International Journal of Machining and Machinability of Materials (11 papers in press)
Surface morphology and effect of cutting force and temperature in formation of the white layer during hard machining
by Sanjib Kr Rajbongshi, Deba Kumar Sarma
Abstract: In hard machining, different tribological phenomenon occur, out of which white layer formation and surface characterization are an important aspect. The white layer is found to be harder and fragile. It may cause a crack and may lead to failure in machined parts. Here, an experimental work is conducted in machining hardened AISI D2 steel. Cutting speed, feed, and depth of cut are taken as the input parameters. The level of each parameter is two. The white layer development process considering the impact of cutting force, temperature and morphology of hardened surfaces, etc. are covered in the study. The study of white layer morphology and hardness are carried out with FESEM and Micro-Vickers tester. The parametric study reveals occurrence of white layer due to the cutting force and temperature. Temperature has an important effect in increasing the surface hardness due to which the thickness of white layer changes. ANOVA analysis showed that cutting speed is the influencing variable for white layer thickness and microhardness, whereas depth of cut is influential for temperature, flank wear and cutting force.
Keywords: White layer; microhardness; cutting force; temperature.
Effect of rake surface textures spacing and width on the cutting performance of inserts in dry machining of Titanium alloy
by Amal Siju, Sachin Waigaonkar
Abstract: One of the crucial parameters that can be altered to improve machining efficiency in metal cutting is reducing the friction between tool and chip, especially along the rake surface of the tool. Studies have shown that many parameters of the micro or nanoscale texturing on the tool surface may influence its competence in reducing friction. However, the influence of texture parameters like width, spacing, etc. are not well understood, especially in the dry machining of hard alloys. In this experimental investigation, uncoated single point cutting tool inserts with different texture geometries on their rake surface were tested for adequacy in the typical turning operation of Titanium alloy. The novelty of the study involves identifying the influence of texture spacing and width on the cutting parameters at different feeds in the dry machining of the Ti-6Al-4V alloy. The surface characterization of the inserts shows how the textured surface was damaged under the machining regime. Chip morphology analysis was conducted to study the effect on chip thickness and shear plane angle. Inferences were made on the effect of texture dimensions on the frictional forces during machining.
Keywords: surface texturing; single-point cutting tool; chip-morphology; coefficient of friction; machinability; Ti alloy.
Diamond turning of optical materials: A review
by Bhaskar Goel, Sehijpal Singh, RamaGopal V. Sarepaka, Vinod Mishra, Neha Khatri, Vivek Aggarwal, Keshva Nand, Raj Kumar
Abstract: Single point diamond turning SPDT is key technology to overcome the shortcomings of conventional machining of optical components. In last decade, researchers explored various factors of SPDT to improve the machinability of optical materials. Collection of these studies in the form of detail review is missing. In this paper, existing literature has been studied in three categories of optical materials i.e. ductile, polymers and brittle materials keeping in view of their usage for lenses and molds. Most of the authors have analysed the effect of three input variables namely depth of cut, spindle speed and tool feed rate on surface roughness. This paper emphasizes on review of effect of all the input variables i.e. nose radius, depth of cut, rake angle, feed rate, tool overhang, spindle speed etc. Effect of all these process variables are reviewed not only on surface roughness but also on profile error and waviness error.
Keywords: Single point diamond turning; grey relational analysis; profile error; ductile regime machining; surface roughness; sub-surface damage; waviness error;.
Improving the Micro-Electrical-Discharge Drilling Performance of Carbon Fiber-Reinforced Polymer: Role of Assisting-Electrode and Shaped Tool
by Hrishikesh Dutta, Kishore Debnath, Deba Kumar Sarma
Abstract: This paper presents the investigation on the fabrication of though micro-holes in carbon fiber-reinforced polymer composites using micro-electrical-discharge drilling method coupled with assisting-electrode and rotary tools of copper and brass. Bisphenol-A based epoxy resin LY 556 having medium viscosity and hardener HY 951 were used for the fabrication of composites. The sizes of the fabricated micro-holes were in the range of 600-830
Keywords: Micro-electrical-discharge drilling; carbon fiber-reinforced polymer; machining time; surface morphology; regression analysis.
Estimation of surface roughness in a turning operation using industrial big data
by Kaustabh Chatterjee, Jian Zhang, Uday Shanker Dixit
Abstract: Surface roughness prediction in a turning process is of paramount importance. However, there is hardly any physics-based model that can predict it accurately. Recently, thanks to advancements in information technology, there are an ample amount of data in the industry. This article proposes a methodology to estimate surface roughness in turning based on industrial big data. An attempt has been made to extract and preserve the concise, useful information to reduce the burden on data storage. The proposed methodology predicts the lower, upper and most likely estimates of the surface roughness. A case study containing 35000 datasets is simulated using a virtual lathe to demonstrate the efficacy of the methodology. The whole region of data is divided into 81 cells, and model fitting is carried out in each cell. The developed model based on industrial big data provides reasonable prediction of surface roughness.
Keywords: Surface roughness; Data analytics; Multiple-linear regression; Turning; Outliers; Machining; Cook’s distance.
Study of tool wear progression and optimization while machining mono and hybrid zinc aluminium based MMCs
by Rajaneesh Marigoudar, Shashidhar P S, Sadashivappa Kanakuppi, Dharmendra B V, Manjunatha T S
Abstract: \r\nThe effect of graphite addition to conventional composites and making it hybrid for better machinability is the motto behind this work. Here ZA43+SiC mono composite and ZA43+SiC+Graphite hybrid composite are machined under dry condition. Machining is executed using commercially available coated carbide SNMG 090308 tool. Cutting variables viz. machining speed, feed rate and depth of machining are varied and for each machining trial fresh cutting edge is used. Tool damage is measured while machining both the categories of materials and are compared. It is noticed that the hybrid composite causes less damage in comparison with mono composite. The reason may be due to powdered graphite present in the composite which is responsible for reduction in the friction. Graphite being solid lubricant prevents tool getting abraded by the hard workpiece and promotes easy machinability. Statistical analysis done on the results gives the details about most influencing variable to the machining process. The tool wear during composite machining is greatly influenced by machining speed and feed. Optimum machining parameters can be drawn considering material composition for less tool wear condition.\r\n
Keywords: Hybrid MMC; Stir Casting; Coated carbide; Tool Wear; Abrasion; Graphite; Self Lubrication.
Machining austempered ductile iron Impact of the cutting edge geometry on tool wear and surface quality
by Jörg Hartig, Benjamin Kirsch, Jan C. Aurich
Abstract: In general, the performance of cutting tools are determined by its cutting material specification, macrogeometrical shape, cutting edge design and coating. The cutting edge geometry can be considered as one of the most important factors for optimizing cutting tools. By using cutting edge preparation, tools can be tailored to the machining task. A homogeneous preparation is either applied to resist high loads in the machining process or to optimize the resulting surface. Inhomogeneous cutting edge preparations can individually be designed to the machining task to match both target criteria simultaneously. In the following article, the cutting edges of tungsten carbide indexable inserts were prepared homogeneously and inhomogeneously. Tool wear and machining results during turning and drilling austempered ductile iron (ADI) 900 were investigated.
Keywords: cutting edge design; tungsten carbide; austempered ductile iron; turning; drilling; tool wear; surface roughness; machining; machinability; PVD coating; optimization.
Performance Evaluation of Cu-W-Si Green P/M Composite Electrode for Surface Modification of P20+Ni Steel using Electrical Discharge Machine
by J.L. Ramdatti, A.V. Gohil, Vineet Jain, K.G. Dave
Abstract: The current experimental research is being carried out to investigate the correlation between the process parameter of the electrical discharge machine (EDM) with the composite electrode (Cu-W-Si) produced through the process of powder metallurgy (P/M). The experiments on P20+Ni die steel were planned and performed using the rotatable second-order central composite (CCD) design. The mathematical response model was obtained through response surface methodology. MRR, TWR and SR have been studied on the significance of compaction pressure (Cp), peak current (Ip), pulse-on time (Ton) and duty cycle (?). ANOVA was conducted to investigate the contribution percentage of the parameters. The optimal set of process parameters was obtained using a multi-objective optimization technique called "composite desirability. The predicted result of responses were confirmed with the experimental results. The reasonable agreements between predicted and experimental results of MRR and TWR have been obtained with error lie within 5.19% and -3.33% respectively.
Keywords: EDM; P/M composite electrode; Response surface methodology (RSM); Multi-objective optimization; Material removal rate; Tool wear rate,Surface roughness; Composite desirability.
Effects of cutting speed and milling method on cutting forces, tool wear, tool life, and surface roughness in high-speed shell milling of Inconel 718 with coated carbide insert under emulsion flood cooling strategy
by Anthony Chukwujekwu Okafor, Theodore Nwoguh
Abstract: Inconel 718 use in aerospace and nuclear industries has gained wide interest due to the need to improve its machinability. This paper presents the results of experimental investigation of the effects of face milling methods and cutting speed on machinability of Inconel 718 with carbide inserts under conventional emulsion flood cooling strategy (CEF-CS) as a benchmark for comparing alternative Vegetable-oilbased MQL Cooling Strategy (VO-MQL-CS). The machinability parameters investigated are cutting force components, tool wear, burr formation, surface roughness, and tool life, under up- and down-milling at cutting speeds of 30, 40, and 50 m/min and constant chip load. Lower cutting forces, tool wear, burr formation, surface roughness, and significant improvement in tool life and volume of material removed are achieved in down-milling over up-milling by 1,677%, 2,150%, and 1,004% at 30, 40, and 50 m/min respectively. Down-milling at 40 m/min cutting speed under CEF-CS with coated carbide inserts is recommended as benchmark.
Keywords: Inconel 718; Cutting forces; Up- and down-milling; Tool wear; Emulsion flood cooling; Surface roughness.
Preparation, characterization and testing of graphene self lubricated tungsten carbide tools for sustainable turning
by Amrita M, Kamesh Bodduru, Srikanth R R
Abstract: Cutting fluids are commonly used for cooling and lubrication in machining but are unsafe to environment and cause health problems in workers. Though dry machining can be used to eliminate this problem, it is not preferred, owing to high temperature and friction. Additives with higher thermal conductivity and lubricating properties can increase the cooling and lubricating capabilities of cutting tools. Present work aims to check the feasibility of preparing graphene self lubricated tungsten carbide tools using powder metallurgy and adding varying concentration of graphene. Prepared tool materials are tested for tribological and thermal properties. Both Inconel718 and Ti6Al4V are machined using graphene self lubricated tools. Addition of graphene in minute quantities to tungsten carbide tools enhanced the tribological and thermal properties and also showed improvement in turning performance.
Keywords: Sustainability; graphene; tungsten carbide; hardness; tribology; machining; Inconel718; Ti6Al4V.
Development and experimental validation of numerical formulations of a heuristic model in WEDM of H13 tool steel
by Meinam Annebushan Singh, Koushik Das, Deba Kumar Sarma
Abstract: Proper identification of the effect of various process parameters in wire-electrical discharge machining process is a very important area that needs a thorough analysis. Also, the advancement in technology has considerably limited the user interface. The knowledge of the interdependence of these parameters will prove to be an important criterion to further enhance the machining technique. The present work focuses on the thorough analysis of the effect of the interdependence of process parameters in machining of H13 tool steel. Experiments were performed to obtain the material removal rate for different conditions. A finite element based backtrack numerical solver is developed to simulate the working voltage with the experimental results. The analyses show the interdependence of voltage, current, pulse on and off-time. A power allometric based heuristic model is formulated to identify the parameters interdependence. The proposed heuristic model has been validated with the experimental results, performed at random parametric conditions.
Keywords: EDM; FEM; MRR; heuristic model; FEM; H13 too steel.