Tool life

This paper presents the tool life of the end milled Inconel 718, which is part of a material that is difficult to be machined. Previous researchers found that tool life in machining aged Inconel 718 is shorter compared with other materials. However, this observation required further investigation. Thus, a raw grade Inconel was proposed in this experiment. The experiments were performed using TiAlN-coated carbide. The studied milling parameters were the cutting speed, Vc, from 90 to 150 m/min; feed rate, fz, from 0.15 to 0.25 mm/rev; depth of cut, ap, from 0.3 to 0.5 mm; and radial depth of cut, ae=1 mm. The application of the cutting fluid used in this experiment was a minimum quantity lubricant, which
had the advantage of cooling effectiveness and low consumption of cutting fluid. The results showed that the feed rate, fz, was the primary factor controlling the tool life. The combination of Vc=115 m/min, fz =0.15 mm/tooth, as well as ap =0.5 mm and ae =0.15 mm gave the longest tool life that served 95.38 min in operation.

Machining parameters has an important factor on tool wear and surface finish, for that the manufacturers need to obtain optimal operating parameters with a minimum set of experiments as well as minimizing the simulations in order to reduce machining set up costs. The cutting speed is one of the most important cutting parameter to evaluate, it clearly most influences on one hand, tool life, tool stability, and cutting process quality, and on the other hand controls production flow. Due to more demanding manufacturing systems, the requirements for reliable technological information have increased. For a reliable analysis in cutting, the cutting zone (tip insert-workpiece-chip system) as the mechanics of cutting in this area are very complicated, the chip is formed in the shear plane (entrance the shear zone) and is shape in the sliding plane. The temperature contributed in the primary shear, chamfer and sticking, sliding zones are expressed as a function of unknown shear angle on the rake face and temperature modified flow stress in each zone. The experiments were carried out on a CNC lathe and surface finish and tool tip wear are measured in process. Machining experiments are conducted. Reasonable agreement is observed under turning with high depth of cut. Results of this research help to guide the design of new cutting tool materials and the studies on evaluation of machining parameters to further advance the productivity of nickel based alloy Hastelloy - 276 machining.

In this paper, experimental investigations are carried out by end milling process on hardened tool steel, Impax Hi Hard (Hardness 55 HRC) a newly developed tool steel material used by tool and die making industries. Experiments are performed with an aim to study performance investigations of machining parameters such as cutting speed, feed, depth of cut and width of cut with consideration of multiple responses viz. volume of material removed, tool wear, tool life and surface finish to evaluate the performance of PVD coated carbide inserts and ball end mill cutters. It has been observed through scanning electron microscope, X-ray diffraction technique (EDX) that chipping and adhesion are active tool wear mechanisms and saw-toothed chips are formed while machining of Impax Hi Hard steel. It is also noticed out that tool life is not enhanced while machining with minimum quantity lubricant than dry machining. From the investigations, it is observed that hard machining can be considered as an alternative to grinding and EDM, traditional methods of machining difficult-to-machine materials i.e. hardened steel with hardness greater than 50 HRC with a scope of improved productivity, increased flexibility, decreased capital expenses and reduced environmental waste.

Two PVD coated powder metallurgy high speed steel (PM-HSS) gear cutters were investigated when machining helical gears made from AISI 19MnCr5 steel with hardness between 140 and 180 HV. Machining trials were carried out with gear cutters coated with TiAlN (nano layers) and TiN (mono layer). Crater and flank wears were measured and analysed after all the machining trials. Analyses of the worn tools show that the TiAlN coated gear cutter performed better than the TiN coated gear cutter. This can be attributed to its nano layers and the higher hardness of the TiAlN coating. The dominant tool wear mechanisms were adhesion, abrasion, delaminating of the coating layer and chipping of the cutting edge.

Tool wear is one of the most important considerations in machining operations, as it affects surface quality and integrity, productivity, and cost. The most commonly used model for tool life analysis is the one proposed by F. W. Taylor about a century ago. Although the extended form of this equation includes the effects of important cutting conditions on tool wear, tool life studies are mostly performed under stable cutting conditions where the effect of chatter vibrations are not considered. This paper presents an empirical attempt to understand tool life under vibratory cutting conditions. Tool wear data are collected in turning and milling on dif- ferent work materials under stable and chatter conditions. The effects of cutting conditions as well as severity of chatter on tool life are analysed. The results indicate significant reduction in tool life on account of chatter, as expected. They also show that the severity of chatter, and thus the vibration amplitude, greatly reduce t...

The demand for the use of nickel-based superalloy such as Inconel 718 is increasing in aerospace industry as it is efficient for energy and has excellent properties. In this paper, the experimental studies of tool wear mechanism and tool life in ball nose end milling of Inconel 718 is presented under minimum quantity lubricant (MQL) condition. The evaluations of the results are focusing on the comparison of up-milling and down-milling operations using physical vapor deposition (PVD) - coated carbide inserts. Machining parameters; depth of cut, feed rate and cutting speed are considered during the evaluation. The experimental results showed that down-milling operation has better results in terms of tool wear than up-milling operation. Chipping on cutting tool edge was the primary reason that responsible to notch wear with prolong machining.

Titanium alloy (Ti-6Al-4V) can be economically machined with high-pressure coolant (HPC) supply. In this study, an artificial neural network (ANN) model was developed for the analysis and prediction of tool wear parameters when machining Ti-6Al-4V alloy with conventional flow and high-pressure coolant flow, up to 203 bar. Machining trials were conducted at different cutting conditions for both rough and finish turning operations with uncoated carbide (K10 grade) and double TiAlN/TiN, PVD coated carbide (K10 substrate) inserts. The cutting parameters (cutting speed, feed rate, depth of cut, coolant pressure, and tool type) and the process parameters (cutting forces, feed force, machined surface roughness, and circularity) were used as input data set to train the three-layered feed- forward, back-propagation artificial neural networks. The networks were trained to predict tool life and wear rate separately. The results show that the correlation coefficients between the neural network ...

Machinability aspect is of considerable importance for efficient process planning in manufacturing. Machinability of an engineering material may be evaluated in terms of the process output variables like material removal rate, processed surface finish, cutting forces, tool life, specific power consumption, etc. In this paper, graph theoretic approach (GTA) is proposed to evaluate the machinability of tungsten carbide composite. Material removal rate is considered as a machinability attribute of tungsten carbide to evaluate the effect of several factors and their subfactors. Factors affecting the machinability and their interactions are analyzed by developing a mathematical model using digraph and matrix method. Permanent function or machinability index is obtained from the matrix model developed from the digraphs. This index value helps in quantifying the influence of considered factors on machinability. In the present illustration, factors affecting machinability of tungsten carbide are grouped into five broad factors namely work material, machine tool, tool electrode, cutting conditions, and geometry to be machined. GTA methodology reveals that the machine tool has highest index value. Therefore, it is the most influencing factor affecting machinability.

In the present investigation it is shown how the tool life of heavily loaded cold-forging dies can be predicted. Low-cycle fatigue and fatigue crack growth testing of the tool materials are used in combination with finite element modelling to obtain predictions of tool lives. In the models the number of forming cycles is calculated first to crack initiation and then during crack growth to fatal failure. An investigation of a critical die insert in an industrial cold-forging tool as regards the influence of notch radius, the amount and method of pre-stressing and the selected tool material is reported.

Experiments have been carried out in an attempt to monitor the change of workpiece surface roughness caused by the increase of tool wear, through the variation of the vibration in finish turning, under different cutting conditions. The vibration was measured by two accelerometers attached to the tool and the parameter used to make the correlation with surface roughness was the r.m.s. of the signal. The tool of one experiment was photographed at different stages of the cut in order to explain the wear formation and the behaviour of surface roughness as the cutting time elapsed. The material machined was AISI 4340 steel and the tool was coated carbide inserts. The results show that vibration of the tool can be a good way to monitor on-line the growth of surface roughness in finish turning and, therefore, it can be useful for establishing the end of tool life in these operations. Another conclusion is that, when coated tools are used, the behaviour of surface roughness as cutting time elapses is very different from that when uncoated tools are used.

This paper presents an approach to establish models for tool life in end milling of titanium alloy Ti-6Al- 4V using uncoated carbide inserts under dry conditions. Small central composite design (CCD) was employed in developing the tool life model in relation to primary cutting parameters such as cutting speed, axial depth of cut and feed. Flank wear has been considered as the criteria for tool failure and the wear was measured under a Hisomet II Toolmaker's microscope. Further testing was stopped and an insert rejected when an average flank wear greater than 0.30 mm was achieved. Design-expert version 6.0.8 software was applied to establish the first-order and the second-order model and develop the contours. The adequacy of the predictive model was verified using analysis of variance (ANOVA) at 95% confidence level.