Manufacturing Improvement – the Probabilities of Success.

Statistics are the foundation of the Six Sigma methodology and can be very useful in understanding manufacturing performance and for planning manufacturing improvement. It might be surprising to know that a lot of useful statistical data is likely already available in your manufacturing database.

For example, it is very useful to understand the defect rates in a manufacturing process and how to apply the calculation ‘Rolled Throughput Yield’ (RTY). Simplistically, if the rate of conformance for each step of a sequential process is known, the probability of producing a defect free unit can be found by multiplying each probability and subtracting from 1.

For example, if the rate of conformance for 5 sequential steps is .95, .97, .98, .93 and .92, the Rolled Throughput Yield, or the probability that a unit will conform is .773, or 77.3%.

Another example is with conformance sampling. Let’s say that out of 52 items, 4 are known to be defective. Suppose that one item is randomly selected and without putting the item back, a second and then a third item are randomly selected.  Using a statistical formula, the probability that two of those three selected items are defective can quickly be found as 1.3%.

Statistics can be used in many ways that benefit the manufacturer and for more info, an overview of Six Sigma methodologies can be at found the American Society for Quality website (ASQ). Since a lot of useful data might be sitting right there in your manufacturing database waiting to be calculated, why not increase your probability of success, and give statistics a try...!

If you have any questions about this or any other Six Sigma topic, feel free to get in touch with me at Central Nervous Systems.

Matt.