In short: the ERP keeps the company’s records: orders, invoices, stock, cost. An MES (Manufacturing Execution System) keeps a record of what happens on the shop floor, in real time: what is being made, from which batches, by whom, on which machine and with what result. They do not replace each other, they complement each other. The boundary between them is usually where data gets lost.
What the ERP does
The ERP is the office’s program: purchasing, sales, invoicing, accounting, stock by warehouse, cost. Many ERPs also have a production module, with recipes, production orders, material issues and finished goods receipts. For a small plant with simple processes, that module may be enough.
The limit shows on the shop floor. The ERP learns what happened after someone enters the data, usually at the end of the shift, the day or the month, from a form filled in by hand. For accounting, that is enough. For production, the information arrives too late and too summarised.
What an MES does
An MES works where things are made. Operators record operations on a tablet or terminal as they do them, and the system checks on the spot:
- that the material used is the one in the recipe and from the allocated batch, by scanning;
- that process parameters and in-process checks are within limits;
- that the machine is available, clean and checked;
- who did each step and when.
The result is the full history of every batch and a real-time picture of the department: which orders are in progress, where something is stuck, how much was consumed against the standard.
Where they overlap and where the flow breaks
The two overlap on recipes, production orders and consumption. The break usually happens in three places:
- Material issues: the ERP deducts materials from the theoretical recipe, not from what was actually used. The differences end up at stock-taking.
- The batch: the ERP knows raw material was consumed, but not from which batch and for which finished batch.
- Time: what happened at 10 a.m. is known the next day, when nothing can be corrected any more.
Signs the ERP is no longer enough on the shop floor
- Actual consumption becomes known only at stock-taking.
- When a complaint arrives, rebuilding a batch’s history takes days.
- Planning is done in a separate file, because the ERP does not see what is really in progress.
- Quality checks between stages stay on paper.
- The same data is entered twice: once on the form, once in the ERP.
- Customers or auditors ask for traceability by batch, and the answer is put together by hand.
How the two connect
| The ERP sends to production | Production sends back to the ERP |
|---|---|
| items and, where relevant, recipes | actual consumption, by batch |
| sales orders that require production | finished goods declared, with batch and quantity |
| raw material stock | losses and scrap |
| open purchase orders | the status of production orders |
The link is made via API, directly from the database or through files, depending on what the ERP allows. What matters is that each piece of information has a single place where it is entered.
MES, WMS and LIMS
Two more systems appear around production. The WMS, the warehouse software, keeps stock by location and the movements between the warehouse and the line. The LIMS, the laboratory system, keeps samples and test results. In small and mid-sized plants, all three can be modules of the same application, on the same database, which makes the links much simpler.
How to start
You do not have to digitise the whole plant at once. A path that works: the warehouse on scanning and batches, then a single production line with orders, consumption and checks in the system, then the other lines and planning. We described in detail what software for industrial manufacturing has to cover and, separately, the requirements of pharmaceutical production, where GMP rules change a lot.
Frequently asked questions
What does MES mean?
Manufacturing Execution System: the software that records and controls in real time what happens on the shop floor, from releasing the production order to the finished product.
Do I need an MES if the ERP has a production module?
Not necessarily. If processes are simple, batches do not matter and data can be entered at the end of the day, the ERP module is enough. An MES is justified when you need batch traceability, in-process checks or actual consumption.
Do I have to replace the ERP to have an MES?
No. An MES connects to the existing ERP, and each keeps its role: the ERP for documents, stock value and cost, the MES for what happens on the shop floor.
How long does an MES implementation take?
It depends on the number of products, lines and links to other software. Starting on a single pilot line greatly shortens the road to the first results.
At DataFlows we build production software on the same platform as the DataFlows Depo WMS and the pharmaceutical manufacturing system, connected to the ERP you already have. Tell us about your plant.
