| PT. Indomobil Suzuki International Plant Cakung is an industry company of otomotive that produces parts of 2W and 4W. This research is focused to parts of 2W especially part crank case RH XA 363/681 because this part crank case RH XA 363/681 has the largest defect. In this production process related with die casting process which used injection machine. The defect calculation obtained that the largest defect is variable type and that is hardness deviation. The cause of this hardness deviation is the setting of injection machine in die casting process that was doing by trial and error. This research has an intention for getting the optimal parameter composition in setting machine so can improve the hardness of crank case. This research to find the setting optimum used Taguchi method and Response Surface method. Taguchi method is used to obtain factors that give significant effects to hardness of crank case. After that, Response Surface is used to find optimum level from the significant factors. The result of this research, obtained that the significant factors are pressure machine in plungger, velocity of plungger, temperature of dies, time of cooling, and cycle time. Optimum setting from the five factors are pressure machine in plungger 675 kg/cm2, velocity of plungger 3 m/s, temperature of dies 225°C, time of cooling 14 sec, and cycle time 64 sec. Using optimum setting, process capability is increased become 1.02 larger than 1, that means the process is very good in producing product appropriate with the company specification. |