If you work in a structural steel fabrication shop, this probably sounds familiar: the model is done in Tekla, the order is in the ERP, and yet nobody on the shop floor can tell you where a given beam is right now, which heat it was cut from, or who welded it against which WPS. That information lives on paper, in spreadsheets and in chat groups. A manufacturing execution system exists to close exactly that gap.
What is MES? The short definition
A Manufacturing Execution System (MES) records and controls the execution of production on the shop floor: which operation, on which part, with which material, by whom, when, and with what result. If the ERP says what should be built and what it costs, the MES says what is actually being built right now and what state it is in.
The reference standard is ISA-95, which describes a plant in layers: level 4 is business planning (ERP), level 3 is manufacturing operations management (where MES sits), and the levels below are machine and line control. MES is the bridge between the office and the floor.
What does a manufacturing execution system actually do?
The classic MESA model lists eleven functions. For a steel fabricator, these are the ones that matter most:
- Product tracking and genealogy: every part is linked to its parent plate or section, its heat number and the mill test certificate (MTC).
- Dispatching: which parts go to cutting, drilling, welding or painting today.
- Shop-floor data collection: start and finish of each operation captured when it happens, not written from memory at the end of the shift.
- Quality management: inspections, NDT results, non-conformance reports (NCR) and corrective actions, all attached to the same part.
- Document control: welders work from the current WPS and drawing revision, not last month's.
- Performance analysis: progress reported from finished parts and tonnage, not estimates.
Why MES looks different in steel fabrication
Most "what is MES" articles assume high-volume, repetitive production. Structural steel isn't like that. A project has thousands of one-off parts, drawings change mid-job, and the client or inspector expects a full history for every beam and column. That shifts the priorities:
- Data comes from the model, not from typing. If someone has to re-key the part list from Tekla, errors are built in from day one.
- Heat-to-part traceability. When a material certificate is questioned, you need to know within minutes which parts came from that plate and where they are now. The same heat-to-part records are what a digital product passport for steel will be built on.
- Weld quality and records. WPS, welder qualification (WPQ) and NDT results must be tied to the part, so the manufacturing record book (MRB) at handover is generated, not assembled by hand.
- Working without internet. Large fabrication halls often have poor Wi-Fi. A system that stops when the network drops gets abandoned.
A real example: Fidar MES
At Fanpino we built an MES specifically for structural steel fabrication, called Fidar. Following one part through it makes the definitions concrete:
- Tekla to BOM: the model comes in through a Tekla plugin and the bill of materials is generated automatically. Importing the same model twice creates no duplicate; a changed model creates a new version. Details in Tekla to BOM without manual re-entry.
- Heat → material → part: for any part you can see which material and which heat number it came from.
- The shop floor, even offline: the floor app runs on tablets, keeps working when the connection drops and syncs later. We tested it in airplane mode. Why that matters: offline shop floor vs cloud MES.
- Quality linked to the part: WPS/WPQ, NDT, coating, NCR and corrective action are all attached to the part, and the MRB is built from that data. More in this article.
- Dashboards, planning and procurement: progress KPIs, production planning, nesting and material purchasing live in the same system, not a separate spreadsheet.
MES vs ERP in one paragraph
ERP is about money, orders, inventory and accounting, and usually works at the level of days or weeks. MES is about production itself, at the level of minutes and individual parts. They are not competitors: ideally the ERP hands orders to the MES, and the MES reports actual material use and progress back. For which one a steel fabricator needs first, see MES vs ERP for steel fabrication.
Common mistakes when rolling out MES software
- Starting with dashboards. A dashboard fed by manual entry is empty within two months. Get data flowing automatically from the source first.
- More work for operators. If logging an operation is harder than writing it on paper, paper wins. Floor screens have to work on a tablet, with gloves, in the local language.
- Rebuilding the ERP. The MES doesn't need its own accounting or inventory; it needs to exchange data with the ERP you have.
- Ignoring network outages. The first outage that stops the floor is the last day people trust the system.
- Big-bang go-live. Roll out in stages and let each one settle before the next.
FAQ
Is MES only for large plants?
No. Mid-sized, project-based shops that care about traceability and quality records benefit too, as long as the system starts simple and doesn't add work on the floor.
On-premise or cloud?
Both work. When project data is sensitive or the internet is unreliable, on-premise makes more sense. What matters more than where it runs is that the floor keeps working offline. If your shop also works around scheduled grid cuts, see planning a steel fabrication shop around power cuts.
How long does an MES rollout take?
It depends on scope. Start with the data spine (model import, BOM, traceability), then add the shop floor and quality. Trying to launch everything at once is the most common way these projects stall.
Where does AI fit?
AI only helps once clean, connected data exists. In Fidar the AI assistant came last and is read-only. Data first, AI after.
