Lens focal distance and auxiliary gas type utilized in CO2 laser cutting are two important parameters affecting process measures such as cuts width and quality at desired cutting speeds. This research work focuses on cuts width and quality in CO2 laser cutting with a power of 4000W on two types of steel sheets at different focal distance values and using different types of auxiliary gas. The effect of focal distances of 5” and 7.5” as well as utilizing oxygen and nitrogen as auxiliary gas on cut width and quality in 304L stainless steel and St37 steel sheets were investigated. The size of cut widths was measured using an optical microscopy. The results demonstrate that cuts performed at the focal distance of 7.5” are wider than those created at the focal distance of 5”. It is also observed that with increased workpiece thickness, the use of focal distance of 7.5” is more feasible because cuts are faster; need lower laser power, and use less amount of auxiliary gas. When using oxygen as auxiliary gas, the main factor affecting the cutting efficiency is the oxidation reaction, whereby oxidation energy is added to laser power which results to an increased energy level in the cutting region. This means that using oxygen as auxiliary gas makes it possible to cut thicker sheets at higher cutting speeds as compared to that of nitrogen. However, when using oxygen as auxiliary gas, the quality of cuts appears to be lower and their width larger as compared to cuts performed by nitrogen auxiliary gas. تفاصيل المقالة

Material removal rate (MRR) and cutting volume efficiency (αVol) in laser cutting of commercial polyamide (Nylon) sheets have been studied in this research. A CO2 laser cutting machine with the power of 100 W was used to cut polyamide (PA) sheets with thicknesses of 2 to 8 mm. The beam spot size on the upper surface of the sheet was 0.1 mm. The maximum cutting speeds for a variety of powers and thicknesses were specified under the same other laser cutting parameters. The specific point energy (Esp) was calculated for every combination of maximum cutting speed and power. Results show that for a given power, the maximum cutting speed exponentially decreases with increasing sheet thickness. The MRR increases logarithmically with power and for a given power, it rises as the sheet thickness decreases. The αVol increases with power until it reaches the apex of efficiency, then it slightly reduces with increasing power. Overall, the αVol decreases with increasing sheet thickness and Esp. تفاصيل المقالة