T o improve productivity and quality of machining process using EDM, a lot of electrodes such as coated and alloy electrodes has been applied. Study on multi-objects optimization in EDM with coated electrode will increase number of application of this field into practice. In this study, material removal rate (MRR) and surface roughness (SR) in EDM using nickel coated aluminium electrode were optimized simultaneously using T aguchi-AHP-Topsis methods. Technological parameters including Peak Current (I), Gap Voltage (U) and pulse on time (Ton) were investigated. Titanium alloy (Ti-6Al-4V) was selected as workpiece in experimental process. T he results show that combination among T aguchi-AHP-Topsis methods is suitable to solve multi-objects optimization in EDM. The optimized technological parameters are I = 30 A, T on = 500 µs, U = 50 V and optimized quality criterias are MRR = 0.17 mm 3 /min and SR = 8.76 µm.

The vibration integrated into die-sinking electrical discharge machining is a relatively new solution, so it has been creating the interest of researchers. In this paper, the authors studied the effect of low frequency vibration attached onto workpiece to efficiency of diesinking electrical discharge machining. Copper electrode and SKD61 die steel were selected to investigate. Material removal rate, tool wear rate and surface roughness were quality indicators investigated in this study. Experimental results showed that the low frequency vibration has a positive effect on the efficiency of die-sinking electrical discharge machining. Comparing to die-sinking electrical discharge machining traditional, when the vibration unit is integrated onto work-piece in die-sinking electrical discharge machining, the largest increase of material removal rate was 34.94 %, the greatest reduction of tool wear rate was 16.0 % and the largest reduction of surface roughness was 26.36 % and profile of machined surface was better.

This paper presents an optimization of dressing conditions for SKD-11 steel grinding using HaiDuong grinding wheel made in Vietnam. Taguchi method was used to design experiment and calculate the optimized dressing conditions. Effects of the six input parameters including feed rate (S), depth of rough dressing cut (aedr), rough dressing times (nr), depth of finish dressing cut (aedf), finish dressing times (nf) and non-feeding dressing (nnon) with 4 levels on the machined surface roughness were investigated for optimization process. To find out the influence degree of each input parameter on output results, S/N ratio was analysized. Experimental results show that the average surface roughness after 3 times of the repeated experiments was 0.208 μm and deviation was 11.23% comparing with the predicted values.

This study is to determine effects of the dressing parameters to the flatness tolerance (Fl) when grinding SKD11 steel using HaiDuong grinding wheel and also propose the suitable dressing parameters to obtain the smallest flatness tolerance. In this paper, the effects of the six input parameters including feed rate (S), depth of rough dressing cut (ar), rough dressing times (nr), depth of finish dressing cut (af), finish dressing times (nf) and non-feeding dressing (nnon) to the flatness tolerance were investigated. To find out the influence of each input parameter on output results, the S/N ratio was analysized. Evaluated experimental results show that, the average flatness tolerance was 4.05μm and deviation of this value was 11.38% compared with the predicted value.