In the steps of implementing TPM comprehensive productivity maintenance at the enterprise, the assessment of overall equipment performance (or OEE for short) is always focused. So what is OEE and how is OEE calculated? The following article will answer for businesses who want to learn about this parameter.
I. What is I. OEE?
Overall equipment efficiency is the most popular standard in the world to measure the productivity and operating efficiency of a machine and equipment as a percentage. OEE helps businesses identify problems with equipment usage and maintenance, determine the % of productive time, and is a standard metric for tracking progress in fixing these problems. Accordingly, a 100% OEE score represents perfect performance: that is, no downtime, smooth and fast production, quality products.
II. How to calculate OEE:
OEE is given based on 3 factors:
- Availability: operating rate over time
- Performance: Value representing the performance (speed, continuity) of the device calculated from the operating speed performance and actual performance
- Quality: Ratio of the actual number of OK products produced to the total amount of inputs (materials)
1. Availability
Availability takes into account factors that affect the usability of a machine, including all factors that could affect planned production for a substantial period of time (usually a few minutes or so) longer) such as unplanned stops (such as equipment failures and material shortages) and planned stops (such as transition times).
It is calculated using the formula:
| Availability = (Theoretical running time – Machine downtime) / Theoretical running time |
You can come across this formula as replacing (Theoretical Operating Time – Machine Downtime) with Machine Run Time
2. Performance
Performance
takes into account performance loss or degradation, including all factors that cause production equipment to operate at less than its maximum possible running speed (including Slow Cycles and Small Pauses).
It is calculated using the formula:
| Performance = (Number of products x Cycletime) / Theoretical running time – Machine downtime |
In there:
Cycletime or ideal cycle time is the theoretically fastest time to produce a product in minutes. This parameter is usually measured and calculated by different complicated methods, depending on the type of equipment. Cycletime when multiplied by Total Produced Theoretically gives the Ideal Total Production Time, which is the theoretically fastest time to produce the specified total number of products.
Here is a simple example of how Performance is calculated:
| Product | Value | Explain |
| Ideal cycle time | 1 minute | The fastest theoretical time to manufacture this product. |
| Gross product | 300 | Total amount of product produced in this shift. |
| Machine Run Time | 330 minute | Total running time of a working shift |
| Efficiency | 90.9% | (Ideal cycle time × Total products) / Run time machine = (1 × 300) / 330 |
3. Quality
The quality ratio is used to consider the quality of non-guaranteed products (NG goods) that do not meet quality standards, including later reworked products.
Quality is calculated by the formula:
| Quality = Total qualified products / Quantity of qualified products + Quantity of goods |
In the simplest terms, the OEE concept is the ratio of Effective Production Time to Planned Production Time. In fact, the score is calculated as follows:
| OEE = Availability x Performance x Quality |
As such, OEE takes into account all the losses (Stop loss, speed loss, and quality loss) during machine operation, creating a truly efficient measure of production time.
III. OEE scale and rating levels
The concept of OEE is effectively used both as a benchmark and as a baseline measure.
- When used as a benchmark, OEE is used to compare the performance of a production device with industry standards or to compare performance across different shifts on the same piece of equipment.
- When used as a baseline, OEE is a metric that helps to track the efficiency of a manufacturing device over time while eliminating waste.
When seen as a kind of benchmark, what does OEE mean?
A 100% OEE score represents perfect production performance: no downtime, smooth and fast production operations.
For manufacturers with an OEE score of 85%, those are world-class manufacturers. This is also the long-term goal for many ambitious manufacturing enterprises.
For businesses with a score of 60%, this is a typical sign when your production system needs to improve a few points to achieve a good performance score.
However, there are also many businesses that only achieve an OEE score of 40%. This result is an alarm bell for this business that needs to immediately start monitoring and improving its production efficiency. A score of 40% is a low score, and most companies can easily improve their score through simple measures, such as monitoring the cause of downtime and addressing each cause from a large extent. smallest to smallest)
IV. What are the factors affecting the OEE index?
A highly efficient factory with high productivity will have a high OEE. On the other hand, a low OEE indicates that the factory has many hidden tasks along with underutilized resources that are generating losses. Here are the major losses that increase OEE:
- Stoppage due to machine failure – Loss of stopping function or deterioration of machine function.
- Installation and Adjustment – Loss related to the operation of installing machinery to change, adjust production operations.
- Replacement of parts and equipment – Loss related to the change of equipment that wears out over time in the production operation.
- Start-ups and shutdowns – Loss of speed and output when starting and shutting down machinery.
- Intermittent and Idling – Loss of running capacity due to minor problems, unspecified timing, or idling.
- Speed Loss – The loss in machine speed (ton/hour) when the machine is not running at its design capacity.
- Scrap and remanufactured – It is the loss of damaged and unusable products and the loss of time and cost to repair and rework that product.
- Planned shutdown – Planned shutdown (Power outage, machine stop to PM, stop machine to eat rice…). This loss does not affect the overall performance of the equipment but reduces the production time leading to a decrease in the production output of equipment and processes.
V. Application of iMAG production management software to optimize OEE
iMAG is a smart factory production management software developed and copyrighted by VULETECH. VULETECH is a factory automation solution company with more than 12 years of experience in successfully deploying management software systems for manufacturing enterprises.
iMAG is a comprehensive production management support solution that contributes to the complete digitization of production activities. iMAG provides end-to-end visibility into manufacturing operations, allowing managers to: identify areas for improvement in both product design and related manufacturing processes, and implement Make the necessary operational adjustments for smoother and more efficient production.
In each factory, the iMAG solution enhances overall equipment performance and production capacity through machine maintenance scheduling. iMAG supports strict control of equipment operation status, from which businesses can develop appropriate maintenance plans, help businesses proactively produce production resources, optimize monitoring of equipment and machinery, and improve equipment maintenance. Improve efficiency in the maintenance of production equipment, thereby avoiding the impact of unexpected machine breakdowns as well as eliminating waiting time due to machine failure.
Vu Le Technology Company Limited – specializes in industrial automation equipment, factory automation solutions and robotics.
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Hotline: (028) 3620 8179 / 3620 8176 / 3620 8177
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Mail: info@vuletech.com
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