Ten Minutes. How Bad Can It Be?
At 10:23 AM on a Tuesday, a conveyor motor trips on a Tier 2 automotive stamping supplier outside Detroit. The line goes down. Maintenance is called. By 10:33 AM, the motor is reset and the line is running again.
Ten minutes of downtime. The maintenance tech marks it as a minor electrical fault. The supervisor logs it in the system. Life goes on.
Except that ten minutes cost the facility somewhere between $8,000 and $40,000 — depending on the line, the customer, and what was in the production queue. And the facility's operations manager probably doesn't know that.
Here is how to calculate it — and why the number matters more than most leaders realize.
The Direct Cost: Lost Units
Start with the simple math. If your line runs at 120 units per hour and it's down for 10 minutes, you've lost 20 units. At a typical Tier 2 margin of $18–$35 per unit (depending on part complexity), that's $360–$700 in direct lost production.
That number alone probably doesn't alarm anyone. A $500 loss is manageable. But this is where most downtime cost calculations stop — and where they go wrong.
The Indirect Costs That Nobody Tracks
Labor idle cost If 12 people are on that line and they're standing idle for 10 minutes, you've burned 2 hours of labor. At $28/hour fully loaded (wages plus benefits plus overhead), that's $56. Small. But it's real money that produced nothing.
Recovery labor cost After the line restarts, the team doesn't instantly return to full speed. There's a ramp-up period — typically 5–15 minutes for a cold restart, depending on the process. You've lost another 10 minutes of partial output. Add another $25–$40.
Overtime exposure If that line had a committed shipment due at end of shift and the 10-minute stoppage pushed you behind, you may need to run overtime to recover. At time-and-a-half for 12 people for one hour, that's $504 in additional labor cost — for a ten-minute event.
Customer expediting cost In a JIT automotive supply chain, your customer's assembly plant is running on your parts. A shipment that arrives 2 hours late because you were recovering from a downtime event may trigger an expedited freight charge — $800–$2,500 for a spot truck. That charge almost always falls on the supplier.
Line scheduling disruption In facilities running multiple SKUs across shared equipment, a 10-minute stoppage forces a reschedule. The next job's setup time is compressed. Changeover quality suffers. You may see a spike in scrap rate for the first 50 units after restart. If scrap runs at 4% normally and jumps to 9% for the first 100 units post-restart, that's 5 additional scrap units — at full material cost, not just margin.
The Hidden Cost: Tier 1 and OEM Relationship Risk
This is the cost that never appears on a P&L but is arguably the most significant.
Automotive OEMs and Tier 1s track supplier delivery performance meticulously. Most use a score — IATF compliance, on-time delivery percentage, PPM (parts per million defect rate) — that directly affects your position on the approved supplier list and your eligibility for future sourcing awards.
A 10-minute downtime event that causes a late shipment can drop your on-time delivery score from 98.2% to 97.9%. That fraction-of-a-percent movement might seem cosmetic. At the next sourcing review, it's the difference between being invited to bid on a new platform and being told your business is going to a competitor.
No spreadsheet captures that cost. But it's real.
Building a True Downtime Cost Model
To understand what downtime actually costs your facility, build a model with five inputs:
- ◆. **Units per hour at target rate** — your true line speed, not the theoretical maximum
- ◆. **Margin per unit** — the contribution margin, not gross revenue
- ◆. **Labor on the line** — headcount × fully-loaded hourly rate
- ◆. **OT exposure** — what percentage of downtime events lead to overtime recovery
- ◆. **Customer impact probability** — based on your schedule buffer and shipment frequency
Run this model for your three most common downtime causes. You will almost certainly find that one or two categories of downtime — equipment failures, material shortages, or changeover problems — are responsible for the majority of your true cost.
That's where to invest in prevention.
Why Tracking Downtime in Real Time Changes the Math
The operators in most facilities know when a line goes down. What they often don't know is the pattern — which equipment fails most often, which shift sees the most downtime, which products are most frequently interrupted.
Without that pattern data, maintenance resources are allocated by squeaky-wheel logic: the equipment that broke most recently gets the most attention. Real-time downtime tracking shifts the logic to data-driven prioritization: the equipment with the highest annualized downtime cost gets the preventive maintenance investment.
The difference between reactive maintenance and preventive maintenance at an automotive supplier typically represents 15–25% of total maintenance budget — money that goes from fixing failures to preventing them.
See how OpsOS tracks this in real time → [Book a Demo](https://opsos.pro/#contact)
Related: [OEE Explained for Plant Managers Who Don't Have Time for Textbooks](/blog/oee-explained-plant-managers) | [How Detroit Auto Suppliers Are Losing $50K/Month Without Knowing It](/blog/detroit-auto-suppliers-losing-money)
Frequently Asked Questions
QWhat is the full cost of a 10-minute downtime event at an automotive supplier?
A 10-minute downtime event can cost between $8,000 and $40,000 when you include direct lost production, labor idle time, recovery labor, overtime to meet shipment commitments, expedited freight charges, and increased scrap rates during restart. Customer relationship risk adds additional long-term cost.
QHow does downtime affect automotive supplier scorecards?
Downtime that causes late shipments directly impacts on-time delivery scores tracked by OEMs and Tier 1 customers. Even fractional decreases in delivery percentage can affect supplier status and eligibility for future sourcing awards.
QHow should I build a downtime cost model for my facility?
A downtime cost model needs five inputs: units per hour at target rate, contribution margin per unit, fully-loaded labor cost on the line, overtime exposure rate, and customer impact probability based on schedule buffer and shipment frequency.