Pilot Experiment Practical Report

5 RESULTS AND DISCUSSION: PILOT EXPERIMENTS

5.1 Pilot Experiments
It is necessary to identify the factors affecting the responses and their feasible working ranges. From literature survey, the important process parameters affecting MRR and Ra were identified as: Ton, Toff, IP, WT and SV. The next step is to identify experiment domain for each of these process parameters. This work employs the pilot experiments for identification of feasible working ranges of process parameters. One factor at a time approach (OFT) has been employed for the pilot experimentation. Each trial was conducted by varying each parameter at five different levels while keeping all other parameters randomly at constant values. In each trial, 6 mm by 6 mm and 5 mm thick

The values of the other parameters were kept constant and their values are given as Ton = 110 unit, IP = 210 unit, WT = 5 unit and SV = 20 unit. The experimental data obtained while machining are provided in Table 3. Figure 16 depicts the effect of pulse off time on MRR. It can be observed that material removal rate decreases linearly with increase in the pulse off time. This is due to the fact that with increase in Toff, the non- cutting time increases and therefore, material removal rate decreases. So, for reducing machining time, Toff should be set at lowest possible level. Further, when Toff was reduced below 51unit, wire breakage was observed and therefore lowest level of Toff was fixed at 51 unit. From Fig. 17, it can be observed that surface roughness fallows no specific trend with Toff. It can be observed that with increase in Toff, Ra decreases initially and again increases at higher level of Toff. The increase in Ra drastically at higher level of Toff could be due to noise

The values of the other parameters were kept constant and their values are given as Ton = 110 unit, Toff = 57 unit, IP = 200 unit and WT = 5 unit. The experimentally observed data for the performance measures for different values of SV are given in Table 6. Figure 22 depicts the effect of SV on MRR. The material removal rate firstly increases and then decreases linearly with increase in SV. It can be observed that from Fig. 23 that surface roughness firstly decreases, then almost remains constant and thereafter increases with increase in