Coronary stents are manufactured through a sequence of processes and each step demands the process control to assure surface quality. This study is focused on the influence of laser cutting parameters and electropolishing on average surface roughness and back wall dross percentage for fiber laser cutting of AISI 316L coronary struts. A preliminary test and a design of experiments (DOE) were implemented to determine the limiting cutting conditions and the effect of these parameters on quality indicators. Preliminary results identify four cutting zones from a non-cut zone to a burned zone, in a frequency range between 1000 and 1500 Hz and a peak power between 160 to 180 W for clean cuts. From the DOE results, several interactions between factors were observed; however, a laser frequency of 1000 to 1500 Hz and a cutting speed of 250 mm/min minimize the backwall dross percentage and the surface roughness to values less than 2% and 0.9 μm, respectively. After the laser conditions selection, coronary stents were manufactured and electropolished to reduce the surface roughness on the strut edge. Electropolishing results indicate a surface roughness reduction from 0.9 μm to 0.3 μm after 300 s of electropolishing time.
Laser Micro-Spot Welding (LMSW) of metal sheets is a process widely used in medical, automotive and aerospace industries. This paper shows a process parameter selection for LMSW with AISI 302 stainless sheets, 254 μm in thickness. Experimental tests considered laser power, exposure time and focal distance parameters. The experimental setup produces the laser focal point over the part surface with a focal distance of 13.00 mm. The best results were obtained with an unfocused beam at a focal distance of 16.00 mm. Under the experimental conditions of this research, successful joining of AISI 302 thin sheets through LMSW is achieved with a combination of 175 W of average laser power and 0.25 s of exposure time (or a combination of 125 W and 1.00 s.). The width of the heat-affected zone (HAZ) was found to be 8% larger than the spot weld width, in average.