Machine downtime reason codes for CNC shops (ready-to-use list)

The list above as a free downtime log: one row per stop with the time it stopped and restarted, the reason from a dropdown, and the minutes, group and breakdown-or-pause filled in for you. A Summary sheet adds the month up by group and by machine and works out breakdown count and MTTR (mean time to repair).

A report is only as good as the reason column. With sixty codes, operators tap the first plausible one and the top reason becomes “other”. With eight groups and two or three reasons each, the choice is obvious at a glance — and the weekly report can be read at the group level (setup vs tooling vs material) before drilling into a reason.

Word every reason the way the operator experiences it. The operator hears spindle noise; the engineer later finds a bearing. Ask for the noise; record the bearing as root cause afterwards.

A pause is the operator’s call and ends when they tap resume. A breakdown is a fault: it should alert the supervisor and owner immediately, hold the machine in the down state until someone clears it, and carry a root cause and corrective action afterwards. That gives every breakdown a start, an end and a person who confirmed it — which is what makes a downtime report believable. This is how downtime tracking in OpeEye treats the two.

Rank the week’s minutes by reason. The top line is next week’s project — usually a setup group reason or “waiting for material” in a job shop. Fix it, watch the ranking for two weeks, take the next line. OEE moves because availability moves; availability moves because the top reason shrank.