The question usually gets asked about one machine, in a meeting where somebody has just complained about how that machine looks or where somebody has slipped. Asked that way it cannot be answered, because "get the oil off" is not one goal. On a machining centre or a press, oil is present in several roles at the same time: as a film on the outside of a guard that has been collecting dust for a month, as sludge in the chip conveyor carrying swarf, as a lubricant inside the guideways where it is supposed to be, and as a hazard on the floor around the base. A method that clears the guard can fail on the conveyor and ruin the guideway inside the same hour.
So the honest answer is conditional, and the conditions are knowable if somebody writes them down. What follows covers what the oil on metalworking equipment actually is, what heat does to it, what "the oil is gone" has to mean before any method can be judged, which parts of a machine change the plan, what a data sheet does and does not tell you, and how to settle the question on one machine during planned downtime instead of in a meeting. It is about equipment surfaces. Workpiece cleanliness and the inside of fluid systems are different problems with different owners, and they come at the end of this article as exclusions rather than as promises.
Name the oil before judging the method
A shop that says "we have oil on the machines" is describing several unrelated deposits that happen to look similar. Slideway oil is formulated to cling under load, which is why it is still there after a wipe and why it is meant to be there. Hydraulic oil arrives as mist from vents, breather caps and rod seals, then settles as a thin, even film over a wide area, and as a local deposit where a fitting weeps. Cutting fluid thrown off a spinning spindle coats the inside of enclosures, the underside of the hood and the wipers. Press and drawing compounds carry additive packages that harden under heat and light until they are no longer soft. Grease and assembly compound sit at bearings and at the places someone packed them. Handling soil from bare hands and packaging oiler rounds out the list at handles, doors and control panels.
The carrier is only half of the deposit, and the other half decides the method. Oil from a grinding or honing operation carries fine abrasive. Oil in a chip conveyor carries swarf. Heat releases the carrier; it does nothing to the solids, so a film sitting on a mat of fines will soften and then be wiped across the surface rather than lifted off it. A water-based coolant is a further trap: what dries on a guard is not an oil film but a residue of solids, additives and biocides that can feel waxy and be mistaken for oil. Treat it as its own deposit and judge any method against it separately.
Before a method is judged, spend a minute reading the deposit on the surface you actually intend to clean. A fresh film has no raised edge and a clean cloth glides over it. A polymerised film looks dull under a work light held low and to the side, the cloth drags, and the edge of the patch is slightly darker. A bound deposit has a crust you can lift with a plastic scraper and a gritty feel when you rub a little between clean fingers. Those three states set the ceiling for every method, and a trial run on the wrong state produces a verdict about the method that is simply wrong.
Decide what "the oil is gone" means, because there is more than one answer
This is the part most discussions skip, and it is the part that decides whether the answer is yes or no. Write down which of the following the work is for, then judge the method against that one standard.
- Safe to touch and to walk on. Handles, buttons, steps, platform edges, the floor within a metre of the machine. The test is a white cloth on a grip and a dry sole on the walking line. Heat with a cloth clears grip films well; the floor is its own task with its own drainage and its own slip rules, and cleaning a machine does nothing about the floor that is already coated.
- Presentable for an audit, a customer visit or a handover. The test is oblique light across a panel and a fixed photograph taken from the same spot before and after. This is where machine tool steam cleaning earns its place: on painted enclosures carrying a fresh or moderately aged film, heat plus a short dwell and a cloth removes what a cold cloth only smears.
- Finding where a leak actually starts. An oily machine hides its leak, because every drip from above lands in the same stained area. Degrease a section, dry it, run the machine, and look at bare metal to see where the first bead appears. This is the strongest case for hot cleaning on metalworking equipment, and it is a diagnostic use rather than a cosmetic one. It does not repair anything, and the section has to be re-protected if it is a slideway or a joint.
- Making a maintenance task possible. Reading a wear mark, seeing a hairline crack, torquing a joint without gloves slipping, putting a cover back on a clean flange face. Heat helps on the outside of what the technician can reach. It does not reach behind a panel or inside a housing, and the parts that come apart are cleaned at the parts washer, not under a steam lance.
- Keeping the oil that belongs there. Guideways, ballscrews, racks, bearings and the surfaces under way covers carry a film that is a functional lubricant. Stripping it is a failure unless the lubrication schedule is run again the same day, and flash rust on bare steel shows up hours later, not during the clean. For these surfaces the right answer is to protect them, not to clean them.
- Preparing a surface for paint, a repair coating or a bonded patch. Here the standard is not visual; it is set by the coating or adhesive manufacturer, and it usually asks for a chemically clean, residue-free, dry surface. Steam leaves water behind in seams, can flash-rust bare steel, and does not rinse out the salts and additives that drawing compounds and coolants leave. A water-break test on bare metal is the practical check, and if the break does not hold, the surface preparation specification governs and hot cleaning alone will not pass.
One machine can pass three of these and fail two in the same shift, which is why the question as usually asked has no answer and the question "which surface, for which purpose, verified how" has a very specific one. Treating industrial equipment oil removal as a single job with a single pass mark is what makes these projects stall; in practice it is a set of separate jobs that happen to share one machine.
What heat does, and what it does not do
A steam machine delivers heat in a form that condenses on contact with a cooler surface, and the useful work happens in that moment of condensation. The heat softens an aged film so that a cloth can lift it while the deposit is still mobile. That is the whole mechanism, and it explains the operator's real controls: distance, pass speed, and how long the steam stays on one patch. Those three change the result more than any figure on a specification table. A short pass repeated while the surface is warm beats one long pass that floods the area, and force applied where heat and time were missing is the most common sign of a method being used badly.
Machines that switch between dry and wet steam are giving the operator two different amounts of water to work with. The drier mode carries less moisture and is what you want near control panels, electrical enclosures, labels and anywhere the job has to be dry again quickly. The wetter mode carries more heat into a stubborn deposit and leaves more water behind, which means drainage, drying time and a check for water collected in seams. Choosing between them is a decision about your site, not a setting to be left alone.
What it does not do is just as important as what it does. It does not dissolve or rinse; there is no chemistry doing the work, so additives and salts from coolant and drawing compounds are moved, not neutralised, and they need a rinse and a cloth. It does not lift grit, so a crust loaded with abrasive or swarf needs mechanical removal first and hot softening as an aid. It does not clean the inside of a coolant tank, a sump, a hydraulic reservoir, a filter housing or the way-oil circuit, and it does not stop a leak, it only shows you where one is. It does not grant a hygiene claim; if a standard has to be met, your own verification meets it. And condensate goes where you did not spray: under nameplates, behind panels, beneath fastener heads, along the base of a column, and into any cable gland that has an unsealed path.
The parts of a metalworking machine that change the plan
Enclosure panels and guards are the easy surfaces, with one caveat: paint that has been baked by years of machine heat, or that has been touched up, should be tested at a lower edge or inside a door before the visible face is treated. Polycarbonate windows, decals, data plates and screen bezels are the surfaces people regret, so mask them or work around them and test a corner first.
Electrical cabinets deserve their own paragraph because steam finds paths that liquid water never does. Cable glands that have never been splashed in normal service will admit vapour, and the vapour condenses on the cool interior metal, on terminal blocks and on the inside of a door. Close the cabinet, seal the openings you can see, use the drier mode near them, and treat the interior as off-limits unless someone is prepared to prove it dry afterwards.
The chip conveyor, the swarf bins and the outside of the coolant tank are usually the heaviest deposit on the machine and, more often than not, the source of the film everywhere else, because that is where mist and carry-off land and where people never wipe. They are also mechanical assemblies with bearings and drive chains, so the plan for them includes drying and re-lubrication, not just cleaning. The hydraulic power unit is the opposite case: its film is a record of where the machine leaks, so cleaning it is worth doing deliberately, with the machine warm, and with the expectation that you will now see something you could not see before.
Then there is the arithmetic nobody writes down. The area you can actually clean is the area you can reach minus the area you have decided to protect, and on a modern machine the protected area is large. A schedule that counts only spray minutes will make every method look unreliable, because the real job includes cooling the machine, masking, drying, and checking seams after the operator has gone home.
Reading a data sheet as a capability rather than a promise
Take a published specification as an example of how to read one. The listing for the PowerDe HW02 fixed steam cleaning machine gives a steam temperature of 160 degrees Celsius and a vapour pressure of 0.8 MPa. Those are two readings of one condition, saturated steam, and they describe what the machine generates rather than what arrives at the surface at the end of a long hose. It is a fair and useful question to ask a supplier whether such figures are measured at the boiler or at the nozzle. The same listing gives a heating power of 6 kW and an 80 L tank in stainless steel with a tap-water inlet; read those as the length of a work cycle and the distance to a tap, not as square metres per hour. The working voltage of 220 V means your electrician confirms a suitable dedicated circuit at the point where the work will actually be done. The safety features named on the page, covering leakage, short circuit, high temperature, high voltage, water shortage and high-voltage explosion, protect the machine. They do not protect your wiring, your operator or your floor, and none of them shorten a drying time.
Items that are not on such tables are worth asking for in writing before anything is decided: hose and wand lengths, warm-up time from cold, how long one tank lasts in each mode, how long recovery takes after a refill, which accessories are supplied, and what the spares and warranty terms are. A supplier who answers those questions in writing has usually thought about your kind of work; one who answers with the same brochure has not.
Site conditions, each with a name against it
Four conditions decide whether any of this is workable, and each one belongs to a person in your building rather than to the equipment supplier. Power: a suitable circuit at the working point, checked by your electrician, with the cable route kept clear of oil and chip paths. Water: where the inlet will connect, and how far the walk to a tap is when the tank runs down, since a tank is a buffer and not a supply. Drainage: where the warm, oily run-off goes, and whether a separator or interceptor is required, which is a matter for the local drainage authority and not for a machine brochure. Access and the room itself: a fixed unit of this class occupies roughly 1200 mm in length, 800 mm in width and 1200 mm in height including handles, so the doors, ramps and the final working position have to be measured rather than imagined, and indoor work needs ventilation, floor falls that carry water away from what you have just cleaned, and a lamp that can be held low to look at a surface at the angle where film shows.
Settle it on one machine, against the standard you chose
Pick one machine during planned downtime, and pick one purpose from the list above. Write the acceptance wording before anyone touches the machine with a lance, in observable terms: what a cloth must look like, what an oblique light must show, what a photograph from a fixed point must not contain. Tape a strip down the middle of one panel so that half of it stays untouched and the comparison is honest. Change one thing at a time, distance or dwell or pass count, and record which. Time the whole thing, including cooling the machine, masking, warm-up, refilling, drying and the seam check afterwards, because that total is what a schedule has to hold. Look again several hours later for flash rust on bare steel and for water that has migrated to a low seam overnight. Write one line per surface, not one line per machine.
Send that record, rather than a summary of it, to whoever you are talking to, and read the result per purpose. A panel that passed the presentation test has not passed the coating-preparation test. A guard that came up clean says nothing about the conveyor, which is a different deposit with a different answer. If the trial fails, the record usually says why: the state was misread, the deposit was loaded with abrasive, the surface needed protection rather than cleaning, or the room cannot support the water. Those are useful findings, and they are the ones a meeting never produces.
Where the answer is yes, and where it is not
Yes, for external surfaces on painted and bare metal where the deposit is a film rather than a crust, and where the work has to be done with little water and a short drying time: control surrounds, walkways, upper areas, panels near equipment that must go back into service. Yes, as a diagnostic step, because a degreased section on a warm machine shows where a leak begins in a way that no amount of wiping over an oily surface will. Yes, for handover, pre-inspection and the kind of presentation work that a customer visit or an audit turns on.
Not, on its own, for the lubricant that is supposed to be on slideways and screws; not for deposits bound with abrasive or swarf unless mechanical removal comes first; not for the inside of coolant tanks, sumps, reservoirs and filters; not for surface preparation that a coating or adhesive specification governs; and not for the leak itself, which is a maintenance job that cleaning only makes visible.
The question worth taking to a supplier is therefore not whether steam removes oil from metalworking equipment. It is which oil, on which surface, for which purpose, checked how, and what the machine will do at the end of a hose in your building rather than in a specification table. If you want that conversation with a written answer, contact PowerDe with the surfaces, the deposits and the conditions from your own shop, and ask for confirmation in writing.
