Edge Preparation Research Articles

Thermo-mechanical study of single and multi-pass welding of CSEF steel for residual stresses and deformations considering solid state phase transformation

The present study involves thermo-mechanical modelling of submerged arc welding of CSEF (Creep Strength Enhanced Ferritic) steel plate of thickness 10 mm as single pass and multi-pass welding. A square butt joint with no edge preparation and a V-butt joint with 15° included angle are considered for SAW welding. The martensitic-austenitic transformation phenomenon in P91 steel was also implemented with specific changes in the properties of the weld and base material. It is observed that SAW process with single pass demonstrates stable residual stress distribution, whereas in multi-pass weld, the residual stresses show uneven distribution across the weld. The longitudinal residual stresses are higher in magnitude comparing to transverse residual stresses for both the welding cases. The single pass SAW weld fusion zone has shown compressive stress throughout the thickness of the plate with maximum value at the top side. However, in multi pass weld, the compressive residual stresses have multiple peak values along the weld thickness. The deflection pattern is not effectively altered with multi pass with slight difference from single pass. Therefore, it is suggested that if possible, single pass weld can be preferred over multi pass weld.

Machinability and Surface Integrity Characterization in Hard Turning of AISI 4320 Bearing Steel Using Different CBN Inserts

The thermomechanical interaction between the cutting tool and the workpiece in any material removal process is a key factor in defining the efficiency and productivity of the process. It is especially important in cutting hard-to-machine materials such as titanium- and nickel-based alloys or hardened steels. The productivity of the process can be defined in terms of machining time, intervals of tool change (due to tool wear) and surface integrity characteristics such as dimensional tolerances, surface roughness and the machining-affected zone. The objective of this work is to conduct a comprehensive study of the performance of three different industrial-grade CBN cutting inserts during hard turning of AISI 4320 case-carburized steel. The CBN inserts all had the same geometry but used different edge preparation and coating technologies. To quantify tool performance, the cutting forces and tool wear were measured at consistent intervals and the surface integrity of the workpiece was characterized in terms of surface roughness, white and dark layer depths, micro-hardness and residual stresses. Results show that the stability of the cutting edge on two of the tested inserts plays an important role in determining tool life (where 60% higher tool life was achieved compared to the other tested insert with unstable cutting edge), cutting force stability and the formation of compressive residual stresses on the surface of the turned workpiece

Weldability of S700MC steel welded with the hybrid plasma + MAG method

The paper describes the microstructure of welded joints produced by the plasma+MAG (Metal Active Gas) method of S700MC high yield strength steel (700 MPa). Welded joints of thermomechanical steel have been made with different values of heat input. The results of metallographic research of welded joints, microstructure of the weld and heat affected zone, hardness distribution and impact toughness are presented. The heat affected zone consists of two sub-zones with different grain size and lowered hardness. The tensile test show that strength of welded joints was slightly reduced and the bending test revealed no crack formation in the weld. The impact toughness of measured welded samples with V-notch in HAZ (heat affected zone) reached high values that are higher comparing to samples with notch placed in the weld area. The investigation results show that the use of plasma concentrated heat source together with MAG welding arc does not significantly change the structure and deteriorate properties of welded S700MC thermomechanically treated high strength steel. The hybrid plasma+MAG welding method has a potential to become a beneficial alternative to other welding processes due to its high efficiency, reduced amount of weld metal content or limited requirements for a preparation of edges of welded joints.

Influence of drag finishing parameters on the cutting edge radius of solid carbide mills

Paper deals with the cutting-edge preparation of milling tools by drag finishing. The aim of the experiment was to determine the optimal parameters of the process on a prototype device for edge preparation. The prototype device was based on a 3-axis milling centre and the drag finishing media used was Al2O3 granulating. Tools for the experiment were manufactured on a tool grinding machine Reinecker WZS 60 from the cemented carbide rod with chemical composition WC+Co (10%). After that, the tools were drag finished. Then, cutting edges radii were measured on a Zeiss SURFCOM 5000 surface and form measuring machine. The effect of process parameters such as spindle rotation speed, feed rate and time of the drag finishing on the size of the cutting-edge radius and shape was examined. The experiment design was described as well as measurement and evaluation of the output values. Purpose of the experiment and multi-criteria analysis described in this article was to determine the influence of process parameters on the cutting-edge radius sizes when drag finishing the cemented carbide mills.

Impact of cutting tool wear on residual stresses induced during turning of a 15-5 PH stainless steel

Abstract Finish turning is one of the key operations governing the residual stresses below the machined surface. The residual stress state depends on the cutting conditions and on the selected cutting tool system, i.e. macro geometry, cutting edge preparation as well as tool grade. However, tool wear often affects the interaction between the tool and the workpiece leading to severe modifications of the residual stress state. This work aims at investigating the influence of cutting tool wear on the surface integrity in longitudinal turning of a 15-5PH stainless steel. First, an experimental sensitivity study is performed to assess the effect of various wear modes on the residual stresses. Then a numerical model has been developed to understand the experimental observations and connect them to the thermomechanical loadings and local data within the near surface. The impact on residual stresses of three types of wear were tested (flank face wear, rake face wear and adhesion on the cutting edge) with the same cutting condition (Vc =120m/min, ap = 0.2 mm and f = 0.2 mm.rev-1). Based on the experiment, the numerical simulation proposes to observe the impact of wear on thermomechanical loadings by simulated a tool with a rounded cutting edge, a crater on the rake face and high flank face contact length. It follows that the impact of the rake face wear is extremely low, contrary to the rounded edge or the flank face wear which increased the contact length and significantly impact the loadings.

Cutting edge radius preparation

Abstract The paper deals with the cutting edge preparation of milling tools by drag finishing. The aim was to determine the influence of parameters of cutting edge preparation on the cutting edge radius size of cemented carbide milling tools. The article describes the influence of cutting edge preparation on milling process, the tool treatment, surface roughness of machined material. The cemented carbide material with chemical composition WC + Co (10%) was used for this research. The tools were manufactured on the Reinecker WZS 60 grinding machine from cemented carbide rod. The cutting edge radius size and surface roughness were measured on Zeiss SURFCOM 5000 measuring machine. Prototype machine based on Dugard EAGLE 1000 milling machine with container which contained Al203 granulate was used for the cutting edge preparation. In this experiment, spindle rotation speed, feed rate and time were varied

Using multi-criteria analysis to evaluate the impact of drag-finishing technological parameters on the carbide tool radius

Abstract Article describes the usage of multi-criteria analysis of drag finishing in order to determine the optimal parameters of the process on a prototype device for edge preparation. The prototype device was based on a 3-axis milling center and the drag finishing media used was Al2O3 granulate. Tools for the experiment were manufactured on a tool grinding machine Reinecker WZS 60 from the cemented carbide rod. After that, the tools were drag finished. Then, cutting edges radii were measured on a Zeiss SURFCOM 5000 surface and form measuring machine. The effect of process parameters such as spindle rotation speed, feed rate and time of the drag finishing on the size of the cutting edge radius and shape was examined. The experiment design was described as well as measurement and evaluation of the output values through multi-criteria analysis in the Minitab software. The results of the multi-criteria optimization were summarized and compared. Purpose of the experiment and multi-criteria analysis described in this article was to determine the influence of process parameters on the cutting edge radius sizes when drag finishing the carbide tools – special carbide milling tools

Effect of edge preparation technologies on cutting edge properties and tool performance

Edge preparation has gained widespread use due to its low cost and high impact. Various edge preparation methods are reported in the literature. Choice of edge preparation techniques influences the edge properties and the ensuing tool performance. The current work investigates the influence of three different edge preparation methods, brushing, drag finishing, and wet abrasive jet machining on the performance of tungsten carbide inserts during orthogonal turning. Edge preparation not only changes the geometry but also the properties of the edge. Experimental results show that a drag finished edge has the lowest edge surface roughness (Ra = 0.42 μm), while abrasive jet machining can induce 63% greater compressive residual stress than the unprepared tool. Reduction in tool wear was observed at the same stage of cutting length in the prepared edges alongside improved edge hardness. A thermomechanical finite element analysis is performed to evaluate the thermomechanical behavior of all the cutting edges. Results demonstrate that the use of prepared cutting edges enhances stress distribution and reduces the temperature. Experimental results confirm that the drag finished edge has the best overall performance out of the three edge techniques with lower cutting temperature, better stress distribution, lower cutting forces, reduced flank wear, and reduced roughness of the machined surface finish.

Machinability Study of Hardened 1045 Steel When Milling with Ceramic Cutting Inserts.

Intermittent machining using ceramic tools such as hard milling is a challenging task due to the severe mechanical shock that the inserts undergo during machining and the brittleness of ceramic inserts. This study investigates the machinability of hardened steel AISI 1045 during face milling using SiAlON and whisker (SiCW) based ceramic inserts. The main focus seeks to identify the effects of cutting parameters, milling configuration, edge preparation and work material hardness on machinability indicators such as resultant cutting force, power consumption and flank tool wear. The effects of these varying cutting conditions on performance characteristics were investigated using a Taguchi orthogonal array design L32 (21 44) and evaluated using ANOVA. Results indicate lower resultant cutting forces were recorded with honed edge inserts of SiAlON ceramic grade. In addition, a decrease in resultant cutting forces was associated with reduced feed rates and increased hardness. The feed rate and cutting speed were also identified as the greatest influencing factors in the amount of cutting power. The main wear mechanisms responsible for flank wear on the ceramic inserts are micro-scale abrasion and micro-chipping. Increased flank wear was observed at low cutting speed and high feed rates, while micro-chipping mostly ensued from the cyclic loading of the radial tool edge form, which is more susceptible to impact fragmentation. Thus, the use of tools with chamfered tool-edge preparation greatly improved observed wear values. Additional confirmation tests were also conducted to validate the results of the tests.

A new cutting edge surface reconstruction method for hard whirling tools

Edge surface reconstruction is the prerequisite for evaluating the quality of cutting edge preparation. However, accurate modelling for edge surface has great challenge in terms of accuracy and efficiency. This paper aims to develop a new method to solve this problem. The proposed method uses laser scanning confocal microscope to obtain the selected section data and introduces fractal interpolation to reconstruct the edge. To ensure the accuracy, the transition point identification method based on approximate curvature difference is presented. A novel data flattening process is also performed to avoid shape copying. Results show that the edge radius fitted with the points in the transition zone is close to the experimental value. Data flattening prevents the shape between interpolation points copying the edge macroshape. The proposed reconstruction method takes much less time than the surface scanning method, and its measurement accuracy is higher than that of the coordinate measuring machine method.

Manufacturing and preparation of micro cutting tools: influence on chip formation and surface topography when micro cutting titanium

Cutting edge preparation is widely used in conventional cutting processes. It stabilizes the cutting edge and is done to improve coating adhesion. However, the preparation of the cutting edge is accompanied by an increase in cutting edge roundness. This rounding results into larger effective negative rake angles, especially at small undeformed chip thicknesses, as they prevail in micro and ultraprecision processes. In this paper, the influence of the cutting edge micro geometry at very small undeformed chip thicknesses is investigated. A sharp, a rounded and a chamfered cutting edge are manufactured and examined at undeformed chip thicknesses of 0.4 µm, 5.2 µm and 10.0 µm. The resulting chip formation, forces and surface quality are examined when orthogonal cutting commercially pure titanium, a material used for example for bio-applications.

Effects on tool performance of cutting edge prepared by pressurized air wet abrasive jet machining (PAWAJM)

Abstract Edge preparation techniques are used to shape a proper edge microgeometry for enhanced tool performance. However, depending on the edge preparation method, the edge properties are also altered. Most of the reported work is limited to the effect of edge micro-geometry. In this paper, cutting edges prepared by pressurized air wet abrasive jet machining (PAWAJM) were evaluated from several aspects including tool edge geometries, tool surface quality and topographies, edge hardness (H) and residual stresses. Furthermore, the influence of the prepared edge on the tool performance of uncoated tungsten carbide cutting inserts with different average cutting edge rounding ( S ¯ ) as well as different form factor (K) were experimentally investigated through the orthogonal turning of AISI 4140 alloy steel. Results show that the performance of the prepared cutting edge depends on the combined effect of the initial state of edge geometry and edge properties For symmetric edges (form factor K = 1), the optimum range for average cutting edge rounding ( S ¯ ) was found to be 20 μm to 30 μm when using cemented carbide tools for dry machining AISI 4140 steel at a feed rate (f) =0.1 mm/rev, width of cut = 3 mm, and cutting speed (vc) = 300 m/min.

Cutting edge preparation of cutting tools using plasma discharges in electrolyte

The paper deals with the issue of cutting edge preparation and tool treatment before coating. In this article, the novel method called edge preparation by plasma discharges in electrolyte is presented. The mechanism of material removal is based on melting and vaporisation instead of abrasion and it is not influenced or limited by the hardness of the tool material. The shape of the vapour-plasma envelope leads to intensive material removal from the edges of cutting tools. This phenomenon was applied to round the sharp edges of electrically conducting cutting tools. The tested cutting tool material of samples was cemented carbide. The cutting edge radii were formed by immersing the cutting tool into an electrolyte. The increasing the processing time results in a larger cutting edge radius. The values of cutting edge radii increased from 10 μm to 45 μm in 50 s of treatment by plasma discharges in electrolyte. Moreover, the grinding marks on the surfaces of the cemented carbide turning insert prepared by plasma discharges in electrolyte were smoothed. The quality of surface roughness of cemented carbide samples was increased. If cemented carbide turning inserts are prepared using plasma discharges in electrolyte after grinding then the values of surface roughness parameter Ra will be lower from 0.223 μm to 0.186 μm in the cross direction to the grinding marks and from 0.183 μm to 0.117 μm in the longitudinal direction.

Ультразвуковая сварка впрессовкой в постоянный и переменный зазор изделий из жестких пластмасс

A technique and a tool for ultrasonic welding by pressing a connecting element into a constant gap is proposed. The welded joints of plates arranged parallel to each other prove to be consistent in terms of strength and transparency. It is established that the coefficient of concentration of energy released per unit of volume of the parts being welded greatly depends on the contact area between them. When designing a welded seam, it is necessary to ensure edge preparation to reduce the contact area between the welded parts. In the case of a V-shaped protrusion in the design, the angle at its top should be approaching 90. The optimal technological parameters for ultrasonic welding by pressing into a constant gap are determined.

A systemic investigation of tool edge geometries and cutting parameters on cutting forces in turning of Inconel 718

In metal cutting process, size effects and edge effects have a significant influence on cutting forces and therefore on the machining performance. This paper facilitates those behaviors with different cutting tool geometry, i.e., round edge and chamfered edge, using analytical cutting force prediction models when turning Inconel 718 with round cutting inserts. Analytical methods used for different edge preparation are developed with the consideration of size effects and edge effects. Then, an attempt is made to analyze the cutting investigations of the influence of size effects and edge features. The cutting forces and edge forces are estimated with the modified Johnson–Cook constitute model considering the size effects and edge effects. Rounded edge coefficients and chamfered edge coefficients estimated with different analytical methods are used in calculating edge forces for rounded edged tools and chamfered edged tools, respectively. Simulations with finite element model (FEM) and cutting experiments are used to verify the proposed model. Finally, the detailed influences of size effects, edge geometries, and feed rate on the cutting forces are studied based on the proposed model and FEM simulations.

Improvement of the joint quality in the high-frequency induction welding of pipes by edge modification

High-frequency induction welding (HFIW) is among the most commonly used methods for producing roll formed pipes. In this paper, weld quality is evaluated through examining the weld properties, in order to obtain the effect of edge preparation on improvement of weld quality. Temperature distribution in the weld zone is studied through the groove shape of the weld joint, and the other parameters such as current, frequency, and linear speed, considered constant, are equal to 1400 A, 150 kHz, and 25 m/min respectively. The mechanical and metallurgical properties of the weld metal were evaluated by tensile test and metallography. The appropriate temperature distribution resulted from modifying the shape of the connecting edges, leading to a reduction of 27% in the mean size of the grains in the weld zone. The results also show that by increasing the temperature of welding, the heat-affected area expands and the other areas decrease. When the results of the metallography tests of the weld zone were compared, a more uniform weld width was observed in the welded specimens with modified edges. The results also showed an 18% decrease in the weld width in specimens, compared with the specimens without edge preparation.

Analysis on mechanical properties of gas tungsten arc welded dissimilar aluminium alloy (Al2024 & Al6063)

Abstract In this project dissimilar aluminium alloys (Al2024 & Al6063) are welded using tungsten inert gas welding in the butt joint with single V edge preparation. The welding is carried out with modifying three set of parameters such as current, gas flow rate and root gap. Welded materials is then subjected to various mechanical behaviour analyses such as tensile strength, hardness, corrosion test and microstructure analyze also carried out using scanning electron microscope for metallurgical study purpose. The main aim is to analyze how welding process parameters changes affect the mechanical behaviour of the aluminium alloys.

Microstructural characterization and mechanical properties of K-TIG welded SAF2205/AISI316L dissimilar joint

Motivated by increasing productivity and cost-effectiveness, the feasibility of Keyhole Tungsten Inert Gas (K-TIG) welding for joining SAF2205/AISI316L dissimilar materials was presented. Single pass autogenous welding was achieved on 5.6 mm thick plates at a speed of 35 cm/min without using any filler materials and edge preparation. In-depth investigation into the weld was conducted by optical microscope, scanning electron microscope, Thermo-Calc simulation, microhardness, tensile test and impact toughness test. The results show that in order to produce defect free dissimilar joint, the torch deviation should be kept at zero to one mm towards AISI316L side. The austenite fraction increased with torch deviation shifted from SAF2205 side to AISI316L side, along with the variation in ferrite morphology from massive type to lath shape. Defect free joints possess better tensile properties than AISI316L base metal, indicating sufficient strength level for such dissimilar joint. Poorer toughness of the samples with 1 mm torch deviation towards SAF2205 side and 2 mm deviation towards 316L side is a result of imbalanced phase structure, ferritic-asutenitic solidification mode as well as harmful precipitates in the weld. It has been demonstrated that the K-TIG welding process offers an efficient way to produce sound and high quality dissimilar joint between SAF2205 and AISI316L, with 0–1 mm torch deviation towards 316L side being the desired options in terms of overall material properties.

The Influence of Surface Treatment of PVD Coating on Its Quality and Wear Resistant

The article deals with a determination of the influence of a cutting edge preparation on the quality and wear resistance of coated cutting tools. Cutting inserts made from a sintered carbide with a deposited layer of PVD coating were selected for measurement. Non-homogeneity caused by the creation of droplets arises in the application layer during the process of applying the coating by the PVD method. These droplets make the surface roughness of the PVD coating worse, increase the friction and thereby the thermal load of the cutting tool as well. Also, the droplets could be the cause of the creation and propagation of droplets in the coating and they can cause quick cutting tool wear during machining. Cutting edge preparations were suggested for the improvement of the surface integrity of deposited layers of PVD coating, namely the technology of drag finishing and abrasive jet machining. After their application, the areal surface roughness was measured on the surface of coated cutting inserts, the occurrence of droplets was tracked and the surface structure was explored. A tool-life test of cutting inserts was carried out for verification of the influence of surface treatment on the wear resistance of cutting inserts during the milling process. The cutting inserts with a layer of PVD coatings termed as samples A, B, and C were used for the tool-life test. The first sample, A, represented the coating before the application of cutting edge preparations and samples B and C were after the application of the cutting edge preparation. A carbon steel termed C45 was used for the milling process and cutting conditions were suggested. The visual control of surface of cutting inserts, intensity of wear and occurrence of thermal cracks in deposited PVD layers were the criterion for the evaluation of the individual tests.

Surface quality evaluation after milling Inconel 718 with cutting edge preparation

Nickel alloys have the ability to resist extreme conditions; as a result, they are in evidence among different industrial areas. Nickel alloy machining is often associated with high manufacturing costs and low productivity. Cutting-edge tool geometry is one of the key factors in order to enable high-performance cutting operations with these alloys. Besides that, the cutting fluid use can reduce friction and temperature. On the other hand, dry machining brings environmental benefits and, in addition, it can protect the factory worker from several diseases caused by the contact with the cutting fluid. Therefore, experimental tests were realized, focusing on understanding the surface integrity behavior after milling of Inconel 718. The experiments occurred with the use of original and polished tools. Besides that, the milling process was performed in dry and MQL conditions. The texture, roughness, hardness, and affected layer were tightly studied. A great difference was found in texture and roughness behavior among dry-machined surfaces and with MQL application, due to thermal and friction effects. Cutting-edge preparation showed better results in this case, as original tool edges were sharp. The smaller affected layer deformations were obtained by original tools with MQL application, and hardness measurements did not exhibit significant variation. Among the tested conditions, the best performance was achieved with the use of MQL and, in general, cutting-edge preparation did not show significant variation.