Optimizing New Manufacturing Processes
The process for implementing new manufacturing lines is almost the reverse of the one for current manufacturing lines shown in Figure 8.1. TQM and SPC tools and charts should be in place for new six sigma products. In the event that six sigma has already been achieved, and control charting is not being used because of low defect rates, other tools of TQM should be implemented, such as run charts and Pareto diagrams for monitoring and reviewing DPU (PPM) and DPMO levels of defects in manufacturing.
New production lines should be optimized for selecting the most favorable equipment, material, and processes for achieving six sigma. As discussed in the previous chapter, design of experiments (DoE) tools could be used effectively to originally design as well as survey the marketplace for the optimum choices of material, equipment, and processes. Several approaches discussed earlier could be used:
• Large experiments to evaluate different materials and the processes needed to produce them concurrently. This is the most comprehensive approach but could be difficult to achieve because of the time pressures involved in new product introduction
• Successive smaller experiments leading in the direction of steepest ascent. This could be applicable if the effort to perform the experiments and the measurement of the quality characteristic is relatively easy and quick.
• A screening experiment to quickly determine the most likely significant factor alternatives, and then a more in-depth experiment to select the best levels or processing parameters of significant factors. This is the preferred method since it offers the most efficient approach to process and product optimization.