Shigeo Shingo, the granddaddy of lean thinking industrial engineers once wrote, “Time is the shadow of motion” and a lot of other things that sound more cryptic than they should thanks to the wonders of inadequate translation. Nonetheless there’s deep wisdom in the words he left us in his many books words, much of which he gained while working as a consultant at Toyota alongside Taiichi Ohno and his disciples in building up key parts of what became the Toyota Production System.
We could say that “Motion is the shadow of information” although Shingo meant human motion as part of manual work, where I mean movement of goods, or more properly what should be called transportation or conveyance. To avoid any confusion, we will go with “Conveyance is the shadow of information.” Motion may in fact be the shadow of information, something we can explore another time. Conveyance in the broadest sense includes roller devices which use gravity to move items, conveyors and which use electrical power, pallets of goods moved by forklifts powered by gas, automated storage and retrieval systems, trucks moving stacked pallets of goods, trains, ships, airplanes, and blimps someday again hopefully before too long.
Transport of goods does not add value. It uses time and energy but does not create value. Yet there is a very specific set of terms, concepts and tools related to logistics within TPS to enable the overall production system to function. It may seem odd to build systems around conveyance, which is one of the seven types of waste along with defects, overproduction, motion, waiting and inventory. None of the other wastes receive this treatment in quite the same way, with the possible exception of inventory as a subset of a logistics system. This should tell us something about conveyance. There is an important difference. Although it does not add value by transforming the form or function of a a product, we could say that conveyance does change the location of the item in a way that is value added to the customer. Of course we could also say that the customer does not want to pay for the transportation cost, but neither would everyone like to have the producer of every good and service they consume literally next door in today’s industrialized consumer society. So conveyance, transportation, distribution and logistics is here to say. We might as well learn to lean it.
The conveyance system within a warehouse or factory should be considered not as a necessary evil or a wasteful cost to be eliminated through automation. The proper way to understand conveyance is as the reflection of information flow as physical goods. Certainly the aim of any system is to deliver what the customer wants at the speed, cost and and quality that they want. Conveyance as an activity should be minimized whenever it does not improve safety, quality, delivery or cost. But to skimp on the development of the conveyance system because it is adding effort in an inherently non value added process is equivalent to saying “inspection is a waste, let’s get rid of it” without fully understanding what it takes to have a system of built in quality, which very much relies on checking one’s work and the existence of a QA department to perform audits on the product and the process.
The conveyance system can only be as good as your information flow. Without a properly constructed conveyance system, it is impossible to check on the speed and accuracy of your information flow. Lovers of SAP and digital dashboards may argue differently, but it’s a question of speed and accuracy my friends. A big assumption I am making here is that lean conveyance (production and movement) is triggered by a pull linked to the customer. SAP may be a better push conveyance management system, but I don’t implement push so who knows. The more material, locations and touches you have within a well-constructed conveyance system, the more room for improvement you have in your information. Material is created and moves because of information in the form of instruction. Instruction comes from planning, which comes from either customer orders or a release based on a forecast. All of this is information. This information has a far greater cost impact on a company than anything that happens in on the warehouse or factory shop floor. Without a strong conveyance system this information is invisible. It’s data, not facts, and while we can defend with data, we can only properly manage by fact.