OEE (or Overall Equipment Effectiveness) is the ultimate tool for measuring and eliminating process waste. Wikipedia defines it as “a hierarchy of metrics developed by Seiichi Nakajima in the 1960s to evaluate how effectively a manufacturing operation is utilized.” OEE combined with rigorous process improvement efforts can drive significant cost savings, reduce stress of daily operations, and increase manufacturing capacity. Simply put, you’re not doing Continuous Improvement or Lean if you’re not using OEE. The metric itself is taken by multiplying Availability (%) x Rate Attainment (%) x Yield Attainment (%).
To implement OEE effectively, you need to track each of these indicators on a continuous basis and perform the OEE calculation for a line, shift, factory, or entire manufacturing network on the interval that you see fit. Here are a few steps to implement OEE:
- Capture the % Availability. This is the efficiency lost while the line is not in operation (but the labor force is on the clock). Create a spreadsheet that allows line operators to input the time it takes to start up the line (from clock-in to steady state). Also capture other planned downtimes such as changeovers and shutdown times. Finally, capture each unplanned downtime loss as well.
- Capture the % Yield Attainment. This is a measure of the efficiency lost due to producing sub-par quality product. This calculation is done simply by taking the total good units produced divided by the total units produced.
- Capture % Rate Attainment. This is essentially the efficiency lost while running less than the maximum possible run rate. To capture this this, develop maximum theoretical run rates for each product on each production line. This should be done by an Industrial Engineer or trained professional. If you don’t have one on staff, you can contract someone to do it or use what I call the maximum empirically demonstrated rate, which is the fastest rate the line has demonstrated in it’s history for the given product. From there, track your total throughput and divide by your theoretical max rate to get your % total losses. Then subtract out % Availability and % Yield Losses. The remaining losses are rate losses.
Then multiply the three indicators across and the result is your OEE, which is a measure of perfection. 100% OEE represents zero efficiency losses. Once you have began tracking these metrics on an ongoing basis, you can aggregate this data to calculate your OEE anytime you want. The more frequently you can report this information, the more actionable the metric is for you. You certainly don’t want to wait weeks or months to find out there is a serious problem; but daily reporting is usually sufficient. Reporting by shift is even better.
With all of that said, the best way I’ve seen to implement OEE is a tool called Impruver at www.impruver.com. It’s the best free tool out there and it calculates and reports OEE for you by product, line, shift, and even team or individual team members. You could simply have your operators enter each production run into the system and the tool does the rest. It takes less than a minute to enter a production run. It even sets your theoretical max rates for you based on your best demonstrated rate. Then it updates the standard automatically when a run is entered that exceeds the previously established rate. In other words, you don’t have to set or update production standards – the tool does it all for you. It’s great!
OEE is the benchmark for measuring factory performance and can be used across all industries to highlight areas that can be made more efficient. It’s a metric that can be used to drive substantial cost savings along with targeted process improvements.
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