What’s Up With Downtime? How To Evaluate Machine Performance BY RICHARD ETRA Is your equipment’s output not in line with your expecta- tions? If not, is this due to low run speeds, or excessive downtime?
this article, let’s define downtime as crewed or scheduled time during which a machine is not producing. Technically, although more difficult to capture, that includes time when the machine is turning over with no sheets fed through it. Furthermore, let’s exclude setup time. Of course, if a state-of-the-art flexo folder gluer is ca- pable of two-minute setups and a rotary die cutter of as little as four minutes, and your crew is taking ten to fifteen minutes, that needs to be addressed. However, let’s con- sider that, along with sub-par run speeds, to be productivi- ty issues and leave them for another discussion. So, for our purposes, let’s focus on scheduled produc- tion time excluding setups and scheduled downtime such as preventive maintenance, lunch, and breaks. Defining when setup begins and ends, and whether that includes downtime, can be a bit nebulous, but keep in mind that we don’t need precise numbers. The approach presented here is to identify high level issues and then zero in on the root causes. Thus, if we know how many hours were scheduled, and exclude reported setups, etc., even though these times may be inflated, the remaining time is, by our definition, downtime. How do you collect this downtime data? Do your crews record them on hard copy logs? If so, your data are only as good as the crew’s attention to detail. Do they capture all the downtime? Are they meticulous in their entries or do
If you wish to evaluate equip- ment utilization, Overall Equipment Effectiveness (OEE) is a good tool, as it compares actual performance to that of a fully utilized machine operating at the manufacturer’s specified optimal run speed and setup duration. If your $5,000,000
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investment is scheduled to run only ten hours per week, and setup and run speeds are perfect, its utilization is still poor, and this will be reflected in low OEE. However, if your objective is to measure productivity, this metric is not meaningful as it includes factors, such as scheduling, which are not within the control of your plant’s production personnel. Low run speeds can be due to sub- optimal crew performance, machine issues, or external factors that constrain the operation. We will not address run speeds in this article and limit ourselves to downtime. Downtime can be defined in many ways depending upon how the information is to be used. For the purpose of
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• Machinery selection • Plant layout • Project Management • Consulting
A true corrugated industry veteran with nearly 50 years’ experience, Richard Etra can help you with every aspect of box plant operation. Contact Richard today for a no-cost consultation: email: richard_etra@etracorrugatedsolutions.com ph: 917-647-9520
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August 28, 2023
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