Medical Enclosure Cleanability: Why the Seam Fails Before the Steel Does
A medical enclosure is usually rejected for cleanability, not for corrosion. The steel will outlast the device. What fails is the geometry: an unsealed seam, a sharp internal corner, a weld bead inside a channel, or a fastener head that creates a pocket. None of that is a material problem, and none of it shows up in a quotation.
Fulei Metal builds medical enclosures from customer drawings in stainless 304/316 and aluminium, in Ningbo, China, since 2016 — with the cleanability features drawn in rather than added later.
What actually fails an inspection
| Feature | Why it fails | What to draw instead |
|---|---|---|
| Intermittent weld on a horizontal joint | Each unwelded gap is a reservoir that a wipe cannot reach | Continuous weld, dressed flush on the cleanable side |
| Sharp 90° internal corner | A cloth cannot reach into the corner; residue accumulates | Radiused corner, minimum 3 mm where the geometry allows |
| Flat horizontal top surface | Liquid sits and dries; becomes a growth site | Sloped or domed top so liquid runs off |
| Exposed fastener heads on a cleanable face | Each head creates a pocket and a thread that traps residue | Countersunk and sealed, or fasteners moved to a non-cleanable face |
| Weld bead inside a gasket channel | The bead creates a ridge that the gasket cannot seal against | Bead dressed flush inside the channel, or welding sequence changed |
| Overlapping lap joint | The lap creates a capillary gap | Butt joint with a continuous weld |
| Unsealed cut edge | The exposed laminate wicks liquid and stains | Edge sealed, or a folded hem |
Cleanability by environment
| Environment | Cleaning method | Design requirement |
|---|---|---|
| Patient care area | Wipe with alcohol or quaternary ammonium | No horizontal residue traps; smooth, non-porous surfaces; sealed seams |
| Procedure room | Wipe plus occasional disinfectant fog | As above, plus no upward-facing crevices where fluid can pool |
| Sterile processing | Wash plus sodium hypochlorite | 316, continuous welds, no crevices; chloride exposure rules out 304 |
| Laboratory | Wipe plus reagent splash | Material matched to the reagents in use, not to a generic “chemical resistant” claim |
| Non-patient technical room | Occasional dusting | Cleanability is not the driver; cost and function are |
Surface finish and what it does
| Finish | Cleanability | Note |
|---|---|---|
| Electropolished | Best | Lowest roughness; used where cleanability is the acceptance criterion |
| Brushed, consistent grain | Good | Predictable to clean; grain direction must be agreed so it does not trap |
| Mill finish (2B) | Acceptable | Fine for non-patient areas; harder to clean than brushed |
| Powder coated | Poor in patient areas | Chips at edges and exposes bare metal; coating fails under repeated wiping |
Brushing and mirror polishing run in our own workshop. Electropolishing and passivation run on audited partner lines that we specify and inspect.
What we build, and what we do not
We build the enclosure with the cleanability features your drawing specifies: continuous welds dressed flush on the cleanable side, radiused internal corners, sloped tops, sealed cut edges, and fasteners positioned away from cleanable faces.
We do not validate cleanability, and we do not certify that an enclosure is “cleanable” to any standard. Cleanability is verified on your device, in your environment, by your validation process. What we provide is the geometry you specified, built to it, with dimensional records showing it was.
What to put on the drawing
- Weld standard — continuous, and which side the bead is dressed on
- Internal corner radii, minimum and typical
- Slope requirement on horizontal surfaces, with the angle
- Fastener treatment — countersunk and sealed, or relocated
- Surface finish and the roughness requirement if one applies
- Cut edge treatment — sealed or hemmed
- Which faces are “cleanable” and which are not, so the weld and finish plan can be built accordingly
Frequently asked questions
Can you guarantee our enclosure will pass a cleanability inspection?
No. Cleanability is a property of the complete device in its service environment, validated by your process. What we can do is build the geometry you specified — continuous welds, radii, slopes, sealed edges — and give you the dimensional record showing it was built that way.
Is a welded enclosure always better than a bolted one for medical?
For patient-care enclosures, usually yes: fewer joints means fewer places for residue to sit. Bolted construction wins where the enclosure has to be opened for service, and it is acceptable when the joints are on non-cleanable faces. Tell us which faces are cleanable and we will say which construction suits.
What is the smallest internal corner radius you can hold?
It depends on the material and the forming method. Laser-cut and welded corners can be radiused to roughly 3 mm; pressed corners depend on the tooling. If your drawing calls for a radius we cannot hold with the method chosen, we will say so at review rather than deliver a sharper corner than specified.
Do you passivate medical stainless enclosures?
Yes, on an audited partner line, to the specification you name. Passivation after welding removes the free iron that welding leaves behind, which matters wherever the enclosure will see moisture or disinfectant. Ask for the record at quotation stage if your device file needs it.
What lead times apply?
Simple samples 3–7 days; complex first articles 15–20 days; production batches 25–35 days, quoted after drawing review. Freight is quoted separately to your port.
Do you hold ISO 13485?
No, and we do not claim to. Our quality system is documented to ISO 9001, with third-party audit evidence available under NDA: TÜV Rheinland MIC-ASI243729 and Bureau Veritas MIC-ASR263630. If your supplier qualification requires ISO 13485, we are not the right supplier for that part of the programme.
Send the drawing and the cleaning regime
Send the drawing with the cleaning method and the disinfectant in use. Those two decide the material, the weld standard and the finish — and they are the two things most often left off a medical enclosure enquiry.