OEE Calculation differs with Manufacturing Processes Ranjith Kumar DSM July 16, 2019Measurement is one of the most toughest jobs in the production line. It needs a lot of effort to measure and analyse a production process in order to check the efficiency of production. Fortunately, OEE is the key production metrics, and you can easily calculate and apply it to any manufacturing processes. But the entire spectrum in fact deserves their own method of calculating OEE. In other words, OEE calculation differs with different manufacturing processes. This is because the manufacturing processes have varied ideal cycle time, production yields etc. The manufacturing process includesRepetitive manufacturingDiscrete manufacturingJob shop manufacturingContinuous processBatch processIt is very important to understand the process in order to apply the right form of the OEE Calculation for the right results. Hence, In this blog we capture the manufacturing process and their OEE Methods.Repetitive ManufacturingRepetitive manufacturing refers to the ongoing production of same production of same product for an extended period of time. The Quantity produced does not have a terminal value. Instead, the process targets a certain quantity for production in each successive period. This situation most commonly arises when an industry has a steady stream of orders that do not vary over time. OEE CalculationAvailability – The percentage of time that a machine is actually able to produce parts out of the total time that it should be able to produce parts. This number includes breakdowns, setups, and adjustments. The calculation for availability is simply the actual production time, including set up, out of the planned production time. Then it is necessary to set, time lost due to downtime through machine failure, lack of input materials, lack of operators, against the calculation.Availability = Runtime / planned production timeRuntime = planned production time – stop timePerformance – It is the actual achieved run rate against the ideal run rate for the machine. Since the repetitive manufacturing produces same products without expected variability, We should keep ideal run rate as constant. Consequently, the performance can be calculated as followsPerformance = (Total parts / operating time) / Ideal run rateQuality – It is the measure of good products divided by bad products.Quality = good parts / Total partsDiscrete ManufacturingDiscrete manufacturing is a order based production that is the production in individual production order. In other words, it is a production of distinct items.Therefore, we should measure Ideal cycle time as count (parts/time). OEE CalculationAvailability – It is the comparison of potential operating time and time in which the machine is actually making products.Availability = Runtime / Planned production timePerformance – It is the comparison of actual output with what the machine should be producing in the same time frame.Performance = (Ideal cycle time * Total count) / RuntimeQuality – It is the comparison of number of parts per product made and the number of parts per product produced that meet customer specification.Quality = Quantity of good parts / Total quantity madeJob Shop ManufacturingJob Shop is a type of manufacturing process in which a small batches of variety of custom products are made. In addition, this deals in customization and relatively small production runs.OEE CalculationAvailability – The planned downtime factor refers to schedule lapses, alloted breaks. In Job shop, some causes of downtime negatively affect OEE, but others do not. For example, if a machine is down for a long time, the operator can’t find the right tools to set up the machine which negatively affects OEE. But if a machine is idle, simply because it has no more work on schedule, though it is still available if it need. Therefore, depending on the situation, this may not have a negative impact on OEE.Performance – Generally to calculate performance, we require a standard “ideal” cycle time. But in the job shop nothing is standard. Instead of trying to apply a single ideal performance by machine we should apply only a unique ideal performance rating to each machine/part combination.Quality – Quality can be determined as good parts produced among the total parts produced.Batch ManufacturingBatch is the method of manufacturing where the products are made as specified groups or amounts within a time frame. Hence, Batch can go through a series of steps in a large manufacturing process to make the final desired product. But, there will be a pause between each step as a batch moves through. Therefore we need to calculate OEE differently. OEE CalculationAvailability – It is the operating time divided by planned production time. In addition, the operating time is the difference between planned production time and downtime. Further, the downtime occurred may be stop time or setup time. And also the planned production time refers to the time between a batch being scheduled and time it goes to a running state. Hence the availability can be calculated as followsAvailability = operating time / planned production timeOperating time = Planned production time – DowntimePlanned production time = Batch duration – Scheduled timePerformanceperformance = Total product quantity / (theoretical production rate * operating time)In addition, the rate is essentially an ideal throughput for each process unit in terms of capacity over time.Quality -We can determine quality by dividing the actual product yield from target product yield.Quality = Actual product yield / Target product yieldContinuous processContinuous Process is a flow production method used to manufacture, produce or process materials without interruption. Similarly, it is the production of undifferentiated products. we should measure Cycle time as flow (volume/time). OEE calculationAvailability – we can calculate it by dividing actual running time from time available for running.Availability = Actual running time / Time available for runningPerformance – Generally we should calculate performance by relating actual performance of equipment. But we cannot apply this metric to continuous process due to the varying performance of multiple equipments forming process chains. Hence we can calculate performance asActual Hourly rate / Average of Hourly rate overtimeQuality – We can calculate Quality by dividing good parts from total parts.Quality = good parts / Total partsGet your Daily Production report and OEE calculation automated completely with the Pace DPR.Talk to our experts to discuss about your requirements at your shop floor to improve your manufacturing productivity.