Comparative testing of three modified metaheuristic algorithms - the cyclic algorithm of the bat family (Loop BFA), the hybrid cuckoo search and the firefly algorithm (H-CS-FA) and the modified krill herd algorithm (MKH)was performed in the paper. The authors tested these algorithms in relation to original ones and the effectiveness of the modifications was confirmed for each individual algorithm. Here, the effectiveness of all three algorithms was verified on two engineering problems in the field of metal cutting - optimization of the body of the turning knife and optimization of the eccentric of the clamping tool. In both cases, multi-objective optimization with two objective functions was performed. By comparing the obtained optimization results as well as the speed of convergence, appropriate conclusions about the efficiency of the algorithms and recommendations for their application were made.