Powder coating is the finish most industrial enclosures are specified with, and most disputes about it come from three sentences that were never written on the drawing: which faces are cosmetic, which faces must stay conductive, and how thick the film should be. This page covers the specification points that decide whether the coating helps or hurts the project.
What the Drawing Has to Say About Coating
A finish callout is not a colour. To quote and inspect coating properly, the drawing needs the colour reference, the gloss or texture expectation, the surfaces that are visible in service, and the places where coating is not allowed at all.
The Specification Points That Matter
| Colour reference | RAL or a physical sample. A photograph is not a reference, because screen and lighting change the reading. |
|---|---|
| Film thickness | Outdoor and industrial enclosures are commonly specified in the 60–90 µm range for a single-coat polyester system. State the value if your own quality system measures it, and we will confirm it at quotation. |
| Pre-treatment | Degreasing and phosphating before powder, which is what makes the coating stay on after a scratch rather than lifting from the steel. |
| Masking schedule | Threads, earthing studs, bonding faces and mating surfaces. Coating is an insulator and it adds thickness, so these are marked before finishing rather than corrected after it. |
| Cosmetic surfaces | Tell us which faces are looked at in service. It changes handling, packing and how much rework is worth doing. |
| Touch-up expectation | What is acceptable on a small defect after assembly, and what has to be rejected. |
Where Coating Problems Come From
The most common failure is not adhesion; it is fit. Powder adds a measurable build-up on every coated face, so a door, a gland plate or a bracket that fit before coating can bind or sit proud after it. The second is masking that was never specified, which leaves a part that cannot be earthed or a thread that no longer takes a fastener. The third is weld spatter and sharp edges under the coating: coating follows the surface it is applied to, so an edge that was not dressed shows through.
Corrosion testing is project-specific. Where a drawing calls for a salt-spray result to ISO 9227, or for coating thickness measurement, that requirement is agreed before production and included in the quotation, together with the record you will receive. Where the finishing step is carried out by a specialist partner, that is stated clearly rather than presented as an in-house operation.
Coating and the Wider Process Route
Coating sits at the end of the route, so everything upstream has to be right first: welds dressed, edges deburred, hardware either fitted and masked or fitted afterwards. On an enclosure program this sequencing is agreed once and repeated on every batch — see hardware installation, assembly and export packaging for the steps that have to line up with it.
An Example Coating Note
A drawing note that can be quoted and inspected looks like this: “Powder coat, polyester, RAL 7035, semi-gloss, 60–90 µm, all external surfaces. Mask M6 threads, earth stud positions marked E1–E4, and the mating faces of the door and frame. Visible surfaces: front and both sides.” Every item in that sentence answers a question the finishing shop would otherwise have to ask, and every item is checkable after the parts come back.
The masking list is the part buyers most often leave out, and it is the one that turns a good part into a rework job. Once the coating has cured, a masked area cannot simply be reopened: the coating has to be removed mechanically, which marks the finish around it.
Questions Buyers Ask About Powder Coating Standards Industrial Metal Enclosures
Can you powder coat to a RAL number?
Yes. Give the RAL reference or send a physical sample. We confirm the reference at quotation stage and, for repeat orders, keep the same reference on file so the colour does not drift between batches.
Can I have some areas left unpainted?
Yes, and it is easier to do properly if it is planned. Earthing studs, bonding faces and threaded holes can be masked, and masking plugs can be fitted to threads. Mark them on the drawing, because coating cannot be removed afterwards without damaging the finish.
Do you carry out salt spray testing?
Salt spray and coating thickness checks are added where the drawing calls for them, and the requirement is agreed before production. Testing is carried out against a stated standard, and the report is issued with the batch rather than as a separate claim.
Drawing Files Needed for Powder Coating Standards Industrial Metal Enclosures
For a useful quotation, send drawings, quantity, material, finish and assembly requirements. Violet Gao will review your project and reply with technical feedback.
Request a QuoteWhat stands behind this quotation
- Manufacturing since 20162,500 m² Ningbo plant — 3 laser cutting machines (including newer TRUMPF), 4 CNC press brakes and 10 welding stations.
- Shipped to more than 30 export marketsEnclosures, cabinets and formed parts supplied to OEM buyers across Europe, North America and Asia.
- 123 documented product casesMedical device housings, HVAC and heat pump enclosures, agricultural and livestock equipment, industrial hydraulics, material handling trolleys and EV charging cabinets.
- Factory evidence you can checkTUV Rheinland audit reference MIC-ASI243729 and Bureau Veritas reference MIC-ASR263630 available for buyer review under NDA.
Before you send drawings: an NDA is signed on request · first-article inspection is carried out before a batch continues · pricing is staged from prototype quantity to repeat volume · pre-shipment photos and packing records are prepared when the project needs them.