Leaderboard

Overall equipment effectiveness (OEE) is one of the most effective and commonly utilized tool in lean methodology and lean manufacturing. Importance of OEE lies in : 1.Identifying the source of inefficiency 2.Quantifying the degree of inefficiency 3. Labelling the quality of goods produced/service rendered OEE combines three factors namely -1) availability 2) performance 3) quality Ideal OEE score is 100%, meaning production of cent percent defect less products/process, at maximum speed possible, and with no interruptions/breakdown. The output emerging from Ideal OEE is called as planned output Availability: availability accounts for planned and unplanned breakdowns or interruptions. The unplanned fractions may be due to equipment failure, material shortage, manpower crunches, change over time etc. Availability can be calculated in different ways:- Availability= Runtime/Planned production time Where Runtime =Planned production time- breakdowns Gross output= Planned output- loss of output due to availability losses Availability Rate(a)= Gross output /planned output Performance: It takes into account the performance loss because of process operating at submaximal or slow speed and also accounts for small stops in between leading to loss of efficiency and sell optimal production. The probable causes of poor performance can be: - Low quality input material - Old equipments with wear and tear - Small duration stops, may be due to some minor jams or process congestion(Long duration stops are generally classified under availability domain) Net Output= Gross Output-loss of output due to speed loss Performance rate(p) = Net output/Gross output Quality: Quality accounts for any defects/scraps due to some flaw in any of the process. Valuable output= Net Output-loss of output due to scraps/quality issue Quality Rate(q)= Valuable Output/Net Output OEE=a*p*q Six Big Losses: The three types of major losses have been further subdivided to yield 6 types of big losses, that an organization is prone to suffer because of equipment/process related issues. -Availability loss: 1) Unplanned stops 2) Planned stops - Performance loss 1) Slow Cycles 2) Small stops - Quality loss 1) Production Rejects/scraps 2) Startup Rejects/scraps Ways of eliminating/mitigating the six big losses: - Availability losses: 1. Equipment failure: - Regular preventive maintenance of the instrument, with linkage to computerised maintenance system(CMMS) - Tracking the downtime - Investigating the reasons for each shutdown/downtime 2. Setup and adjustments: - Batch production instead of equipment delivering throughout the day, to minimize the retooling adjustments throughout day. - Single minute exchange of die(SMED): switchover/change from one process to another process in production in a single minute or single digit time frame, less than 10 minutes. - Performance losses: 1. Idling/Minor stops: - Prompt signaling and initiation of action - Patterns of performance loss, needs to be analyzed - Process standardisation 2. Speed reduction: - Adequate maintenance of equipment to prevent wear and tear and maintain the speed and efficiency - Continuous improvement by regularly looking for the ways to remove waste, inefficiency and improve operation - Quality losses: 1. Production rejects/process defects: - Direct inspection of the equipments and materials, providing regular maintenance. - If defects become overwhelming and routinely detected, then change of the equipment remains the best economically viable option in long run. 2. Reduced yields/start up rejects/scraps: - Usually predictable ones, sometimes an inherent part of the process and commonly attributed to setups, changeovers and initial warm up of equipments. Can be prevented by: - Reduced initial production- Production of small batches at startups, rather than large batches - Reduced Variation: maintaining uniform equipment settings, standard and uniform material quality in all batches and stringent quality control.