When evaluating robot maintenance, the price of the intervention is almost always what gets looked at. But the number that really matters is rarely calculated: how much each hour with the line stopped costs. And it's usually, by far, the highest cost in the whole equation.
What goes into the cost of a stoppage
It's not just 'the repair'. An unplanned stoppage drags several costs at once:
- Unproduced output: the units you stop producing and their margin.
- Idle labour: line operators unable to work.
- Deadlines and penalties: deliveries that slip, with possible contractual costs.
- Restart and quality: ramp-up time and possible scrap on resuming.
A simple estimate
A quick way to approximate it:
Cost/hour ≈ (units per hour × margin per unit) + hourly cost of idle labour + pro-rated penalties and restart.
Run the numbers with your real figures. For most lines, the per-hour result comfortably exceeds what an annual maintenance plan costs. That's the figure that justifies investing in availability.
Why a breakdown costs more than preventive
Preventive maintenance has a known, planned cost. The breakdown adds the repair cost plus the unplanned downtime. Preventive doesn't remove the risk, but it reduces it; and when the unexpected still happens, what makes the difference is how fast it's resolved.
How a contract reduces that cost
A maintenance contract attacks downtime cost directly:
- Guaranteed response time for breakdowns.
- Reserved critical-part stock for your models: the part isn't 'ordered', it's already there.
- Preventive visits that avoid much of the breakdowns.
- A single point of contact for ABB, KUKA and FANUC, without coordinating several suppliers.
What to look at when comparing contracts
Don't stop at the annual price: compare the response time, whether it includes parts stock, what the preventive covers and the traceability they give you of each robot. That's what determines how much your downtime risk really drops.
Frequently asked questions
How do I calculate the cost of an hour of downtime?
Unproduced output (units × margin) + idle labour + penalties + restart. Usually higher than it seems.
Why does a breakdown cost more?
Because the repair cost adds to the unplanned downtime, the highest component.
How does a contract reduce it?
Guaranteed response, parts stock, preventive and a single point of contact: it shortens or avoids the stoppage.