Grease on factory machinery is easy to notice while it builds up, and easy to argue about once it is gone. It accumulates on housings, way covers and gearbox seams until the floor turns slippery, a belt starts to slip, or an auditor points at an oily machine and asks what your cleaning standard actually is. The moment the job is assigned – to in-house staff or to a contractor – someone needs a written answer to a simple question: how clean is clean enough?
That answer is the acceptance criteria. Written properly, it removes disputes over rework and payment, and it protects the machine from a cleaning job that goes too far or stops too early. Written vaguely, it guarantees an argument after the fact. Here is what a practical set of criteria should include.
Agree on the criteria before anyone starts cleaning
Acceptance criteria are not an inspection form you fill in at the end. They are a short agreement made while the machine is still dirty: which surfaces are in scope, what a pass looks like on each one, how the check will be carried out, and who signs off. A press, a machining centre and a conveyor will each need slightly different wording, which is exactly why criteria are written per machine or machine group rather than as one factory-wide slogan.
What the criteria should spell out
1. A surface list, not a slogan
“Clean the machine” is not a criterion. List the surfaces in scope – housing panels, guards, tables and chucks, way covers, splash panels, chip conveyors, motor and gearbox housings – and state which are cleaned, which are wiped only, and which are off limits. For factory machinery degreasing, this list is also the right place to record where the grease comes from: way oil, cutting-fluid mist, chain lubricant and hydraulic seepage each behave differently during cleaning and leave different evidence behind.
2. A pass or fail level, with an inspection method attached
Every cleanliness level needs a way to check it. Workable wording sounds like this: no visible grease film or sludge under normal workshop lighting; no transfer to a white cloth wiped across the surface; underlying paint or bare metal visible on housings and guards; no packed residue along seams and fasteners. Hidden areas – behind guards, inside belt covers, under the table – need their own line and their own tool: an inspection light, a mirror, or the guard removed during a planned stop. If you do not name the method, the inspector will improvise and the person who did the cleaning will contest the result.
3. The agreed cleaning method, and its limits
The criteria should name the method allowed for each machine group and what it must not touch. Solvent wiping, emulsion spray, hot-water washing and steam each remove grease in a different way, and each has boundaries: safe distance from electrical enclosures, bearings that must not be washed out, belts that must stay dry, open guideways that should not be flooded. Naming the method up front also tells you which residue – chemical film, wash-water runoff or loosened grease – you will be checking for afterwards.
4. Preparation and safety conditions
Acceptance should fail on safety as well as on appearance. Lockout/tagout in place, electrical panels and components covered, floor protection and drainage arranged, rinse water collected where required, and no slip hazard left behind. A machine that looks spotless sitting in a puddle has not passed.
5. Drying and restart readiness
State the drying requirement explicitly: surfaces wiped or blown dry, no standing water in recesses, and way covers, sensor areas and electrical connection points checked last. Whenever water or steam is used, “dry and ready to restart” belongs in the same sentence as “clean”, otherwise it quietly becomes optional.
6. Re-lubrication after degreasing
This is the line most sets of criteria forget. Any degreasing good enough to strip old grime will also strip working lubricant from guideways, chains, ball screws and bearing points. Acceptance should require re-lubrication to the machine’s lubrication chart before sign-off. Skip it, and the first production run after cleaning runs half dry – and the cleaning problem returns as a wear problem.
7. Evidence, authority, and what happens on failure
Keep before-and-after photographs of each machine group, a signed checklist naming the inspector, and a stated rejection rule: if any line item fails, that surface is re-cleaned and re-checked, and sign-off waits. Name the person who holds the authority to reject. A criterion nobody is allowed to enforce is decoration.
Where high-temperature steam changes the conversation
Your choice of method changes what the criteria have to check. Compared with solvent wiping or low-pressure washing, industrial steam cleaning equipment works by turning a small amount of water into superheated steam, so the final check focuses on moisture and lifted grease rather than on chemical film and wash-water runoff, and drying time is usually shorter.
If the plant has a fixed wash area, a stationary unit is a common fit. The Fixed Steam Cleaning Machine PowerDe HW02, for example, is published with a 6 kW heater, a steam temperature of 160°C, 0.8 MPa vapour pressure and an 80-litre stainless tank on 220 V supply. Copying agreed temperature and pressure figures like these into the method section makes “the steam did its job” something you can verify, rather than a matter of opinion.
A checklist you can adapt to your plant
- The machine or machine group in scope, with its surface list
- Grease sources identified: way oil, cutting fluid, chain lubricant, hydraulic seepage
- A cleanliness level for each surface group, each with its inspection method
- Hidden-area checks and the tools they need
- The allowed cleaning method, with no-touch zones listed
- Safety conditions: lockout, covers, drainage, no slip hazard
- A drying standard and restart readiness
- Re-lubrication to the lubrication chart after degreasing
- Photo evidence, a named inspector, and a rejection and re-clean rule
None of this is exotic, which is exactly why it works. The plants that never end up arguing about a cleaning job are usually the ones that wrote ten plain sentences down before the first hose was picked up – and made the same person answer for the dirt and for the clean.
