The Six Sigmas
For our sixth blog post, we want to talk about Six Sigma, everyone’s favorite manufacturing buzz word. Made popular even outside of manufacturing by 30 Rock where Alec Baldwin’s Jack Donaghy continually asserts “he knows the Six Sigmas who work at GE,” Six Sigma is mostly about quality maximization. Without a statistics lesson, it relates that there should be six standard deviations (sigmas) between the average measured unit and the nearest “failure” condition. This assumes a normal distribution and implies a quality level goal of 3.4 defects per million opportunities or products. In other words, failure is inevitable, but can be minimized.
More than that though, Six Sigma implies a slew of methodologies and tools. We are going to focus on those here and how they can have a positive impact on your manufacturing environment.
Methodology 1 – DMAIC
Define, Measure, Analyze, Improve, Control. This is focused on existing processes, and how to improve them. Seems simple enough, but each has a focus.
Define the system and requirements for the project.
Measure the current process and collect data.
Analyze the data to find relationships. Search for hidden factors and look for root causes.
Improve the process through a pilot by implementing your favorite techniques.
Control the process to ensure outside influence cannot impact changes or revert back to old state.
At the end of this framework, new insights should be found to perfect the processes. This is once again focused on quality, but as we know, without quality, production fails. It is also a cyclical process, so once an improvement is made, it’s time to DMAIC again.
Methodology 2 – DMADV
Often called DFSS or Design for Six Sigma, this is utilized when planning new processes. Define, Measure, Analyze, Design and Verify. Similar in verbs, and end goal as DMAIC, just proactive.
Define the new goal and process requirement.
Measure the critical characteristics, risk, capability and capacity.
Analyze to see where alternatives are essential.
Design the process and make decisions based on the analysis.
Verify the correct decisions were made.
At the end of this process, a stable, reliable process should be functioning. Of course this does not mean the work is done. Six Sigma is an ongoing effort, so when DMADV is done, DMAIC starts.
Some Tools to Use
Many of the tools developed for Six Sigma are common knowledge and are synonymous with lean manufacturing. We’re going to look at a few of the most common, here which any company should be implementing, even if they aren’t aware.
5 Whys: By asking “Why?” five times, you usually get close to a root cause which can be actioned. By asking the simplest question, we get to the most honest answer. While incredibly powerful, it often will point to a specific issue, when a systemic issue may be at play. Regardless, it is a great first tool to employ when looking at a process.
Poka-yoke: Is Japanese for “error-proofing.” This is an interlock that stops an unintended function. Often related to safety (a robot cell cannot start while a person is sensed for instance), but can also be important for quality. Think along the lines of how would one stop a sand blast operator from over-blasting a part? Maybe a timer on the blast cabinet that turns off the flow of material before it could be damaged.
Value Stream Mapping: Is the process of mapping the process flow, and looking for overlapping lines in a physical plant. If lines are crossing, there is a possibility of a mix up. It also shows excessive movement, allowing us to see waste.
Root Cause Analysis: This may be the most mentioned tool in quality teams around the world. It is exactly as it sounds, all about getting to the root of the problem. By eliminating external factors or events, we can see what truly cause our problem. Once we know the problem, we can fix it.
Conclusion:
I hope this simple article has given some better context on the topic of Six Sigma. While not exhaustive, I believe this is enough to help start the conversation. The goal is to understand what questions to ask. You don’t have to be a black belt or green belt to apply these concepts, and they can be helpful in so many fields. At MFG Concepts we apply each of the tools and methodologies to everything we do. Contact us today and see where we could help implement them in your process.
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