Carbide Tools In Machining Research Articles

A new approach of measurement and analysis of PVD - TiAlN coated carbide tools in machining of Monel 400 alloy under hybrid cooling conditions

This research work focuses on the efficacy of minimum quantity lubrication (MQL) and cryogenic carbon dioxide (CO2) cooling in high-speed machining of nickel-based alloy. CO2 and MQL supplied in the rake face were compared to CO2 and MQL in turning of Monel 400. Tool wear, temperature, surface roughness, and microstructural assessments were done to compute the cooling influence of distinct approaches. Energy dispersive spectrometry (EDS) mapping is employed to investigate the abrasion and adhesion mechanisms. The wear levels were reduced under the use of the hybrid approach; the decrease in flank wear value relative to the hybrid condition is 78%, 36%, and 27%, and in terms of crater wear, the reduction was 78%, 54%, and 48% over dry, MQL, and cryo CO2 conditions, respectively. Findings have portrayed that the lessening of temperature at the cutting area with the hybrid condition reduces the roughness by 58%, 44%, and 20% over dry, MQL, and cryo CO2 cutting strategies, respectively. Moreover, verdicts of the investigation confirm smaller grain size and high hardness under cryo cooling condition.

Milling Behavior Analysis of Carbon Fiber-Reinforced Polymer (CFRP) Composites

In recent years, carbon fiber-reinforced polymer (CFRP) composites materials are frequently used in many areas such as aerospace, military, automotive, construction, marine vehicles, wind turbines, motorcycles, bicycles, sport, electrical and household appliances due to superior properties of this material such as high specific strength, high stiffness and high corrosion resistance. While the parts produced with this material are durable and lightweight, the increase in CFRP composite material usage requires the development of processing methods with low cost and high quality. The surface quality in milling of CFRP composite materials is an important issue due to the influence of surface quality of the produced parts on the assemblage. It has also importance on the fatigue resistance of the machined parts. On the other hand, CFRP composite material is seen as one of the hard-to-cut materials due to its low thermal conductivity and abrasive nature. Rapid tool wear occurring during the milling process deteriorates the surface quality, leads to the decline in production due to the machine tool downtime and it thereby causes a cost increase accordingly. Therefore, diamond tools are widely used in machining of CFRP composite material due to their high hardness, while these tools are expensive. In order to overcome the tool cost issue, cemented carbide tools are used to cut CFRP composite material. Although carbide tools have higher toughness than diamond ones, their hardness is low. Therefore, they are commonly protected by a hard coating to increase their surface hardness and wear resistance. However, the tool life and cutting performance of the carbide tools in machining of CFRP material need to be improved. In this study, after investigation the studies on milling process of CFRP composite materials in the current literature, the emerging developments were presented. Cutting tool geometry and materials used in the relevant area are compiled. Tool wear mechanisms that occur during the milling process, the failures in CFRP composite material and the solutions to prevent these failures are discussed.

On the Formation Mechanisms of Adhering Layer during Machining Metal Material

Built-up Layer (BUL)/Built-up Edge (BUE) formed on the tool surface can be treated as a protective, thermal barrier or lubricant films especially in the extreme severe conditions when machining the metal materials, which can sustain the tool effective and wear resistance. In order to have a thorough understanding of the adhesion effect during machining, experiments have been carried out to investigate the performance and the formation mechanisms of adhering layer on the carbide tool in machining of aluminium alloys A6063, carbon steel S45C and difficult-to-cut hardened steel S45C (H-S45C). The morphology of tool adhered surface was examined by employing Scanning Electron Microscopy (SEM), the dimensions of adhering layer were measured by Laser Scanning Microscopy (LSM) and the elements on the tool were analyzed by Electron Probe Micro Analyser (EPMA), respectively. The atomic-scale cluster adhesive friction model is proposed to explain the tool-chip contact conditions, which considers the nature of the shear strain, shear strain rate and temperature distribution in the secondary deformation zone. The model is a dynamic model and the rate equation approach can be applied to estimate the formation process of adhering layer during machining. Results have shown that the adhering layer will give rise to BUL on the tool rake face and the BUE on the cutting edge and clearance face.

Design and simulation of thermal residual stresses of coatings on WC-Co cemented carbide cutting tool substrate

Large thermal residual stresses in coatings during the coating deposition process may easily lead to coating delamination of coated carbide tools in machining. In order to reduce the possibility of coating delamination during the tool failure process, a theoretical method was proposed and a numerical method was constructed for the coating design of WC-Co cemented carbide cutting tools. The thermal residual stresses of multi-layered coatings were analytically modeled based on equivalent parameters of coating properties, and the stress distribution of coatings are simulated by Finite element method (FEM). The theoretically calculated results and the FEM simulated results were verified and in good agreement with the experimental test results. The effects of coating thickness, tool substrate, coating type and interlayer were investigated by the proposed geometric and FEM model. Based on the evaluations of matchability of tool substrate and tool coatings, the basic principles of tool coating design were proposed. This provides theoretical basis for the selection and design of coatings of cutting tools in high-speed machining.

Performance evaluation of coated carbide tool in machining of stainless steel (AISI 202) under minimum quantity lubrication (MQL)

The benefits of cutting fluids in machining are well known, but their use is accompanied by health and environment hazards. Moreover, strict environmental regulations make the manufacturers to switch over to dry turning, which is not feasible during machining of sticky material like stainless steel and Inconel etc. Therefore, the use of minimal quantities of lubricant (MQL) can be regarded as an alternative solution and a step towards green machining. In the present investigation an attempt has been made to explore the potential of MQL turning of stainless steel with coated carbide cutting tool. Turning under MQL conditions has shown superior results (in terms of flank wear and machined surface roughness) over wet and dry turning. Signal to noise (S/N) ratio as per Taguchi design revealed speed and MQL as significant parameters for minimizing flank wear and surface roughness, whereas feed can be set within range. The optimum combination of parameters are cutting speed (58 m/min), feed rate (0.06 mm/rev.) and MQL flow rate (100 mL/h) for flank wear and cutting speed (23 m/min), feed rate (0.07 mm/rev.) and MQL flow rate (150 mL/h) for surface roughness. Taguchi optimized conditions were validated through multiple response optimization using desirability function.

Interface delamination study of diamond-coated carbide tools considering coating fractures

Interface delimitation is one of the major failure modes of diamond-coated carbide tools in machining. On the other hand, diamond coatings are prone of cracking easily due to its brittleness, which may affect interface delaminations. To study any influence between the two failure modes, micro-scratch testing on diamond-coated carbide tools was conducted and finite element (FE) modeling was developed to simulate the scratching process. In scratch testing, normal and tangential forces as well as acoustic emission signals were recorded to detect coating delaminations and crack initiations. Scratched samples were also observed by optical microscopy to determine the corresponding critical load of delaminations and cracking initiations. In the FE scratch simulation, a cohesive-zone interface and the extended finite element method (XFEM) were applied to investigate delamination and coating fracture behaviors, respectively. The cohesive elements were based on a bilinear tractionseparation model and XFEM was implemented to model cracking behavior in a diamond coating with a damage criterion of the maximum principal stress.The major findings are summarized as follows. The coating fracture energy has a negligible effect on the critical load for interface delaminations, and similarly, the interface fracture energy has no effect on the critical load for coating cracking, indicating that the two failure modes are mostly uncoupled for the testing range in this study. From the experiments and simulations, it is estimated that the coating fracture energy of the samples tested in this research is in the range of 120 to 140J/m2, and the diamond-carbide interface fracture energy is from 77 to 192J/m2. Moreover, increasing the coating Young's modulus will increase the critical load for coating delaminations, but decrease the critical load of coating cracking.

Adhering layer formation and its effect on the wear of coated carbide tools during turning of a nickel-based alloy

Abstract Experiments were carried out to investigate the performance and the wear mechanisms of PVD-TiAlN coated carbide tool in machining of nickel-based alloy GH4169. Adhering layer was formed around the cutting edges under various cutting conditions. The worn surfaces of tool were examined and the elements on the tool surfaces were analyzed by employing scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), respectively. The results of SEM micrographs and EDS analyses showed that adherence of workpiece material occurred on both the rake and flank faces under all cutting conditions, and the dominant wear modes of the tool were flank wear, crater on the rake face, and notching at the depth of cut line. The adhering layer protected tool surfaces from the scrubbing action of hard carbide particles, but accelerated the process of the element from tool material diffusing into the workpiece material. In addition, the adhering layer experienced a periodic “formation–stacking–plucking” process at the depth of cut line, leading to the formation of notching.

TURNING STUDIES OF DEEP CRYOGENIC TREATED P-40 TUNGSTEN CARBIDE CUTTING TOOL INSERTS – TECHNICAL COMMUNICATION

In the present work, coated tungsten carbide tool inserts of ISO P-40 grade were subjected to deep cryogenic treatment at −176°C. Turning studies were conducted on AISI 1040 workpieces using both untreated and deep cryogenic treated tungsten carbide cutting tool inserts. The turning performance was evaluated in terms of flank wear of the cutting tool inserts, main cutting force and surface finish of the machined workpieces. The flank wear of deep cryogenic treated carbide tools was observed to be lower than that of untreated carbide tools in machining of AISI 1040 steel. The cutting force during machining of AISI 1040 steel was lower with the deep cryogenic treated carbide tools when compared with the untreated carbide tools. The surface finish produced on machined AISI 1040 steel workpieces was superior with the deep cryogenic treated carbide tools as compared to the untreated carbide tools.

Thermal Protection Shield Concept for Diamond Impregnated Tools

Due to their better mechanical and physical properties diamond tools have largely replaced cemented carbide tools for machining of mineral materials like concrete and rocks. The decomposition tendency of diamond has to be taken into consideration during the manufacturing process as well as during their employment in machining tools. By using water cooling the diamond decomposition is reduced, but the contamination of occupied buildings by concrete/rock-watermixture and the need of water supply units on building sites are unfavourable. However, absence of water cooling lead to an increased tribological and thermal wear of conventional diamond tools. Due to the heat development the diamonds in direct contact with mineral materials as well as the diamonds in deeper layers are deteriorated. The Institute of Materials Engineering pursues a novel thermal protection shield concept, in which thermal insulating materials such as Al2O3, ZrO2 or glass in diamond impregnated composite structures act as heat shield, which protects diamonds in deeper layers against high temperature and graphitisation. Before the effectiveness of this concept could be investigated suitable composites have to be manufactured. In this paper the powder metallurgical production processes of diamondalumina- cobalt-composites with varying alumina and cobalt particle sizes, their microstructures and porosities are described. In comparison to composites with larger alumina particle sizes it could be observed that the distribution of alumina particles with particle sizes below 70 ,m in the cobalt matrix is uniform and the porosity of the composite decrease.

Wear of rotary carbide tools in machining of Al/SiCp composites

With the projected widespread application of Metal Matrix Composites, it is necessary to develop an appropriate technology for their efficient and cost-effective machining. This paper deals with the study of feasibility of rotary carbide tools in the intermittent machining of Al/SiCp composites. A rotary tool holder was designed and fabricated for this work. Experiments were designed using Taguchi Methods to analyse the influence of various factors and their interactions on the flank wear of rotary carbide tools during machining. A tool-life model describing the effect of process, tool and material dependent parameter on the magnitude of flank wear of a rotary carbide tool is proposed.

Machinability of ceramic and WC-Co green compacts

Machining pressed compacts of ceramic and WC-Co materials can be the most cost effective way of forming the bodies prior to sintering when the required number of pieces is small. In this study, in order to clarify the machinability for turning, the and the WC-Co green compacts unsintered were machined under different cutting conditions with various tools. Absorbing chips by vacuum hose decreases tool wear. The tool wear becomes larger in the order of the ceramic, CBN and cemented carbide tools in machining the green compacts. In machining the WC-Co green compacts, the tool wear becomes larger in the order of the ceramic, cemented carbide and CBN tools. The land of cutting edge does not affect tool wear. When machining with cemented carbide tool, the tool wear i equal cutting length is nearly identical in spite of the increase of cutting spee, and the roughness of machined surface was the best in the cutting speed of 90 m/min. The tool wear decreases with the increase of rake angle and relief angle and with the decrease of nose radius. The machined surfaces become worse with the increase of feed rate and depth of cut, and with the decrease of rake angle and relief angle. The tool wear is not affected by the feed and depth of cut.