air flow honeycomb vent

Welding & Assembly Process for Large‑Size air flow honeycomb vent – How We Do It in Our Shop

Large honeycomb vents are a different story from small panels. Small ones you can flip around on a workbench. Big ones – two or three meters long, a meter wide – you can barely move them, let alone weld them.

We do this in our shop. Large honeycomb vents, from core to frame to finished product, have their own process. No theory here. Just how it's actually done.

Frame Welding – Start with a Frame

First step for a large honeycomb vent – weld the frame. The honeycomb core is soft. It can't stand on its own. It needs a rigid frame to hold it.

Frames are usually aluminum extrusions. U‑channel frames are easier – cut the slots, bend to shape, weld only at the corners. H‑section frames are more work – all four corners need 45° miters, all four corners get welded.

Aluminum frame welding uses TIG (tungsten inert gas). Not just any welder can do it – aluminum dissipates heat fast, so current, gas flow, and filler rod all have to be dialed in. After welding, the frame can't be warped. A warped frame won't seat the honeycomb core.

Large frames have another problem – they tend to bow. We straighten them on a surface plate after welding, using clamps and careful persuasion, holding flatness within 0.5 mm.

Different frame shapes: besides U and H, there are L‑shaped, C‑shaped, and custom profiles. The choice depends on your cabinet mounting – some need flanges, others are recessed.

Core Attachment – Locking the Honeycomb in Place

Frame welded. Now the honeycomb core has to be attached to it.

The honeycomb core is layers of thin metal foil stacked together. Two main ways to connect it to the frame.

Spot welding (resistance or laser spot). Lower cost, medium strength, medium shielding performance, good for general commercial use. Spot welding is fast, works for high volume. But spot welds only connect at the weld points – electrical continuity between core and frame isn't as good as brazing.

For large panels, the challenge is spacing the welds evenly so there are no gaps. We use multi‑point spot welders – weld heads arranged in rows or a matrix, pressing down in one shot to weld the entire edge. After welding, the core and frame need a continuous conductive path.

High‑temperature vacuum brazing. Higher strength, better shielding, handles up to 700°C, corrosion‑resistant. Vacuum brazing heats the whole assembly in a vacuum furnace, letting the filler metal flow into every gap between core and frame – metallurgical bond. The whole panel goes into the furnace in one shot. Continuous joints, good conductivity.

But large‑size vacuum brazing has its own headaches. The furnace might not be big enough. Or the thermal cycle isn't uniform – the edges heat up faster than the middle, filler flow is different. So we have two furnaces – one small for precision parts, one large specifically for big panels.

Assembly Challenges for Large Sizes

Small honeycomb vents? Core‑to‑frame gap is easy to control. Large ones? Stack tolerances from the core and frame add up. Gap might be uneven. Too large, and it won't weld. Too small, and the core won't go in.

Our approach: make the core slightly oversize, then press it into the frame with a hydraulic press. Interference fit holds it in place, then we weld. This ensures contact around the entire perimeter.

Large cores also tend to deform. Lifting, handling, pressing into the frame can crush honeycomb cells. Crushed cells don't conduct. So we use dedicated lifting fixtures – never grab it by hand.

Surface Treatment – Finishing After Welding

After welding, large vents need surface treatment. Bare aluminum, left alone in a humid environment, oxidizes in months. Shielding drops.

Standard treatment is trivalent chromium passivation (Surtec 650) – conductive, low contact resistance, RoHS‑compliant, meets MIL‑C‑5541F Type II Class 3 corrosion resistance. Higher‑grade options include electroless nickel plating, tin plating, powder coating, electrocoating.

Large panels need special attention – honeycomb cells are deep. Coating has to penetrate the channels to be effective. Powder coating? Spray with cells facing up, electrostatic charge pulls powder into the walls, flip it a few times for even coverage.

Gasket – Final Step

After welding and surface treatment, the last step – install the gasket. Gasket installed backwards, crooked, wrong compression – the panel leaks when mounted.

Gasket types depend on requirements: neoprene sponge with Monel wire mesh, beryllium copper fingers, conductive rubber overmolding. Large panels have long gasket perimeters. No gaps at the splice – RF leaks from the joint.

Two approaches: pre‑formed gaskets (cut to size, vulcanized at the splice) and field‑applied adhesive gaskets (more flexible, but takes skill).

Common Problems

Weld shrinkage. Large aluminum frames shrink after welding. Ends up smaller than expected. We pre‑set weld allowances and post‑machine after welding.

Core shift. Pressing the core into the frame unevenly pushes it to one side. We use multi‑point press fixtures to keep it centered.

Non‑uniform brazing temperature. Large panels in a vacuum furnace – edges reach temperature first, middle lags. We add radiation shields inside the furnace to even out the heat field.

Warping. Panels coming out of the furnace can bow during cooling. Clamp them during cooling, or straighten on a surface plate immediately after.

Bottom Line

Welding and assembling large honeycomb vents isn't just scaling up a small‑panel process. Frame welding, core attachment, vacuum brazing, surface treatment, gasket installation – every step has to be adjusted for large sizes.

Materials: stainless 304/316L, carbon steel, brass, Hastelloy, aluminum. Welding: spot welding or high‑temperature vacuum brazing. Surface treatment: nickel plating, tin plating, passivation, powder coating.

We make large honeycomb vents. Send us your specs.