Browsing by Author "Kechagias, John"

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    The impact of process parameters on surface roughness and dimensional accuracy during CO2 laser cutting of PMMA thin sheets
    (MDPI, 2021-07-07) Ninikas, Konstantinos; Kechagias, John; Salonitis, Konstantinos
    This study investigated the impact of the laser speed and power, and the position and orientation of the samples, on the average surface roughness (Ra) and dimensional accuracy (DA) during CO2 laser cutting of polymethyl methacrylate (PMMA) thin sheets. A mixed five-parameter fractional factorial design was applied, and thirty-six measurements for the Ra and DA were obtained. The experimental results were analysed using ANOM diagrams, ANOVA analysis and interaction plots of all parameters. It was concluded that the laser speed is the critical parameter for both surface roughness and dimensional accuracy, resulting in strong interactions with laser power and positioning parameters. It was also shown that Ra values are affected by the orientation of the specimen and can be minimized when the samples are aligned in the laser travel direction. Finally, it was proved that lower laser speed improves the average roughness but reduces the dimensional accuracy.
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    Optimization of cut surface quality during CNC Plasma Arc Cutting process
    (North Atlantic University Union, 2016-08-10) Tsiolikas, Aristidis; Kechagias, John; Salonitis, Konstantinos; Mastorakis, Nikos
    Optimization of cut surface quality during CNC plasma-arc cutting (PAC) of mild steel plates is presented. Using design of experiments (DOE) the optimum process parameters are estimated. The process parameters tested include cutting speed, cutting height and arc voltage. Analysis of means (ANOM) and analysis of variances (ANOVA) were used in order for the effect of each parameter on the surface quality to be assessed.
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    Quality performance evaluation of thin walled PLA 3D printed parts using the taguchi method and grey relational analysis
    (MDPI, 2020-05-19) Aslani, Kyriaki-Evangelia; Chaidas, Dimitrios; Kechagias, John; Kyratsis, Panagiotis; Salonitis, Konstantinos
    This paper investigates the quality performance of FDM 3D printed models with thin walls. The design of experiments method (DOE) was used and nine models of the same size were fabricated in a low-cost 3D printer using polylactic acid (PLA) material. Two limited studied parameters were considered (extraction temperature and wall thickness), each one having three levels. External X and Y dimensions were measured using a micrometer, as well as four surface roughness parameters (Ra, Rz, Rt, Rsm) with a surface tester. Two optimization techniques (the Taguchi approach and Grey relational analysis) were utilized along with statistical analysis to examine how the temperature and wall thickness affect the dimensional accuracy and the surface quality of the parts. The results showed that high extraction temperature and median wall thickness values optimize both dimensional accuracy and surface roughness, while temperature is the most important factor.
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    Sustainability assessment for manufacturing operations
    (MDPI, 2020-05-29) Saxena, Prateek; Stavropoulos, Panagiotis; Kechagias, John; Salonitis, Konstantinos
    Sustainability is becoming more and more important as a decision attribute in the manufacturing environment. However, quantitative metrics for all the aspects of the triple bottom line are difficult to assess. Within the present paper, the sustainability metrics are considered in tandem with other traditional manufacturing metrics such as time, flexibility, and quality and a novel framework is presented that integrates information and requirements from Computer-Aided Technologies (CAx) systems. A novel tool is outlined for considering a number of key performance indicators related to the triple bottom line when deciding the most appropriate process route. The implemented system allows the assessment of alternative process plans considering the market demands and available resources.