PVD Coated Carbide Inserts Research Articles

Design Optimization of Cutting Parameters Using Taguchi Method and ANOVA during High-Speed Machining Hardened H13 Steel

High-speed machining thoroughly hardened tool steels has emerged as a competitive finishing technology for making dies and molds. The objective of this paper is to develop an optimization method for the better (i. e., lower value) surface roughness in terms of cutting parameters when high-speed milling hardened H13 steel. The cutting parameters to be considered were cutting speed, feed per tooth, radial depth of cut, and axial depth of cut, respectively. A series of high-speed milling experiments of hardened H13 steel using PVD coated carbide inserts without any cutting fluids were performed to measure the surface roughness data. Taguchi orthogonal arrays, signal-to-noise (S/N) ratio, and analysis of variance (ANOVA) were used to evaluate the effects of cutting parameters on surface roughness and to find the optimal factor/level combination for the better surface roughness. The investigations of this study would be used for design optimization of cutting parameters to obtain the better surface roughness.

Investigations on hard machining of Impax Hi Hard tool steel

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.

Experimental study on machining of titanium alloy (Ti64) by CVD and PVD coated carbide inserts

Titanium is a material which is used in aerospace and other industries is difficult to machine. Due to the growing acceptance of titanium in many industries, near-nett shape of these materials by machining cannot be eliminated fully. There are problems encountered when machining titanium in shops working with aircraft alloys. Machining of titanium alloys requires cutting forces slightly higher than those needed to machine steels, but these alloys have metallurgical characteristics that make them more difficult to machine than steels of equivalent hardness. The beta alloys are the most difficult titanium alloys to machine. This paper discusses the study of metallurgical and microstructure analysis of Ti-6Al-4V alloys. Experiments were carried out using two different inserts having different coating methods (PVD and CVD) and different nose radius (0.8 mm and 1.2 mm). The performance of machining has been studied in terms of cutting force, tool wear and surface finish.

Modelling the correlation between cutting and process parameters in high-speed machining of Inconel 718 alloy using an artificial neural network

An artificial neural network (ANN) model was developed for the analysis and prediction of the relationship between cutting and process parameters during high-speed turning of nickel-based, Inconel 718, alloy. The input parameters of the ANN model are the cutting parameters: speed, feed rate, depth of cut, cutting time, and coolant pressure. The output parameters of the model are seven process parameters measured during the machining trials, namely tangential force (cutting force, F z ), axial force (feed force, F x ), spindle motor power consumption, machined surface roughness, average flank wear (VB), maximum flank wear (VB max) and nose wear (VC). The model consists of a three-layered feedforward backpropagation neural network. The network is trained with pairs of inputs/outputs datasets generated when machining Inconel 718 alloy with triple (TiCN/Al 2O 3/TiN) PVD-coated carbide (K 10) inserts with ISO designation CNMG 120412. A very good performance of the neural network, in terms of agreement with experimental data, was achieved. The model can be used for the analysis and prediction of the complex relationship between cutting conditions and the process parameters in metal-cutting operations and for the optimisation of the cutting process for efficient and economic production.

Tribological properties and dry machining characteristics of PVD-coated carbide inserts

Tools for cutting operation are subject to very high abrasive, adhesive, and thermal loads. Process security and preparation quality as well as a sufficiently high tool life demand for the development of hard coatings with reduced seizure tendency, high hot hardness, and increased wear resistance especially under dry machining conditions. TiAlN coatings are the state-of-the-art coatings for machining operations. Hard materials on chromium basis like CrN or CrAlN are preferably used for bending and stamping tools. Thus, these coatings could have a high potential in machining operations. The aim of using chromium-based coatings is to redirect the heat from the workpiece and tool into the chip, thus acting as a thermal barrier. Due to their high oxidation resistance, CrN and Cr x Al y N coatings were deposited on WC/Co inserts. In order to find improved coatings for dry machining operations, mechanical characterizations and turning tests were performed. The characterization of the coatings includes fundamental properties such as thickness, hardness, and critical load. With Glow Discharge Optical Emission Spectroscopy (GDOES), depth profile analyses were executed. SEM analyses supplemented the picture of the scratch tests. Turning operations were performed in model tests to characterize the dry machining characteristics. The wear properties of CrN and Cr x Al y N coatings were compared with industrially coated (Ti,Al)N carbide inserts. Calculations of the friction coefficient supplemented the tests.

Wear of Coated Carbide Tools When Machining Nickel (Inconel 718) and Titanium Base (Ti-6A1-4V) Alloys

Nickel base, Inconel 718, and titanium base, IMI 318 (Ti-6A1-4V) alloys were machined with single (TiN) and multiple (TiN/TiCN/TiN) PVD coated carbide inserts at high cutting conditions in order to evaluate their performance and also to analyze their failure modes. The machining results show that coating material(s), tool geometry, machining parameters as well as material properties can singly or jointly affect tool performance and failure modes. Flank wear was the dominant failure mode at cutting speeds up to 42 m/min for the Inconel 718 alloy and up to 100 m/min for the IMI 318 alloy when machining at feed rates up to 0.25 mm/rev and depth of cut up to 2.00 mm. Excessive chipping/flaking off of tool particles and premature edge fracture also contributed to tool rejection, particularly when machining with the multi-coated inserts due to their sharp edges and instability of the machining system at higher speed conditions. The multi-layer coated tools generally produced lower flank wear rates, thus the best overall performance in terms of tool life, due to the higher resistance of the TiN/TiCN/TiN coatings to flank wear relative to the single TiN coating. Presented at the 53rd Annual Meeting In Detroit, Michigan May 17–21, 1998