Re: Six Sigma Project on Reducing Plastic Injection Molding Rejects
my recommendation would be to provide a Pareto-Trend of the defects currently experienced.
you might look at the last 6-12 months of data (whatever makes sense) and pareto by quantity of occurence (assuming that cost to fix is the same for each defect type - regrind? if cost isn't the same, then you might also pareto by cost for each defect type).
then take each of the top 5-10 defect types, trend the occurence rate for the same period of time as the pareto. (Do not trend cost only occurrence rate, monthly or weekly depending on volumes.) This show demonstrates whether or not the defects are stable, increasing, decreasing or if a spiek occurred and has since been corrected. it adds info to the pareto that will help with prioritization of which defects you should pursue.
I would aslo repeat this for each of the top product types - there are likely differences in some defect occurrences based on product types.
you would then select the top defect/products as the target for your project
In my handouts I use a portrait format with a tall pareto that has the trend charts positioned to the right of their pareto bar...in an overhead I show the pareto on one slide then the trend charts in pareto order on a second slide...