Roughness Of Cutting Edge Research Articles

Influence of different wet-blasting pressure on the surface integrity and tool cutting performance of hybrid CVD-TiN/TiCN/α-Al2O3/TiN coated tools

This paper investigates the effect of wet-blasting pressure on the surface integrity and tool cutting performance of hybrid CVD-TiN/TiCN/α-Al2O3/TiN coated tools. The hybrid TiN/MT-TiCN/α-Al2O3/TiN multilayer coating was deposited on the surface of the cemented carbide inserts by chemical vapor deposition (CVD) technique. Then the coated inserts were subjected to wet-blasting by aluminum oxide with varying pressure. The coatings were characterized by scanning electron microscopy, white light surface profiler, and X-ray residual stress diffractometer. The results indicate that the average residual tensile stress of the α-Al2O3 layer on the rake face of CVD-coated inserts gradually decreased with the increase of wet-blasting pressure. When the wet-blasting pressure reached 0.24 MPa, the residual tensile stress was transformed into compressive stress. It was accompanied by increased cutting edge roughness and cutting edge radius, reduced cutting edge coating thickness, and a change in rake face surface roughness. To understand the effect of the surface integrity change on the cutting performance of CVD-coated inserts, a case study designed for AISI 4340 steel machining under continuous and intermittent cutting conditions is performed. When the Al2O3 layer on the cutting edge is not peeled off by wet-blasting, the change of residual stress from tensile to compressive in the rake face of CVD-coated inserts can effectively improve the fracture failure resistance of inserts in continuous and intermittent cutting processes. When the Al2O3 layer on the cutting edge is peeled off by wet-blasting, the fracture failure resistance during intermittent cutting will be significantly reduced.

Design of tool grinding processes for indexable inserts made of rocks

Using natural rocks as alternative cutting tool material poses a possibility to meet actual environmental, economic and geopolitical challenges. The present state of knowledge, however, is not sufficient to allow a knowledge-based design of the tool grinding process of cutting tools made of rock. For this reason, this study presents an investigation of the significance of the grinding process parameters and grinding tool specifications for the flank face and cutting edge roughness as well as for the cutting edge microgeometry besides an analysis of the scatter of the grinding results in tool grinding of rock inserts. Thus, the study contributes to a knowledge-based design of tool grinding processes of rock tools. In this context, confocal and focus variation microscopes are used besides SEM images to investigate the above mentioned factors in the plunge face grinding of rock inserts from five different rocks. The results identify the axial feed velocity of the plunge face grinding process as a highly significant influence factor for cutting edge roughness and microgeometry, while cutting speed only shows a significant influence on cutting edge microgeometry. Besides that, highly significant influences of the used rock type and the abrasive grain size are identified for all three mentioned factors. Grinding result analyses show a scatter between 0.04 and 25.00 µm depending on the parameter and rock investigated. Additionally, recommendations for the design of the tool grinding process of rock tools are presented deduced from the obtained results.

Marker-free identification of milled surfaces by analyzing stochastic and kinematic surface features by means of wavelet transformation

This article presents a marker-free component identification of milled workpiece surfaces. For the identification, unique features from a 2-D profile are detected in the 3-D frequency domain. Knowing the influence of process parameters, tool runout, cutting edge roughness during flank milling on the stochastic surface generation, a profile cut can be set, which is as unique as a human fingerprint. Experimental investigations show a false-positive-rate of 10-20 for a confocal measurement of the surface as well as for the usage of an industrial camera.

Factorial Analysis of Fiber Laser Fusion Cutting of AISI 304 Stainless Steel: Evaluation of Effects on Process Performance, Kerf Geometry and Cut Edge Roughness.

Factorial Design-of-Experiment analyses were applied for conventional and beam oscillation fiber laser cutting of 10 mm thick AISI 304 stainless steel. Considered factors in case of the conventional process with a static beam involve both laser and cutting gas parameters, in particular the laser power, the focal plane position, the cutting gas pressure, the nozzle stand-off distance as well as the nozzle diameter. The conducted trials were evaluated with respect to the achievable cutting speed, the cut kerf geometry and the cut edge roughness. Noticeable correlations between cut edge roughness and cut kerf geometry stimulated the development of a corresponding Computational Fluid Dynamics (CFD) model of the cutting gas flow through the kerf. A specific approach of data synchronization revealed that the experimentally determined roughness values do well correlate with numerically computed values of the backward directed component of the gas-induced shear stress and that the cut kerf geometry as internal process-inherent boundary condition influences relevant cutting characteristics more than controllable external cutting gas parameters. Finally, effects of circular beam oscillation were investigated by an additional factorial analysis considering the laser power, the focal plane position, the oscillation frequency and the oscillation amplitude as factors. The results demonstrate the potential of beam oscillation techniques for quality improvements in laser cutting.

Investigation of the Effect of End Mill-Geometry on Roughness and Surface Strain-Hardening of Aluminum Alloy AA6082.

Micro-milling is a promising technology for micro-manufacturing of high-tech components. A deep understanding of the micro-milling process is necessary since a simple downscaling from conventional milling is impossible. In this study, the effect of the mill geometry and feed per tooth on roughness and indentation hardness of micro-machined AA6082 surfaces is analyzed. A solid carbide (SC) single-tooth end-mill (cutting edge radius 670 nm) is compared to a monocrystalline diamond (MD) end-mill (cutting edge radius 17 nm). Feed per tooth was varied by 3 μm, 8 μm and 14 μm. The machined surface roughness was analyzed microscopically, while surface strain-hardening was determined using an indentation procedure with multiple partial unload cycles. No significant feed per tooth influence on surface roughness or mechanical properties was observed within the chosen range. Tools’ cutting edge roughness is demonstrated to be the main factor influencing the surface roughness. The SC-tool machined surfaces had an average Rq = 119 nm, while the MD-tool machined surfaces reached Rq = 26 nm. Surface strain-hardening is influenced mainly by the cutting edge radius (size-effect). For surfaces produced with the SC-tool, depth of the strain-hardened zone is higher than 200 nm and the hardness increases up to 160% compared to bulk. MD-tool produced a thinner strain-hardened zone of max. 60 nm while the hardness increased up to 125% at the surface. These findings are especially important for the high-precision manufacturing of measurement technology modules for the terahertz range.

Analysis of the Tribological Conditions in Grinding of Polycrystalline Diamond Based on Single Grain Friction Tests Using the Pin-Disk Principle

Cutting tools made of polycrystalline diamond (PCD) are used for machining of aluminum alloys, fiber-reinforced plastic composites and wood. Compared to cemented carbide tools with geometrically defined cutting edges, PCD tools offer significant advantages with respect to tool life. High demands regarding the cutting edge roughness and the quality of the rake and the flank face usually require a grinding process with diamond grinding wheels. The PCD grinding process, however, is characterized by low material removal rates and high grinding wheel wear. The material removal rate and the grinding wheel wear, in turn, highly depend on the process state variables process force and process temperature. However, the relationship between these process state variables and the process input variables is largely unknown. This work provides a contribution to the closure of this knowledge gap by means of an adapted friction law. A single grain friction test stand using the pin-disk principle was developed, which enables a measurement of the friction force and the contact zone temperature for normal forces and relative speeds that are common in PCD grinding. During the experiments, the specification of the PCD disc, the cross-sectional area of the friction sample made of monocrystalline diamond as well as the process parameters normal force and relative speed were varied. In addition, the tests were carried out without lubrication as well as with a minimum lubrication. A high correlation between the contact force and the coefficient of friction was determined. This relationship was mathematically formulated in a friction law. In addition, a direct influence of the contact force and the relative velocity on the contact zone temperature was identified. The knowledge gained leads to an improved understanding of the PCD grinding process and thus enables a more efficient grinding process design.

Study of correlation between edge roughness and gas flow characteristics in laser beam fusion cutting

Fiber laser fusion cutting trials on AISI 304 stainless steel sheets of 10 mm thickness were performed with the aim to gain further insights into the striation formation process on cut edges. The study is based on a factorial Design-of-Experiment (DoE) approach with consideration of laser power, focal plane position, gas pressure, nozzle stand-off and nozzle diameter as control factors. Analyzed responses include the achievable cutting speed, the cut kerf geometry and the cut edge roughness. In addition, numerical simulations of the cutting gas flow were carried out for adapted kerf geometries and gas parameters. The evaluation of these results reveals strong correlations between experimental roughness values and the numerically computed rear-directed shear stress component within the transition zone between cutting front and cut edge surface. This finding supports the hypothesis that the particular characteristics of the boundary layer zone of the cutting gas flow affects the structure and roughness of cut edges.

Laser cutting using off-axial supersonic rectangular nozzles

Laser cutting is a well-established process in the industry, mainly for cutting metallic materials such as steels. However, the utilization of this laser technique to process advanced materials, such as ceramics or some aluminium alloys, is restricted due to the formation of a large heat affected zone (HAZ), rough cut edges, presence of dross, or thermal cracks. These defects are closely related to the performance of the assist gas during the removal of molten material. Previous works have demonstrated the impressive improvement in cut quality with the utilization of off-axial supersonic axisymmetric nozzles to inject the assist gas. This is due to the higher removal of molten material. However, these results can be even improved if the geometry of the gas jet is tailored to the cut kerf. In the present work, a cutting head with an off-axial supersonic rectangular nozzle was developed to improve the efficiency of the current assist gas injection systems. The performance of this system was compared with that of a converging (coaxial) nozzle, and an off-axial supersonic axisymmetric nozzle during the processing of Al2024-T3 sheets. Results demonstrated the superior performance of the new assist gas injection system in terms of cut quality and productivity (cut edge roughness was 6.5 times lower, and the cutting speed is 1.98 times higher as compared to the results found for a converging coaxial nozzle).

Surface Changes of PathFile after Glide Path Preparation: An Ex Vivo and In Vivo Study

IntroductionThe aim of this study was to evaluate the changes in the surface profile of rotary nickel-titanium (NiTi) files designed to prepare a glide path and conventional stainless steel (SS) hand files when used in extremely narrow canals both in clinical and experimental conditions. MethodsThis ex vivo/in vivo study used either SS #10 K hand files or the PathFile system (Dentsply Maillefer, Ballaigues, Switzerland) to establish a glide path in maxillary molars with narrow root canals (defined as canals that bound a #8 K-file at the working length). After treatment, all files were cleaned and scanned using a noncontact laser profilometer. Changes to the surface profile (Ra cutting edge waviness = RaCEW) and roughness (Ra cutting edge roughness = RaCER) of the cutting edges and the surface roughness of the flute area (Sa flute roughness = SaFR) were analyzed. Results#10 K-files had significant increases in all types of measurements (RaCEW, RaCEW, and SaFR) after the preparation of second mesiobuccal canals compared with the control group (P < .05) in both studies. In the ex vivo study, the PathFile (P1) had no significant changes in the surface profile from baseline but had a significant increase in the surface roughness of the flute (SaFR) (P < .05). PathFiles that were used 3 times in vivo had a significant increase in roughness (flute and cutting edge) values across all PathFile sizes compared with control values. ConclusionsThis study showed that PathFiles had significantly less surface defects compared with SS files after the preparation of narrow canals, indicating their possible benefits when establishing a glide path in extremely narrow canals.

Cutting edge—flatting and roughness measurement—to monitor blunting and chipping of the drill cutting edge when drilling CFRP

Tool wear is a major challenge when drilling CFRP. Cutting edge rounding quantifies the blunting of the cutting edge by considering the events happening in the flank–cutting edge–rake zone together by fitting a circle to this zone. The two interface zones, however, undergo wear in different ways. While the flank–cutting edge interface becomes rounded, the rake–cutting edge interface flattens out with drilling. Two new parameters, flank rounding (FR) and cutting edge flatting (CEF), are introduced to measure the damage to the flank and cutting edge, respectively. The nature of CEF and FR variation along the cutting edge shows that both are related. The chipping of the cutting edges is studied using a parameter called cutting edge roughness by monitoring the cutting edge topography. The progression of FR and cutting edge roughness along the length of the cutting edge shows that chipping may be related to the nature of FR progression. CEF could be easily measured using a simple measuring microscope and can be used to monitor drill wear.

Fibre laser cutting stainless steel: Fluid dynamics and cut front morphology

In this paper the morphology of the laser cut front generated by fibre lasers was investigated by observation of the ‘frozen’ cut front, additionally high speed imaging (HSI) was employed to study the fluid dynamics on the cut front while cutting. During laser cutting the morphology and flow properties of the melt film on the cut front affect cut quality parameters such as cut edge roughness and dross (residual melt attached to the bottom of the cut edge). HSI observation of melt flow down a laser cutting front using standard cutting parameters is experimentally problematic because the cut front is narrow and surrounded by the kerf walls. To compensate for this, artificial parameters are usually chosen to obtain wide cut fronts which are unrepresentative of the actual industrial process. This paper presents a new experimental cutting geometry which permits HSI of the laser cut front using standard, commercial parameters. These results suggest that the cut front produced when cutting medium section (10mm thick) stainless steel with a fibre laser and a nitrogen assist gas is covered in humps which themselves are covered by a thin layer of liquid. HSI observation and theoretical analysis reveal that under these conditions the humps move down the cut front at an average speed of approximately 0.4m/s while the covering liquid flows at an average speed of approximately 1.1m/s, with an average melt depth at the bottom of the cut zone of approximately 0.17mm.

Influence of Alloying Elements on the Laser Cutting Process

This paper presents an experimental investigation into how different alloying elements affect the laser-oxygen cutting process. Small variations in chemical composition of the material can lead to major changes in the overall laser-oxygen cutting process. The changes can appear as differences in cut edge roughness and/or adherent dross on the bottom of the cut. The primary causes of the process sensitivity have been identified as changes in surface tension and viscosity of the molten material in combination with changes in the exothermal reaction in the cut zone.

The preparation of cutting edges using a marking laser

During the machining process, high mechanical and thermal loads occur at the cutting edge. Such loads can cause tool failure. Specifically non-uniform and sharp cutting edges that have a low cutting edge stability lead to such failures. In order to enhance the tool performance, the cutting edges are prepared by manufacturing both a pre-defined cutting edge geometry, and an appropriate cutting edge roughness. This paper describes the use of a low-cost marking laser for the preparation of cutting edges as an alternative to conventional preparation techniques, such as brushing or blasting. Cutting edge radii of 9–47 μm can be prepared with a machining accuracy of 1.5 μm. The maximum preparation time for an individual cutting edge is approximately 10 s. Uncoated indexable inserts manufactured in this way were tested in a face milling operation. The results of these investigations (using prepared cutting edges) show both an increase in tool life and an improved surface roughness of the machined workpieces compared to those using non-prepared cutting edges.

Effect of process parameters and optimization of CO 2 laser cutting of ultra high-performance polyethylene

The aim of this work is to relate the cutting edge quality parameters (responses) namely: upper kerf, lower kerf, ratio of the upper kerf to lower kerf and cut edge roughness to the process parameters considered in this research and to find out the optimal cutting conditions. The process factors implemented in this research are: laser power, cutting speed and focal point position. Design of experiment (DoE) was used by implementing Box-Behnken design to achieve better cut qualities within existing resources. Mathematical models were developed to establish the relationship between the process parameters and the edge quality parameters. Also, the effects of process parameters on each response were determine. Then, a numerical optimization was performed to find out the optimal process setting at which the quality features are at their desired values. The effect of each factor on the responses was established and the optimal cutting conditions were found.

Experimental optimisation of the gas-assisted laser cutting of thick steel sheets

We report on the experimental optimisation of the oxygen-assisted CO2 laser cutting of low-carbon sheet steel 5 to 25 mm in thickness. It is shown that the cut edge roughness is minimal when the energy input per unit volume of the material removed and the incident beam power per unit sheet thickness remain constant at ∼20 J mm-3 and ∼200 W mm-1, respectively, over the entire range of sheet thicknesses examined. The corresponding Péclet number is Pe = 0.5. These results can be used to determine the optimal beam power and cutting speed for a particular sheet thickness. At sufficiently large thicknesses, the conditions that ensure the minimum roughness can be written in the form of relations between nondimensional parameters.

Acoustic and Optical Monitoring of High-Power CO&lt;sub&gt;2 &lt;/sub&gt; Laser Cutting

In this paper, the development of a monitoring system for high-power CO2 laser cutting of thick steel plates (&gt;15 mm) is reported. The aim of this system is to increase the robustness and autonomy of the laser cutting process of thick plates, which is still characterized by more narrow process windows compared to cutting of thin sheets. The applicability for monitoring purposes of two types of sensors is investigated: the acoustic microphone and the photodiode. For both types, correlation between the sensor output and the cut quality is investigated. Both contour cutting and piercing are covered in the study. The full penetration of the piercing can be monitored by both sensors. Furthermore quantitative relations between cut quality parameters and photodiode signal parameters could be determined: the mean level of the photodiode signal correlates well with the drag of the striations and dross formation, whereas the standard deviation proves to correlate well with the occurrence of burning defects and the cut edge roughness.

Factors of Generating Surface Roughness in Cutting

As factors of generating roughness in cutting, first we consider the replica of the cutting edge roughness, and estimate clarity of the replica with multiple correlation coefficient between edge profile and generated profiles on a work after cutting. Next we consider the after-effect of the surface roughness of works before cutting, and estimate the degree of after-effect with singular correlation coefficient between the initial and refinished profiles. Both the replica and the after-effect depend on the properties of materials and cutting conditions, but the after-effect can no longer be recognized after the feather cutting. Lastly abnormal roughness, which is generated by disturbance of built-up edge, is estimated with partial correlation coefficient, and auto-generated roughness, which is caused by the non-uniformity of grain size and hardness of materials, is estimated with auto-correlation coefficient. These abnormal and auto-generated roughnesses also depend on both the properties of materials and cutting conditions, but the latter may be found only in the case of fine cutting.

A Study on the Roughness of Machined Surface of Metals : The Effect of Roughness of Tool Cutting Edge

This paper describes an experimental research to find the effect of the degree of tool finishing on the roughness of machined surface. By orthogonal cutting of mild steel we observed the relation between the roughness of cutting edge of tools finished with several kinds of method and the roughness of machined surfaces. This experiment reveals that the surface roughness is not affected by the roughness of cutting edge, if it is less than a certain limit, and that the increase of surface roughness eith roughness of cutting edge is attributed to the growth of built-up edge.