September 22, 2014
In a recent post we have explored how MES is the best suited for scheduling jobs at the shop-floor level. Also, how MES transforms the tactical plans and schedules, to operational plans and schedules which can be controlled and changed in real-time, thereby making scheduling more fact based, flexible and fast. Today we will explore the basics of operational scheduling and what comprises the process. We will also understand how the MES automates this process and makes it more proactive considering the dynamic environment a modern plant is exposed to.
To begin with, any production schedule needs a production process, a sort of model of the plant to be configured in the system. It is critical to define all possible components of the process including but not limited to- plant equipment, personnel and their specific details, capabilities and constraints. Then products may be defined, including their specs, material inputs, recipes, routing, etc. Next is to provide a work breakdown matrix defining each and every process activity, tasks, sub-tasks, resource matrices and resource processing times. Once a basic model of the process has been incorporated into the MES application, orders may be loaded in the application. It is important to highlight here that order definition and loading can be automated, as the MES application has the capability to interact with applications at the planning level such as the ERP and can access the required data directly from such an application. At this stage, production details may be added in terms of batch sizes, production priorities, quantities currently in the WIP, waiting to be released for production, finished goods in the logistics bay. Also at this stage, expected delivery dates may be provided for individual products in case of discrete manufacturing or for delivering a set amount of produce in case of process manufacturing. Once the master data is provided the system is ready to begin the activity of scheduling.
To generate a schedule it is extremely important to define an optimization criterion, as no application would be able to perform trade-offs which are common in a manufacturing plant without a clearly defined logic and priority. The optimization criterion which a plant’s management or even higher management may choose, could be any of the following or a combination or a priority as long as they don’t contradict each other- reduce overall cycle time, maximize resource utilization/uptime, maximize delivery date fulfillment, minimize process waste etc. We will explore these optimization criteria in greater details in a future post. Once the optimization criteria is set, an operational schedule may be generated using the MES schedule engine, which is an automated process which uses the application’s in-built logic to provide. Also, the criteria provided to generate the optimum schedule as per the current conditions of the plant and factors in the demand (from ERP), current orders in hand, resource availability (both material and machine), operator availability/ability, priorities, optimization criteria, recipes and routes defined.
Once a schedule is generated automatically, it may be fine tuned. Again, this activity may be performed manually, say in a case where an order needs to expedited due to the customer’s urgency/request or automatically in case of contingencies, such as machine breakdown or material unavailability. Many activities can be performed to edit the schedule manually, such as reset the optimization criteria, change priorities, lock an order schedule to be executed irrespective of changes in priorities/optimization criteria.
At this stage a decision may be taken to either continue with the current schedule along with the changes or regenerate the schedule if the conditions have changed drastically from when the schedule was first set. The schedule thus generated/re-generated and fine tuned can then be viewed as a whole and can be mapped against strategic KPIs and other pre-defined performance metrics, at this stage the schedule may be edited one last time or be considered ready for release. The prepared schedule may also contain instructions for operators/maintenance personnel, pre-defined as per a particular operation, product or recipe. Upon release, the schedule may automatically identify which stage of the process a product has reached and subsequently provide instructions to concerned personnel to further execute their tasks smoothly.
Once released, the schedule remains available to accommodate changes as they occur dynamically as the process is executed following the schedules. The MES application is intelligent enough to accommodate contingencies, as and when, they occur on the shop-floor and provide the optimal alternative considering the current set of conditions. Scheduling and re-scheduling the shop-floor schedule, becomes a much more easier and analytical task if an MES is used for the function and can lead to better more controlled operation than ever before. Some of the key advantages of scheduling through an MES could be- improved scheduling time, better more accurate decisions, better delivery commitments, on-time/as-promised delivery, improved reaction time, improved communication due to instant status updates, reduced mistakes, real-time updates. All the above benefits will thereby ensure better customer service and satisfied customers and a more efficient and well executed/controlled operation.
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IIoT Has a "Thing" for MES. Why IoT Platforms Won’t Replace MES for Industry 4.0
by Iyno Advisors and Critical Manufacturing