Solving The Low Yield Problem Of H Product By Using Six Sigma Method

As the newest high security level golden bank card of I company, H product was launched at the end of 2011 and rapidly access to the market of Europe and Asia. It would become the most important product of I company over the next 5 years. However, at the beginning of the mass production the yield of H product wander for the a long time in a lower level, and is also quite lower than the target, which do not only make the high level of operating cost, but also leads to a decline in customer satisfaction. The volume of H product is at the downward trend. So how to effectively reduce the H product defect rate and thus improve its yield is the key problem in the thesis and the most important opportunity for I company as well.First of all the article introduced the background and its significance, the research goal and the content then introduced the basic theory of Six Sigma and research status in the domestic and aboard. In this paper, the article closely follow the model of DMAIC: Define-Measure-Analyze-Improve-ControlIn Define phase through the Pareto and 8- Dimensions we ultimately determined the two critical defect that totally impact H product yield: Runner Remnant(Defect rate: 1.44%) and Air vent flash(Defect rate:0.54%). In the mean while we defined the project target which is decrease the defect rate of Runner Remnant to 0.54% and the defect rate of Air vent flash to 0.16%. We also formed the project team and its timeline.In Measurement phase through the SIPOC and Process Mapping, PFMEA, we initially identified the possible root cause of Runner Remnant which are: 1. Cutter hardness of soft rubber base; 2. Improper position of the cutter thimble; 3. Improper cutter length; 4. With or without cutter. The possible root cause of Air vent flash which are: 1. Molding temperature; 2. Gap in-between top and bottom cavities; 3. Compound injection speed. We also defined the effective sample size: 8000 pcs.In Analysis and Improve phase through the hypothesis test, one factor ANOVA, Multiple proportion test, full factors design of experiment we finally determined the main reasons of the above the two key defects and then this article developed and deployed the appropriate improvement. For Runner remnant: 1. Directly change the basis of cutter to hard type; 2. For thimble length and location, 2nd place with short thimble, 3rd place with short thimble and 4th place with long thimble. For Air vent flash: 1. Finalized the injection of Compound speed as 80 and the shim in-between the top and bottom cavities as 20 um.In Control phase to address these critical causes to take effective long-term control plan FMEA, process control plan, SOP and annual work skills assessment, etc. And the outcome of the improved monitoring by SPC to reduce Runner Remnant from the original 1.44% to 0.18%, Air vent flash from the original 0.54% to 0.11%, thus greatly improving the H product yield, the yield of H products increased from the original 96.69% to 98.92%, creating an annual benefit for the company amounted to more than 180 million RMB, reducing the company’s operating costs, but also greatly improved customer satisfaction and confidence.Ultimately, the article summarizes the research work of the whole project and also the application of Six Sigma management after I company research prospect was put forward.