| A | Production scheduling is one of least well understood elements of Lean transformations. Traditional ERP suppliers generally try to force-fit their Theory-of-Constraints (TOC) schedulers into a Lean mold.
However, TOC scheduling is only moderately effective in creating leveled production schedules to meet Lean objectives. TOC approaches simply cannot achieve the granularity to level production over shorter intervals (e.g., days, shifts). And they optimize on constraints, rather than on demand flow, yielding different outcomes.
Lean philosophy generally eschews automation in favor of visual methods. In many ways, automation is viewed as obscuring what lies in front of you on the shop floor. That said, there are important roles for automation in Lean implementations, particularly in the areas of Kanban management and production scheduling.
ERP vendors have been generally effective in implementing e-Kanban support; and their supplier network hubs are integral to an effective e-Kanban solution across the supply chain.
But most ERP vendors have not directly attacked the level scheduling challenge with Heijunka schedulers. As a result, the majority of Lean shops that have implemented level production schedules utilize spreadsheets to drive daily operating plans on the shop floor. In our research, we've concluded that the spreadsheet works effectively in limited Lean implementations, but tends to break down in large scale, enterprise-wide implementations; it's simply not a scalable approach for a variety of reasons.
We often see a confusion between "Flow" and "Lean" in the scheduling area. Lean shops are using the principles and practices derived from the Toyota Production System developed by in the late 1970s. Whereas flow-based production is based on a variation of this system, as developed by John Costanza and promoted by the John Costanza Institute (JCIT).
Because hundreds of manufacturers sent people to JCIT for education in his Demand Flow approach, the use of flow concepts and systems exist in a number of companies.
Flow and Lean share similar principles, but the execution differs. Lean scheduling is done with a Heijunka scheduling tool, while a Flow schedule is done with a demand-driven planning technique on a given pacemaker work cell. Both approaches are TACT (or demand driven), and both are designed to level production across the plant by scheduling a pacemaker operation, pull material with Kanbans, and reduce inventory and waste.
However, the Heijunka scheduling approach is visual and simpler to understand and execute. It simply factors the current tact and target inventory levels (in days) and then sequences the order of products in relationship to daily demand. The Demand Flow Technology used by JCIT considers resource constraints in its calculation for a given production line, which requires more complex calculation.
I am aware of only two software vendors who support a true Heijunka scheduling capability: Factory Logic and Pelion Systems. Both vendors have scheduling products that may integrate with other ERP systems, including certain ERP partner-certified integrations (e.g., both Factory Logic and Pelion are SAP-certified).
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