“The machine was down for two hours” can mean it was broken, or that nobody had loaded it. Those are different problems, owned by different people — which is why the two words are worth keeping apart.
Side by side
Can the machine run?
- Downtime
- No
- Idle time
- Yes
Typical causes
- Downtime
- Breakdown, alarm, crash, broken tool
- Idle time
- No material, no operator, waiting for first-off
Usually owned by
- Downtime
- Maintenance
- Idle time
- Production planning and supervisors
Shows up in
- Downtime
- MTBF and MTTR
- Idle time
- Utilization and scheduling
| Downtime | Idle time | |
|---|---|---|
| Can the machine run? | No | Yes |
| Typical causes | Breakdown, alarm, crash, broken tool | No material, no operator, waiting for first-off |
| Usually owned by | Maintenance | Production planning and supervisors |
| Shows up in | MTBF and MTTR | Utilization and scheduling |
Why the split matters
Lump them together and the biggest number goes to the wrong team. A machine that sat for an hour waiting for blanks, logged as “down”, sends maintenance to look at a perfectly healthy machine — while the real cause, the material flow, stays untouched.
Kept apart, the two numbers each point somewhere: downtime to reliability work (see MTBF and MTTR), idle time to planning and staffing.
Telling them apart automatically
ThingConnect reads alarms from the controller. A stop with a critical alarm open is recorded as alarm time; a stop without one — or with only an alarm you’ve marked as non-critical, like a door warning — is recorded as idle. Handling time after each part is carved out separately, so normal loading doesn’t count as either.
Idle stops can then be given a reason, which is how “idle” turns into “waiting for material: 40 minutes”. See downtime tracking.