On the basis of the grinding process experiments for SiC ceramic workpiece, grinding process parameters are measured on the multi-sensor fusion detection test platform and experimental results are analyzed. Lempel–Ziv complexity (LZC) is introduced to reflect the integrated grinding process stability due to kinds of factors such as vibration from grinding machine parts and noise from experimental platform. The greater the LZC is, the fewer period factors are in the grinding process, which reflect the nonlinear correlations in the grinding process impacting on grinding process. A method is given based on LZC for analyzing grinding process stability. Under consideration of experimental results, a predictive model for surface quality is given by the Kernel Principle Component Analysis and Modified Extreme learning machine method (KPCA-MELM), and grinding process parameters can be optimized too. KPCA-MELM predictive model overcomes disadvantages of MELM predictive model of the randomness of weight ω and threshold value b by introducing improved genetic algorithm, which makes the roughness predictive error more accurate with the maximum error of 4.803%.

Referencing special energy model, a new gun drill mechanics model was established and the influence of the cutting parameters on axial force and torque was based on 15-5PH solid solution stainless steel through theoretical analysis and cutting tests. On the basis of the existing model, the model coefficients were modified under various cutting conditions and the integral area of the cutting edge was enlarged. The eccentricity at the bottom of the drill groove was taken into account in the integral area of the cutting edge. In the meanwhile, the torque calculation was simplified reasonably according to the theoretical analysis. The feasibility of the model was verified by experiments and the influence of cutting parameters on the axial force and torque was analyzed. The experiment data had shown that the relative error between the calculated values and the experimental values were within the acceptable range. The axial force and torque increased with the increase in cutting speed and feed rate.

ABSTRACTThe goal of this research is to investigate and monitor machining mode transitions during nanoscale scratching of IZO-coated Pyrex glasses using atomic force microscope (AFM). Among the AFM nanomachining mode features, which include elastic/plastic deformations and crack generation, pile-up (by ploughing) is a key surface phenomenon that can represent plastic deformation characteristics, such as a sign of chip making. Moreover, because the pile-up formation mechanism of coated materials is reported to be distinct from that of bulk materials, the examination of pile-up in coated materials is challenging, along with brittle transition (crack initiation). In this research, the pile-up formation and crack initiation, that occur during nanoscratching, were examined and analyzed near the coating-substrate (glass) boundary. In addition, acoustic emission (AE), a sensing scheme with nanoscale sensitivity, was introduced to detect significant machining state variations and mode transitions. Experimental and analysis results indicate that the proposed scheme is viable for characterizing/monitoring the nanoscale machining of coated materials.

ABSTRACTDressing is a sharpening operation aimed to produce a specific groove shape on the active surface of the wheel. The preparation of grinding tools in special way is the most important enabling factor in the grinding process. It greatly influences the subsequent geometry of the workpiece. As the groove shape of the wheel surface determines the shape of the surface patterns, therefore, it is essential to produce desired groove on the wheel cutting surface before grinding. Therefore, an elliptical groove surface pattern model is proposed based on grinding with dressed wheel. An elliptical tip tool is used for the dressing process to make grooves on the wheel instead of sharp tip tool or rounded tip tool in the previous work. The dressing tool passes helically over the surface of the grinding wheel for making grooves. After that, the grooved wheel passes over the flat surface to generate elliptical patterns. The results showed the three-dimensional geometry of the surface patterns with elliptical groove which are uniformly distributed on the workpiece. An experiment is carried out for the verification of the simulation results and it is revealed that the simulation results agreed well with the experiment.

ABSTRACTA methodology of modeling chip geometry of flat helical end milling based on a variable flow stress machining theory is presented in this article. The proposed model is concerned with the variation of the width of cut thickness. The nonuniform chip thickness geometry is discretized into several segments based on the radial depth of cut. The chip geometry for each segment is considered to be constant by taking the average value of the maximum and minimum chip thickness. The maximum chip thickness for each chip segment is computed based on the current width of cut, feed per tooth and the cutter diameter. The subsequent radial depth of cut is subtracted from the discretized size of the width of cut to obtain the minimum chip thicknesses. The forces for each segment are summed to obtain the total forces acting on the system of the workpiece and the tool. The cutting forces can be predicted from input data of work material properties, cutter configuration and the cutting conditions used. The validation of the proposed model is achieved by correlating experimental results with the predicted results obtained.

ABSTRACTAdvanced finishing processes, both bonded and loose abrasive type, can be used effectively for microfinishing of internal tubular surfaces. However, generation of uniform finish without altering the geometric form is a key challenge in many of the existing methodologies. Rotary elastoabrasive finishing is proposed as a new methodology to meet similar requirements. Elastoabrasives in the form of mesoscale balls are flexible and convenient to use without any slurry/liquid medium and are capable of controlling the abrasion through an elastomeric backup. The mechanics of material removal and the effect of elastomeric medium in the proposed methodology are discussed, supplemented by systematic experimental investigation using response surface methodology. The average roughness of hardened steel tubes with initial roughness 0.160 μm was significantly reduced to 0.017 μm, after a processing time of 40 min without altering their cylindricity. The experimental setup with rotary attachment presented in this paper is demonstrated to be a flexible system for fine finishing tubular specimens, sleeves, and high aspect ratio bores, which find extensive industrial applications.

ABSTRACTThis article describes the experimental investigation of abrasive water jet (AWJ) cutting on AA5083-H32 aluminum alloy. In this study, the influence of varying the jet impingement angles and abrasive mesh sizes with different water jet pressures, on the output parameters for the AWJ cutting of the aluminum alloy, was analyzed. The experimental results found that the output parameters, namely, the depth of penetration, top kerf width, kerf taper ratio, surface roughness, and abrasive contaminations, were strongly influenced by the combined effect of oblique jet impingement angles and abrasive mesh sizes on AWJ. Also, it is noticed that oblique jet impingement angles have more influence on the output cutting responses than the normal jet impingement angle, and consequently, each abrasive mesh size has an influence on the different output responses for the AWJ cutting of AA5083-H32. Scanning electron microscope and microhardness tester were used to examine the different cutting regions of the kerf wall surfaces. The Energy-dispersive X-ray spectroscopy analysis was used to confirm the amount of silicon particles embedded in the AWJ cut surfaces. The adequacy checking of the experimental data for the AWJ cutting performance models has been analyzed through the residual plots using the statistical software.

ABSTRACTHigh-performance machining of free-form surfaces is highly critical in automotive, aerospace, and die–mold manufacturing industries. Therefore, electrochemical machining (ECM) process has been used in such cases in that sense. The most important challenges of using ECM process are the lack of accuracy and difficulty in designing proper machining tool (cathode) surfaces. In this article, a simplified mathematical model is presented to obtain a cathode surface for ECM of free-form surfaces which have high curvatures. In this theoretical approach, the finite-element method (FEM) is used to solve the 3-D Laplace equation and to determine the potential distribution between the anode (workpiece) and cathode (tool) surfaces. A compact and simple program was developed to obtain a proper cathode surface that only requires some nodal coordinates on the anode surface and boundary conditions. In this work, a trial cathode surface is constructed for a given gap distance. For the determined ECM parameters, cathode shape that satisfies the boundary conditions is obtained for the 45th layer. The results are compared with the literature and ANSYS Workbench for verification. The developed theoretical approach benefits simpler and faster FEM solutions, accurate cathode surface, and consequently correct form of machined surface.

ABSTRACTThe main objective of this study is to investigate the effect of Cu–Cr and Cu–Mo powder metal (PM) tool electrodes on electrical discharge machining (EDM) performance outputs. The EDM performance measures used in the study are material removal rate (MRR), tool electrode wear rate (EWR), average workpiece surface roughness (Ra), machined workpiece surface hardness, abrasive wear resistance, corrosion resistance, and workpiece alloyed layer depth and composition. The EDM performance of Cu–Cr and Cu–Mo PM electrodes produced at three different mixing ratios (15, 25, and 35 wt% Cr or Mo), compacting pressures (Pc = 600, 700, and 800 MPa), and sintering temperatures (Ts = 800, 850, and 900 °C) are compared with those machined with electrolytic Cu and Cu PM electrodes when machining SAE 1040 steel workpiece. Analyses revealed that tool materials were deposited as a layer over the work surface yielding high surface hardness, strong abrasion, and corrosion resistance. Moreover, the mixing ratio, Pc, and Ts affect the MRR, EWR, and Ra values.

ABSTRACTAn experimental study is carried out for single-pass radial-mode abrasive waterjet (AWJ) turning of a short carbon–fiber-reinforced polyetheretherketone (PEEK) specimen to understand the machining process and the effects of major process variables (feed speed, water pressure, abrasive mass flow rate, nozzle tilt angle, and rotational surface speed) on the major machining performance measures, that is, the depth of cut, material removal rate (MRR) and surface roughness. It is found that high water pressure, normal nozzle impact angle and high rotational speed with suitably selected feed speed and abrasive flow rate may be selected to achieve a high MRR without significantly compromising the surface roughness. Mathematical models for the three cutting performance measures are then developed for use in process control.