What is MES? Manufacturing execution systems explained

What does an MES do?

In a shop that runs on paper travelers, spreadsheets or a whiteboard, the status of production is only as current as the last time someone walked the floor or collected the forms. An MES records that information while the work is done. When an operator starts, pauses or finishes a job, the time, machine, person and quantity are captured on the spot.

An MES typically tracks:

• Work orders and operations: which part goes through which steps on which machine, and which step it is at now.
• Times: planned and actual run time, setup time, waiting.
• Downtime: when, for how long and why a machine stopped.
• Counts and scrap: good and bad parts, and the reasons for defects.
• People: which operator worked on which job, and for how long.
• Quality and maintenance: inspection results, maintenance plans and records.

From that data come delivery forecasts, machine utilization, efficiency and measures like OEE. The real gain is that "where is this job?" is answered on a screen instead of by a phone call.

MES vs ERP vs MRP

The three are often confused because all three deal with production. The difference is the question each one answers and the time scale it works on.

MRP (material requirements planning) is usually a module inside the ERP today. ERP and MES do not replace each other; they complement each other. The ERP supplies the production order and the materials, the MES records how the work was done and reports finished production back to the ERP. How that link works is on the integrations page.

ISA-95 and MESA: where MES sits and what it covers

The international ISA-95 standard (IEC 62264) splits a plant's systems into levels. Levels 0–2 are the machines, sensors and PLCs; level 4 is business planning such as the ERP. The MES sits at level 3, between them: it turns the plan into work the shop can do and reports what the shop did back to the plan.

MESA, an association of vendors and users, describes eleven functions an MES can cover. The ones that matter most to job shops are:

• Resource status and allocation (machines, people, tooling)
• Detailed scheduling and dispatching of work
• Data collection (from operators or machines)
• Labor management (who, on which job, for how long)
• Quality management
• Maintenance management
• Product tracking and traceability
• Performance analysis (efficiency, OEE)
• Document control (drawings, work instructions)

Not every MES does all of these, and it does not need to. For a small or mid-sized shop, the right system is the one with the functions that solve today's problem and that operators actually use.

Signs a shop needs an MES

• Finding out where a job is means walking the floor or calling someone.
• Delivery dates are guesses, and they are often missed.
• Real machining times are unknown, so quotes come out either too high or at a loss.
• Several versions of the tracking spreadsheet are going around and none is up to date.
• Nobody knows how long machines sit idle or why they stop.
• Scrap and rework are noticed at month end, with no reason recorded.
• Hours per operator per job can only be pieced together from paper forms.

If two or three of these sound familiar, the loss is usually in information, not in the machines. How to move off spreadsheets step by step is covered in moving from Excel to an MES.

What to look for when choosing an MES

Cloud or on-premise?

With a cloud (SaaS) MES there is no server to set up; you pay a monthly or yearly subscription and updates arrive on their own. Installed on your own server (on-premise), data never leaves the plant and an internet outage does not affect production, but the server is yours to look after. Defense suppliers and companies that do not want data off site usually choose the second.

How easy is it for operators?

Operators produce an MES's data. If starting a job takes more than a few taps, records are skipped and the system stops being trusted. Badge or barcode sign-in, working on a tablet or phone, and a plain screen make the difference. Let an operator try the terminal before you choose.

The link to your ERP

Retyping finished production into the ERP is extra work and a source of errors. Choose an MES with a ready connection to your ERP, and ask exactly what that connection sends and what it receives.

Operator input or machine data?

Some MES products read data straight from machines (PLC, OPC UA, MTConnect). That is more precise, especially for catching small stops, but it is not possible on every machine, needs extra hardware on older ones and makes rollout longer. A system based on operator input works from day one whatever the make and age of the machines. For most shops, operator input is the right place to start.

How much does an MES cost?

Prices vary widely with scope and deployment. Cloud MES products are usually sold as a monthly subscription tied to the number of machines or users, with low setup costs. On-premise systems come with a license fee, installation and consulting services, and yearly maintenance; large enterprise MES projects can take months of customization.

When comparing, look beyond the license: how long rollout will take, how many people need training, and who will keep the system up to date. The most expensive MES is the one that is installed and not used.

What is ModernMES?

ModernMES is an MES built for job shops that work to project or order and for small to mid-sized factories. It runs in the cloud or on your own server, in English and Turkish. Operators start, pause and finish jobs on a terminal that opens in the browser or on their own phone; the data comes from what operators record. Production can be booked in SAP Business One, SAP S/4HANA, Microsoft Dynamics 365 Business Central, Odoo and other ERPs.

Current plans and prices are in the pricing section, and you can see what it looks like in the live shop floor demo. The 14-day free trial needs no credit card.

Frequently asked questions