mean time between assist
**Mean time between assist** is the **average operating time between operator interventions that recover the tool without full maintenance failure events** - it captures automation interruptions that erode throughput even when hard downtime stays low.
**What Is Mean time between assist?**
- **Definition**: Elapsed productive time divided by number of assist events in a period.
- **Assist Examples**: Robot recovery, cassette re-seat, transient sensor reset, or minor jam clearance.
- **Difference from Failure Metrics**: Assists are short interruptions, not full breakdowns requiring repair work orders.
- **Automation Relevance**: High assist frequency limits lights-out operation capability.
**Why Mean time between assist Matters**
- **Hidden Productivity Loss**: Frequent assists consume labor and create micro-stoppages not visible in MTBF alone.
- **Staffing Impact**: Low MTBA increases operator attention burden and reduces line efficiency.
- **Stability Indicator**: Improving MTBA usually reflects better controls and hardware tuning.
- **Quality Link**: Repeated assists can correlate with handling defects and process variability.
- **Scalability Constraint**: Poor MTBA prevents reliable unmanned or low-touch operation.
**How It Is Used in Practice**
- **Event Coding**: Log assist types distinctly from maintenance failures for clean analytics.
- **Pareto Review**: Rank top assist modes by frequency and cumulative interruption time.
- **Corrective Programs**: Eliminate recurring assists through hardware fixes, recipe safeguards, and operator standard work.
Mean time between assist is **a critical metric for real automation maturity** - raising MTBA reduces labor interrupts and unlocks more stable high-volume operation.