Following my article on balanced vs. unbalanced lines, I have been refining my model for constrained based scheduling and with this additional insight, I’ve been able to tweak steps to improve its overall effect.
I have also extended the scheduling concept into a loading diagram that easily shows where potential conflicts exist within the schedule, using the constraint as not only the pace setter, but also as the trigger to feed new work into the process. If you get the urge to load the available capacity on the non-constrained steps with additional work to maximise step efficiency, fight it. Balancing each step of the process will result in excess WIP and won’t improve throughput. Remember, you can only deliver the capacity of the constraint.
This unbalanced process has an amazing effect in reducing the WIP levels in the process and also reducing actual manufacturing lead time. The reduction of WIP makes it easier to control product quality, housekeeping and GMP and importantly, provides available time in the non-constrained steps of the process to focus on those tasks traditionally regarded as non-value adding. What we forget is, specifically in the Pharmaceutical industry, and increasingly in food and FMCG industries is that the final product is not able to leave our warehouse until all compliance requirements are satisfied. This in turn results in congestion, lost sales, affects cash flow, constrains working capital and reduces return on investment (ROI)
In order to support this approach, we need to align both our scheduling and our performance measures. Scheduling becomes an interactive function, with the scheduler being an actively involved in the daily events in the production departments. Monthly schedules are compiled to reflect the commitments for a specific financial period, and this is then broken down into weekly buckets for easy management. The objective of the monthly schedule is twofold, firstly to ensure that we can meet phased demand (Customer service and overhead recovery) and secondly as the basis for the monthly performance measure. The weekly buckets are generated from this schedule, and are adjusted at a specific time each week, in order to ensure that the following week’s schedule takes slippage into account. The cut off date allows the department time to set up and publish shift rosters, and for staff to make the necessary transport arrangements to and from work. Each week must have a realistic schedule that guides the production team and also for short term measures.
Performance measurement happens at 2 levels, Weekly measures show our performance against the short-term schedule, and the monthly measure shows consistency and highlights opportunities for lasting improvements. Using either of these on their own will cause us to believe we are better than we actually are (weekly measures), or also result in lost improvement opportunities (monthly measures)
Business and Manufacturing theories can become overwhelming, and it is easy to get lost in the mathematical or statistical models that underpin them.
Our natural tendency is to avoid them and carry on in the best way we know how, or to use parts without understanding the impact on the whole. Failure then reinforces the belief that they are too academic or simply don’t work in the real world. We have found that using select parts of these theories in conjunction with one another provides a simple approach to compliant productivity and will enhance your performance and continuous improvement drives, whether driven purely from a financial or compliance need, or part of an organization development initiative.