Laser machining of die steel (En-31): an experimental investigation to study the effect of process parameters

Author(s):  
Amit R. Patel ◽  
Sanket N. Bhavsar
Author(s):  
A. R. Patel ◽  
S. N. Bhavsar

Experiments were performed based on response surface methodology (RSM) to investigate the process parameters effect on the features of hole geometry. Cutting speed (of 500-1000 mm/min), laser power (of 2000-4000 W), frequency (of 800-2000 Hz), duty cycle (of 75-95%), and gas pressure (of 0.05-0.15 bar) were considered as variable parameters. Deviation in the dimension of entrance and exit holes, heat affected zone (HAZ) on the upper & lower edge, and roughness were the output to analyse the cutting quality of 14 mm thick normal and heat-treated (HT) EN-31 die steel using 4 kW CO2 laser. For untreated plate, minimum taper angle was achieved with low cutting speed, higher laser power, and gas pressure. Higher cutting speed, low laser power, and higher gas pressure result in the minimum HAZ. For the HT plate, the mid-range of parameters results in the minimum taper angle and HAZ. An optimised model was developed, and the confirmatory test gives roughness up to 0.27 microns and it shows good agreement with the mathematical model. At the cross-section of holes, striation pattern, resolidified layer, and corner qualities were visually inspected. Surface damage near the cutting edge was observed using scanning electron microscopy.


2020 ◽  
Vol 66 (3) ◽  
pp. 184-192 ◽  
Author(s):  
Sanjay Sundriyal ◽  
Vipin ◽  
Ravinderjit Singh Walia

The Powder-Mixed Near-Dry Electric Discharge Machining (PMND-EDM) methodology has proven to be efficient in terms of machining rate, surface morphology, and environmental friendliness, unlike traditional EDM. In this study, the presence of a conductive metallic powder (zinc) in the dielectric medium was responsible for changing the topography of the workpiece (EN-31) and resulted in a higher micro-hardness value of the machined component. In this research, an approach has been made to optimize the significant process parameters by using a Taguchi L9 orthogonal array (OA) to obtain machined components with higher values of micro-hardness, which was measured in terms of Vickers hardness HV. The selected process parameters were tool diameter, mist flow rate, metallic powder concentration, and dielectric mist pressure. By introducing foreign particles (metallic powder), the topography of the machined products has been improved, and the micro-hardness value was found to be enhanced. The confirmation experiment was performed for optimal process parameter settings, and the enhanced microhardness value was found to be 506.63 HV in the machined EN-31 die steel.


Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3206
Author(s):  
Xuehui Chen ◽  
Xin Xu ◽  
Wei Liu ◽  
Lei Huang ◽  
Hao Li ◽  
...  

This paper studies the compound effect of liquid medium and laser on the workpiece and analyses the law of material surface temperature change during the processing. Taking 7075-T6 aluminum alloy as the research object, the surface temperature field of aluminum alloy processed using water-jet-assisted laser machining under different process parameters was simulated using finite element software. In addition, the temperature field of the material surface was detected in real-time using the self-built water-jet-assisted laser machining temperature field detection system, and the processing results were observed and verified using an optical microscope, scanning electron microscope, and energy spectrum analyzer. The results show that when the water jet inflow angle is 45°, the heat-affected area of the material surface is the smallest, and the cooling effect of the temperature field of the material surface is better. Considering the liquidus melting point of 7075 aluminum alloys, it is concluded that the processing effect is better when the water jet velocity is 14 m·s−1, the laser power is 100 W, and the laser scanning speed is 1.2 mm·s−1. At this time, the quality of the tank is relatively good, there are no cracks in the bottom of the tank, and there is less slag accumulation. Compared with anhydrous laser etching, water-jet-assisted laser etching can reduce the problems of micro-cracks, molten slag, and the formation of a recast layer in laser etching and improve the quality of the workpiece, and the composition of the bottom slag does not change. This study provides theoretical guidance and application support for the selection and optimization of process parameters for water-jet-assisted laser etching of aluminum alloy and further enriches the heat transfer mechanism of multi-field coupling in the process of water-jet-assisted laser machining.


2011 ◽  
Vol 29 (13) ◽  
pp. 1484-1491 ◽  
Author(s):  
A. Hallajisani ◽  
S. J. Hashemi ◽  
W. J. Murray Douglas

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