Unless your ERP system comes with an APS system this one is dead wrong. Solving scheduling problems with standard ERP/MRP logic is equivalent to trying to solve a three-dimensional problem with two-dimensional logic. In other words, it simply can’t be done in a timely manner.
Although this sounds like a good idea, it really isn’t. Very few ERP vendors, if any, had the skill set needed to develop and implement their own scheduling module, so they went out and bought an APS software company. A detailed explanation as to why this approach does not work can be found in the chapter that is titled “A Simplified History of ERP Systems” in The Little Blue Book on Scheduling.
The short answer is: even if they have successfully integrated APS into their ERP offering (and this is not a given), most ERP companies do not have the skill set to continue developing the APS system, and they lack the skill set to implement it properly. ERP companies like to deliver cookie cutter modules with some options. This approach does not work in the APS world where your system needs to work at a level of detail allowing you to model the real world you live in. If your schedule makes no sense to shop floor operators, they will not follow it and your APS system will be of no value to you.
Once again, this sounds like a good idea but it usually isn’t, and there is a chapter, titled “Excel, the False Messiah” in The Little Blue Book on Scheduling that gives a full explanation as to why this is not a good idea. The illusion that Excel gives you some control is quickly offset by the exorbitant amount of time it takes to keep the schedule current. Excel does not contain any of the built- in benefits that come with a good scheduling system such as a visual schedule, easy data integration, and the ability to use sequencing rules. If the schedule does not reflect current reality, then it is of no use to you.
Replacing complex ERP logic with Kanban and demand-based manual systems is very tempting, but of course, it has its limitations. Toyota themselves recognized the limitations of these techniques in a demand-driven business model. This is because manual systems do not give you the ability to plan around your capacity constraints. This becomes critical once the buffers of time and inventory have been removed from the equation. In most cases, an APS system will support and improve your lean initiative.