Tool life

The domain of life planning and personal development includes the important techniques of values clarification, strengths identification, goal setting and action planning. In the past two decades practices such as life coaching have grown in popularity (Green, Oades & Grant, 2006). Moreover, in mental health contexts, the recovery movement has challenged the illness and deficit focus (Andresen, Caputi, Oades, 2006;

An optimum experimental design to determine the coefficients of the Extended Taylor's Equation in machining is proposed. The technique is based on the minimisation of the ratio between maximum and minimum singular values of the matrix of sensitivity of the tool life related to the machining parameter variations. This procedure generates the best set of cutting conditions to be used in tool life tests which results in a fast convergence of the coefficients and their confidence intervals. This technique was compared to the commonly used fractional factorial design when face milling AISI 1045 steel with cemented carbide cutting tools. The results showed a considerable reduction in the number of tests required to obtain a reliable equation when the optimum experimental procedure was used when compared to the factorial design.

This paper presents a study for the development of first- and second-order tool-life models at 95% confidence level for turning high strength steel. The tool-life models are developed in terms of cutting speed, feed rate, and depth of cut, using response surface methodology and design of experiment. The effects of the main cutting variables (cutting speed, feed, and depth of cut) on tool life have been investigated by the application of the factorial design method. All of the cutting tests were performed using uncoated carbide tools under dry conditions. Tool-life contours have been generated from these model equations and are shown in different plots. Dual-response contours of metal removal rate and tool life are shown also. The results are presented in terms of mean values and confidence levels. © 1998 Elsevier Science S.A. All rights reserved.

http://ac.els-cdn.com/S0924013697004354/1-s2.0-S0924013697004354-main.pdf?_tid=7ea8c4dc-1d34-11e4-b1a5-00000aab0f6c&acdnat=1407307382_b0d7d5d96bfabc738bde8c6860d2acd2 
http://www.sciencedirect.com/science/article/pii/S0924013697004354

Tool performance of conventional tools is poor and a major constraint when used in milling titanium alloys at elevated cutting speeds. At these high cutting speeds, the chemical and mechanical properties of Ti6Al4V cause complex wear mechanisms. In this paper, a fine-grain polycrystalline diamond (PCD) end mill tool was tested, and its wear behavior was studied. The performance of the PCD tool has been investigated in terms of tool life, cutting forces, and surface roughness. The PCD tool yielded longer tool life than a coated carbide tool at cutting speeds above 100 m/min. A slower wear progression was found with an increase in cutting speeds, whereas the norm is an exponential increase in tool wear at elevated speeds. Observations based on scanning electron microscope (SEM) and energy dispersive spectroscopy (EDAX) analysis suggest that adhesion of the workpiece is the wear main type, after which degradation of the tools accelerates probable due to the combined effect of high temperature degradation coupled with abrasion.

The eternal goal achieving optimum gear manufacturing results in a quick and flexible way can be obtained by efficient machine tools and thorough processes know how. Gear manufacturing is associated with complicated generating kinematics, chip formation and tool wear mechanisms. To capture quantitatively the tool wear progress and the cutting loads, empirical, analytical, numerical as well as FEM-based methods describing the chip geometry and predicting the tool life and cutting forces have been developed. The application of innovative tool materials and coatings, optimized tool geometries and appropriate conduct of reconditioning procedures contribute to the significant reducing of the manufacturing cost.

In Southwest Asia, sickle blades first appear early in the sequence of the transition to agriculture. In the past, detailed qualitative research on silica bearing blade stone tools focus on the characterization of use-wear traces such as polish types and accrual rates. In this paper we approach the study of sickle blades slightly different, choosing to examine tool life-history by developing a method to quantitatively estimate harvesting intensity. The method centers on an experiment of cutting cereal stalks and measuring stone blade edge thickness under a scanning electron microscope as a proxy for cutting time. We end with regressing the experimental results to provide an estimation of how intensively archaeological sickle blades recovered from the site of Dhra’, Jordan were used for harvesting. The results, while preliminary, enable an initial interpretation of sickle blades as important tools with long use-life histories during the early Neolithic in the Southern Levant.

This paper describes hard machining which offers many potential benefits over traditional manufacturing techniques. In this work, investigations were carried out on end milling of hardened tool steel DIEVAR (hardness 50 HRC), a newly developed tool steel material used by tool- and die-making industries. The objective of the present investigation was to study the performance characteristics of machining parameters such as cutting speed, feed, depth of cut and width of cut with due consideration to multiple responses, i.e. volume of material removed, tool wear, tool life and surface finish. Performance evaluation of physical vapour deposition-coated carbide inserts, ball end mill cutter and polycrystalline cubic boron nitride inserts (PCBN) was done for rough and finish machining on the basis of flank wear, tool life, volume of material removed, surface roughness and chip formation. It has been observed from investigations that chipping, diffusion and adhesion were active tool wear mechanisms and saw-toothed chips were formed whilst machining DIEVAR hard steel. PCBN inserts give an excellent performance in terms of tool life and surface finish in comparison with carbide-coated inserts. End milling technique using PCBN inserts could be a viable alternative to grinding in comparison to ball end mill cutter in terms of surface finish and tool life.

One of the main goals of the metal-mechanical industries is the reduction of the production costs through the productivity increase. In the attempt to reach this goals, many researchers have been used the hot machining method. This method consists, basically, in the heating of the work piece hundreds of degrees Celsius above room temperature with aid of an external source of heat. Thus, the reduction of the shear stress of the material of the piece is gotten and, hence, is possible to obtain a smaller wear of cutting tool in relation to the conventional machining. This paper presents a review of hot machining, where the different techniques are presented together their results. This review paper presents a survey on variation in process parameter i.e. temperature, cutting speed, feed etc. and their effect on surface roughness, hardness, material removal rate, tool wear, tool life.

Surface engineering approaches are being increasingly employed for enhancing the effective life of twist drills with a view to reduce machining costs. The electro-spark coating (ESC) technique provides a promising means of depositing wear resistant coatings that can potentially enhance the performance of these tools. However, it is often necessary to also optimize the machining conditions for coated tools to achieve an enhanced tool life. In the present investigation, varying spindle speeds were employed at a fixed vertical feed to evaluate the performance of WC–8Co ESC coated HSS drills in comparison to bare HSS drills. The number of holes drilled before reaching a preset average flank wear (0.5 mm), or catastrophic failure of the drill, was taken as the measure of tool life. The drill flank wear, monitored at regular intervals, as well as the cutting torque and thrust measured for all holes, were considered to be the key criteria for optimizing the cutting conditions. Results indicate that the WC–8Co coated drill tool life can be increased by a factor of more than 5, depending on the machining conditions selected. Furthermore, flank wear of the drill was found to increase rapidly at the end of drill life. Cutting torque data was also found to provide a useful indicator for predicting the end of tool life.

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.