MES on the shop floor: from paper shifts to OEE

At most plants I walk into, shop floor data exists in three versions that do not agree: the foreman’s log, the section head’s report, and the chief engineer’s memory. Each version is true in its own way. None of them can carry a decision about money.

Why OEE is more honest than the plan

OEE — overall equipment effectiveness — is the product of three factors: availability (how long the machine could actually run), performance (how fast it ran against the standard), and quality (what share of output was good). Its value is not the absolute number but the fact that you cannot improve it with a story. If availability drops, the machine stood still, and the next question is why.

A plan is either met or missed. OEE tells you where the time went, and that is the only conversation that produces a work list.

Why paper keeps winning

The paper log beats software on three counts: it is always at hand, it works with gloves on, and it forgives. A foreman records a stoppage in one line instead of picking from a twenty-item dropdown. Any system slower than paper at data entry gets filled in at the end of the shift from memory — and you end up with beautiful data unrelated to reality.

MES does not start with sensors

The most common mistake is starting with equipment. Sensors go in, data flows, and then nobody can agree whether a changeover counts as downtime and whose downtime it is. MES starts with two reference lists.

• A single operations list. One operation, one name across the whole plant. While two shops call the same thing differently, there is nothing to consolidate.
• A downtime classifier. The key artefact of the entire project. Fifteen to twenty causes grouped by area of responsibility: equipment, material, people, planning, external. Go past twenty and the foreman starts picking “other,” and the meaning is gone.

Three stages that actually work

1. Manual entry. A tablet or kiosk on the floor, a stoppage logged in two taps: cause and duration. The goal is not precision but habit — and testing the classifier against a live shift.
2. Semi-automatic. Operation start and end come from the system; the human confirms and explains deviations. This is where the first honest OEE numbers appear.
3. Sensors. Signal taken from the machine where it pays for itself. By now you know which stoppages cost the most, so sensors go there rather than everywhere.

What not to do

• Don’t automate the chaos. If the operation standard is not agreed, automated performance figures become a disputed number and people negotiate instead of working.
• Don’t punish the first honest numbers. The moment low OEE costs someone their bonus, OEE becomes high. The data dies in week one.
• Don’t compute OEE for the whole plant. An average across shops hides the bottleneck. Measure the critical equipment.
• Don’t drop paper on day one. Two weeks in parallel is the price of trusting the new numbers.

What the first honest month gives you

Usually an unpleasant but useful picture: a large share of losses turns out to sit not in breakdowns but in changeovers, waiting for material, and shifts that do not hand over cleanly. That is good news — organisational losses are removed faster and cheaper than worn-out equipment. But you only see them once a stoppage stopped being a line in a notebook and became a record with a cause and a timestamp.