Experimental study on variations of WIPLOAD control in semiconductor wafer fabricaiton environment

WIPLOAD Control has been proposed and evaluated as an effective job release control methodology. This paper presents a further simulation experimental study on two variations of WIPLOAD Control in semiconductor wafer fab environment. The first variation mechanism is to control separate WIPLOAD for each part type at a specified level under the situation when the type of job going to be released next can be controlled. The second variation is a mechanism with additional release control points along the production line. The performance of the WIPLOAD variations are compared with that of the original WIPLOAD Control and other existing release methods including CONWIP and Constant release in semiconductor manufacturing environment. The experimental results indicate that by breaking down the control of overall fab WIPLOAD into controlling WIPLOAD level for each part type, cycle time performance can be improved especially with respect to the standard deviation of cycle time.