts were nearer to or better than the PCBN inserts. Results showed that tool life of carbide inserts decreased at higher cutting speeds. The surface roughness achieved under all cutting conditions for coated-carbide-treated/untreated inserts was comparable with that achieved with CBN inserts and was below 1.6 μm. The white layer formation and microhardness variation is less while turning with cryogenically treated carbide inserts than the CBN and untreated carbide. At low to medium cutting speed and feed, the performance of carbide inserts was comparable with CBN both in terms of tool life and surface integrity.

Performance of carbide and ceramic tools in the milling of compact graphite iron - CGI

Grey cast iron (GCI) is the most common material used in diesel engine blocks. However, to increase the pressures in the combustion chamber when this kind of alloy is used, it is necessary to increase the block wall thickness, what raises its weight and, consequently, does not fulfill the requirements. Thus, the compacted graphite iron (CGI) appears as an alternative for such application. It has characteristics of heat conductivity and damping similar to the GCI, but with superior mechanical properties, making possible the manufacturing of lighter engines with better performance. However, the use of CGI presents as disadvantage its worse machinability, when compared with GCI, stimulating development of machining techniques and cutting tool materials. The goal of this work is to analyze the performance of two tool materials (carbide and ceramic Si3N4) in the finishing milling of the fire face of the engine block made of CGI. To reach this goal these two materials were compared in terms of wear mechanisms and tool life in different cutting speeds. The main conclusion was that, for conditions similar to those used in this work, carbide is better than ceramic in terms of tool life in the milling CGI.

Tool life and wear mechanism when machining Hastelloy C-22HS

▶ We do experimental study wear mechanism and tool life with coated carbide . ▶ Study the tool wear and life occur during the machining of Hastelloy C-22. ▶ Optimization of the variables to increase too life of the cutting tools. ▶ Results indicated that PVD cutting tools performed better than CVD cutting tools. This paper describes the wear mechanism and tool life when machining Hastelloy C-22HS with coated carbide. The experiment was conducted using four different cutting tool materials under wet condition – namely, Physical Vapor Deposition (PVD) coated with TiAlN; TiN/TiCN/TiN; Chemical Vapor Deposition (CVD) coated with TiN/TiCN/Al 2 O 3 ; and TiN/TiCN/TiN – to study the tool behavior, in terms of wear and tool life machining of Hastelloy C-22HS. Tool failure modes and wear mechanism were examined at various cutting parameters. Flank wear, chipping, notching, plastic lowering at cutting edge, catastrophic and wear at nose were found to be the predominant tool failure for the four types of cutting tools, especially with CVD tools. Attrition/adhesion, oxidation and built-up edge (BUE) are the wear mechanisms observed in all cutting tools. The results obtained indicated that PVD cutting tools performed better than CVD cutting tools, in terms of tool life with current parameters.