Walk through a machining shop on any given shift and you will see water used in places that have little to do with the cutting process: hose-downs of the sheet-metal covers, the chip conveyor housing, and the floor around the machine base. That exterior wash is a routine chore, and it is also one of the easier line items to cut. Before you buy new equipment to reduce it, you need a defensible way to measure what the current process actually costs. This article sets out a practical evaluation sequence that maintenance and EHS staff can run without instrumentation beyond a flow meter, a meter log, and a list of the cleaning tasks the team performs.
Start by separating the cleaning task from the habit
Most factories do not know their exterior-cleaning water use because the task was never defined. Ask three shift supervisors how the machine enclosures get cleaned and you will get three answers: one hoses the panels down at the end of every shift, one wipes them weekly, and one only touches them before an audit or a customer visit. Those are different processes with different water demand, not one process done inconsistently.
Write down, for each machine class, what the cleaning is meant to achieve. Cutting oil and coolant mist settle on the outside of the machine and leave a film. Coolant residue is what drives the “slippery floor near the machine” complaint, and it is also what makes the panels look neglected. A cleaning task that targets oil film is a different requirement from one that targets loose chips. Fixing the definition first prevents you from evaluating a method that was never fit for the job.
This step matters because the water figure you derive later is only meaningful when the task frequency and the soil type are pinned down. A baseline built on “we wash the machines sometimes” cannot be compared to anything.
Measure per task, not on the plant meter
The plant water meter will not help you. Exterior machine cleaning is a small share of total consumption and it is buried under cooling towers, parts washers, domestic use, and process demands. Divide a monthly bill by the number of machines and you get a number nobody will defend in a meeting.
What works is a clamp-on or inline flow meter on the hose bib or the wash-down branch used for the task, or a simpler approach: run the task and time it, then multiply elapsed minutes by the measured flow rate of the nozzle in use. A bare hose left running and a trigger gun with a shutoff are not the same device and can differ by a wide margin, so measure the nozzle you actually have on the lance. Record the figure as litres per machine per event, and multiply by how many events happen in a month.
Then log the second and third numbers that decide whether the process is expensive:
- Labour minutes per machine per event, from setup to the hose being coiled — this is usually larger than the water line.
- Downtime or restricted-access time around the cleaning event, including time the machine is blocked from production while it is being washed or left wet.
- Wastewater handling: where the run-off goes, what it carries, and whether oil and coolant residue put it in a stream that needs separation or a permit condition.
Water is rarely the largest single cost in exterior machine washing. It becomes the headline number mostly in sites that charge for water and sewer on volume, or in sites where the run-off is contaminated enough that disposal is a real expense. Put all four numbers on one line per machine class, and the improvement target becomes obvious.
Match the cleaning method to the soil, not to the tool you already own
With the baseline in hand, the question changes from “how do we use less water” to “what actually removes this film”. Cold or warm water with a hose lifts loose chips and dust. It struggles against polymerised coolant and cutting oil, which is why the hose time keeps creeping up: the operator adds time because the soil is not releasing. Repeated scrubbing and chemical detergent are the usual responses, and both add labour, chemical cost, and run-off load.
Heat does the work that volume is being used to approximate. machine tool steam cleaning applies superheated water at low flow, which softens and mobilises oil film so it can be wiped or flushed away with far less liquid. Where the soil on your machine exteriors is oil-based, that distinction — heat versus pressure versus volume — is the single biggest driver of water demand, and it is the reason a low-volume machine can beat a hose on total cost even though it looks slower and more specialised on the shop floor.
For enclosed cabinets, way covers, and areas near electrical enclosures, low liquid volume is also a reliability point rather than only an environmental one. Standing water finds its way into panel seams, cable chains, and sensor connectors; a process that leaves surfaces damp rather than wet reduces the risk of corrosion and the follow-up inspection. Where the plant needs CNC machine cleaning equipment specified as part of a planned maintenance routine, the specification should state the soil being removed and the acceptable residual moisture on the machine, not just the cleaning medium.
Put an equipment trial inside your own measurement
Do not evaluate a supplier's demonstration on their stand. Run the trial against your baseline, on your machines, with your operators. Fix the trial scope in advance: the same machine classes, the same soil condition, the same number of events. Then record the same four numbers you captured for the hose process. That comparison is what makes the capital case, and it also tells you whether the equipment fits the physical space.
Fixed and mobile configurations change the result as much as the cleaning medium does. A fixed unit plumbed to a water supply suits a bay where machines sit in one place and the cleaning route is stable; a battery-fed mobile machine suits shops where machines are re-layouted often, or where the wash point is shared with vehicles and other assets. PowerDe's Fixed Steam Cleaning Machine PowerDe HW02 is a 220 V unit with a 6 kW heater, steam temperature around 160°C, vapour pressure of 0.8 MPa, an 80 L SUS304 tank, and a tap-water inlet, which is the configuration to compare when the cleaning point is permanent and the utility connection is available. Its listed protection features — leakage, short-circuit, high-temperature, high-voltage, and water-shortage — are the kind of checklist your electrical maintenance lead will want verified against your own supply and earthing arrangement before the unit goes near a machine enclosure.
Also confirm the training burden and the consumable and service path. A machine that a single trained operator can run is worth more than a marginally better machine that requires a specialist, because cleaning frequency is what protects the asset. Shenzhen PowerDe Automation Precision Equipment is a manufacturer of industrial cleaning equipment alongside its automation and process equipment lines, and it lists customised configurations for buyers whose cleaning tasks do not fit a standard catalogue unit.
Build the case as a cost-per-machine number
Compare the baseline and the trial as cost per machine per month: water and sewer, labour, downtime, chemical purchase and dosing, wastewater handling, and the annualised equipment cost. Present it that way rather than as a percentage saving, because the reader who approves the purchase cares about the line item on their own budget, not the ratio.
Two secondary effects are worth stating in their own terms, without inflating them. A machine that looks clean is a signal about shop discipline that auditors and customers notice, and oil film on walkways around the machine base is a slip hazard that shows up in incident records. Neither belongs in the water calculation; both belong in the memo that supports it.
The evaluation itself costs little: a flow measurement, a task definition, and one controlled trial. Run it before you shop, and you will be buying against numbers your own plant produced.
