The Little Blue Book On Scheduling

MES Limitations


This was another recognition that despite having their roots in MRP, ERP companies provided limited functionality for the people who actually did the day-to-day work of manufacturing.


The reality is that although MES systems filled a huge hole for the chemical industry, the pharmaceutical industry and other process industries, in general discrete manufacturers have not adopted them. I think there are two reasons for this.


Unlike APS systems, this was something that could be added to ERP systems and as a result many ERP vendors did add MES capabilities to their offerings.


Many discrete manufacturers thought that MES systems were too complex for their needs and either used the ERP module or they opted for simpler, less expensive ways of collecting data from the plant.


I think it is important here to explain why the ERP vendors did not just build their own APS modules. APS systems are difficult to develop because they must manage time constraints without using time buckets. The only way to do this is to create something called a scheduling engine. The power and flexibility of an APS system is directly related to the effectiveness of its scheduling engine and scheduling engines are very complex. In short they cannot be built quickly or with just database technology.


Planning and scheduling systems should reflect the things that make a business unique including strategic objectives.


As we all know, complexity has its problems and in my opinion many ERP vendors have lost sight of the basics. Apart from confusing their users, there are other, even more serious consequences to this strategy.

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