Cut Edge Surface Roughness Research Articles

Experimental evaluation of cut quality and temperature field in fiber laser cutting of AZ31B magnesium alloy using response surface methodology

Fiber laser cutting of AZ31B magnesium alloy was studied to assess the effect of laser cutting process parameters on the resultant cutting temperature near the cut kerf and the resultant cut quality. To systematically analyze the effect of parameters on the temperature variation and cutting edge surface roughness during the cutting process of the AZ31B magnesium alloy, the Response Surface Methodology (RSM) was utilized to fit a quadratic polynomial model through the experiments. The influence of three main factors including speed of cutting, power of laser and nozzle distance on the major responses of temperature near the cut kerf, average surface roughness of the cutting edge and the cut kerf quality was then evaluated.Changes in the cutting speed had no serious impact on the quality of the cut kerf.Laser power levels from 800 to 1000 W were suitable for laser cutting of magnesium alloy sheets. The results showed thatvariations in the nozzle distance and laser emitted power had a remarkable effect on the temperature variation around the cut kerf width. Changing the nozzle distance and thereby creating different laser beam diameter had a more significant influence on the temperature variation rate (about 15 %), in comparison to the laser power. The nozzle distance had a huge effect on the cutting edge surface roughness due to the significant variation of laser beam energy density and beam diameter and hence, the cut kerf dimensional changes.The optimal cutting condition was obtained at the minimum roughness according to the investigated parameters levels, which included the cutting speed of 6 m/min, the power level of 1000 W and the nozzle distance of 0.8 mm. The SEM images from the top surface of the cut kerf implied the existence of oxidation in the magnesium alloy kerf edges.

Performance of cryogenically treated WC drill using tool wear measurements on the cutting edge and hole surface topography when drilling CFRP

Drilling CFRP poses major challenges from the perspective of rapid tool wear and poor hole quality, with the development of higher strength fibers further accentuating these problems. Cryogenic treatment is one way of increasing tool hardness thereby improving tool life and hole quality through longer retention of cutting edge sharpness. In this study, tool wear is monitored by measuring flank wear, cutting edge flatting (CEF), peak flatting (PF) and cutting edge surface roughness (CESR). While flank wear is unable to distinguish the better performance of the cryo-treated drill from the untreated drill, the other wear parameters are able to account for the better hole quality (exit delamination) produced by this drill. CEF and PF are direct measures of the extent of cutting edge blunting unlike flank wear which measures wear along the flank due to rubbing. Fiber pullout is the primary reason for deterioration in surface finish and Rz and Rv are better measures than Ra in estimating surface quality.

A new and comprehensive characterisation of tool wear in CFRP drilling using micro-geometry and topography studies on the cutting edge

Cutting edge micro-geometry and topography changes when drilling carbon fiber reinforced polymer (CFRP) are monitored. The micro-geometry changes are characterised using four parameters – cutting edge flatting (CEF), peak flatting (PF), flank rounding depth (FRD) and flank rounding width (FRW) - in addition to flank wear (FW). Four drills (three carbide drills and one diamond coated drill) are tested. The uncertainty of the estimated parameters is <2 μm. Edge-chipping, is studied by measuring the cutting edge surface roughness (CESR) and is found to be dependent on the initial cutting edge radius (CER). Diamond coated drill retains its edge micro-geometry (undergoing CEF of <1/3 of carbide drills) and edge topography (CESR change of <1/5 of carbide drills) and produces holes of better quality up to 300 holes. The proposed wear characterisation method is found to provide a better and more direct measure of cutting edge deterioration than the existing wear parameters.

Long-pulse quasi-CW laser cutting of metals

Long-pulse quasi-CW laser cutting of metals is well suited to small-scale manufacturing settings where process flexibility is of high value and investment capacity is limited. This process refers to cutting operations performed with millisecond laser pulses obtained through modulation of the pump source to achieve continuous-wave (CW) operation over limited time intervals. The ability to minimize heat conduction losses, comprising the vast majority of absorbed laser power at low velocity, allows processing of relatively thick sections compared to what would be possible at the same average power with a CW laser source. The present study quantifies the reduction in heat conduction losses with pulsed exposure by employing a simple power-balance representation of the heat flow problem. Laser-cutting experiments are performed with inert and active assist gases on 1- and 4-mm thick steel samples, varying peak power (0.3–3 k W), pulse energy (0.3–12 J), repetition rate (25–1000 H z), and velocity (1–40 m m/s). The lowest minimum laser cutting power and highest cutting efficiency are achieved with maximum peak power and lowest permissible pulse overlap for a continuous cut. Under these conditions, heat conduction losses are reduced by more than 60% with nitrogen assist gas compared to CW exposure and more than 50% with oxygen. The calculated average cutting front temperatures are 450–630 ∘C and 620–900 ∘C, respectively, well below the melting temperature of steel. Lowest dross adhesion and cut edge surface roughness are obtained with oxygen assist gas, leading to both the lowest minimum average cutting power and highest cut quality. These results demonstrate an efficient process that improves the feasibility of low velocity laser cutting and therefore the range of industrial applications in which laser technology can employed.

Optimization of Laser Cutting Quality with Design of Experiments

AbstractLaser cut quality is strongly influenced by the cutting process parameters. In this study, 5 mm mild steel is cut with a high brightness 2.5 kW diode laser. The process parameters are optimized using systematic design of experiment (DOE) to obtain burr free laser cuts with minimal cut edge surface roughness. Varied factors include cutting speed, gas pressure, focus position, nozzle diameter and nozzle distance. The goal of this work is to relate these factors to burr formations and cut edge surface roughness. The relationship is generated and validated with help of a mathematical model, which is then used to predict and minimize burr heights and cut edge surface roughness.

Computer Aided Taguchi-Fuzzy Multi-Optimization of laser cutting process

Today's fast growing sheet metal industries are demanding overall improvement in cut quality rather than improving different quality characteristics individually. The laser cutting has proven to be the quality cutting process for almost any category of materials with few limitations. The multiple quality characteristics may be improved by controlling the process variables at optimum level. The paper presents a methodology for the simultaneous optimization of multiple quality characteristics in laser cutting process by developing the software 'CATFMO' Computer Aided Taguchi-Fuzzy Multi-Optimization. The software results have been validated by comparing the published experimental data and found suitable. This methodology has been applied for simultaneous optimization of kerf width, cut edge surface roughness and heat affected zone in laser cutting of difficult-to-laser-cut Aluminium alloy sheet.

Optimization of Multiple Quality Characteristics in Laser Cutting of Difficult-to-Laser-Cut Material

This paper presents experimental study of laser cutting of Aluminium alloy sheet with the aim to optimize multiple quality characteristics such as cut edge surface roughness and kerf deviation, simultaneously. The Taguchi method combined with Grey relational analysis has been used for parameter optimization. The Principal component analysis and entropy measurement method have been used for eliminating co-linearity and deciding the weighting factors, respectively. The results indicate considerable improvements in multiple quality characteristics.

Experimental Investigations on Fusion Cutting Stainless Steel with Fiber and CO2 Laser Beams

First results of an experimental study on inert-gas fusion cutting stainless steel with different types of laser are presented. In particular, the cutting capabilities of a fiber and a CO2 laser beam with similar Rayleigh length have been compared as a function of material thickness with respect to achievable maximum cutting speed, cut edge surface roughness and cut kerf geometry. The most interesting finding achieved so far concerns the observation that the cut kerfs are nearly identical in size but differ qualitatively in shape for both laser teypes.

Multiple quality optimization in laser cutting of difficult-to-laser-cut material using grey–fuzzy methodology

This paper investigates the laser cutting performance of 1 mm Duralumin sheet with the aim to improve quality of cut by simultaneously optimising multiple performances such as cut edge surface roughness, kerf taper and kerf width. The experimental data obtained by Taguchi methodology-based L27 orthogonal array experimentation have been used in the hybrid approach optimization of grey relational analysis and fuzzy logic theory. The predicted optimum results have been verified by conducting confirmation experiments. The verification results show an overall improvement of 19 % in multiple quality characteristics. The effects of significant factors on quality characteristics have also been discussed.