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By Herb Lichtenberg
Whistles are blowing, phones are ringing and people are scrambling all over the factory floor. There has just been a major equipment breakdown and it looks like it will take days to repair and get the plant running again. Just think of the lost production, the late orders and the unhappy customers.
When something like this happens, it gets a lot of attention from all levels in the organization. It’s happened to me on several occasions and these can be gut-wrenching times. For instance, I once managed a blooming and rolling mill complex. The blooming mill was powered by a 10,000-hp steam engine and everything had to go through that one mill. One of the two piston rods failed from fatigue. The piston blew through the cylinder head and was found 80 feet down the motor room.
Luckily, no one was in the room at the time, but we ended up losing two and a half days (61 hours, actually) repairing the engine, its foundation and gearing. The incident got a lot of attention with an investigation, root cause analysis and a new procedure so it wouldn’t happen again.
Sound familiar? These things happen in every plant, and, if dealt with properly (investigation, root cause analysis, implementation of countermeasures), won’t happen again. But these single-event losses are not the real killers of production unless they occur frequently or are the result of a systemic problem such as an ineffective preventive maintenance program. The real killers of productivity are small events we take for granted or consider part of the process.
In the same complex, we experienced a delay that occurred on an average of twice per shift, three shifts per day, 365 days per year. Changing the “hot saw” was a routine, seven-minute delay and was considered a necessary part of the process. It was hardly ever mentioned in our daily meetings, even though it cost us an average of 255 production hours each year. Now, that’s something everyone, including the brass, should have gotten excited about. But a seven-minute delay in production just didn’t generate much concern.
“When a plant goes down, people notice, but when it slows down, there isn’t a big sense of urgency.”- Herb Lichtenberg
However, the guy whose job it was to sharpen the saws saw the waste. Working with tool steel and carbide insert vendors, he came up with a new saw design that lasted twice as long, adding 127 hours of production time per year to the mill’s output. As this example illustrates, repetitive short-duration delays that are considered part of the process, or are considered minor issues, can be a gold mine of productivity improvements.
Another gold mine can be found when production speeds are reduced because of equipment, process or procedural matters. Speed is the second factor in the OEE calculation. In my experience, both from managing plants and assessing them as a consultant, speed often can cause a major loss of productivity. In fact, in many of the plants I’ve assessed, speed losses were higher and eliminated more production than unplanned downtime. When a plant goes down, people notice, but when it slows down, there isn’t a big sense of urgency.
For example, we were asked to assess a crushing and conveying operation. Management was concerned about lost production equipment downtime caused. The assessment, however, showed that 15,000 tons per day were lost through planned and unplanned downtime, and that more than 16,000 tons were lost because of speed loss each day. Our investigation pointed out two primary reasons for the speed loss. The first was low load factors on the belts attributable to several operating factors, and the second was that the setpoint on the feeder belt was reduced manually whenever material was flowing to a particular stock pile.
The control system captured load factors and setpoint automatically, but the causes for the reduced production rates weren’t captured. While all production stoppages were routinely reviewed, slowdowns weren’t part of the daily review process.
“Gold is where you find it.” But successful miners know where to look and have the proper tools to get at the ore. So, in your search for improved productivity, calculate your plants OEE and map the losses. Then, dig into the data to uncover those nuggets hidden in repetitive small delays and production slowdowns. At the same time build a better foundation by improving the business process for equipment maintenance, process control and data capture. You’ll be rewarded with more golden nuggets of productivity than even Midas could imagine.