Automating the wrong station buys inventory, not throughput

If the station you automate is not your constraint, you have not bought more output. You have bought a faster way to make work in process pile up somewhere else.

A plant owner calls because the palletizing station at the end of a line is manual and two people are stuck there. Reasonable problem, obvious solution. Then we ask what the line actually produces against what it is rated for, and it turns out the filler upstream jams several times a shift and the real output is less than half the rating. Those two people are not slow. They are waiting.

Automating that palletizer would be a perfectly good project that produces no additional output whatsoever. The cases still arrive at the rate the filler allows. What changes is that two people are freed, which may well be worth doing on its own, but it is a labor decision rather than a throughput decision and it should be justified as one. Anybody who sells it to you as a throughput project is either not paying attention or hoping you are not.

This matters because the two justifications carry very different numbers. A labor case is bounded by what those people cost and whether they have somewhere more valuable to go. A throughput case is bounded by what additional output is worth, which is usually much larger. Confusing them is how a project gets approved on one set of arithmetic and judged on another.

The test is not complicated. Walk the process and ask, at each station, whether it is waiting for work or whether work is waiting for it. Stations that are usually waiting are not your constraint. The one where work piles up in front is. Automate that one, and everything downstream gets busier. Automate anything else, and the pile just moves.

There is a version of this that is genuinely worth doing anyway. If the constrained station cannot be automated, taking labor off an unconstrained one and redeploying those people to the constraint can help. But that is a deliberate decision made with open eyes, not an accident discovered six months after installation.

And sometimes the honest answer is that your money is better spent on maintenance than on a robot. If a jamming filler is costing you half your rated output, fixing it will almost certainly pay back faster than any cell we could sell you. We would rather tell you that and keep the relationship than sell you a robot that solves the wrong problem.