Most often when we think of a wheel, it’s in the context of transportation, one of the more obvious and ever-present of the 7 wastes. In fact, the first likely use of a wheel and axle was not for transport but for processing – actual work. According to the Smithsonian, the potter’s wheel dates to 3500 BC. The wheel and axle wasn’t used for human transport (chariot) for several hundred more years; and the idea of carting material apparently took several millennia after that! The wheelbarrow was invented around 100 AD in China, and it took another thousand years more for it to appear in Europe.
From a human standpoint these conveyance devices are designed to reduce strain. In a technical sense, it can be said they multiply our capability to do work; at least the force-times-distance kind of work: W= f x d. Problem is, that although conveying material on wheels is embedded in our thinking as an improvement over manual transport it’s actually a mechanization of waste. We may think the wheel has multiplied our ability to do work, but it really has multiplied the amount of waste we can create. Odd.
Over the centuries additional wheels were added to the basic cart, enabling conveyance of even more material with less work [sic] in a single trip. Then, in 1936, the invention of the shopping cart at Humpty Dumpty supermarkets became the prototype for more recent improvements to conveyance: A four-wheel, multi-level steel wire cart, this invention replaced a hand-carried basket, enabling shoppers to gather all groceries in a single pass. The shopping cart, however, also required wider aisles and larger checkout counters. Then the aisles were widened again, this time to accommodate pallet loading of the larger amounts of material needed to accommodate a new concept: EOQ. Why buy just a little, when you can have so much more in an economy pack? Carriages became larger still to accommodate bulk quantity shopping. All of these innovations were intended to make it easier for the customer to buy more – and, of course, to encourage them to buy more.
There are more than a few parallels in industry. AVG’s, pallet jacks, forklifts, and conveyors are all “improvements” on the basic cart. These machines typically require wider aisles, deeper and higher shelving, new training, and maintenance and, of course, more space to park the machines – kind of like the tail wagging the dog. Too often, rather than rethinking the cause of the waste, we automate around it. Shigeo Shingo referred to these as “superficial improvements.” An automatic guided vehicle (AGV) mechanizes the waste of transportation; or an automated storage and retrieval system (ASRS) facilitates the waste of storage. Worker strain may be reduced by a superficial improvement, but the actual waste remains and sometimes even increases. A stockroom manager, for example, lamented to me recently “I have less people now, but it takes longer to kit a job than when we did it manually. The machine is a bottleneck and the factory waits for parts.” Unfortunately, these expensive superficial improvements become sunk costs, hard to undo because they are depreciable assets. Thank you, management accounting.
One more insidious re-invention of the wheel is the stationery or almost-stationery wheel. To the casual observer, these are the wheels that are on the cart that appears as if it’s for transportation; actually, that cart never moves except to move it out of the way. Moveable storage becomes an option when material staged in front of a process has overflowed to a point that it must be staged in the aisles; funny that this is called “work in process.” Of all uses or abuses of the wheel, this one is tops on my personal list: the appearance of conveyance. We assume that if there is a wheel, then there must be movement. Mr. Shingo’s comment that the “The worst waste is the one we cannot see” comes to mind.
Here is an improvement exercise for you to try in your own facility: First take an inventory of carts and answer these questions:
What is the total number of carts?
What is the total floor space they occupy?
How many are actually used for conveyance?
How many are really only for storage or are kept on hand in case of storage overflow?
How can you reduce each of these numbers by half?
Please let me know how much production space you liberate.
PS GBMP, a licensed affiliate of the Shingo Insitute, is offering the following workshops in the coming months. The courses introduce the Shingo Model™ and Guiding Principles on which to anchor your current continuous improvement initiatives and to fill the gaps in your efforts towards ideal results and enterprise excellence. Consider joining us at an event near you soon. To read more and register visit http://www.gbmp.org/shingo-institute-courses.html
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