The Impact of Process Parameters on Surface Roughness and Dimensional Accuracy during CO2 Laser Cutting of PMMA Thin Sheets

Konstantinos Ninikas,Konstantinos Salonitis,John Kechagias

doi:10.3390/jmmp5030074

Konstantinos Ninikas, Konstantinos Salonitis + Show 1 more

Open Access

https://doi.org/10.3390/jmmp5030074

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Abstract

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.

Highlights

Laser cutting is a widespread process in numerous manufacturing industries [1]
Most of the reported research is focused on the laser cutting of metallic materials, in recent years laser cutting applications in polymeric materials have been researched
Chen et al [14] investigated the effects of assisted gas flow rate (10–30 NL/min), pulse repetition frequency (5–15 kHz), cutting speed (1–2 mm/s), and defocused point (–1, 0, 1 mm) on average surface roughness and optical transmittance of 6 mm polymethyl methacrylate (PMMA) plates during 100 W CO2 laser cutting

Summary

Introduction

Laser cutting is a widespread process in numerous manufacturing industries [1]. This processing technology is being constantly improved while contributing to the progress of industrial production in all engineering fields worldwide. Choudhury and Shirley [13] studied the laser cutting (CO2, 500 W, continuous wave) of various polymeric materials (PC, PP, and PMMA) to evaluate the effect of the LP (200–400 W), cutting speed (3.3–6.6 mm/s) and air pressure (0.25–0.35 MPa) on laser cutting quality (average surface roughness, mean HAZ depth, and dimensional accuracy) They used a CCD design and RSM methodology. Chen et al [14] investigated the effects of assisted gas flow rate (10–30 NL/min), pulse repetition frequency (5–15 kHz), cutting speed (1–2 mm/s), and defocused point (–1, 0, 1 mm) on average surface roughness and optical transmittance of 6 mm PMMA plates during 100 W CO2 laser cutting They observed Ra values between 0.38 and 2.8 μm and optimised the process using grey relational analysis. From the ‘nominal’ dimension (20 mDAmX)=fo20r e–a(cXh1 +dXir2e+ctXio3)n/3

Design of Experiment

Results and Discussion

Effects of the Process Parameters on the Average Surface Roughness

Effects of the Process Parameters on the Dimensional Accuracy