The Toyota Production System on Software

Nonstock Production

Just-in-Time flow means eliminating the stockpiles of in-process inventory that used to be made in the name of economies of scale. The focus is on making everything in small batches, and in order to do this, it is necessary to be able to changeover a machine from making one part to making a different part very quickly. In software development, one way to look at set-up time is to consider the time it takes to deploy software. Some organizations take weeks and months to deploy new software, and because of this they put as many features into a release as possible. This gives them a large batch of testing, training, and integration work to do for each release. On the other hand, I expect the antivirus software on my computer to be updated with a well-tested release within hours after a new threat is discovered. The change will be small, so integration and training are generally not a concern.

Zero Inspection

The idea behind autonomation is that a system must be designed to be mistake-proof. There should not be someone looking for a machine to break or testing product to see if it is good. A properly mistake-proofed system will not need inspection. My video cable is an example of mistake-proofing. I can't plug a monitor cable into a computer or video projector upside down because the cable and plug are keyed. So I don't need someone to inspect that I plugged the cable in correctly, because it's impossible to get it wrong. Mistake-proofing assumes that any mistake that can be made will eventually be made, so take the time at the start to make the mistake impossible.