OEE – Overall Equipment Effectiveness...
Information | Understanding | Best Practice.
Measurement of OEE (Overall Equipment Effectiveness) is based on understanding the “Availability”, “Performance” and “Quality” of an item of process equipment (or other asset under review) and the “Planned Production Time”.“Planned Production Time”.
The “Planned Production Time” is “all time” less the time that there is no intention to run a process.All time is effectively, 24 hours per day, 7 days per week, 365 days per year. Such a measure is normally calculated in hours or seconds, depending on the process being measured, for example, in a high volume process producing thousands of product per day, then the measure can be in seconds of available time, if however, the process is much lower volume then “all time” might be measured in hours.
The times where there is no intention to operate a process is known as the “schedule loss time” and could include night closure, annual plant shutdowns, weekends where there is normally no production, breaks for lunch, etc.).
“Planned Production Time” = “All time” minus the “Schedule Loss Time”
Availability:
Measures the uptime of an item of process equipment versus the planned production time. The uptime is determined by subtracting the total of all downtime events which happened during the planned production time. The downtime events include planned and unplanned downtimes.Planned downtimes include activities such as machine set-up, changeovers, end of process clean-up time, and other getting ready & shutting down activities.
Unplanned downtimes include events such as equipment failures, tool replacement due to tool failure, material shortages, material changes, labour shortages.
The actual amount of time a process is operating minus the downtime events, provides the “run time” of the process equipment.
Availability = Run Time / Planned Production Time
Note:
Run time = The amount of time an item of process equipment is operational.
– Overall Equipment Effectiveness (OEE)
– Visual management
– Flow layout
– Kanban control
– 5S method of control
– Levelled scheduling
– Etc. Etc..
Information | Understanding | Best Practice >>>
Performance:
Measures the throughput of a process versus the optimal throughput. It is a measure of how fast the process is operating versus the potential capability of the process. Performances losses will include events such as running an item of process equipment at a reduced speed, equipment idling, minor stoppages.Performance = (Ideal Cycle Time * Total Count) / Run Time
Note:
Ideal Cycle Time – The fastest theoretical possible time to manufacture one component of output
Total Count – The total number of component outputs produced, includes units of output that do not meet requirements over the period under measurement.
Run time – The amount of time an item of process equipment is operational.
Quality:
Measures the level of acceptable output from an item of equipment. To determine the quality measure, you need to determine the quality losses. Quality losses include, scrap, rework, repair, or any reason where output does not meet the required standards.Quality = Good Count/Total Count
Note:
Good Count – The total number of component outputs produced, that fully meet requirements over the period under measurement.
Total Count – The total number of component outputs produced, includes units of output that do not meet requirements over the period under measurement.
There are two widely applied methods of measuring OEE, a relatively simple approach (option #1) and a more complex approach (option #2). For an organization starting to utilize OEE, the simple approach may be more than sufficient. As with any such measure, the method of measurement, is often not key, what is key to continuous improvement, is consistently in measurement, combined with continuous application and improvement.
OEE Measurement – Option #1
OEE = (Ideal Cycle Time* Good Count) / Planned Production TimeNote:
Ideal Cycle Time – The fastest theoretical possible time to manufacture one component of output.
Good Count – The total number of component outputs produced, that fully meet requirements over the period under measurement.
Planned Production Time – Is “all time” less the time that there is no intention to run a process.
Example:
Consider an item of processing equipment operating 2 * 8 hour shifts, where 1000 units of output are produced each hour. Output quality is recorded at 98% good, i.e. 980 acceptable units of output each hour. In theory, when the item of equipment was installed, it was designed to produce one unit of output every 3 seconds.
One hour equals 3,600 seconds.
The above information summarized is:
Planned Production Time = 57,600 seconds ( 16 hours * 3,600 seconds per hour)
Ideal Cycle Time = 3 seconds
Total Good Count = 15,680
OEE = (Ideal Cycle Time* Good Count) / Planned Production Time
= (3 * 15,680) / 57,600
= 81.25%
OEE Measurement – Option #2
OEE = Availability * Performance * Quality.“Lean” & “Just-In-Time”.
– Basic working practices
– Total Productive Maintenance
– Design for manufacture
– Set-up reduction
– Operations focus
– Total staff involvement
– Overall Equipment Effectiveness (OEE)
– Visual management
– Flow layout
– Just-In-Time Supply
– Pull scheduling & Push systems of control
– Kanban control
– 5S method of control
– Levelled scheduling
– Etc. Etc..