Introduction
OEE is the abbreviation of Overall Equipment Effectiveness. It is a simple and practical production management tool. It has been widely used in manufacturing industries in Europe and the United States and in multinational enterprises in China. The equipment comprehensive efficiency index has become an important standard to measure the production efficiency of enterprises and one of the important means of TPM implementation.
This article introduces the connotation of OEE and the application value of OEE for production managers. If you are interested, let's read it together.

1. What is OEE?
Generally, each production equipment has its own theoretical capacity. To achieve this theoretical capacity, it is necessary to ensure that there is no interference and quality loss. OEE is used to show the ratio of actual production capacity to theoretical production capacity. It is an independent measuring tool.
 
OEE is composed of three key elements: availability, performance and quality index:
OEE=availability x performance index x quality index

Including:
Availability=operation time/planned working time
It is used to evaluate the losses caused by downtime, including any event that causes planned production downtime, such as equipment failure, shortage of raw materials and changes in production methods.
Performance index=ideal cycle time/(operation time/total output)=(total output/operation time)/production rate
Performance is used to evaluate the loss of production speed. It includes any factors that cause the production to not run at the maximum speed, such as equipment wear, unqualified materials and operator errors.
Quality index=good products/total output
The quality index is used to evaluate the loss of quality. It is used to reflect the products that do not meet the quality requirements (including reworked products).
 
The first application of OEE can be traced back to 1960, when it was used as a key measure of TPM (total production and maintenance). TPM is a factory improvement method. Mobilize employees' autonomy by mobilizing their ownership. So as to continuously and rapidly improve the manufacturing process level.

2. OEE calculation example
Suppose that the working time of a certain equipment is 8h a day, the pre-shift planned shutdown is 10min, the fault shutdown is 30min, the equipment adjustment is 35min, the theoretical processing cycle of the product is 1min/piece, a total of 400 products are processed in a day, and there are 20 waste products, so the OEE of this equipment is calculated.
According to the above
Planned running time=8 * 60-10=470 (Min)
Actual running time=470-30-35=405 (Min)
Effective rate=405/470=0.86 (86%)
Performance=400/405=0.98 (98%)
Quality index=(400-20)/400=0.95 (95%)
OEE=efficiency * performance * quality index=80%
In the above example, we only listed some causes of the event. In practical application, it may include any causes related to production. OEE can accurately tell you how efficient the equipment is, how much is lost in which link of production, and what improvements you can make.
 
Using OEE tools for a long time, enterprises can easily find bottlenecks that affect production efficiency, and improve and track them to achieve the purpose of improving production efficiency.

3. OEE and six major losses
All kinds of bad loss of the equipment will have a direct impact on the equipment.
 
Because loss in English means waste and loss, we call all kinds of reasons that lead to equipment downtime, failure, loss and other adverse conditions loss items, which specifically include:
1. Failure loss;
2. Die change and adjustment loss;
3. Loss of idling and suspension;
4. Deceleration loss;
5. Quality defects and rework;
6. Commencement loss, etc.
The purpose of reducing equipment loss is to improve the comprehensive utilization rate of equipment, ensure that the equipment does not produce defective products, and improve production efficiency. To reduce equipment loss, first of all, let's understand the six major losses of equipment.

Failure shutdown/loss refers to the loss of time caused by failure shutdown and the loss of quantity caused by defective products. Sudden and significant equipment failure caused by accidental failure is usually obvious and easy to correct; Frequent or chronic minor faults are often ignored or omitted.
Since accidental failures account for a large proportion of the total loss, many enterprises have invested a lot of time to find and avoid such failures. However, it is very difficult to eliminate these accidental failures.
Therefore, research on improving equipment reliability must be carried out. In order to maximize equipment efficiency, failure must be reduced to zero. Therefore, it is necessary to change the view that failure is inevitable in traditional fault maintenance.
The loss of replacement and commissioning refers to the loss caused by shutdown and waste products due to replacement and commissioning, which generally occurs when the production of one product is completed and the replacement and commissioning of another product is carried out.
In order to achieve the replacement in a single time (less than 10 minutes), the loss of the entire replacement time can be reduced by clearly distinguishing the internal replacement time (the operation can be completed after the machine is stopped) and the external replacement time (the operation can be completed when the machine is running), and by reducing the internal replacement time.
Idle and pause loss refers to the loss caused by a pause due to misoperation or a short pause when the machine is idle. For example, some workpieces block the top of the chute, causing the equipment to be idle; Due to the production of defective products, the sensor gave an alarm and shut down the equipment. It is obvious that this pause is different from failure shutdown, because production can be resumed by removing the blocked workpiece and restarting the equipment.
The deceleration loss refers to the difference between the design speed and the actual speed. The speed loss has a great obstacle to the efficiency of the equipment. It should be carefully studied to eliminate the difference between the design speed and the actual speed.
There are many reasons why the actual speed of the equipment is lower than the design speed or the ideal speed, such as mechanical problems and quality defects, historical problems or equipment overload. Generally, by revealing potential equipment defects, carefully improving the speed of operators can help solve the problem.
Quality defects and rework refer to the quality defects and rework in the production process caused by equipment failure. Generally, accidental defects can easily be eliminated by resetting the equipment to normal state. These defects include a sudden increase in the number of defects or other obvious phenomena. The causes of chronic defects are difficult to find, and are often omitted or ignored. Defects requiring rework also belong to chronic losses.
Start-up loss is the loss generated in the initial stage of production (from equipment startup to stable production). The amount of these losses varies with the stability of the process state, the maintenance level of equipment, fixtures and molds, and the proficiency of operating skills. This loss is large and potential. In actual production, it is generally considered that the loss of starting operation is inevitable without discrimination, so it is rarely eliminated.