Abstract: Ti-6Al-4V super alloy is an important engineering material with good strength to weight ratio and a wide range of applications in a number of engineering
fields because of its excellent physical and mechanical properties. This work determines optimum process parameters such as pulse on time, peak current, gap voltage and flushing pressure, which influence the micro-electro discharge machining (EDM) process during machining of Ti-6Al-4V using combined methods of response surface methodology (RSM) and fuzzy-technique for order preference by similarity to ideal solution (TOPSIS). Central composite design (CCD) is used in the experimental investigation, and a decision making model is developed to identify the optimum process parameters in the micro-EDM  process, which influence several machining criterions such as material removal rate (MRR), tool wear rate (TWR), overcut (OC) and taper. Triangular fuzzy numbers are used to determine the weighting factor for each process criterion. Further a fuzzy-TOPSIS method is used to select the most desirable factor level combinations. The proposed technique can be used to select optimal process parameters from various sets of combinations of process parameters in
a micro-EDM process.

Key words: Micro-EDM , Ti-6Al-4V , Fuzzy-techniquefor order preference by similarity to ideal solution(TOPSIS) , Micromachining