Matt Barber
CMMS and EAM are often used as if they mean the same thing. Vendors don't help: plenty of CMMS products now call themselves EAM, and some EAM products are sold to teams that only need a CMMS.
The two overlap a lot. The difference is mostly about scope, and about who the system is really for. Then there's MES/MOM, which has maintenance capability of its own and holds the downtime data both of them need. And there's ERP, which already covers more of the asset side than many people realise.
A quick note on terms. Strictly, MES covers production. MOM covers production, quality, inventory and maintenance, so it's MOM's maintenance capability I mean here. Most people search for "MES", so I use MES/MOM.
What a CMMS does
A CMMS (Computerised Maintenance Management System) helps a maintenance team get the work done. Its focus is the day-to-day:
- Maintenance work orders, from request to close
- Preventive maintenance schedules, by time or usage
- Labour and failure history for each asset
- Spare parts and the maintenance stores
It's usually run by the maintenance team, often for a single site. It's quick to implement, and many are cloud products priced per user.
What an EAM does
An EAM (Enterprise Asset Management) system manages physical assets across their whole life, from acquisition to disposal. It includes everything a CMMS does, and adds:
- The full asset lifecycle, including capital planning and replacement
- Asset costs and depreciation, linked to finance
- Reliability and criticality analysis
- Standards and performance across many sites
- Permits to work and contractor management for asset-heavy operations
It's usually owned at enterprise level, by asset management, engineering and finance as well as maintenance.
What ERP covers
ERP can do a fair amount of what an EAM does. Most ERPs already hold:
- The fixed asset register, with depreciation and asset value
- Capital projects and investment approvals
- Maintenance costs, spare parts purchasing and stores
- Supplier and contractor management
Many ERP suites go further, with maintenance orders and preventive schedules of their own, and some include a full EAM module. So before buying a separate EAM, check what your ERP already covers.
What MES/MOM does for maintenance
MES/MOM knows what each machine is doing right now: run hours, cycle counts, downtime and its reasons, speed losses and what the operator just reported. That's exactly what usage-based maintenance and MTBF need.
A MOM platform goes much further than supplying data. Its maintenance capability replaces the need for a CMMS, with production and maintenance in one connected platform. That brings benefits a separate CMMS can't match:
- One source of truth for downtime. Production and maintenance work from the same downtime records and the same KPIs, so nobody argues about whose numbers are right.
- Maintenance triggered automatically. A breakdown recorded on the line raises a maintenance request straight away, with the machine, the reason and the order already attached.
- Operators doing autonomous maintenance. Checks, cleaning and lubrication tasks appear on the screen operators already use, and anything abnormal goes straight to the maintenance team.
- One schedule both teams can see. Planned maintenance sits in the production schedule, so production and maintenance agree on when each machine is free.
- Preventive maintenance on real usage. Run hours and cycle counts come from the machines, not from estimates.
On top of that, you get the work orders, labour, spare parts and maintenance history you'd expect from a CMMS.
Side by side
| CMMS | EAM | ERP | MES/MOM | |
|---|---|---|---|---|
| Main question | How do we get maintenance done? | How do we get the most value from our assets over their life? | What are our assets worth, and what do they cost to run? | What is each machine doing right now, and why did it stop? |
| Scope | Maintenance work | The whole asset lifecycle | Asset register, finance, purchasing and often maintenance orders | Live machine status and, in a MOM, full maintenance management |
| Typical owner | The maintenance team | Asset management, engineering, finance and maintenance | Finance, with maintenance and purchasing | Operations, with maintenance |
| Sites | Often one | Usually many | Many | One or many |
| Finance | Light: parts and labour costs | Deep: asset value and capital planning | Deep: depreciation, capital and cost | Downtime cost, not asset value |
| Typical fit | Smaller sites with lighter assets | Asset-heavy operations with advanced needs | Most manufacturers, for the asset finances | Every plant. A MOM replaces the CMMS |
Which do you need?
- Running, or choosing, a MOM platform? Its maintenance capability replaces the need for a CMMS.
- An MES for production only, or no shopfloor system yet, and the main problem is getting PMs done? A CMMS, fed with run hours and downtime from the MES where there is one, will work. But be aware that you'd be adding to a point solution architecture, which I advise against. The better option is to step back and re-evaluate your long-term vision for the shopfloor first.
- Leadership asking about asset value, replacement and capital spend? Check what your ERP covers first. It often handles the asset finances already.
- Asset-heavy, with advanced needs such as complex spare parts, reliability engineering, linear assets or regulatory asset records across many sites? That's where a full EAM earns its place.
- Unsure? Start with the problems. If nobody is asking about asset value or lifecycle cost, you probably don't need an EAM.
How they work together
With a MOM platform, maintenance work lives alongside production on the same data. With an MES focused on production only, the MES feeds run hours, counts and downtime to a separate CMMS, which plans and records the maintenance work. ERP holds the asset register and the costs. Where an EAM is also needed, MES/MOM covers the day-to-day maintenance and feeds counters and downtime to the EAM for asset management. Whatever the split, one system should own downtime reasons and one should own the work order. I cover that boundary in EAM, CMMS and MES: who owns the maintenance work order?
My view
A good MOM platform replaces the need for a CMMS. Its maintenance capability covers operator requests, work orders, preventive maintenance on actual run hours, and spare parts. Running a MOM and a separate CMMS side by side would be silly: two versions of downtime, and an interface to maintain between them.
If you run an MES that covers production only, it can feed a separate CMMS, and that works. But a full MOM is the better overall solution.
For the asset side, look to ERP first. It covers the asset register, depreciation and capital spend for most manufacturers, and some ERPs go much further. A full EAM is for asset-heavy businesses with advanced needs, where asset lifecycle and financial data go beyond what MOM and ERP cover together.
Which question is your maintenance system really answering today: getting the work done, or managing the assets?
