Mean Time to Repair
MTTRMean Time to Repair (MTTR) is the average time required to fix a failed piece of equipment and return it to service.
Mean Time to Repair (MTTR) is a maintenance key performance indicator (KPI). It measures the average time spent performing a repair on a machine after a failure occurs. The clock for MTTR starts when a technician begins the repair work. It stops once the equipment is fully operational again. This metric specifically tracks the efficiency of the repair process itself.
On the shop floor, a low MTTR indicates that maintenance teams can diagnose and fix problems quickly. This minimizes production downtime and its associated costs. A high MTTR can signal issues. These may include a lack of trained technicians, unavailable spare parts, or poor diagnostic tools. Tracking MTTR helps managers identify bottlenecks in their maintenance workflow.
Manufacturers implement MTTR tracking through a Computerized Maintenance Management System (CMMS) or a Manufacturing Execution System (MES). Technicians log the start and end times for each repair in a work order. The system then calculates the MTTR for specific assets, departments, or the entire plant. Analyzing this data helps justify investments in technician training, spare parts inventory management, and improved standard operating procedures for repairs.
A stamping press failed four times in one quarter. The individual repair times were 2 hours, 4 hours, 3 hours, and 3 hours. The total maintenance time was 12 hours, so the MTTR for that press is 3 hours (12 hours / 4 repairs).
What is considered a good MTTR?
A 'good' MTTR varies by industry and equipment complexity. The goal is not a specific number but continuous improvement to reduce the average repair time.
Does MTTR include the time spent waiting for a technician or parts?
No. MTTR measures only the active repair time, from when work begins to when the machine is operational. Total downtime includes waiting periods.
How is MTTR different from MTBF (Mean Time Between Failures)?
MTTR measures the time to repair a failure (maintainability). MTBF measures the time between failures (reliability).
What are the most common ways to reduce MTTR?
You can reduce MTTR by improving technician training, creating clear repair procedures, and maintaining an organized inventory of critical spare parts.
Can a low MTTR be a bad thing?
Yes, if it comes from rushed, low-quality repairs that lead to repeat failures. The focus should be on efficient and correct repairs, not just speed.
Mean Time Between Failures
MTBFMean Time Between Failures (MTBF) is the average time a piece of equipment operates before it breaks down.
Downtime
Downtime is any period when a machine or production line is scheduled to run but is not producing goods.
Preventive Maintenance
PMPreventive Maintenance (PM) is regularly scheduled work performed on equipment to lessen the likelihood of it failing.
Computerized Maintenance Management System
CMMSA Computerized Maintenance Management System (CMMS) is software that organizes, schedules, and tracks all maintenance activities for a facility's equipment.
Overall Equipment Effectiveness
OEEOverall Equipment Effectiveness (OEE) is a metric that measures manufacturing productivity by combining equipment availability, performance, and quality.