OEE (Overall Equipment Effectiveness)
WHAT IS OVERALL EQUIPMENT EFFECTIVENESS?
The gold standard for calculating manufacturing efficiency is OEE (Overall Equipment Effectiveness). Simply stated, it determines the amount of time spent producing that is genuinely profitable. An OEE of 100 percent indicates that you are producing only Good Parts as quickly and efficiently as possible, with no Stop Time. That means 100 percent Quality (only good parts) and 100 percent Performance (as quickly and efficiently as possible) in OEE terms.
OEE = availability x performance x quality
- Produced right product — performance
Performance = 100 x Total Product Quantity Theoretical Product Rate x Operating Time
Performance = (Ideal Cycle Time × Total Count) / Run Time
(1/Ideal Cycle Time) * Operating Time = Capacity
Total Parts Produced / Capacity = Performance(%)
- Produced in right way — quality
- Quality = Good Count / Total Count
(Total Parts Produced — Total Scrap) / Total Parts Produced = Quality(%)
- Produced in right time — availability — Availability = 100 x Operating Time Planned Production Time = 100 x (Planned Production Time — Downtime) (Batch Duration — Scheduled Time)
Availability (%) = Run Time(operating time) / Planned Production Time
*Shift Length — Planned Downtime = Planned Production Time
*Planned Production Time — Unplanned Downtime = Operating Time
Operating Time = (Planned Production Time — Downtime) Quality = 100 x Actual Product Yield (or Concentration) Target Product Yield (or Concentration)
— — — — — —
— — — -
NAT = Net Available Time (Scheduled Production Time — Planned Down Time)
NOT = Net Operating Time (Net Available Time — Unplanned Down Time)
IOT = Ideal Operating Time (Time to Produce All Parts at Rate)
LOT = Lost Operating Time Due to Production of Scrap or Non-Saleable Product
- Availability % = NOT / NAT * 100
- Performance % = IOT / NOT * 100
- Quality = (IOT — LOT) / IOT * 100
- OEE = (IOT — LOT) / NAT
— -
Availability is Run Time / Planned Production Time
Performance is Actual Cycle Time / Ideal Cycle Time
Quality is Good Products / Total Products Produced
— — -
Identifying the Six Major Losses :
One of the main goals of TPM and OEE initiatives is to reduce and/or eradicate the Six Big Losses, which are the most common causes of manufacturing productivity loss. The Six Big Losses are listed in the table below, along with how they apply to the OEE Loss categories.
- Breakdowns
- Setup and Adjustments
- Small Stops
- Reduced Speed
- Startup Rejects
- Production Rejects
