In manufacturing, quality data is a lot like water. Both can take on many forms. Data, like water, hangs in the air all around us and it also accumulates at ground level. Too much of either can drown us, while not enough can deprive us.
Today, data seem to be raining down from the sky
thanks to ongoing innovations in automation and connected devices. I’ve spoken with quality professionals and operators who are dealing with terabytes of data coming from their equipment every few minutes.
Trying to sift through this flood of data can overwhelm even the most Six Sigma-savvy quality professional. It all becomes increasingly murky, making it difficult to find those “golden nuggets” of actionable insight. After all, the reason why we collect data is to learn what’s happening on the manufacturing floor so that we can improve our processes, prevent issues, and determine where to expend our efforts and resources. Such data-driven knowledge presents a distinct competitive advantage for forward-thinking manufacturers.
In this blog, we’ll explore an innovative way to surface these nuggets of knowledge—grading.
A New Way to Look at Quality Metrics
Say I have a company with multiple manufacturing sites, each with several lines. If I’m like most manufacturers, I want to aggregate the data from every line and site to look at some summary statistics. I want enterprise-level visibility to find which sites are doing well, which sites are doing poorly, and what needs attention.
Traditionally, I would look at metrics like Cpk and Ppk ratios that compare specifications limits to the spread of a process’ output in terms of standard deviations.
However, these metrics have a few shortcomings:
- Cpk and Ppk are typically understood by only a limited number of people on staff
- Cpk and Ppk report how good or bad a process is, but they do not provide any visibility whether the problems are unique or systemic
- Cpk and Ppk ratios are designed to focus on single streams (one part, one process, and one feature). They cannot be used as enterprise-level comparative metrics.
Parts per Million (PPM) is another common process metric but it requires proper normalization and is not very intuitive for most decision makers. However, what is easily comprehendible for most users is yield
. Quality performance grading presents a new yield-based way to assess manufacturing performance.
Quality performance grading
combines a simple letter (A, B, C) and a number (1, 2, 3) to indicate how a specific data stream is performing based on daily summary records. There are a total of nine possible grades (A1, A2, A3, B1, B2, B3, C1, C2, and C3). A grade can represent a part, process, feature, or entire manufacturing site.
- The letter grade represents the potential yield of the stream, i.e. expected yield assuming perfect centering on target using the level of variability. A distribution spread that falls well within the specification limits gets an A grade. A B grade is when the distribution width is equal to the range of the specification limits. A C grade is when the distribution cannot fit within the specification limits. A is the best letter grade possible.
- The number grade indicates performance yield, i.e. expected yield using centering. A perfectly centered process is a 1. A number grade of 2 means the process is not centered. A process that is woefully off center will earn a number grade of 3.
Exclusive to the InfinityQS Enact®
platform, grading provides a unique way to roll up and interpret performance across many products, processes, and sites. But it also goes one step further, allowing you to quickly drill down into specific data streams. You can dive into each stream to determine where to focus your attention for the greatest return on investment (ROI) and most effective quality wins.
Whether you have a single plant or multiple, grading allows you to quickly identify where and how to make the biggest impact on quality, processes, and business performance. Gold starts to emerge out of the murky depths of the data.
Going After the “A3”
Based on Enact’s grading system, a grade of A1 indicates the highest-level performance, with minimal or no scrap—it’s right on target. A C3 grade depicts a process that has low potential and even lower performance. C3 is where you want to deploy your quality improvement teams that resolve systemic issues.
However, a grade of A3 reveals a stream that is highly capable but way off center. There’s a lot of room for easy improvement here. The “3” tells us we have a poor yield, but the “A” tells us that we should
have the potential to perform at 100-percent yield by simply retargeting the process.
Although not always, many times the fix is a matter of operator training or modifying the process set up. But we wouldn’t have been able to quickly isolate the opportunity here without quality performance grading.
In this way, grading is a great tool for quality professionals who not only need to uncover hidden insights within data, but also require an agile way to prioritize their resources and efforts. If you are trying to maximize every resource and make the biggest impact for the least amount of effort, going after the A3 grades will be your best bet for quick returns.
Seeing the Big Picture
To help with comparative analysis and prioritization of improvement efforts, Enact includes several ways to look at grades across multiple streams.
You can create a Grading Matrix
that summarizes all the streams that meet each grade. You can drill down into the streams under different grades. For instance, you can see which ones are A3’s, which are where your easy wins are going to be. You can see where your C3’s are, which are going to be your major improvement initiatives. The primary benefit of this view is you can target streams based on amount of effort.
shows the site grade for each critical feature across multiple plants. Color codes make it even easier to spot areas that need attention. You can click a grade to see layered details that reveal the grades for individual processes or parts. A site summary is especially helpful for determining:
- How each line is performing
- How various parts perform on each line
- How features within a process measure up
What you get with quality performance grading is a fast and easy way to find nuggets of process improvement knowledge hidden within seas of data. The simple, letter-number combinations and color codes make it even easier to prioritize your actions. You can take your quality to the next level and gain an edge over the competition—and that’s worth every ounce of gold.
Take advantage of the technology at your fingertips today: contact one of our account managers (1.800.772.7978 or via our website
) for more information.