Workpiece Roughness Research Articles

Analysis of form Error and Roughness of Hardened Steel Workpieces Internally Turned with Different Tools in Long Overhangs

Abstract Internal turning process is a very important and widely used process for enlarging and finishing holes. Especially for the components that work with external members, this operation needs to assure surface and geometric quality. In that case, the correct definition of working parameters will directly contribute to the quality of component. Aim of the current research was to analyse the form error and the roughness of workpieces submitted to internal turning process using boring bars in long overhangs with three different internal tools (steel, carbide and antivibrating tool). For the experiments, heat-treated DIN EN 1.2842 (ISO 90MnCrV8) steel with 58 HRC of hardness was submitted to boring process using CBN (cubic boron nitride) inserts, and a boring bar with the most possible rigid clamping system (Easy Fix). The workpiece roughness and circularity were measured using a profilometer and a form error measuring machine. The measurements provided the data to identify the boring bar levels of stability, and the workpiece micro and macro geometric errors. The experiments allowed to conclude that, for all toolbars, the evaluated errors kept constant with increasing L/D ratio during stable clamping conditions, without any vibration. On the other hand, higher values of overhangs, limited to L/D>4.25 for steel tool, can cause serious damages in the cutting system if the antivibration tools or the carbide will be not used.

Investigation into the Effects of Roller Pressing on Hardness, Roughness and Elastic Modulus of Wooden Workpieces

The paper investigates the effects of roller pressing on the hardness, roughness, and elastic modulus of wooden workpieces. For research purposes, a roller pressing device based on purely mechanical processing was designed and developed. Four different levels of pressing force have been applied to eight different types of wood: cherry, fir, alder, linden, beech, walnut, oak, and ash. The obtained results indicate that the proposed processing method can significantly improve the hardness, elastic modulus, and surface quality of wooden workpieces. The ash sample exhibited the largest relative increase in hardness (175.9%), while the most significant relative increase in the elastic modulus (66.73%) was measured on the linden sample. The largest relative decrease in surface roughness (54.75%) was achieved on the alder sample. For all types of wood except for fir, in which case an increase in pressing force did not produce the desired reduction of roughness, correlation coefficients indicate a strong relationship between the pressing force as an input variable and the elastic modulus, hardness, and roughness as output variables.

Milling chatter detection with WPD and power entropy for Ti-6Al-4V thin-walled parts based on multi-source signals fusion

Unstable cutting has a relatively large negative impact on the machining quality and efficiency of thin-walled parts. It can easily cause severe vibration of milling systems, resulting in poor surface roughness of workpieces. Although some promising signal processing methods, such as wavelet packet decomposition (WPD), have been applied to process nonlinear signals, few studies have paid attention to determining a wavelet basis and the number of decomposition layers in WPD. Parameters of WPD play a crucial role and they are often empirically determined. In this paper, an adaptive denoising model based on WPD and recursive least squares with a variable forgetting factor (RLSVFF) is firstly established, and the influence of the forgetting factor in the model on signal denoising are investigated. Then, a novel chatter detection method based on multi-source signals fusion using WPD and power entropy is presented. On this basis, an automated selection method based on a margin indicator and power is proposed for applications to WPD. And the influence of different parameters of WPD on a margin indicator and power are investigated. In order to improve the efficiency of different levels of signal acquisition, a method based on a stability lobe diagram (SLD) is used to design experimental parameters. Compared with traditional denoising models and chatter detection methods based on a single signal, simulation and experimental results show that the adaptive denoising model and chatter detection method based on multi-source signals fusion proposed in this paper can more reliably detect the occurrence of early chatter and different levels of chatter.

Application of an integrated method to improve the quality of manufacturing parts of electronic warfare devices

Objectives. The development of technological methods with the purpose of increasing the structural strength of defense engineering products can be carried out by creating new methods for obtaining and processing parts or improving traditional methods based on an integrated (synergistic) approach. The article presents a complex method for surface treatment of parts and assessment of the hardness and surface roughness of the initial workpiece from alloys of the Al–Mg system to improve the quality of manufacturing the module cases of the MSP-418K product related to electronic warfare devices.Methods. This approach consists in the vision of a metallic material as a system subjected to a chain of technological impacts in the process of chemical, thermodynamic, and mechanical interaction of its components. The workpieces were obtained by metal pressure treatment according to various schemes and temperature conditions Then they were processed with a blade tool using a dynamometer. The resulting cut was examined using a metallographic method along the entire end face from the outer surface to the center of the sample of workpieces.Results. Experiments were carried out for the case of Al–Mg alloys. It made it possible to reveal the relationship between the parameters of the change in the structure of the material being processed and the stability of the cutting process, as well as the quality of the surface during finishing turning.Conclusions. The proposed technological solutions based on a synergistic approach provided a balanced improvement in material parameters by eliminating the shortcomings of the original semi-finished product. The obtained experimental data allowed concluding the deformation of workpieces according to complex schemes at low temperature has a beneficial effect on the machinability of the metal material, ordering the structure and improving the quality of the surface of the parts. Using a synergistic approach, it became possible to correct the poor technological heredity of material properties obtained in previous operations: the surface quality of the workpieces due to the continuity of the processed material and the strength properties of parts for critical and especially critical purposes were improved. The existing technological process for manufacturing the “petal” part was changed in practice using an integrated method, which made it possible to improve its technological and technical characteristics.

Effect of graphene nanoplatelets on the mechanical properties and cutting performance of alumina nanocomposite ceramic tools prepared using the SPS-HF dual sintering method

Al2O3/graphene nanoplatelets (GNPs) materials were prepared using the spark plasma sintering-high-frequency (SPS-HF) dual sintering method. The mechanical properties and microstructure of the composites were observed, and the effects of the sintering process and GNPs on the composites were analyzed. Under the sintering condition of a temperature of 1350 °C, pressure of 35 MPa and holding time of 8 min, the optimal mechanical properties of Al2O3 ceramic tool materials were obtained. The addition of GNPs had a positive effect on the mechanical properties of Al2O3 materials. Results show that the SPS-HF dual-sintering method shortens sintering time significantly. Compared to Al2O3 ceramic material, the composite material with 0.5 vol% GNPs had better mechanical properties than the Al2O3 ceramic material, with its flexural strength and fracture toughness being increased by 15.3% (617 MPa) and 63.4% (6.7 MPa m1/2), respectively. The toughening mechanisms of Al2O3/GNPs ceramic nanocomposites are graphene pull-out, graphene breaking, crack deflection, and crack branching. Dry machining tests of 40Cr hardened steel were carried out using an Al2O3/GNP ceramic tool and an Al2O3 ceramic tool. Compared with the Al2O3 ceramic tool, the life of the Al2O3/GNPs ceramic tool was increased by 16.3%, the workpiece roughness was decreased by 9.2%, and the friction coefficient was reduced by 12.8%, confirming the improvement of cutting performance by adding GNPs to ceramic tool materials.

Influence of GO on surface process mechanism in barrel finishing

ABSTRACT Barrel finishing is a widely used finishing technology with simple operation and wide applicability. However, the grinding fluid is used in this process, causing the problem of chemical oxygen demand (COD) exceeding the standard. It brings about environmental issues, wastewater treatment problems, and increased manufacturing costs. Therefore, a new kind of grinding fluid containing nanoparticles with a low COD value for barrel finishing is proposed. The grinding fluid is composed of graphene oxide (GO), sodium dodecyl benzene sulfonate (SDBS), and deionized water. The surface roughness of the aluminum alloy workpiece was improved under the grinding fluid containing nanoparticles GO. The influence of GO on surface process mechanism in barrel finishing was researched. In grinding fluid, the SDBS is adsorbed on GO by a self-assembly effect, forming new molecules. It affects the tribological behavior through the solid–liquid physicochemical interaction. Analyzing the tribological behavior indicates that GO plays a lubricating role by tribochemistry, which affects the workpiece surface roughness in barrel finishing. The grinding fluid containing nanoparticles with a low COD value reduces the difficulty of wastewater treatment and meets the green production need.

Experimental study of machined surface quality in ultrasonic vibration-assisted turning of 5A06 Al-Mg alloy

The 5A06 Al-Mg alloy is a soft material, and the phenomenon of knife sticking is extremely serious during cutting, likewise, it is easy to generate build-up edges. Therefore, it is difficult to acquire good surface quality in turning. For this purpose, the ultrasonic theory and cutting theory are fully combined in this study, and the machining mechanism of conventional turning (CT) is changed by applying ultrasonic vibration (UV) to the cutting tool, so as to build up the machining results. The turning experiments of 5A06 Al-Mg alloy with or without UV are carried out under different process parameters, and through which the effects of ultrasonic amplitude (UA), feed rate (FR), cutting depth (CD) and cutting speed (CS) on the surface roughness of machined workpiece are investigated and analyzed. The consequences show that the process parameters have a different degree of effect on surface roughness. And there are special process parameters suitable for UV assisted turning (UAT), under which the processing results of UAT is obviously better than that of CT. In addition, it is found that by contrast experiment of surface topography under ideal process parameters built-up edges, surface scratches and other phenomena are not easy to arise in UAT to obtain the better surface topography than CT.

About a new method to enhance the productivity of die sinking EDM

In order to control the EDM inter-electrode gap, the regulation is usually done indirectly by measuring the ignition delay or the average gap voltage, and the axes positions of the machine are adjusted accordingly.The machine efficiency strongly depends on the performance of this gap width controller.The problem in the procedure described above, lies in the comparably slow response time of the machine mechanics, in the tens of millisecond range, with respect to the discharge frequency, which is in the kHz range. The machine mechanics cannot follow it, therefore the performance of the machine is affected in terms of material removal rate, electrode wear, and surface quality.However, adapting the electrical discharge parameters can be typically 1000 times faster than moving the machine axis.This paper shows how it is possible, by adapting in real time the ignition voltage of every pulse to the gap width, to realize a sort of electronic servo system. Additional generator parameters are adjusted for every pulse as a function of the gap width, such the pulse interval etc. Moreover, the mechanically coupled servo system, and the electronic one complement each other.Experimental results show a remarkable increase of the discharge frequency and consequently of the material removal, without penalizing the other technological results, i.e. the inter-electrode gap, the workpiece roughness, the tool electrode wear.

Шероховатость и микротвердость ультрамелкозернистого титана Grade 4, подвергнутого безабразивной ультразвуковой финишной обработке

Increasing the fatigue resistance of implants is an important scientific and technical problem. One of the solutions to this problem is the high-strength state formation due to the ultrafine-grained (UFG) structure. However, high-strength alloys are characterized by greater sensitivity to stress concentrators and the surface roughness parameter. In turn, implant designs, as a rule, imply the presence of concentrators in the form of various grooves, threaded elements, etc., and the manufacturing technology supposes mechanical processing with an ambiguous effect on a finished product surface. The application of additional surface finishing, for example, abrasive-free ultrasonic finishing (AFUF), is a solution to this problem. This work aims to study the effect of different AFUF modes on the microhardness and roughness of a cylindrical blank made of Grade 4 commercially pure titanium in the UFG state. During the study, the authors assessed the effect of the rotation frequency of a workpiece and the static force of pressing the tool against the processed workpiece on the surface parameters; carried out microstructural studies of the obtained samples. The results showed that processing titanium in the UFG state by the AFUF method leads to a significant increase in the surface microhardness and a decrease in its roughness. For example, depending on the mode, the increase in microhardness can reach from 2 to 3.5 times. The authors investigated the effect of a power level of ultrasonic treatment on roughness and microhardness and considered various variants of surface pretreatment. The study identified that an increase in the speed of rotation of a workpiece reduces the roughness of a machined workpiece, while the microhardness increases.

Investigation of Influential Discharge Parameters on Machining Characteristics Generated by the LC Pulse Generator

The LC generator has many advantages in electrical discharge machining (EDM). It can generate high gap open voltage and high discharge current pulse with short duration under very low voltage input conditions. The shape of current pulse generated by the LC generator with higher rising speed shows superiority in machining efficiency compared to the conventional RC generator. This paper aims to investigate the influential parameters of the LC pulse generator and analyze how inductance, capacitance and switching frequency influence the discharge current pulse and gap open voltage pulse. The results of investigation are used to match the real discharge conditions by experiments. On the other hand, roughness of machined workpiece, cylindricity of drilled holes, tool wear ratio and material removal rate are investigated under different discharge parameters generated by the LC pulse generator.

Magnetic Abrasive Polishing of Stainless Steel SS304 with Diamond-Based Sintered Magnetic Abrasives

The most critical phase of all the stages needed for quality sample preparation for microscopic study is perhaps surface polishing. Magnetic abrasive polishing is a nonconventional finishing operation that can finish different materials and produce nano-finished surfaces. This study emphasizes the fabrication of a magnetic abrasive polishing setup for metallurgical polishing of specimens. Utilizing this test arrangement, exploratory investigations have been conducted to analyze the impact of five significant interaction factors, specifically the gap between the magnetic pole and the workpiece ([Formula: see text]), the quantity of diamond-based sintered magnetic abrasives ([Formula: see text]), the rotational speed of the magnetic pole (RPM), the grit size of sintered magnetic abrasives ([Formula: see text]), and machining time ([Formula: see text]). The abrasives used in this study were diamond-based sintered magnetic abrasives. The percentage change in surface roughness (PCSR) of the stainless steel SS304 workpiece is the response variable. From the results of the ANOVA study, the most important factor affecting the PCSR of the stainless steel SS304 workpiece is the abrasive grit size (49.49%), and the least important factor is the machining time (4.89%). The differences in scanning electron microscopy (SEM) images and surface profiles of workpieces demonstrate that the developed setup can polish stainless steel SS304 plane workpieces.

Multi-Objective Optimization of CNC Turning Process Parameters Considering Transient-Steady State Energy Consumption

Energy-saving and emission reduction are recognized as the primary measure to tackle the problems associated with climate change, which is one of the major challenges for humanity for the forthcoming decades. Energy modeling and process parameters optimization of machining are effective and powerful ways to realize energy saving in the manufacturing industry. In order to realize high quality and low energy consumption machining of computer numerical control (CNC) lathe, a multi-objective optimization of CNC turning process parameters considering transient-steady state energy consumption is proposed. By analyzing the energy consumption characteristics in the process of machining and introducing practical constraints, such as machine tool equipment performance and tool life, a multi-objective optimization model with turning process parameters as optimization variables and high quality and low energy consumption as optimization objectives is established. The model is solved by non-dominated sorting genetic algorithm-II (NSGA-II), and the pareto optimal solution set of the model is obtained. Finally, the machining process of shaft parts is studied by CK6153i CNC lathe. The results show that 38.3% energy consumption is saved, and the surface roughness of workpiece is reduced by 47.0%, which verifies the effectiveness of the optimization method.

Single-Point Incremental Forming of Titanium and Titanium Alloy Sheets.

Incremental sheet forming of titanium and its alloys has a significant role in modern manufacturing techniques because it allows for the production of high-quality products with complex shapes at low production costs. Stamping processes are a major contributor to plastic working techniques in industries such as automotive, aerospace and medicine. This article reviews the development of the single-point incremental forming (SPIF) technique in titanium and its alloys. Problems of a tribological and microstructural nature that make it difficult to obtain components with the desired geometric and shape accuracy are discussed. Great emphasis is placed on current trends in SPIF of difficult-to-form α-, α + β- and β-type titanium alloys. Potential uses of SPIF for forming products in various industries are also indicated, with a particular focus on medical applications. The conclusions of the review provide a structured guideline for scientists and practitioners working on incremental forming of titanium and titanium alloy sheets. One of the ways to increase the formability and minimize the springback of titanium alloys is to treat them at elevated temperatures. The main approaches developed for introducing temperature into a workpiece are friction heating, electrical heating and laser heating. The selection of an appropriate lubricant is a key aspect of the forming process of titanium and its alloys, which exhibit unfavorable tribological properties such as high adhesion and a tendency to adhesive wear. A review of the literature showed that there are insufficient investigations into the synergistic effect of rotational speed and tool rotation direction on the surface roughness of workpieces.

Development of a new high-shear and low-pressure grinding wheel and its grinding characteristics for Inconel718 alloy

Nickel-based alloy has been widely used due to its outstanding mechanical properties. However, Nickel-based alloy is a typical difficult-to-machine material, which is a great constrain for its application in the manufacturing field. To improve the surface quality of the ground workpiece, a new high-shear and low-pressure grinding wheel, with high ratio of tangential grinding force to normal grinding force, was fabricated for the grinding of selective laser melting (SLM) manufactured Inconel718 alloy. The principle of high-shear and low-pressure grinding process was introduced in detail, which was quite different from the conventional grinding process. The fabrication process of the new grinding wheel was illustrated. A serial of experiments with different processing parameters were carried out to investigate the grinding performance of the developed grinding wheel via analyzing surface roughness and surface morphology of the ground workpiece. The optimal processing parameters of high-shear and low-pressure grinding were obtained. The surface roughness of ground workpiece was reduced to 0.232 μm from the initial value of 0.490 μm under the optimal grinding conditions. It was found that the initial scratches on the ground workpiece were almost completely removed after the observations with the metalloscopy and the field-emission scanning electron microscopy (FE-SEM). The capability of the newly developed high-shear and low-pressure grinding wheel was validated.

EXPERIMENTAL INVESTIGATION AND OPTIMIZATION OF HIGH SPEED MACHINING OF TITANIUM ALLOY FOR BIOMEDICAL APPLICATION

The Ti-6Al-4V alloy is known as materials with high hardness and good mechanical properties. However, the machining process of this material faces many difficulties due to unfavorable machining conditions. When the machining parameters are not selected in accordance with the Ti-6Al-4V alloy, the surface quality of workpieces does not meet technical requirements. Therefore, the appropriate machining parameters are needed to upgrade the surface roughness of workpieces in high-speed machining (HSM) conditions. The main cutting forces Py and Pz, and surface roughness Rz during turning of Ti-6Al-4V alloy in HSM were investigated and evaluated in this study. The response surface method (RSM) was used to conduct experiments and establish the models of Rz, Py, and Pz under various cutting conditions of feed rate ([Formula: see text]), tool nose radius ([Formula: see text]), and approach angle ([Formula: see text]). As a result, the [Formula: see text] value has the largest impact on the Pz. Moreover, the machining parameters such as [Formula: see text], [Formula: see text], and [Formula: see text] have a great influence on the Py. The magnitude of Rz is mainly affected by [Formula: see text] value. Based on the optimal parameters, the average value of the force Pz has decreased from 238[Formula: see text]N to 169[Formula: see text]N, corresponding reduction of about 29%. The value of the force Py has reduced from 184[Formula: see text]N to 118[Formula: see text]N, corresponding reduction of about 36%. In addition, the surface roughness of the workpiece has been improved significantly from Rz of 5.6[Formula: see text][Formula: see text]m to 2.7[Formula: see text][Formula: see text]m under optimal parameters condition. The surface roughness of the workpiece after processing in high speed machining was reduced of 52% compared with cutting under non-optimal parameters condition. The best surface quality and minimum cutting force could be achieved under optimal processing parameters in high speed cutting method.

Study the Effect of Inductor and Pole Geometry on the Surface Roughness and Material Removal Weight Using Magnetic Abrasive Finishing Method

The traditional finishing method cannot keep up with recent labor market requirements, solve the problem of increasing production, improve the surface roughness and accuracy of workpiece. While the unconventional magnetic abrasive finishing (MAF) method has shown as a promising technique that can be used to finish complicated surfaces. MAF finishes metals, alloy, ceramic, and other materials that are difficult to finish by other processes. In another word, MAF improves the quality of surfaces with low cost.
 This paper focuses on optimize and study the effect of inductor and pole geometry (radius of hole, angle of core, angle of pole, radius of pole), on (surface roughness (Ra) and material removal weight (W)) and fined the optimum values that increase the efficiency of MAF method. Taguchi method employed to study the influence of geometry parameters and find the optimum values using orthogonal array L9. The results conclude that the most significant factor that effects change in surface roughness (ΔRa) and material removal weight(ΔW) are radius of the hole (R) and angle of core (α), respectively.

Study of the tool path generation method for an ultra-precision spherical complex surface based on a five-axis machine tool

The improvement of ultra-precision machining technology has significantly boosted the demand for the surface quality and surface accuracy of the workpieces to be machined. However, the geometric shapes of workpiece surfaces cannot be adequately manufactured with simple plane, cylindrical, or spherical surfaces because of their different applications in various fields. In this research, a method was proposed to generate tool paths for the machining of complex spherical surfaces based on an ultra-precise five-axis turning and milling machine with a C-Y-Z-X-B structure. Through the proposed tool path generation method, ultra-precise complex spherical surface machining was achieved. First, the complex spherical surface model was modeled and calculated, and then it was combined with the designed model to generate the tool path. Then the tool paths were generated with a numerically controlled (NC) program. Based on an ultra-precision three-coordinate measuring instrument and a white light interferometer, the machining accuracy of a workpiece surface was characterized, and the effectiveness of the tool path generation method was verified. The surface roughness of the machined workpiece was less than 90 nm. Furthermore, the surface roughness within the spherical region appeared to be less than 30 nm. The presented tool path generation method in this research produced ultra-precision spherical complex surfaces. The method could be applied to complex spherical surfaces with other characteristics.

Fixed abrasive polishing: the effect of particle size on the workpiece roughness and sub-surface damage

Fixed abrasive polishing: the effect of particle size on the workpiece roughness and sub-surface damage

Micro-milling mechanism and surface roughness of high volume fraction SiCp/Al composites

In this paper, a finite element simulation model of diamond tool milling SiCp/Al composites was established. The cutting stress, stress distribution and material removal mechanism of the SiC-reinforced material were studied. At the same time, the correctness of the finite element simulation was verified by a micro-milling experiment. The results show that the main particle removal methods include pulling out, crushing and pressing in and that the particle removal methods are different when the tool is cutting at different positions. With increasing cutting speed, the surface defects of the material are reduced and the surface quality is improved. The main surface defects in the milling process are voids, microcracks, scratches and pits. Through the optimization of cutting parameters, it is found that the milling depth has the greatest effect on the surface roughness, the spindle speed has the second greatest effect, and the feed rate has the least effect. The surface roughness of the machined workpiece is 0.238 μm when the process parameters have been optimized.

Performance of Al2O3-CBN materials and perspective of using hyperspectral imaging during cutting tests

The performance of cutting tool materials (CTMs) influences the quality and lifetime of parts produced with their help. Unexpected fracturing or other failures of the tools lead to defects of parts that exaggerate materials fatigue and fracture processes. For the purpose of Industry 4 and future generations of factories it is important to enable in-situ monitoring of cutting processes while hyperspectral imaging can serve as a powerful tool. Cubic boron nitride (cBN) has extreme hardness and can provide improved wear resistance if mixed with other CTMs. Besides, such materials can be used without cooling liquids that helps to mitigate workplace health risks. The aim of the current work was to understand how well current hyperspectral imaging technologies can track the changes in performance of CTMs with addition of cBN. The paper presents the results of multiple in-situ (obtained during cutting with real lathe) and static (before or after cutting) tests performed with hyperspectral camera. The wear rate of CTMs and roughness of workpieces were measured with the help of scanning electron microscope and 3D optical profiler respectively. The effect of cBN content and effect of TiN or ZrO2 additives on performance of alumina-based CTMs produced by spark plasma sintering technique is presented.