# Chassis, rails, rack enclosures

Part ID: 4.14 · Layer 4 (Servers, racks & integration)

The sheet-metal chassis and mounting rails that trays slide into, and the enclosure (the rack cabinet itself) that houses the whole assembly.

The chassis and rails are the mechanical structure underneath everything else in this layer: sheet-metal trays hold the boards (4.03, 4.04) in place and mount into rails that let a tray slide in and out of the rack enclosure (4.14a) for service. Some rack-scale ODMs build their own cabinets in-house rather than sourcing a separate enclosure, which is notable because it signals how much of the rack's value they're capturing beyond just tray assembly. AI racks change the mechanical design problem in a few ways: liquid-cooling plumbing has to be routed through the chassis alongside cabling, and higher tray weight from liquid-cooling hardware and denser boards puts more load on the rails and enclosure frame than a conventional air-cooled server rack does. For investors, this tier is largely a mechanical-engineering and manufacturing-scale business rather than a technology one, so the interesting split is between the enclosure makers who sell a general-purpose cabinet platform across many customers and the ODMs who build cabinets in-house specifically to keep that margin themselves.

**AI delta:** Liquid-cooling plumbing routed through the chassis, plus the added weight of cold plates, manifolds and denser boards, puts more mechanical load on rails and enclosures than a conventional air-cooled server rack requires.

## Companies

| Company | Role | Confidence | Ownership | Ticker | Note |
|---|---|---|---|---|---|
| Chenbro | manufacturer | inferred | public | 8210.TW |  |
| Foxconn (Hon Hai) | manufacturer | inferred | public | 2317.TW |  |
| King Slide | manufacturer | inferred | public | 2059.TW | rails |
| Wistron | manufacturer | inferred | public | 3231.TW |  |
| AIC | manufacturer | inferred | private |  |  |

Confidence tags: disclosed = company/filing statement; reported = trade press or partner list; inferred = taxonomy lead.