Sheet Metal Parts in Liquid Cooling Systems: CDU Housings, Manifolds and Trays

Liquid cooling has become a data centre topic, and the sheet metal around it is often specified late. Some of the hardware is machined or brazed and some of it is fabricated, and a brief that does not separate the two produces suppliers who cannot quote and buyers who cannot compare. This guide sets out which parts are sheet metal, and how they are made well.

What Is Sheet Metal and What Is Not

Being explicit about this split at the enquiry stage means each part goes to a supplier who can actually make it, and the interfaces between them are defined rather than assumed.

CDU Enclosures and Their Internals

A coolant distribution unit is an enclosure with wet and dry zones sharing one cabinet.

• Separate the wet zone with a floor or a liner so that a leak is contained rather than spread.
• Drip trays under pumps, heat exchangers and fittings, with a drain or a leak sensor pocket.
• Mounting plates stiff enough for a pump, dimensioned so that the pump's mounting pattern is a datum rather than a slot.
• Service access sized for the largest component, because a heat exchanger cannot be removed through a side panel.
• Airflow and blanking panels where the CDU sits in a rack and has to respect the rack's thermal design.
• Hose routing brackets that hold the bend radius and keep flexible hose away from sharp edges.

Manifold Brackets, Clamps and Routing

The manifold is usually supplied as a finished assembly; the sheet metal holds it in the right place.

• Provide a repeatable mounting datum so that every manifold lands at the same height and position.
• Use clamps with a defined rubber or polymer interface so the manifold is not scratched or galvanically coupled.
• Include adjustment where the manifold has to align with a cold plate or a rack position.
• Design brackets for the hose loads, because a filled hose is heavy and a bracket that only carries the manifold will sag.
• Keep flexible hose away from sharp edges and from hot surfaces.

Drip Trays, Containment and Leak Detection

A drip tray is a simple part that is frequently made badly.

• Form a proper sump, so a small leak collects at one point rather than spreading over a flat base.
• Provide a drain and a sensor pocket, positioned where the fluid will actually collect.
• Turn up the edges high enough for the volume being protected, and weld the corners rather than relying on a sealant.
• Direct any overflow away from electrical components and cabling.
• Allow the tray to be removed or cleaned, because a contaminated tray is a maintenance problem.

Material Choice and Galvanic Compatibility

• Aluminium is common for weight and for compatibility with aluminium cold plates and manifolds.
• Stainless 304 or 316L suits parts that see condensate, cleaning chemicals or a corrosive environment.
• Coated steel is acceptable for dry enclosures and for parts that never touch coolant.
• Galvanic pairs matter: an aluminium part fastened with stainless fixings in a wet environment needs isolation, and a copper fitting in an aluminium tray is a corrosion cell.
• Condensate is the hidden exposure, because a cold surface in humid air is wet even if no coolant ever escapes.

Joining Methods for Liquid Systems

Where a joint has to be fluid tight, the specification should say so and the inspection should verify it, because a joint that is sealed only by a gasket can be reassembled wrongly.

Leak Tightness and What the Test Proves

• State the leak rate, not just the word "leak tested".
• Pressure decay is a practical production test for a defined volume at a defined pressure.
• Helium testing is used where the allowable leak rate is very small.
• Water or bubble testing is a quick screen and is often adequate for trays and containment features.
• Test the assembly as it will be used, because a fitting torqued differently on the test bench may behave differently in service.

Finish and Cleanliness

• Mask sealing faces and threaded interfaces so that they stay clean and dimensionally correct.
• Avoid loose coatings inside a wet zone, because a flaking coating becomes contamination.
• Deburr and clean all internal surfaces, and remove swarf and cutting fluid before packing.
• Cap or plug open ports before shipping, so the part arrives clean and closed.
• State the cleanliness requirement in the purchase specification, including the maximum particle size and whether the part must be dry.

First-Article and Production Checks

Our Approach to Liquid-Cooling Sheet Metal

• We fabricate CDU chassis and enclosures, mounting plates, manifold brackets and clamps, drip trays, hose routing brackets and airflow panels.
• We weld and seal the parts that have to contain fluid, and we test them against a stated leak rate where the specification requires it.
• We will tell you when a requested cleanliness or flatness requirement cannot be met by the proposed construction and finish.
• We do not machine or braze cold plates or manifold bodies, and we do not supply pumps, heat exchangers, hoses or coolant.
• Every quotation states which operations are completed in our plant.

Send the wet-zone layout, the interface drawings and the leak rate you need, and the sheet metal scope can be separated cleanly from the parts that belong to another supplier.

Frequently Asked Questions