Actually, this is one of my tasks during my internship period so I try to search more information related to my task.
Overall equipment effectiveness is a measure of total (complete, inclusive, whole) equipment performance–the degree to which the asset is doing what it is supposed to do. OEE is also a three part analysis tool for equipment performance based on actual availability, performance efficiency, and quality of product or output. OEE is used in two formats: “OEE data (information)” (the original intent) and a calculated “OEE percentage.”
1. OEE data (information) are quantified loss reasons categorized by specific equipment related loss types.
2. OEE percentage is a calculated relative comparison metric used for a specific equipment or process over a period of time.
OEE is an improvement tool. It answers the question ‘What do I have to do to increase capacity?”
OEE Percentage Formula
OEE percentages are useful when tracking and trending the performance effectiveness (reliability) of a single piece of equipment or single-stream process over a period of time. Using OEE for multiple aggregated assets is not a valid application of the formula. The following is a basic example of OEE percentage calculation.
OEE % = Availability % x Performance efficiency % x Quality rate %
Availability % = (Actual operating time ÷ Gross available time) x 100
Performance efficiency % = (Actual production rate ÷ Design production rate) x 100
Quality rate % = ((Total units produced – Defective units produced) ÷ Total units produced)) x 100
Why Measure OEE?
- Fast, effective feedback on equipment performance
- Leads to a greater understanding of the process
- Drives improvements by focusing on problem areas
- Avoids expense of purchasing new equipment before making proper use of existing equipment
What Data is Required?
- Time period, ex. 8 hr shift, 12 hr shift, 24 hr shift
- Planned losses, ex. Lunch, breaks, daily meetings, planned maintenance
- Unplanned losses, ex. Breakdowns, stoppage to lack of materials, stoppage due to lack of staff
- Output quantity, rejects, reworks, yield losses (including sampling losses)
- Rated machine speed, ex. Packs per minute
Meal breaks can be excluded from the planned losses, ex. A shift is 7 hr rather than 8 hr.
Using OEE Data and Calculation to Improve Equipment Effectiveness
An example OEE data (14 Major Losses) and OEE percentage calculations for one day (24 hours) of “Machine D” operation are shown below in Table 1. Note how the loss data is listed along with comments on the reasons for the loss.
Overall Equipment Effectiveness Timeline
Timeline illustrations of the concept and components of Overall Equipment Effectiveness losses are shown in Figure 1. These losses are adapted from the original Major Losses and OEE teachings of Seiichi Nakajima (www.swspitcrew.com/…/OEE%200206.pdf)
Williamson, 2006, Using Overall Equipment Effectiveness : the Metric and the Measure, viewed 16 November 2011, http://www.swspitcrew.com
Mardi, 2011, Overall Equipment Effectiveness.