OEE - A Perfectly Imperfect World? Manufacturers invest time and effort in continuous improvement. This usually focuses upon operations, where the reality of everyday events is all too clear. The popular tool that is used, once early day successes have been obtained, is OEE (Overall Equipment Efficiency). Benchmark figures are obtained and improvements made that are measured as improvement in OEE. Even though it is accepted that OEE is a measure rather than an absolute target, it is nevertheless good to achieve the fabled 85% which represents ‘world class’, but does the story end there, or are manufacturers measuring an imperfect world? OEE is a good measure and where acquired automatically with automatic reporting can produce valuable insight into many issues that occur in operations, both day to day and over the longer term. However, the business will not be measured externally by OEE. Externally, the business will be measured by OTDiF (On time delivery in full), which is, given quality to specification, a prime factor in customer satisfaction. OTDiF will be assisted by high OEE as will schedule adherence, but would further improvements be made if attention was made to the disparity between the scheduler’s ‘perfect’ world and the reality of operations? A manufacturing paradox It is theoretically possible to have high OEE and very low schedule adherence, as OEE has no component to measure ‘are we making the correct product today?’. Making the correct product meaning according to the schedule, which, if isolated from operational realities, will be closer to a theoretical wish list rather than what
can be manufactured today, given today’s constraints. Constraints include absence from work by key operational staff, equipment breakdown, ‘hard to make’ products, difficult changeovers, tooling shortages, raw material shortages and many other issues that are the imperfect domain of operations. Integration of scheduling and operations by data driven technology can produce a seamless regime where the realities of operations will become known to the scheduler who can then adapt, and even optimise, to those realities. Equally it will be possible for operations to ‘see forward’ into the future schedule and to make preparations.
A seamless operation Such a seamless regime will allow the scheduler to have detailed insight into ‘difficult’ products, lines (and operators and shifts) that perform better with certain products, and, above all, insight into difficult changeovers. Changeovers represent ‘wasted time’ in the seven wastes of the Lean Manufacturing model. Changeover times where manual data collection is used are frequently reported as the time that what was allowed rather than the actual time; another reason to automate data collection! Assuming that the scheduler has access to advanced production scheduling software, the identified difficult changeovers can be minimised by using ‘what if’ scenarios, which optimise changeovers by re-ordering production runs whilst keeping a watchful eye on ‘promised date’ for sustained customer satisfaction. Without such a seamless regime it is likely that ad hoc schedule changes will be made by operations to make their task more manageable, such activity is pragmatic but often adversely effects schedule adherence, OTDiF and the resulting customer satisfaction (but possibly transiently improves OEE). The rush order An additional benefit in having an integrated scheduling to operations interface is its ability to deal with a ‘rush order’. Most operations will have experienced a rush
order that arrives unexpectedly for many reasons from the downstream supply chain. Customer satisfaction, and profitability, demands a ‘yes, can do’, but how can that be slotted in to the schedule with adversely effecting existing promise dates? If the scheduler has the right scheduling tools and access to the status of the current schedule execution by operations, and access to ERP to ensure that raw material exists, then scenarios can be modelled to conveniently place the rush order into the existing schedule to deliver it, and all the other production orders, on time. Thereby enjoying the revenue of the additional business without eroding customer satisfaction elsewhere. Use something suitable The integration of scheduling with operations is frequently overlooked in manufacturing information programmes. Experience shows that there are readily available benefits to be obtained in such integration. Although early day attempts to achieve proof of concept may be undertaken with bespoke programmes it is recommended that, once functional requirements have been discovered, suitable data acquisition, information management, reporting and advanced planning & scheduling products are investigated, using this approach will bring forward the benefits to the business. Business value and beyond No estimate of potential ROI can be given in a general case but the tight integration of the perfect scheduling world and the imperfect operational world delivers manufacturing competitive advantage quickly and sustainably.
Implementation will require a close dialogue between the solution provider and the manufacturer’s improvement team, thereby keeping work within scope, but also noting additional beneficial activities that are usually revealed by actively discovering and investigating challenges. Evaluation of such a project’s benefits should be continuous to ensure sustainability and also to discover if more can be achieved from the original investment. Summary Integration of scheduling with operations avoids the apparently perfect world of the scheduler colliding with the imperfect world of operations. Schedules will be reliable and realistically utilise equipment and staff according to measured capability, supported by automatically acquired OEE measurements. The two functions can then work in harmony and available effort can be focussed upon more demanding subsequent stages of continuous improvement.
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