Table “Assessing the OEE Level” shows a scheme for assessing the level of control being exercised over the major equipment losses.

Level Item Level 1 (Losses are not even being monitored) Level 2 (Facts are being ascertained) Level 3 (Improvements, backed up by theory, are being implemented) Level 4 (Losses have been minimized)
1. Break- down Losses 1 Sporadic breakdowns have not been distinguished from chronic ones.
2 More breakdown maintenance is carried out than preventive maintenance.
3 Breakdown losses are high.
4 No Autonomous Maintenance system is in place. 5 The service life of parts varies widely.
6 The weak points of the equipment are not known.
1 Sporadic breakdowns have been distinguished from chronic ones.
2 The ratio of breakdown maintenance to preventive maintenance is about fifty-fifty. 3 Breakdown losses are still high.
4 An Autonomous Maintenance system is being installed.
5 The service life of parts is being estimated.
6 The weak points of the equipment have become obvious.
7 These weaknesses are being addressed through corrective maintenance.
1 A time-based maintenance system has been established.
2 The level of breakdown maintenance has fallen below that of preventive maintenance.
3 Breakdown losses have fallen to 1% or lower.
4 The Autonomous Maintenance system is working well.
5 The service life of parts is being extended.
1 A condition-based monitoring system has been established.
2 Preventive maintenance is predominant.
3 Breakdown losses are between 0.1% and zero.
4 The Autonomous Maintenance system is being sustained and improved.
5 The service life of parts is predicted.
6 New equipment is designed for reliability and maintainability.
2. Change- over Losses 1 The situation is uncontrolled, and everything is left up to the operators.
2 Confusion reigns, and changeover times vary widely.
1 Internal and external tasks have been separated, and standard procedures have been established for these.
2 Times still vary.
3 The next issues to address have been identified.
1 Ways of externalising internal tasks are being sought.
2 Adjustment mechanisms are well understood, and action is being taken to eliminate it.
1 Single-minute changeovers are common.
2 Adjustment has been eliminated, and defect-free products are now turned out from the word ‘go’.
3. Speed Losses 1 Equipment specifications are unclear.
2 No product- specific or machine-specific speed standards have been set.
1 Speed-loss-related problems (mechanical and quality-related) have been identified.
2 Tentative speed standards have been set for each product, and are being sustained.
3 Speeds are fairly consistent.
1 Mechanical and quality problems are being addressed.
2 Speeds have been set for particular products, and the causal relationships between speed problems and the structure of jigs, tooling, etc. are being determined.
• Relationships between product quality characteristics and the precision of each section of the equipment have been assessed.
3 Speed losses are low.
1 Improvements to the equipment have enabled it to operate at or above the speeds originally specified.
2 Definitive product- specific speed standards have been set and are sustained. 3 There are no speed losses.
4. Minor- Stop Losses 1 Everything is left to the discretion of the operators, and nobody knows how serious the minor-stop losses are.
2 The situation is unclear, and the location and frequency of the minor stops vary widely.
1 Minor stops are being quantified, with a focus on:
• Where the problems arise, and how frequently.
• The extent of the losses.
2 Phenomena are stratified and their mechanisms are analysed, and actions are being taken on a trial-and-error basis.
1 Minor-stop problems are itemised and targeted for countermeasures, with positive results. 1 Minor stops have been eliminated, making unattended operation possible.
5. Quality Losses (including startup yield losses) 1 Chronic quality defects are largely neglected.
2 Although some countermeasures have been devised, they are not proving effective.
1 Chronic quality problems are being quantified, with a focus on:
• How the problems arise, and how frequently.
• The extent of the losses. 2 Loss-causing phenomena are being stratified, the mechanisms by which they occur are being analysed, and solutions are being implemented.
1 Problems giving rise to chronic quality defects have been identified and addressed, with positive results.
2 In-process detection of quality defects is being researched.
1 Quality defect losses are between 0.1% and zero.

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