Manufacturing execution systems (MES)
A manufacturing execution system (MES) dispatches work to stations, records what happens on the shop floor as it happens and reports it back to planning and ERP.
Its users are operators and team leads working in minutes and shifts, often standing, with gloves, on shared terminals.
Key facts
- In the ISA-95 model, MES sits at level 3, manufacturing operations management. ERP sits at level 4, business planning and logistics.
- MES supports current execution and shift-level work, while also retaining history and supporting longer-term analysis.
- Typical MES input is scans, machine signals and short forms.
- Interruptions in connectivity are expected on the floor, so offline work needs a visible sync state.
- MES screens designed with ERP density are a common mistake.
What it covers
An MES covers execution: which job runs at which station, what the operator records at each step, and what goes back to planning when the step ends. How it differs from ERP, MRP and WMS is described in ERP, MES, MRP and WMS: how do they differ?.
Typical MES screens:
- A station view organised around the job running there
- Operation steps with checklists, instructions and run controls
- Downtime capture with a short, well-ordered reason list
- Shift handover as an explicit step
- A supervisor view of deviations: steps open too long, resources down, jobs that will miss the shift
Who uses it
| Role | Horizon | What they need |
|---|---|---|
| Operator | Current step | What am I doing, against what, and what do I record |
| Team lead or supervisor | The shift | Deviations, blocked steps and late jobs, on a tablet on the floor and on a desktop |
| Planner | Days to weeks | What was produced, consumed and scrapped, reported back to planning |
The screens for each role are described in Role-based production interfaces.
What makes it hard to design
The floor environment. Gloves, noise, variable light and shared terminals set the physical rules: large targets, visual confirmation and fast sign-in. See Scan-first input with manual fallback.
The record structure underneath. Scheduling, shop floor terminals, costing and traceability all read from the work order and job structure. Status held only at order level hides a blocked step, and consumption recorded against the order breaks the trace.
The floor works through network interruptions, and operators need to see whether their entries have reached the system.
Common mistakes
- A downtime reason list of forty options. Operators pick the first plausible one, and loss analysis reflects the order of the list.
- MES screens with ERP density. Operators working in minutes get a planner’s screen.
- Planning and execution on one screen.
- No visible sync state. Entries made offline look recorded when they are not.
Sources: ISA, ISA-95 standard