If a workstation upstream produces a bad part, you can just toss it out and grab another one from the pile.īut large amounts of WIP are costly. If a machine breaks down, the rest of the production line can keep going, because they’ll still have plenty of parts in the queue. If each workstation has a stack of parts waiting to be processed, it’s buffered from failures or problems that might slow down production. In some ways, large volumes of WIP are good. This is known as work-in-process, or WIP. The result is that mass production methods have a lot of partially completed work (parts made but not yet used, partially completed assemblies, etc.) floating around the system waiting to be processed. If I can shave a few seconds off assembly time by having a worker who does nothing but attach part A to widget B, I’m going to do it, and run enough parts through the line to justify their cost. If I have a heat-treat that can run batches of 400 parts, I’m going to try like hell to run 400 parts at a time. If I have a $5 million dollar press, I’m going to be damn sure to get my money's worth and keep it running 24/7 stamping out parts. Products are produced by increasingly specialized (and often increasingly expensive) machines and workers that need huge production volumes to spread their costs over. One problem with mass production methods is that they generate huge inventories. But continuous pursuit of scale eventually becomes counterproductive. Mass production methods are responsible for huge gains in efficiency, and huge drops in cost. This strategy, it should be clear, works. The greater your production volume, the more you can afford the high fixed costs of specialized machines and equipment, the more it’s worth it to capture small efficiencies by vertically integrating, the more you can take advantage of labor specialization by having workers do extremely narrowly defined jobs, and the greater volume discounts you can secure from your suppliers. The Toyota Production System was developed around these constraints, as a way of efficiently producing lower volumes of a wider variety of cars.īuilt upon a foundation of interchangeable parts and the assembly line, mass production is designed around achieving economies of scale by producing things in huge quantities. Even if the market could absorb the huge production volumes of US-style factories, post-war Japan had little capital available for building such enormous production facilities. By contrast, the Japanese auto market was tiny and highly fragmented, requiring small volumes of many different types of cars. The US methods were designed around producing cars by the millions - in 1950, Ford’s Rouge plant alone produced 7,000 cars a day. Toyota, originally a manufacturer of looms and textile equipment, wanted to produce cars, but felt that US-style manufacturing methods were unsuitable to the Japanese market. The Toyota Production System was developed as a response to the mass production methods of Ford and other US car manufacturers in the 1950s. Hopefully that will help us understand whether the methods might be applied to construction. So let’s take a look at exactly how the Toyota Production System works, and why it was an improvement over previous systems. Despite being one of the most publicized and discussed manufacturing techniques in existence, I’ve found that many explanations of the Toyota Production System seem to miss the heart of what it is and (critically) why it works. One of the most recent techniques for improving manufacturing efficiency is the Toyota Production System and its descendants (Just-in-Time, Lean, etc.). My takeaway from this is that if we hope to achieve the kind of productivity improvements in construction that manufacturing has seen, we need to go beyond surface-level understanding (“factories make things cheaper, so we’ll build buildings in factories”), and drill down to the exact mechanisms at work in an improving manufacturing process. And while it’s possible to build a building, and a profitable business, using factory methods, it hasn’t resulted in a quantum leap in construction efficiency - it often yields no cost improvement at all. Typically this means producing buildings in factories, instead of on-site by hand.

Folks have tried over and over again to make construction more efficient by applying lessons from manufacturing.

Toyota production system