Lean Waste 5: Over-processing
Eradicating Waste: The 7 Muda (+1 for the road)
Imagine this. A conveyor belt sends manufactured goods to a workstation. At that work station are two workers, one picks widgets from the end of the belt, the picker, another who packs it, unsurprisingly called the packer. There is a backlog of this inventory before the packer’s station, which as we’ve seen previously in this Lean Waste series is wasteful. However, the rationale given is each person is only doing one thing.
There are several problems here and one which illustrates a particularly common problem. That lean principles can manifest in conflicting advice in the floor when you don’t know what to look for.
Firstly, the person at the conveyor belt who picks off the item isn’t taking the item that far. Indeed, it’s within arms length of the second person. The next thing you can see is the backlog of items before the second person, showing they’re now a bottleneck. Thirdly they are picking up an item put down for them anyway! Which is the real problem with motion (up and down waste as much as traversing the plane of manufacture). If they’re picking it off the belt, they can just put it in the box directly.
The issue here is two-steps when a value increment only occurs after one. The last one to be precise. In essence, over-processing adds the widget’s context switch cost, which is a negative number, to the value chain without adding a corresponding value increment. Given the distance it has to travel; the multiple ‘pick up’ and ‘put down’ steps (two including into the box) and the backlog of items, you’d do well to turn the workstation 90 degrees and have the workers work in parallel, also eradicating the extra ‘pick-up, put-down’ cycle.
Tip: Find bottleneck with more processing steps than you have value increments in the your value chain. They are either two separate increments or you’re over-processing.