Function Of Tool Wear Research Articles

Porovnanie geometrickej presnosti obrobkov po tvrdom frézovaní a brúsení

This paper deals with surface integrity after hard milling of bearing steel 100Cr6. Surface integrity is expressed in terms of shape deviation as well as Barkhausen noise emission. Furthermore, components of cutting forces are also measured as a function of tool wear. Non homogeneity of cutting force distribution within the contact between the milling cutter and workpiece is discussed. The results of measurements indicate that the shape as well as structure remarkable non homogeneity should be expected after hard milling due to missing full contact between milling cutter and workpiece. This non homogeneity can be monitored via Barkhausen noise technique. On the other hand, the competitive grinding cycles produced more homogenous surface and surface state is a function of infeed speed.

Study of the Machining Process of GFRP Materials by Milling Technology with Coated Tools

Glass fibers are often used as reinforcing fibers in reinforced polymers. Composites reinforced with glass fibers (GFRP) stand out with excellent mechanical and physical properties applicable to industrial practice. Machining these composites requires the correct choice of tools and cutting conditions so that the machined surface shows good properties, there is no fiber delamination, thermal stress on the workpiece and the tool, or excessive tool wear. The study was devoted to circumferential milling of fabric-bonded GFRP plates, in which attention was paid to the influence of the abrasive effect of glass fibers on wear and tool life. Attention was also paid to surface roughness after machining, material delamination, and forces during machining were measured. Three end mills of the same diameter with different coatings, number of teeth, and geometry were selected for the study. This choice of tools was intended to achieve various accompanying and subsequent phenomena that were investigated. Milling was performed on a CNC milling center under preselected cutting conditions. The paper summarizes information on fiber delamination and machined laminate damage after milling, tool wear, and surface roughness parameters as a function of tool wear. This paper provides an opportunity for researchers to increase their knowledge of specific aspects of milling GFRP composites, whether with a tool specifically designed for this or not.

Tool wear mechanisms and effects on refill friction stir spot welding of AA2198-T8 sheets

Refill Friction Stir Spot Welding (refill FSSW) is a method for joining similar and dissimilar lightweight metallic materials or thermoplastic polymers. The technique produces welds that feature suitable mechanical properties with advantages such as the possibility of industrial scalability and automation. Still, some challenges need to be overcome in order to increase the adoption of this technique in industry. Tool wear is a key issue for friction-based processes, since it impacts the process costs and quality of the welds. In this study, a total of 2350 welds of AA2198-T8 sheets were performed and the effect of wear on probe and shoulder was investigated. While the probe did not suffer any considerable wear after this number of welds, the shoulder underwent wear in different areas, with distinct wear mechanisms. Adhesive wear and plastic deformation were determined as the primary damage mechanisms affecting different areas of the shoulder. Mechanical testing of selected welds has shown a trend towards reduction in the lap shear strength (LSS) as a function of tool wear. Macrostructural analysis of welds' geometrical features shows that profile changes at the shoulder due to wear led to a trend of reduction in stirred zone area and, consequently, joints’ LSS. Modifications in the worn shoulder profile were suggested as possible causes for changes in hook height, which was identified as a further determining factor to the observed reduction in LSS. Still, all tested welds surpassed the minimum lap shear strength standard requirements for aeronautical applications.

Decomposition of cutting forces with respect to chip segmentation and white layer thickness when hard turning 100Cr6

This paper deals with hard turning of steel 100Cr6 with a hardness of C. Surface integrity expressed in terms of white layer thickness is studied as a function of tool wear and corresponding thermo-mechanical load of the machined surface. Total force is decomposed into components associated with the chip separation Fγ and the component Fɑ, which is associated mostly with the flank wear land. The results of experiments show that normal and shear components of the force Fɑ, increase progressively with the developed flank wear VB and correlate significantly with the white layer thickness. Furthermore, tool wear is also strongly dependent on the insert rake geometry, which contributes to the cutting force component of Fγ associated with the chip separation. For this reason, the chip formation depends on the progress of the tool wear.

Analysis of the Machinability of Carbon Fiber Composite Materials in Function of Tool Wear and Cutting Parameters Using the Artificial Neural Network Approach.

Local delamination is the most undesirable damage associated with drilling carbon fiber reinforced composite materials (CFRPs). This defect reduces the structural integrity of the material, which affects the residual strength of the assembled components. A positive correlation between delamination extension and thrust force during the drilling process is reported in literature. The abrasive effect of the carbon fibers modifies the geometry of the fresh tool, which increases the thrust force and, in consequence, the induced damage in the workpiece. Using a control system based on an artificial neural network (ANN), an analysis of the influence of the tool wear in the thrust force during the drilling of CFRP laminate to reduce the damage is developed. The spindle speed, feed rate, and drill point angle are also included as input parameters of the study. The training and testing of the ANN model are carried out with experimental drilling tests using uncoated carbide helicoidal tools. The data were trained using error-back propagation-training algorithm (EBPTA). The use of the neural network rapidly provides results of the thrust force evolution in function of the tool wear and cutting parameters. The obtained results can be used by the industry as a guide to control the impact of the wear of the tool in the quality of the finished workpiece.

Stationary Shoulder Friction Stir Processing: Influence of Tool Wear on Surface Properties

In the present study, the influence of stationary shoulder friction stir processing (SSFSP) tool wear on the processed surface was investigated. SSFSP is a solid-state process that uses a rotating tool plunged in the material to promote microstructure modification, mainly grain refinement, on the workpiece without melting the material itself. It differs from conventional Friction Stir Processing (FSP) since in the SSFSP the tool shoulder does not rotate and simply slides on the surface. The workpiece processed with SSFSP shows a smoother surface without shoulder marks, and with smaller flash than conventional FSP. The tool wear could slightly change the profile of the shoulder and affects process soundness. SSFSP testing made up of 2880 experiments, each one with a path length of 50 mm, was realized on AA 6082 T6 sheets with 3.0 mm thickness using 1500 rpm tool rotation speed and 300 mm/min welding speed. Optical and confocal microscopy analysis and Vickers micro hardness measurements allowed putting in evidence the characteristics of the processed surfaces and their modifications as a function of tool wear.

Barkhausen Noise Emission in Hard-Milled Surfaces.

This paper reports on an investigation treating a hard-milled surface as a surface undergoing severe plastic deformation at elevated temperatures. This surface exhibits remarkable magnetic anisotropy (expressed in term of Barkhausen noise). This paper also shows that Barkhausen noise emission in a hard-milled surface is a function of tool wear and the corresponding microstructure transformations initiated in the tool/machined surface interface. The paper discusses the specific character of Barkhausen noise bursts and the unusually high magnitude of Barkhausen noise pulses, especially at a low degree of tool wear. The main causes can be seen in specific structures and the corresponding domain configurations formed during rapid cooling following surface heating. Domains are not randomly but preferentially oriented in the direction of the cutting speed. Barkhausen noise signals (measured in two perpendicular directions such as cutting speed and feed direction) indicate that the mechanism of Bloch wall motion during cyclic magnetization in hard-milled surfaces differs from surfaces produced by grinding cycles or the raw surface after heat treatment.

Influence of Tool Wear on Surface State after Turning Stainless Steels

This paper deals with influence of tool wear on surface integrity after turning of stainless steels. Surface integrity is expressed in terms of structure transformation initiated by turning process as well as Barkhausen noise emission. Furthermore, components of cutting forces are also measured as a function of tool wear and their evolution along with developed flank wear VB is presented. The results indicate that presence of carbides in the matrix - their size and density play a significant role in the resistance of the matrix against the structure transformations. The results also indicate that Barkhausen noise technique is sensitive to structure transformations of austenite steels initiated by turning process.

Some Aspects of Surface Integrity after Hard Milling

This paper deals with surface integrity after hard milling of bearing steel 100Cr6. Surface integrity is expressed in terms of shape deviation as well as Barkhausen noise emission. Furthermore, components of cutting forces are also measured as a function of tool wear. Non homogeneity of cutting force distribution within the contact between the milling cutter and workpiece is discussed. The results of measurements indicate that shape as well as structure remarkable non homogeneity should be expected after hard milling due to missing full contact between milling cutter and workpiece. This non homogeneity can be monitored via Barkhausen noise technique. On the other hand, the competitive grinding cycles produced more homogenous surface and surface state is a function of infeed speed.

Non homogeneity of surface integrity after hard milling of high tempered bearing steel

This paper deals with surface integrity after hard milling of high tempered bearing steel 100Cr6. Surface integrity is expressed in terms of shape deviation as well as Barkhausen noise emission. Furthermore, components of cutting forces are also measured as a function of tool wear and their non homogenity within the contact between the milling cutter and workpiece is discussed. The results of measurements indicate that shape as well as structure remarkable non homogeneity should expected after hard milling due to missing full contact between milling cutter and workpiece. This non homogeneity can be monitored via Barkhausen noise technique. On the other hand the competitive grinding cycles produced more homogenous surface and surface state is a function of infeed speed.

In-situ tool wear monitoring and its effects on the performance of porcine cortical bone drilling: a comparative in-vitro investigation

BackgroundDrilling is one of the most widely used process in orthopaedic surgical operation and the same drill bit is used a number of times in hospitals. Using the same drill bit a several times may be the cause of osteosynthesis and osteonecrosis.MethodsIn the present work, the effect of repeated orthopaedic surgical twist drill bit on the tool wear, force, torque, temperature and chip morphology during porcine cortical bone drilling is studied. Results were compared with rotary ultrasonic drilling (RUD) on the same bone using a hollow drill tool coated with diamond grains. A sequence of 200 experiments (100 with each process, RUD and CD) were performed with constant process parameters.ResultsWear area on the drill bit is significantly increased as the drill bit is used repeatedly in CD, whereas no attritious wear was found on the diamond coated grains in RUD.ConclusionsComparative results showed that cutting force, torque and temperature increased as a function of tool wear in CD as the same drill bit was used a number of times. No significant variation in the cutting force and torque was observed in RUD as the number of drilled holes increased.

Chip Formation When Drilling AISI 316L Stainless Steel using Carbide Twist Drill

Knowledge on the chip formation mechanism during drilling is very important to deliver the chips with size and shape as expected. Long chips cannot rid smoothly over drill flutes hence should be avoided while small chips can be removed easily from the machined hole. In this study, performance of a solid carbide twist drill through drilling of AISI 316L stainless steels was evaluated in terms of chip formation. This study aims to better define and further characterize the different chips shape and dimensions as a function of tool wear and cutting conditions in drilling the stainless steel. Experiments conducted on various combinations of cutting speed (18 and 30 m min-1) and feed rate (0.03, 0.045 and 0.06mm rev-1) to present the differences in chip formation. Optical observation and comparative analysis of flank wear of the twist drill were done. As the results of the performed experiments, the lowest cutting speed-lowest feed rate reveals better performance due to desirable chips formation on austenitic stainless steels drilling.

Study of the Relationship between Cutting Speed, Tool Wear and Machining Forces in Turning with Carbide Tool

The understanding of machining processes comprises the study of phenomena such as: chip formation, cutting forces, tool wear mechanisms and the influence of the cutting parameters and machined materials on them. The aim of this work is to analyze the tool wear effects on machining forces during machining of AISI 1040 and 1045 carbon steels with carbide tool. Long-term machinability tests were performed, in which cutting force, feed force and tool wear were measured. Tool life results were analyzed, with best tool lives found for the AISI 1040 steel for all tested speeds. The other variables were analyzed as function of both time and tool wear. On the time domain, strong dependencies were found for both materials for tool wear, cutting force and feed force. The relationship between cutting force and tool wear showed good correlation for both materials, and the same was observed for feed force and tool wear relationship. Weak influence of cutting speed was observed on the relationship between tool wear and machining forces, which suggest that a single equation can describe them for all studied conditions with reasonable accuracy. The regression results are able to predict cutting forces as a function of tool wear with an average error of about 2.6 % during machining of AISI 1040 and 5.2 % for AISI 1045 steel. For the prediction of feed force as a function of tool wear, the average error is about 5.6 % for AISI 1040 and 7.0 % for the AISI 1045 steel, since a restricted domain is established. Data analysis showed a discontinuity in the behavior of feed force as a function of tool wear near the end of the life of the tools for most tests performed with AISI 1045 and some tests with AISI 1040 that suggest backwall wear, which was further evidenced by sudden change of chip form near the end of tool life in AISI 1040 steel.

Tool Life and Process Dynamics in High Speed Ball End Milling of Hardened Steel

In this paper, a comparison of tool life of sintered carbide (with TiAlN coating) and cubic boron nitride (CBN) ball end mills is presented. Experiments were carried out on hardened steel X155CrVMo12-1 plate during milling process with a constant surface inclination angle (α) and variable cutting speeds (vc) and feeds (fz). Cutting forces (Fi) were measured and presented in function of tool wear (VBB). Specific cutting pressures were also estimated in function of tool wear (VBB). Their values are applied to cutting force model formulation, which includes tool wear. The research revealed that in certain range of cutting speed tool life acquired for sintered carbide can be higher than that obtained for cubic boron nitride tool. It was observed, that for cubic boron nitride cutter abrasive wear was dominant independently of cutting speed. In case of sintered carbide, catastrophic wear of cutting edge was found for cutting speed vc = 500 m/min.

Burr produced on the drilling process as a function of tool wear and lubricant-coolant conditions

This work shows the resulting height and shape of the burrs produced by drilling holes with ratio L/D = 3. The tool used in the tests was the solid twist HSS drill coated with TiAlN, with diameter of 10 mm, to drill the microalloyed steel DIN 38MnS6. The height of the burr was studied under different lubricant/coolant systems, namely: dry machining, use of Minimum Quantity Lubrication (MQL) at the flow rate of 30 ml/h, and fluid applied in the conventional way (flooding). The following cutting fluids were used: vegetable oil (MQL), mineral oil (MQL and flooding) and semi-synthetic oil (flooding). The trials were carried out at two cutting speeds (45 and 60 m/min) and the criterion adopted for the end of the test was the catastrophic failure of the drill. The results showed that the height of the burr increases primarily with the wear of the tool and that this increase is almost exponential after 64% and 84% of drills life, for the speeds of 45 and 60 m/min, respectively. Furthermore, the results generally showed that the smallest burr height was obtained for the dry machining and the largest for the MQL systems.

Experimental Modelling of Cutting Forces as a Function of Tool Wear in End Milling

Experimental Modelling of Cutting Forces as a Function of Tool Wear in End Milling

Diagnosis of tool wear based on cutting forces and acoustic emission measures as inputs to a neural network

Cutting forces and acoustic emission measures as a function of tool wear are presented for different cutting parameters and their applicability for tool condition monitoring is evaluated. The best of them, together with cutting parameters, were chosen as inputs to a feedforward, back propagation (FFBP) neural network; some training techniques were applied and their effectiveness is also evaluated. Conventional training of FFBP neural networks very soon leads to overtraining, hence to deterioration in the net response. Training of these nets depends very much on the initial weight values. A good way of finding satisfactory results is to introduce random distortions to the weight system, which efficiently push the net out of a local minimum of testing errors. An even more effective method may be to employ temporary shifts in the weights, alternately negative and positive. This has two advantages: (1) it brings the net to balance between training and testing errors and (2) it enables a great reduction in the number of hidden nodes.