1. What is actually on the exterior surface?
“Dirty” is not a specification. A casting that has just come off the line carries way oil and rust-preventive film. A machine that has run for two years carries that same oil mixed with fine grinding dust and dried coolant, which behaves completely differently once heated. Ask the maintenance team to write down what they see, because the answer decides whether you need a hot-water rinse stage, a dry-steam pass, or both in sequence.
Steam works on oil and grease by lowering their viscosity and lifting them off the surface, not by blast force. That is why the temperature and pressure figures on the machine's data sheet matter here. On the PowerDe HW02 steam cleaner, for example, the published parameters are 160°C steam temperature, 0.8 MPa vapour pressure and 6 kW heating power with an 80 L SUS304 tank. Match those numbers against the contamination you wrote down, and against what the machine enclosure can tolerate.
2. Can the machine's own seals and openings take steam?
This is the question that decides whether the job is safe at all, and it is answered at the machine, not in a catalogue. Walk the enclosure with the maintenance lead and check:
- Where the way covers, bellows and wipers meet the casting, and whether they are intact and seated.
- Electrical cabinets, pendant housings, junction boxes and cable glands, and their ingress-protection rating as installed.
- Breather vents and drain holes that could channel water into the interior.
- Any painted or decal area that is already chalking or lifting.
Anything that fails that walk gets masked or stays dry. If the machine is older, with hardened seals, the practical answer is usually short dry-steam passes rather than a long continuous spray.
3. Dry steam or wet steam for this job?
Dry steam carries more heat per unit of water and leaves far less runoff, which is what you want around cabinets, enclosures and anything close to an opening. Wet steam and hot water carry more mechanical action and are better on thick, built-up grease on flat panels and guards. Machines that let you switch between the two let you use each where it belongs instead of choosing one compromise. The HW02 is listed with dry and wet steam modes plus a vacuum function, so the operator can change the approach from the lance rather than stopping to swap equipment.
4. Where does the runoff go?
Steam cleaning uses little water compared with a hose, but the water that does land on the floor now carries oil, and oil-loaded water still has to be handled as oily waste. Before the first pass, confirm three things: a bunded or drained wash area, a separator or containment that is actually working, and a route for the recovered liquid that your site's environmental permit allows. Getting this wrong is more expensive than the cleaning itself.
5. What does the site's electrical safety rule require?
The cleaning machine is an electrical device operating with water in an industrial environment, so its own supply arrangements are part of the pre-use check. The HW02 runs on 220 V and is described with leakage, short-circuit, high-temperature, high-voltage, water-shortage and high-voltage-explosion protection. Verify the socket, cable route and protective earthing at the location you intend to clean from, and confirm your factory's rule for cleaning near live equipment. If the rule is "isolate first", isolate first.
6. Have you tested on one machine before doing the whole line?
Pick the least critical machine, clean one panel, and then inspect the fasteners, seams and painted edges the next morning. Look for water that has sat in a groove and for flash rust on bare machined surfaces, which is common after any hot wet process. That single test tells you the right nozzle distance, the right pass speed, and whether a light protective film needs to be reapplied after cleaning. Write the result down as the method for the rest of the shop floor.
7. Is the supplier telling you what the equipment is not for?
A supplier who only lists advantages is not much use for a purchase decision. Shenzhen PowerDe Automation Precision Equipment publishes cleaning machines across fixed, hand-pushed and driving-style formats, along with engineering services such as hardware testing and equipment customization. Use that breadth the right way: send your surface, contamination and runoff constraints to the supplier and ask them to state the limits, the required utilities and what needs to be modified for your line. Ask for the parameter sheet, not the marketing page.
A short pre-use checklist
- Contamination identified and written down, with the steam mode chosen against it.
- Seals, cabinets, vents and drains checked; exclusions marked on the machine.
- Dry steam near electrical and openings, wet steam or hot water on heavy grease.
- Runoff route, containment and disposal confirmed against the site permit.
- Supply, earthing and isolation rules confirmed with the site electrician.
- One test panel cleaned, inspected next day, method documented.
- Post-clean protection of bare machined surfaces planned.
High-temperature steam is a good fit for exterior degreasing on milling machines, but it is a process, not a spray. Confirm the contamination, the machine's tolerances, the runoff route and the electrical rules before the lance comes out, and the job becomes repeatable instead of a gamble.
