What is OEE?
The main purpose of OEE, which means ‘Overall Equipment Effectiveness’ in Turkish, is to control and analyze the machinery and equipment in your company to increase their performance. It helps you spot a problem in your operations, determine what percentage of production time is truly productive, and fix outages (interruptions) and breakdowns; it provides you with a standard measure for tracking progress.
To increase your production efficiency, the main goal is to reduce or completely eliminate the most common causes of loss of productivity based on machinery or equipment, called the six major losses. These six losses are divided into three main OEE categories as ‘Usability’, ‘Performance’ and ‘Quality’.
- Equipment failure: Those are the failures caused by planned or unplanned outages during your production. Machine breakdowns, unscheduled maintenance downtimes, and tool failure are common examples.
- Setup and Adjustments: Those are production outages due to changes, machine and tool adjustments, scheduled maintenance, inspections, and setup/warm-up time.
- Idle running and short outages: These are the times when your equipment stops for a short time. It can be caused by jams, flow obstructions, incorrect settings or cleaning. These problems are usually solved by the operator.
- Low speed: Your equipment is operating at slower speeds than the ideal cycle time (the fastest possible time). Worn or poorly maintained equipment due to poor lubrication practices, poor quality materials and poor environmental conditions are common causes of low speed.
- Process defects: It refers to any defective part that leaves our production, including scrapped parts and parts that can be reworked. Incorrect machine settings and operator or equipment errors are common causes of process defects.
- Low efficiency: It refers to the defective parts initially made until stable production is achieved. Like process defects, this can mean scrapped parts and parts that can be reworked. Decreased efficiency is most often caused by changes, incorrect settings and machine warm-ups.
OEE and Efficiency
There are multiple ways to measure your manufacturing efficiency with OEE. When calculated and interpreted correctly, it can significantly maximize your production.
– An OEE score of 100% is considered excellent production; that means you produce only quality parts as quickly as possible, with no downtime.
– An OEE score of 85% is considered world-class for manufacturers and is preferred for a long-term goal.
– An OEE score of 60% is common among manufacturers and indicates that the manufacturer needs significant solutions for improvement.
– An OEE score of 40% is considered low, but is not an abnormal rate for manufacturers who are just starting to monitor and improve performance.
In most cases, a low score can be easily improved with easy-to-implement measures!
We can list the standard OEE criteria required to take these measures as follows;
Target: Real-time production target,
Fact: Actual production number,
Efficiency: Ratio of target to reality; the percentage of how far ahead or behind production is,
Outage duration: It includes all unplanned downtimes for each shift and is updated in real time,
Full productive time: Production time after all losses are subtracted,
Planned production time: The total expected time of your equipment or system during production,
Ideal cycle time: The time required to produce a part,
Uptime: The time your system is scheduled and running for production,
Total count: The sum of all manufactured parts, including those with defects,
Good count: Production of parts that meet quality control standards,
Good parts: Parts that meet the standards and do not need to be remade,
Quality: It refers to manufactured parts that do not meet quality control standards, including those that need to be reworked. It is calculated as Quality = Good count / Total count.
Performance: It considers the number of slowdowns or short outages in production. An excellent performance score in terms of OEE means your process is running as quickly as possible. It is calculated as Performance = (Ideal cycle time X Total counts) / Running time. Availability (Usability): It considers planned and unplanned downtime. A perfect availability score means your operation is consistently running within planned production times. It is calculated as Availability = Uptime / Planned production time.
There are two main ways to calculate OEE in order to monitor the increase in your production efficiency and control your progress;
- Simple calculation: The easiest way to calculate OEE is the ratio of full productive time to planned production time.
OEE = (Good count X Ideal cycle time) / planned production time
- Preferred calculation: OEE Calculation is based on the three OEE factors discussed earlier as below. This is the preferred method of calculation because not only does it show how well you did your OEE score, but you also get three factors of what is causing your losses. (availability, performance and quality)
OEE = Availability X Performance X Quality