The overall equipment efficiency (OEE) is the ratio of the actual production capacity of the equipment to the theoretical capacity, and it is an independent measurement tool.

Generally, each production equipment has its own theoretical capacity. To realize this theoretical capacity, it must be ensured that there is no interference and quality loss. OEE is used to express the ratio of actual production capacity to theoretical production capacity. It is an independent measurement tool.

 

 

OEE is composed of three key elements: availability, performance and quality index:

OEE=Availability*Performance Index*Quality Index

in:

Availability = operating time/planned working time

It is used to evaluate the loss caused by the shutdown, including any event that caused the planned production shutdown, such as equipment failure, shortage of raw materials, and changes in production methods.

Performance index=ideal cycle time/actual cycle time=ideal cycle time/(operating time/total output)=(total output/operating time)/production rate

Performance is used to evaluate the loss in production speed. Including any factors that cause the production to fail to run at maximum speed, such as equipment wear, material failures, and operator errors.

Quality index = good product/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).

Another calculation formula for OEE

OEE=time operating rate × performance operating rate × qualified product rate

Among them, time start rate = start time/load time

However, load time = calendar working time-planned downtime

Start-up time = load time-failure down time-equipment adjustment initialization time (including the time spent in activities such as changing product specifications, changing tooling, changing tools, etc.)

Performance start rate = net start rate × speed start rate

And, the net operating rate = processing quantity × actual processing cycle / operating time

Speed ​​start rate = theoretical processing cycle/actual processing cycle

Qualified product rate = qualified product quantity / processing quantity

The global equipment efficiency OEE is a simple and practical production management tool. It has been widely used in European and American manufacturing and Chinese multinational companies. The global equipment efficiency index has become an important standard for measuring the production efficiency of enterprises. It is also a TPM (Total Productive Maintenance) is one of the important methods of implementation.

The first application of OEE can be traced back to 1960. Use it as a key metric for TPM (full production maintenance). TPM is a method of factory improvement. Arouse the autonomy of employees by mobilizing the spirit of ownership of employees. So as to continuously and quickly improve the manufacturing process level.

If the essential connotation of OEE is investigated, it is actually the percentage of theoretical time and load time used for processing in the calculation cycle. Please note that when expanding the OEE formula, there is

OEE = time operating rate × performance operating rate × qualified product rate

= (Starting time/loading time)×(processing quantity×actual processing period/starting time)×(theoretical processing period/actual processing period)×(qualified output/processing quantity)

= (Starting time×processing quantity×actual processing period×theoretical processing period×qualified output) /(load time×starting time×actual processing period×processing quantity)

Cancel the common factor of the numerator and denominator,

OEE = (theoretical processing cycle × qualified output) / load time = theoretical total processing time of qualified products / load time

This is the ratio of the actual output to the theoretical output during the load time.