scholarly journals The Response Surface Methodology for Optimizing the Process Parameters of Selective Laser Melting

2019 ◽  
Vol 37 (1) ◽  
pp. 27-39 ◽  
Author(s):  
Mathieu Terner ◽  
Thibaud Ricordel ◽  
Jae-Hung Cho ◽  
Jeong-Seok Lee
2015 ◽  
Vol 21 (4) ◽  
pp. 423-432 ◽  
Author(s):  
Luke N. Carter ◽  
Khamis Essa ◽  
Moataz M Attallah

Purpose – The purpose of this paper is to optimise the selective laser melting (SLM) process parameters for CMSX486 to produce a “void free” (fully consolidated) material, whilst reducing the cracking density to a minimum providing the best possible fabricated material for further post-processing. SLM of high temperature nickel base superalloys has had limited success due to the susceptibly of the material to solidification and reheat cracking. Design/methodology/approach – Samples of CMSX486 were fabricated by SLM. Statistical design of experiments (DOE) using the response surface method was used to generate an experimental design and investigate the influence of the key process parameters (laser power, scan speed, scan spacing and island size). A stereological technique was used to quantify the internal defects within the material, providing two measured responses: cracking density and void per cent. Findings – The analysis of variance (ANOVA) was used to determine the most significant process parameters and showed that laser power, scan speed and the interaction between the two are significant parameters when considering the cracking density. Laser power, scan speed, scan spacing and the interaction between power and speed, and speed and spacing were the significant factors when considering void per cent. The optimum setting of the process parameters that lead to minimum cracking density and void per cent was obtained. It was shown that the nominal energy density can be used to identify a threshold for the elimination of large voids; however, it does not correlate well to the formation of cracks within the material. To validate the statistical approach, samples were produced using the predicted optimum parameters in an attempt to validate the response surface model. The model showed good prediction of the void per cent; however, the cracking results showed a greater deviation from the predicted value. Originality/value – This is the first ever study on SLM of CMSX486. The paper shows that provided that the process parameters are optimised, SLM has the potential to provide a low-cost route for the small batch production of high temperature aerospace components.


2018 ◽  
Vol 53 (11) ◽  
pp. 1459-1473 ◽  
Author(s):  
Shiva Dayal Rao B ◽  
Abhijeet Sethi ◽  
Alok Kumar Das

In the present investigation, a continuous wave fiber laser with maximum power of 400 W was used to cut a glass fiber reinforced plastic sheet of 4.56 mm thickness using Nitrogen as assisting gas. The influence processing parameters such as laser irradiance, gas pressure, and cutting speed on the cut surface quality were investigated by using response surface methodology. The different responses of laser cut surface such as upper kerf width, taper percentage along the cut depth, and heat-affected zone on the top surface were measured to analyze the influence of input process parameters on the responses. A statistical analysis on the obtained results was conducted and found that the optimum values of different input process parameters were laser irradiance: 8.28 × 105 watt/cm2, cutting speed: 600 mm/min and assisting gas pressure: 7.84 bar. The corresponding values of responses were upper kerf width: 177.4 µm, taper 0.73%, and heat-affected zone on top surface: 109.23 µm. The confirmation experiments were conducted with the obtained optimum parameter setting and observed that the predicted values and experimental values for upper kerf width, taper percentage and top surface heat-affected zone were within the error limits of 2.52%, 1.84%, and 0.45%, respectively. Furthermore, damages like loose fibers, interlayer fractures, evaporation of matrix material and fiber breakages were observed.


Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 930 ◽  
Author(s):  
Martin Malý ◽  
Christian Höller ◽  
Mateusz Skalon ◽  
Benjamin Meier ◽  
Daniel Koutný ◽  
...  

The aim of this study is to observe the effect of process parameters on residual stresses and relative density of Ti6Al4V samples produced by Selective Laser Melting. The investigated parameters were hatch laser power, hatch laser velocity, border laser velocity, high-temperature preheating and time delay. Residual stresses were evaluated by the bridge curvature method and relative density by the optical method. The effect of the observed process parameters was estimated by the design of experiment and surface response methods. It was found that for an effective residual stress reduction, the high preheating temperature was the most significant parameter. High preheating temperature also increased the relative density but caused changes in the chemical composition of Ti6Al4V unmelted powder. Chemical analysis proved that after one build job with high preheating temperature, oxygen and hydrogen content exceeded the ASTM B348 limits for Grade 5 titanium.


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