Performance Of Cutting Tools Research Articles

Cutting Tool Performance of Laser Coated Diamond Coating and Diamond Facing Inserts

A study of cutting tool performance was conducted using poly-crystalline compact diamond (PCD); laser coated diamond coating tools, diamond facing tools, and C2 carbide inserts. The experiments are designed in a way that the PCD, CVD diamond coatings, diamond facing, and C2 carbide inserts can be tested and compared under the same cutting conditions. Although PCD is still the best cutting material of these inserts, the laser coated diamond and diamond-facing tools are closing the gap. The failure mode of a diamond coated insert can be described in the following steps. It starts with microattrition, during which gradually the coating on the cutting edge is worn out. Then the coating flakes off and the tool ceases to function. The diamond-facing insert has only the rake face treated. The surprisingly good performance of the diamond facing insert suggests that the tool's rake and flank face work as a team. Both diamond coating and diamond facing tools have good cutting performance and provide advantages in making lower cost tools with complex geometry. Presented at the 55th Annual Meeting in Nashville, Tennessee May 7–11, 2000

Characterisation and performance of partially filtered arc TiAlN coatings

It is now being recognised that the level of residual stress in physical vapour deposited (PVD) coatings is yet another important physical property of thin film PVD coating parameters that can critically affect their performance. In this study, titanium aluminium nitride (TiAlN) coatings were deposited using a dual source filtered arc evaporation system with a view to determine the effect of bias voltage increased from −50 to −250 V, the residual stress in the coating as well as the adhesion and cutting tool performance. The X-ray diffraction methods of Bragg–Brentano and glancing angle parallel beam (sin 2ψ) were used to study the texture and residual stress in the as-deposited coatings. The results showed that as the bias voltage increased from –50 to –250 V and the residual stress increased from 7.67 to 11.81 GPa (compressive). However, little change in residual stress was observed with an increase in arc current from 75 to 175 A. All coatings exhibited a preferred orientation in the {111} direction, however, a reduction in the {111} intensity was observed for the coating deposited at –50 V. Coating hardness was observed to increase from 26.3 to 31.7 GPa when the bias voltage was increased from –50 to –150 V. However, no further increase was observed at –250 V. No effect on hardness was noted for any change in arc current. Scratch adhesion results showed little effect on the bias voltage with critical load values of 46, 48 and 43 N for the −50, −150 and −250 V biased coatings, respectively. However, increasing the arc currents above 75 A resulted in a reduction of critical load from 48 N for 75 A to 36 and 37 N for 125 and 175 A arc currents, respectively. Damiler Benz Rockwell ‘C’ adhesion tests carried out also revealed a similar trend. The Al content of the coating was found to decrease with increasing bias voltage but increase with an increase in arc current. Accelerated drill life tests suggested that an increase in residual stress associated with the higher bias voltages does affect tool life. For arc current variation, the balance between intrinsic and extrinsic stresses that contribute to the total residual stress may affect cutting tool life.

Microstructure and Cutting Characteristics of SiC-$Si_3N_4$ Ceramic Cutting Tool

Four SiC-SiNceramic cutting tools with different composition have been fabricated by hot-pressing. Correlations among the annealing time, the corresponding microstructure and the mechanical properties of resulting ceramics have been investigated. The fracture toughness and the grain size of both SiC and SiNin SiC-SiNcomposites increased with the annealing time. 1\`he hardness of SiC-SiNcomposites was relatively independent of the grain size and the sintered density. These ceramic cutting tools were tested under various cutting conditions and compared with the commercial SiNceramic cutting tools. The experimental results were compared in terms of tool life and cutting force. The performance of SiC-SiNceramic cutting tool shows the possibility to be a new ceramic tool.

Effect of TiN coating thickness on performance of HSS cutting tools when machining free cutting steels

Effect of TiN coating thickness on performance of HSS cutting tools when machining free cutting steels

Interaction of (titanium, tungsten) carbonitride with nitrogen : W.Lengauer et al. (Vienna University of Technology, Vienna, Austria.)

PMD combines conventional, balanced magnetron sputtering with an independently generated, arc-discharge plasma to deposit primarily TiN hard coatings for extending the wear life of gear cutting tools as used by General Motors Powertrain (GMPT). The work was begun in 1990 using end-mills coated in an 0.46-m diameter (18-inch diameter) chamber. This showed that the two tool-life controlling processes are deposition temperature and interfacial oxide concentration, control of which resulted in a 2–3× tool life over current commercial coating technologies. In 1994 scaling studies were begun using a 1.22-m diameter×2.44-m long (4-ft diameter×8-ft long) chamber to achieve this same level of performance for gear manufacturing tools such as hobs and shaper/cutters. Analytical modeling was used to correlate quantitatively the target poisoning and system stability with pumping speed, target power, gas throughout and fixture size for both chambers. The modeling was then extended to upscale the process to a 1.37-m diameter×1.52-m high (4.5-ft diameter×5-ft high) production prototype chamber with a 900-kg (2000-lb) capacity. This unit was incorporated into a production prototype facility in Michigan featuring tool degreasing and abrasive blast installations for surface preparation. The operating characteristics of the PMD process and the resulting cutting tool performance are presented.

Aspects of cooling lubrication reduction in machining advanced materials

Coolant lubricants are recognized as undesirable factors in metal cutting, especially in machining advanced and difficult-to-cut materials. For both economic and ecological reasons, as well as because of increasing legislation, efforts are being made to reduce the use of coolants. On account of this, the introduction of dry machining and minimum quantity lubrication (MQL) techniques in machining processes is increasing. The results of the investigations carried out give an overview of the possibilities for influencing the machining of advanced materials, e.g. titanium alloys and extreme low-sulphur steels. The research topics focus on cutting tool performance and wear mechanisms at high cutting speeds while using different lubricants and cooling supply strategies. The investigations and verification experiments contribute to increasing process stability and tool life, improvement of machined surface finish and avoidance of tensile residual stresses.

MODELING THE PHYSICS OF METAL CUTTING IN HIGH-SPEED MACHINING

ABSTRACT Physical modeling of metal cutting was carried out to provide an understanding and prediction of machining process details. The models are based on finite element analysis (FEA), using a Lagrangian formulation with explicit dynamics. Requirements for material constitutive models are discussed in the context of high-speed machining. Model results address metal cutting characteristics such as segmented chip formation, dynamic cutting forces, unconstrained plastic flow of material during chip formation, and thermomechanical environments of the work-piece and the cutting tool. Examples are presented for aerospace aluminum and titanium alloys. The results are suited for analysis of key process issues of cutting tool performance, including tool geometry, tool sharpness, workpiece material buildup, and tool wear.

Plasma-enhanced, magnetron-sputtered deposition (PMD) of materials

PMD combines conventional, balanced magnetron sputtering with an independently generated, arc-discharge plasma to deposit primarily TiN hard coatings for extending the wear life of gear cutting tools as used by General Motors Powertrain (GMPT). The work was begun in 1990 using end-mills coated in an 0.46-m diameter (18-inch diameter) chamber. This showed that the two tool-life controlling processes are deposition temperature and interfacial oxide concentration, control of which resulted in a 2–3× tool life over current commercial coating technologies. In 1994 scaling studies were begun using a 1.22-m diameter×2.44-m long (4-ft diameter×8-ft long) chamber to achieve this same level of performance for gear manufacturing tools such as hobs and shaper/cutters. Analytical modeling was used to correlate quantitatively the target poisoning and system stability with pumping speed, target power, gas throughout and fixture size for both chambers. The modeling was then extended to upscale the process to a 1.37-m diameter×1.52-m high (4.5-ft diameter×5-ft high) production prototype chamber with a 900-kg (2000-lb) capacity. This unit was incorporated into a production prototype facility in Michigan featuring tool degreasing and abrasive blast installations for surface preparation. The operating characteristics of the PMD process and the resulting cutting tool performance are presented.

High-Speed Milling of Dies and Molds in Their Hardened State

This paper presents an experimental investigation of high speed milling of dies and molds. Several critical issues involved with the high speed milling of H13 tool steel of hardness up to 55 HR C, have been studied and explained from a detailed analysis of experimental observations. The experiments were performed using several grades of PCBN ball-nose end mills with various edge preparations. The effect of different process parameters on the tool performance and the surface finish produced was also investigated. The cutting parameters involved were; cutting speeds in the range of 220 to 1320 m/min, feed variation from 0.0254 to 0.1 mm/tooth, axial depth of cut from 0.625 up to 2 mm, and radial width of cut of 0.254 mm. During the preliminary experimental investigation, the tilt angle was kept constant at 10 degrees. Several tests were conducted to study the effect of the different tool path directions on the cutting tool performance. Dry and wet cutting conditions were used and the effect of coolant on the tool life was also determined. The optimum cutting conditions have been specified based on the modes of tool failure, tool life and surface integrity produced.

Effect of tin coating on the performance of HSS cutting tools when machining free cutting steels

Effect of tin coating on the performance of HSS cutting tools when machining free cutting steels

Laboratory characterisation of the wear behaviour of PVD-coated tool steels and correlation with cutting tool performance

Four different characterisation tests have been used to study the wear behaviour of a series of thin (1–4 μm) PVD coatings of TiN, TiCN, TiAlN and CrN on identical M2 tool steel substrates. These include two novel tests involving micro-abrasion and erosion durability. The abrasion method provides values for the intrinsic wear behaviour of both the coating and the substrate from a single test. The erosion test establishes the critical mass of erodent particles required to impact unit area of the coating to cause removal. Standard scratch tests were also performed, and coating failure characterised by both acoustic emission signals and post-test optical examination of the scratches. The performances of the coatings in these tests were compared with those of coated end mills in accelerated cutting tests. The micro-abrasion and scratch tests both showed good correlation with the results of the milling tests; although the erosion test generally discriminated between the coatings, correlation with the other test results was poor.

Sintering Properties and Cutting-Tool Performance of Ti(C,N)-Based Ceramics

Sintering Properties and Cutting-Tool Performance of Ti(C,N)-Based Ceramics

SIMULATION OF ROUTER ACTION ON A LATHE TO TEST THE CUTTING TOOL PERFORMANCE IN EDGE-TRIMMING OF GRAPHITE/EPOXY COMPOSITE

Summary An experimental method of simulating the conditions of router action using a CNC lathe to test the cutting tool performance in peripheral trimming of composite material was developed. Validity of the proposed method is demonstrated by conducting the wear test on carbide inserts. Flank wear was not uniform, and the cutting edge shows abrasive tracks, grooves, and nose rounding. Chipping and edge rounding was dominant in interrupted cutting due to repeated impacts. Less grooving is seen in the interrupted case than in the continuous case. No signs of thermal damage or catastrophic failure was visible on any of the carbides used in this investigation. Machined surface damage was apparent under both cutting modes to the naked eye within 10 seconds of cutting time and life of the carbide is found to be less than 10 seconds.

Multi CVD coated layers and their effect on the performance of cutting tools

Multi CVD coated layers and their effect on the performance of cutting tools

The new diamond technology and its application in cutting tools

Thick-film and thin-film chemical vapor deposition (CVD) cutting tool inserts and end mills were tested in turning and milling applications on high silicon alloys and composite materials against sintered diamond and tungsten carbide tools. Flank wear measurements and scanning electron microscopy were used to characterize the cutting tool performance. In general, CVD thick-film diamond exhibits better wear resistance and comparable impact resistance to sintered diamond as cutting tool inserts and far better wear resistance than tungsten carbide in end mill applications. Thin-film diamond tools also show considerable improvement in wear life over tungsten carbide inserts and end mills in machining abrasive materials.

Hot Pressing and Cutting Tool Performance of Ti(CN)-Based Ceramics

Hot Pressing and Cutting Tool Performance of Ti(CN)-Based Ceramics

An application of the finite element method to the prediction of cutting tool performance

In metal cutting tools the are close to the tool point is the single most important region and conditions at the tool point must be carefully examined if improvements in tool performance, through changes in tool design and material, are to be achieved. The paper describes an analysis of cutting tool performance through a determination of the stress distribution within, and at the boundaries of, the tool wedge. The stressanalysis was based on a two-dimensional model as encountered in orthogonal cutting, using a range of cutting geometries including tools with double rake angles. A finite element technique was employed which can be effectively utilised in the solution of metal cutting problems once the boundary conditions have been established. The results presented demonstrate the significance of the chosen boundary conditions to the analysis of metal cutting. Finally it is argued that the deformation of the cutting edge, especially at the clearance face under the stress field set up in the tool, may well be a determining factor in establishing tool life as based on the flank wear criterion.

切削工具のぜい性損傷に関する破壊力学的研究(第3報)

Analytical results of early fracture and tool life based on fracture mechanics were compared with experimental results in interrupted cutting. The stress intensity factor was calculated by a finite element method using a cutting tool model with an appropriately introduced crack. Calculated values of stress intensity factor, at which the early fracture occurred, was made a comparison with the fracture toughness of tungsten carbide tools and ceramic tool. The tool life of tungsten carbide P 20 was also calculated using the analytical method proposed in the previous report, and the calculated values were found to be consistent with experimental results. The cutting tool performance for the early fracture and the tool life increases in the main with increasing the fracture toughness. These comparisons suggest that the brittle failure of cutting tools can be analytically estimated by the application of the fracture mechanics concept.