An acceptance criterion is a written rule that names a surface, the evidence a crew must collect, and the decision the reviewer makes from that evidence. For machine tool steam cleaning, that rule has to cover a second decision as well, because the same crew is often asked to clean a neighbouring machine in the same session. The line between a pass and a rework is decided by how carefully the wording was written before anyone opened a valve, not by how hard anyone scrubbed.
Write the rule before the machine gets wet
Most disputes about exterior cleaning begin with an unwritten expectation. One person pictures a surface that could carry a clean cloth without picking up grit; another pictures only the obvious chips and pooled coolant being gone. Turning both pictures into sentences on a sheet of paper removes the argument later. The sheet becomes the reference during the work and the reference afterwards when the record is reviewed.
Name the surfaces the exteriors rule covers
A milling machine is easiest to judge when its surfaces are grouped by what happens to them during the clean. The first group is the work area: the outer panels, the doors and windows, the handles, the housing around the tool magazine, the covers of the chip conveyor, and the outside of the coolant tank. Those exteriors are what the crew is allowed to clean, and every criterion on the sheet is written for them.
Keep protected parts out of the rule
The second group is the protected area: ways, ball screws, the tool-changer mechanism, guide surfaces, and the inside of electrical cabinets. These are never part of the exterior task, and the sheet should name them as excluded so that nobody has to guess. Recording the exclusions is what lets a reviewer say that a cleaning passed without implying that anything inside the enclosure was touched.
Sealed openings sit between the two groups. Where a gasket, cable entry, or drain plug could let liquid travel inward, the sheet should say what a closed and secured opening looks like, and the crew should record that they checked it before any liquid was applied.
Make each criterion something a reviewer can see
A criterion that says a panel must be clean cannot be reviewed, because clean is not an observation. Each line on the sheet should name what the reviewer looks for and what settles the question: loose chips and swarf cleared from flat tops and ledges; no liquid pooling in a handle recess or on a conveyor cover; labels and window panels legible; paint surfaces free of the oily film that builds up near the operator station. Where a wipe is the deciding evidence, the sheet says which surface is wiped and what the wipe has to show.
Writing the evidence at this level of detail also fixes the order of the work. Criteria about flat tops and ledges belong at the start of the job; the line about a residual film belongs after the detergent dwell; the question of standing liquid is settled last, when the surfaces have had time to drain.
Decide who signs and what the record holds
An acceptance sheet needs a name beside it. The signer is the person who walked the machine holding the sheet, not the person who scheduled the job. The record itself stays short: the date, the machine identifier, the surfaces covered, any criterion that needed a second pass, and any deviation from the protected-area list. A short record written beside the machine is far more useful during a later audit than a longer one written from memory after the shift.
Match the method to the surfaces the sheet describes
A criterion about an oily film on painted panels is hard to meet with a cold rinse and a cloth, and equally hard to meet with an uncontrolled jet aimed at a gasket. Teams that degrease factory machinery with hot water and steam tend to write tighter criteria, because the method gives them a repeatable way to reach the same result on the next machine. Once the standard depends on CNC machine cleaning equipment, the sheet usually records the mode in use as well as the surface, which makes the two together the basis of the decision.
Machine cabinets vary in door layout, panel access, and how far the conveyor sits from the enclosure, so the equipment chosen for the task should be reviewed against the drawings or a walk-down of the machine itself. PowerDe builds cleaning equipment to a customer surface list rather than to a fixed catalogue duty; the acceptance sheet is the document that turns into that surface list when a plant decides it wants a repeatable method rather than a mop.
Review the sheet after every rework
A criterion that failed twice is a clue that the wording, not the crew, is at fault. If two different shifts disagree about whether a window panel counts as legible, the line needs a clearer description rather than a firmer instruction. Editing the sheet after each disagreement is how a facility's standard stops depending on the memory of whoever wrote the first version.
