Overall Equipment Effectiveness (OEE)

Measures the percentage of scheduled production time that equipment is actually running. This factor accounts for downtime losses—both planned and unplanned.

• Calculation: (Run Time / Planned Production Time) × 100
• Captures: Equipment failures, setups, adjustments, and material shortages
• World-Class Target: > 90%
• Key Distinction: A machine waiting for material is just as unavailable as a broken one. Availability exposes the gap between calendar time and actual operating time.

Measures how fast equipment runs compared to its theoretical maximum speed. This factor captures speed losses and minor stops that prevent reaching ideal cycle times.

• Calculation: (Ideal Cycle Time × Total Parts Produced) / Run Time × 100
• Captures: Slow cycles, operator inefficiency, minor jams, and idling
• World-Class Target: > 95%
• Key Insight: A machine running at 80% of its design speed for an entire shift loses 20% of potential output—even if it never stops. Performance isolates the velocity gap.

Measures the proportion of produced units that meet specifications on the first pass. This factor captures defect losses and rework.

• Calculation: (Good Parts Produced / Total Parts Produced) × 100
• Captures: Scrap, rework, startup rejects, and in-process damage
• World-Class Target: > 99.9%
• Critical Nuance: Reworked parts count as defects in the OEE calculation. Only parts that pass inspection the first time without any correction are considered good. Quality reveals the hidden cost of imperfect output.

OEE is the product of its three components, providing a single metric that represents the proportion of fully productive manufacturing time.

OEE = Availability × Performance × Quality

• Example: 90% Availability × 95% Performance × 99.9% Quality = 85.4% OEE
• World-Class Benchmark: 85% is considered world-class for discrete manufacturing
• Typical Range: Most factories operate between 40-60% without a formal improvement program
• Multiplicative Effect: A weakness in any single factor drags down the entire score. An 85% OEE means 15% of potential output was lost to downtime, slow cycles, or defects.

OEE provides a structured framework for categorizing all manufacturing productivity loss into six distinct buckets, each mapped to a specific OEE factor.

Availability Losses:

• Unplanned Stops: Equipment breakdowns, tooling failures, unplanned maintenance
• Planned Stops: Changeovers, setups, preventive maintenance, cleaning

Performance Losses:

• Minor Stops: Jams, misfeeds, sensor obstructions cleared in under 5 minutes
• Reduced Speed: Worn equipment, operator inexperience, suboptimal parameters

Quality Losses:

• Startup Rejects: Defects produced during warm-up or after changeover
• Production Rejects: Steady-state scrap and rework during normal operation

This taxonomy transforms abstract inefficiency into specific, addressable problems.

The first pillar of OEE, measuring the percentage of scheduled production time that equipment is actually running. It accounts for downtime losses caused by equipment failures, unplanned maintenance, and extended setup or changeover periods.

• Calculated as: Run Time ÷ Planned Production Time
• A score of 100% means the process ran continuously during the planned window without any stops
• Common detractors: unplanned breakdowns, material shortages, prolonged changeovers

The second pillar of OEE, quantifying how fast equipment runs compared to its ideal cycle time. It captures slow cycles and minor stoppages that don't trigger downtime tracking but erode throughput.

• Calculated as: (Ideal Cycle Time × Total Count) ÷ Run Time
• Accounts for reduced speed losses and small, frequent interruptions
• A machine running at 80% of its design speed due to wear or suboptimal settings directly reduces this metric

The third pillar of OEE, representing the proportion of good units produced relative to total units started. It isolates losses from defects, rework, and yield reduction during startup or steady-state production.

• Calculated as: Good Count ÷ Total Count
• Includes units requiring rework, which consume capacity without adding value
• Startup rejects from a cold machine warm-up phase are a classic quality loss captured here

A foundational framework for categorizing all equipment-related productivity waste, directly mapping to the three OEE components. Identifying and quantifying these losses is the first step in targeted improvement.

• Availability Losses: Equipment Failure, Setup & Adjustments
• Performance Losses: Idling & Minor Stoppages, Reduced Speed
• Quality Losses: Process Defects, Reduced Yield (startup scrap)
• This structured taxonomy prevents vague problem statements and enables data-driven root cause analysis

A related metric that measures OEE against all available calendar time (24/7/365), not just scheduled production hours. It exposes the hidden capacity lost to poor planning, lack of orders, or seasonal shutdowns.

• Calculated as: OEE × Utilization
• Utilization is the ratio of Planned Production Time to Total Calendar Time
• A high OEE with low TEEP signals significant untapped capacity due to market or scheduling constraints

A variant metric that measures performance against total operating time, which includes both scheduled and unscheduled time but excludes periods when the factory is intentionally idle. It bridges the gap between OEE and TEEP.

• Provides a more realistic view of asset utilization in demand-constrained environments
• Useful for benchmarking plants with different shift patterns or seasonal demand profiles
• Often used alongside OEE to separate operational excellence from commercial planning effectiveness