The stiffness of multi-articulated industrial robots is very weak, because their structure is an articulated type with some links and joints. Thus it is known that cutting processes for metals are not accepted in machine shop well, but they have a lot of merits for cutting processes, for example, drilling, tapping, and engraving etc, because of the characteristics of their high degree of freedom. The temptation of cutting aluminium was carried out to investigate the feasibility and the limitations or constraints for cutting metals on them. First the mode shapes of 6 degree of freedom welding robot were taken and analysed, and next the cutting processes were practically carried out on it. The results of study were found out to show the feasibility of cutting processes at drilling under 6mm of tool diameter, as well as to have some limitations and constraints, for examples, feed rate, depth of cut and cutting force etc.