A reliable turning process by the early use of a deep simulation model at several manufacturing stages

The future of machine tools will be dominated by highly flexible and interconnected systems, in order to achieve the required productivity, accuracy, and reliability. Nowadays, distortion and vibration problems are easily solved in labs for the most common machining operations by using models based on the equations describing the physical laws of the machining processes; however, additional efforts are needed to overcome the gap between scientific research and real manufacturing problems. In fact, there is an increasing interest in developing simulation packages based on "deep-knowledge and models" that aid machine designers, production engineers, or machinists to get the most out of the machine-tools. This article proposes a methodology to reduce problems in machining by means of a simulation utility, which uses the main variables of the system and process as input data, and generates results that help in the proper decision-making and machining plan. Direct benefits can be found in (a) the fixture/ clamping optimal design; (b) the machine tool configuration; (c) the definition of chatter-free optimum cutting conditions and (d) the right programming of cutting toolpaths at the Computer Aided Manufacturing (CAM) stage. The information and knowledge-based approach showed successful results in several local manufacturing companies and are explained in the paper.The work presented in this paper was supported in some sections within the project entitled MuProD-Innovative Proactive Quality Control System for In-Process Multi-Stage Defect Reduction- of the Seventh Framework Program of the European Union [FoF.NMP.2011-5] and UPV/EHU under program UFI 11/29. Thanks are given to Tecnalia, for collaboration in testing, and especially to Ainhoa Gorrotxategi and Ander Jimenez for the sound work in the project. Thanks to Gamesa Eolica and Guruzpe, for the time, technical advices, and efforts during the analysis in examples

Effect of electropulses on the machinability of a C45E steel

This article compares the machinability of a C45E (AISI/SAE 1045) steel type under two different manufacturing processes: conventional machining and pulsed current assisted machining. The testing procedure consisted on the dry turning, using a coated carbide cutting tool (HM) and high-speed steel (HSS) cutting tools, under two different spindle speeds. In this study cutting tool life is evaluated in function of cutting speed for both machining conditions and both cutting tools. Results show variation on flank wear depending on the tool used and cutting speed, showing an increase in machinability when using the HM tool with the electropulse assisted turning at low cutting speed. Additionally, changes in chip type are found when assisting the process with electropulses. Statistically significant variations in chip dimensions and chip ratio are present, evidencing the differences in the phenomena affecting shear strain. Surface roughness, for its part, is improved when turning with the assistance of electropulses.Peer ReviewedPostprint (published version

Monitoring of Tool Wear and Surface Roughness Using ANFIS Method During CNC Turning of CFRP Composite

Carbon fiber-reinforced plastic (CFRP) is gaining wide acceptance in areas including sports, aerospace and automobile industry . Because of its superior mechanical qualities and lower weight than metals, it needs effective and efficient machining methods. In this study, the relationship between the cutting parameters (Speed, Feed, Depth of Cut) and response parameters (Vibration, Surface Finish, Cutting Force and Tool Wear) are investigated for CFRP composite. For machining of CFRP, CNC turning operation with coated carbide tool is used. An ANFIS model with two MISO system has been developed to predict the tool wear and surface finish. Speed, feed, depth of cut, vibration and cutting force have been used as input parameters and tool wear and surface finish have been used as output parameter. Three sets of cutting parameter have been used to gather the data points for continuous turning of CFRP composite. The model merged fuzzy inference modeling with artificial neural network learning abilities, and a set of rules is constructed directly from experimental data. However, Design of Experiments (DOE) confirmation of this experiment fails because of multi-collinearity problem in the dataset and insufficient experimental data points to predict the tool wear and surface roughness effectively using ANFIS methodology. Therefore, the result of this experiment do not provide a proper representation, and result in a failure to conform to a correct DOE approach

Characterizing acoustic emission signals for the online monitoring of a fluid magnetic abrasives finishing process

To implement an automated fluid magnetic abrasive finishing process, an online monitoring scheme is proposed based on characterizing acoustic emission signals in this paper. According to the material removal mechanisms during the fluid magnetic abrasive finishing process, the acoustic emission generation and characteristics are predicted analytically to be dominated by the interactions between the surface asperities and the abrasive particles. Moreover, the interactions and corresponding acoustic emission events will become weaker as the finishing process progresses and the surface becomes smoother. Experimental studies show that the amplitude and the occurrence rate of continuous acoustic emission waves and intermediate bursts reduce gradually with the progression of the finishing process. Based on these features, root mean squared values and burst occurrence rates, being of the lowest computational requirements, are suggested as online monitoring parameters for an automated and intelligent finishing in fluid magnetic abrasive manufacturing. The proposed method is verified experimentally, showing that the root mean squared values are highly consistent with the measured surface roughness values, which confirms the dynamic mechanisms between the fluid magnetic abrasive finishing and acoustic emission generation sources examined

Investigation and Mathematical Modelling of Optimized Cutting Parameters for Surface Roughness of EN-8 Alloy Steel

The work done in this work deals with the efficacy of cutting parameters on surface of EN-8 alloy steel. For knowing the optimal effects of cutting parameters response surface methodology was practiced subjected to central composite design matrix. The motive was to introduce an interaction among input parameters, i.e., cutting speed, feed and depth of cut and output parameter, surface roughness. For this, second order response surface model was modeled. The foreseen values obtained were found to be fairly close to observed values, showed that the model could be practiced to forecast the surface roughness on EN-8 within the range of parameter studied. Contours and 3-D plots are generated to forecast the value of surface roughness. It was revealed that surface roughness decreases with increases in cutting speed and it increases with feed. However, there were found negligible or almost no implication of depth of cut on surface roughness whereas feed rate affected the surface roughness most. For lower surface roughness, the optimum values of each one were also evaluated

Evaluation of subcooled MQL in cBN hard turning of powder-based Cr-Mo-V tool steel using simulations and experiments

Metal cutting fluids for improved cooling and lubrication are an environmental risk and a health risk for workers. Minimizing water consumption in industry is also a goal for a more sustainable production. Therefore, metal cutting emulsions that contain hazardous additives and consume considerable amounts of water are being replaced with more sustainable metal cutting fluids and delivery systems, like vegetable oils that are delivered in small aerosol droplets, i.e., via minimum quantity lubrication (MQL). Since the volume of the cutting fluid in MQL is small, the cooling capacity of MQL is not optimal. In order to improve the cooling capacity of the MQL, the spray can be subcooled using liquid nitrogen. This paper investigates subcooled MQL with machining simulations and experiments. The simulations provide complementary information to the experiments, which would be otherwise difficult to obtain, e.g., thermal behavior in the tool-chip contact and residual strains on the workpiece surface. The cBN hard turning simulations and experiments are done for powder-based Cr-Mo-V tool steel, Uddeholm Vanadis 8 using MQL subcooled to −10 \ub0C and regular MQL at room temperature. The cutting forces and tool wear are measured from the experiments that are used as the calibration factor for the simulations. After calibration, the simulations are used to evaluate the thermal effects of the subcooled MQL, and the surface residual strains on the workpiece. The simulations are in good agreement with the experiments in terms of chip morphology and cutting forces. The cutting experiments and simulations show that there is only a small difference between the subcooled MQL and regular MQL regarding the wear behavior, cutting forces, or process temperatures. The simulations predict substantial residual plastic strain on the workpiece surface after machining. The surface deformations are shown to have significant effect on the simulated cutting forces after the initial tool pass, an outcome that has major implications for inverse material modeling

A case study on Application of FUZZY logic in Electrical Discharge Machining(EDM)

Electrical Discharge Machining (EDM) is one of the most accurate manufacturing processes available for creating complex or simple shapes and geometries within parts and assemblies. EDM works by eroding material in the path of electrical discharges that form an arc between an electrode tool and the work piece. EDM manufacturing is quite affordable and a very desirable manufacturing process when low counts or high accuracy is required. Turn around time can be fast and depends on manufacturer back log. The EDM system consists of a shaped tool or wire electrode, and the part. The part is connected to a power supply. Sometimes to create a potential difference between the work piece and tool, the work piece is immersed in a dielectric (electrically non-conducting) fluid which is circulated to flush away debris

The present state of surface conditioning in cutting and grinding

All manufacturing processes have an impact on the surface layer state of a component, which in turn significantly determines the properties of parts in service. Although these effects should certainly be exploited, knowledge on the conditioning of the surfaces during the final cutting and abrasive process of metal components is still only extremely limited today. The key challenges in regard comprise the process-oriented acquisition of suitable measurement signals and their use in robust process control with regard to the surface layer conditions. By mastering these challenges, the present demands for sustainability in production on the one hand and the material requirements in terms of lightweight construction strength on the other hand can be successfully met. In this review article completely new surface conditioning approaches are presented, which originate from the Priority Program 2086 of the Deutsche Forschungsgemeinschaft (DFG)

Increasing Efficiency of Ti-6Al-4V Machining by Cryogenic Cooling and using Nanolubricants

Generation of high localized cutting zone temperatures leading to dissolution wear hinders machinability of Ti alloys using uncoated carbide tools and polycrystalline diamond (PCD) tools. In addition, the thermo-plastic instability exhibited by titanium alloys promotes serrated chip formation that causes fluctuations in the cutting forces leading to chatter and severe flank wear. This work considers two methods to mitigate these problems during cutting of Ti-6Al-4V, namely, cryogenic machining to influence chip segmentation, and the use of WS2 blended metal removal fluids (MRF) to influence interface coefficient of friction (COF). Cryogenic machining of Ti-6Al-4V at 45 m/min and 0.15 mm/rev led to easier fracture of chip segments due to decrease in toughness of the material. Analyses of fracture surfaces of the chips showed that the decrease in toughness was due to increased presence of shear ridges at low temperatures. The role of COF was determined using pin-on-disk experiments. Iterative tests of Ti-6Al-4V pins sliding against uncoated WC-Co disk showed that the addition of WS2 nanoparticles to MRF are capable of decreasing the interface COF lower than that under MRF lubricated conditions alone. Orthogonal machining of Ti-6Al-4V at a cutting speed of 29.5 m/min, feed rate of 0.4 mm/rev under dry conditions generated an average cutting force of 400 N. Under MRF + WS2 lubricated conditions, the average cutting force reduced to 190 N, which was 52% lower than dry conditions. The low COF values due to the MRF + WS2 lubricant reduces the interface temperature and thus aids in machining

Surface morphological evolutions on single crystal films by strong anisotropic drift-diffusion under the capillary and electromigration forces

The morphological evolution of voids at the unpassivated surfaces and the sidewalls of the single crystal metallic films are investigated via computer simulations by using the novel mathematical model developed by Ogurtani relying on the fundamental postulates of irreversible thermodynamics. The effects of the drift-diffusion anisotropy on the development of the surface morphological scenarios are fully explored under the action of the electromigration (EM) and capillary forces (CF), utilizing numerous combination of the surface textures and the directions of the applied electric field. The interconnect failure time due to the EM induced wedge shape internal voids and the incubation time of the oscillatory surface waves, under the severe instability regimes, are deduced by the novel renormalization procedures applied on the outputs of the computer simulation experiments.Comment: 41 pages, 18 figures. related simulation movies utilizing numerous combination of the surface texture, see http://www.csl.mete.metu.edu.tr/aytac/thesis/movies/index.ht