Sheet Metal Enclosure Manufacturer in China

Enclosures are the largest single family we build, and the ones that fail at the customer are almost never built badly. They are designed so that something cannot be assembled, cannot be sealed, or cannot pass an earth continuity check after coating. This page is about getting those three things right on the drawing.

Reviewed by Tom, Senior Process Engineer·Dongguan source factory · 11+ years in precision sheet metal

telecom cabinet outdoor — sheet metal enclosure manufacturer

Start with the seal, not the box

A gasket needs a continuous, flat, uninterrupted path. That single requirement eliminates more enclosure designs than any other: a groove that runs into a weld bead, a corner that changes direction across a hinge cut-out, or a flange that is 0.3 mm out of flat all break the seal.

The practical answer is a formed gasket groove in the door or the body — a shallow formed channel that locates a poured or extruded gasket — or a flat continuous flange wide enough to carry a self-adhesive gasket. A groove costs one forming operation and holds the gasket in place through assembly; a flat flange is cheaper but relies on the gasket being positioned correctly by hand, every time.

Choosing how it is joined

Method	Best for	Watch out for
Folded and riveted	Indoor housings, subracks, low volume	Cannot be made watertight without a gasket; rivet heads protrude
Folded with spot welding	Thin zinc-coated steel bodies, paint-grade appearance	Weld marks on the visible face unless planned
TIG welded	Stainless and aluminium, sealing-critical, thin gauge	Distortion on long seams; needs an access path for the torch
MIG welded	Heavier section frames and corner joints	More heat, more dressing, more distortion
Laser welded	Visible seams on thin stainless, minimal dressing	Fixturing matters more than the weld
Screwed	Serviceable assemblies, prototypes	Thread durability in thin sheet → use inserts

Enclosure joining methods and where each one fits

Rack enclosures and 19-inch subracks

A rack-mount enclosure has one non-negotiable dimension set: the 19-inch panel width, the hole pitch and the EIA-310 rail spacing. When those are right, the unit slides in. When they are out by a millimetre on a chassis built from a flat pattern, it does not, and no amount of force fixes it.

The other half of the problem is stiffness. A 1U chassis is a shallow folded tray with a lot of its area removed for ventilation. Perforation percentage is a real design figure here — enough open area for the airflow, but not so much that the tray twists when it is bolted to a rack. Sheet thickness, the return flanges at the sides and the front panel are what stop that.

Fix the rail spacing and the mounting hole pattern first, then design everything else around them.
If EMI is a requirement, say so early — a gasket groove and finger-stock channel change the front flange design.
Vent perforations: agree the open-area percentage with your thermal engineer before the pattern is drawn.
Anything installed from a panel edge needs clearance in the assembly order, not just in the CAD model.

Earth continuity, masking and the last 5%

An enclosure that must be earthed has to have clean metal-to-metal contact that survives coating. Powder coating is an insulator, so any earth path — studs, flange overlaps, gasket-channel lands — has to be masked before the part goes in the oven. Miss it and the enclosure is electrically what it was designed not to be.

The same applies to sealing surfaces, threads and any face that has to stay within a tolerance after coating. Masking is a design decision, not a finishing detail, and it belongs on the drawing.

Frequently asked questions

What thickness should an enclosure be?

It follows from size and duty, not from habit. Small indoor housings work in 1.0–1.5 mm; cabinets that carry a door and hardware are usually 1.5–2.0 mm; a large panel that must stay flat needs either more thickness or a formed stiffener. Thickening the sheet tightens every other constraint, so add a rib before you add a gauge.

Can you make an enclosure watertight?

The sheet metal work can be sealed — welded seams, a continuous gasket groove, masked sealing faces. Whether the assembly reaches a specific IP rating depends on the gasket, the hardware and the cable entry as much as the enclosure, so we agree the requirement and the test method before production rather than quoting a rating.

Should the box be folded or welded?

Fold and rivet for indoor housings at low volume; it needs no fixture and changes are cheap. Weld when the seam must be sealed, must be flush, or must carry load. Welding adds distortion control, dressing and usually a fixture, so it should be a requirement rather than a default.

How do you handle the finish on an enclosure with a door?

The door is a separate part with its own powder coat batch, and both need matching. If the door is coated separately, RAL matching across batches is straightforward but not automatic; we coat them together where the schedule allows and mask hinges, earth points and seal faces.

Do you supply enclosures assembled?

Yes. Gaskets, hinges, locks, earth studs, mounting rails and cable management can all be fitted before packing, which is usually cheaper than doing it at your end and avoids transit damage to loose hardware.