Six sigma - blackbelt level project

Six Sigma: Define

A medical device manufacturing company, with a unique polyurethane casting line for the manufacture of a wound contact layer, used expensive raw materials. Downstream of the main chemical processing line, material was wasted during cutting and slitting processes, which continued to impact all subsequent manufacturing processes. A project was chartered to reduce the waste generated during these conversion processes, and a cross functional team pulled together including engineers, technicians, quality representatives and line operators. The process ‘customers’ were defined as the end customer, the downstream process and the business itself, in terms of its financial performance.

Six Sigma: Measure

In the measurement stage, the team mapped the process. We also measured a baseline for rolled throughput yield for the full manufacturing process, so we would be able to see the impact of the whole project. We collected data on existing waste levels, noting how levels changed over time and dependant on the variant being produced. We designed and performed a gauge R&R to ensure that when the line operators were collecting the data it was accurate & reproducible. The current state process capability was measured.

Six Sigma: Analyse

In the analyse stage I used a variety of statistical tools to review and test data. This included hypothesis testing, regression analysis, ANOVA, fishbone diagrams. A Design of Experiment was also designed and performed to statistically determine which factors had the most impact on waste. The data was also tested for normality, to ensure that any conclusions were robust.

Six Sigma: Improve

Taking the results of the analyse phase the team agreed and implemeneted various improvements to the process. These were agreed and scored using a solution prioritisation matrix. Improvements included optimisiting the width of the pre cult / slit roll stock and optimising slitting patterns using data modelling for minimal waste. The root causes uncovered also leant themselves to the use of lean techniques in the improvement phase, analysing customer demand and creating and implementing production kanbans. The improvements generated annualised cost savings of £68k and cost avoidance of £64k. Rolled throughput yield increased to 89% on the slitting process, from an initial 75% and also to 98% on the cutting process from an initial level of 87%.

Six Sigma: Control

Once the improvements had been made and proven, I worked with the team to define a control plan, to ensure that once we walked away, the improvements would be sustained. This included SOPs and floor markings for the kanban areas, am I-MR chart and control charts with defined trigger points and agreed action plans. Myself and the team then of course celebrated our success!