By HERB LICHTENBERG, Senior VP Practice Director for Production
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 fix 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 horse-power steam engine and everything had to go through that one mill. On this occasion one of the two piston rods fatigued and 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 implementing a 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) will not 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 that are taken for granted or considered part of the process.
In the same complex I managed above, 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, 7 minute delay and was considered a necessary part of the process because the steel had to be cut to length after being rolled. In our daily meetings it was hardly ever mentioned, even though we lost an average of 255 production hours each year for that single reason. 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.
Remember the fuss over the broken piston shaft which caused 61 hours of downtime? Well, the saw change was just considered a part of the process and did not get much attention. However, the guy whose job it was to sharpen the saws saw the waste. By 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. 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. Look at the minor stops your plant incurs. There may be a wealth of productivity to gain with some very simple solutions.
Another gold mine of productivity improvement can be found when production speeds are reduced due to equipment, process or procedural issues. Speed loss is the second factor in the OEE calculation. In my experience, both from managing plants and assessing them as a consultant, it can very often be a major loss of productivity. In fact, in many of the plants I have assessed, speed losses were higher and lost more production than unplanned downtime. When a plant goes down, people notice, but when it slows down, there isn’t that sense of urgency that is present when all production has stopped.
For example, we were asked to assess a crushing and conveying operation. Management was concerned about lost production due to equipment down time. The assessment, however, showed that 15,000 tons per day were lost due to planned and unplanned downtime and that in excess of 16,000 tons per day were lost due to speed loss. As our investigation pointed out, there were two primary reasons for the speed loss. The first was low load factors on the belts due to several operating factors and the second was that the set point on the feeder belt was manually reduced whenever material was flowing to a particular stock pile. The load factors and set point were automatically captured by the automated control system, but the causes for the reduced production rates were not captured. While all production stoppages were routinely reviewed, slowdowns were not part of the daily review process.
Here is another example of the hidden productivity improvement opportunities that can be found in speed losses. We were asked to assess the operation of a beneficiation plant to determine if there was unrealized capacity. The plant bottle neck was considered to be the two primary grinding circuits. Again, equipment availability was thought to be the primary cause of lost production. Our assessment showed that there was indeed unrealized capacity and that the average daily losses due to equipment availability were 3,900 tons per day.
However, the extent of the lost production due to speed loss came as a surprise to management. It was found to be in excess of 4,000 tons per day. As in the previous example, the automated control system captured the speed data and we were able to determine that speeds were reduced for weight, motor load and manual reduction of the set point. However the data regarding the reason for these speed reductions was not captured in any systematic manner. Anecdotal evidence pointed to down-stream problems as the cause of the manual reductions in speed but those reasons were also not captured.
“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 will be rewarded with more golden nuggets of productivity than even Midas could imagine.