Variation: Enemy of Productivity
William A. Levinson, P.E., FASQ, CFPIM is the principal of Levinson Productivity Systems, P.C. He is an ASQ Certified Quality Engineer, Quality Auditor, Quality Manager, Reliability Engineer, and Six Sigma Black Belt, and the author of several books on quality, productivity, and management.
Luck (variation) is no lady and Kismet (fortune) is no gentleman, at least not in product and service realization activities. Variation is a form of what General Carl von Clausewitz called friction: "the force that makes the apparently easy so difficult," and "countless minor incidents, combine to lower the general level of performance so that one always falls short of the intended goal." Variation can wreak enormous havoc in manufacturing operations, and not just in the well-known context of variation in part dimensions. It can degrade operations management by adding cycle time and therefore inventory, and also complicate project planning. It is the reason that lines of irate customers back up at service desks that have, at least on paper, excess capacity. It is also why traffic jams appear out of nowhere during rush hour; all these issues are interrelated.
Once we understand the role of variation, however, we can identify it and often mitigate or remove its effects. Attendees will learn how to recognize the role of variation in all the listed activities, and also what off-the-shelf remedies are available.
Learning Objectives
- Variation is a form of what General Carl von Clausewitz depicted as friction; an aggregation of seemingly minor annoyances that undermine performance, and often fatally.
- Variation in product features is why supposedly interchangeable parts sometimes don't. Variation is reflected by process capability and performance indices, and it can be detected by statistical process control charts for range and standard deviation. W. Edwards Deming's Red Bead demonstration underscored the dysfunctional effects of penalizing or rewarding workers for bad or good results of variation.
- Variation in measurements complicates metrology and is the subject of gage reproducibility and repeatability (gage R&R studies). It makes it possible to reject good parts and accept bad ones. Guard banding can protect the customer from poor quality, at the expense of rejecting additional good products. The ideal is, of course, to have as little measurement variation as possible.
- Variation in processing and material transfer time is why, as demonstrated in Eliyahu Goldratt's matchsticks and dice exercise, it is not possible to run a balanced factory at full capacity without accumulating large bubbles of inventory. If this is happening in your factory, this is why; favorable variation does not offset unfavorable variation.
- This also is why traffic jams appear out of nowhere during rush hour; favorable variation in traffic flow does not offset unfavorable variation.
- Variation in task completion times can also cause projects to finish late because, again, favorable variation (such as one activity finishing early) does not necessarily offset unfavorable variation. The unfavorable variation can, in fact, create a new critical path where none previously existed.
- Goldratt's drum-buffer-rope (DBR) pull production system counteracts the effect of variation, and a protective inventory buffer accumulates only at the capacity-constraining resource (operation with the least capacity) or moving toward it.
- DBR is however just containment for the problems caused by variation. Henry Ford claims to have done what Goldratt proved "impossible" by running a balanced factory at 100 percent capacity, and the only way to do this is to remove all the variation from the system.
Who Should Attend
All quality practitioners operations managers, and production control managers.
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$200.00
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