Appearance
A manufacturer of EV battery trays (Al 6061-T6, 2000 x 1500 x 100 mm, 16 serpentine cooling channels of 10 mm x 1800 mm) used a PCD-tipped gun drill (10 mm, Vc = 250 m/min, f = 0.08 mm/rev, emulsified oil at 40 bar). 16 channels in 2 hours. CMM verified channel position: 8.0 +/-0.2 mm. Pressure test at 5 bar: zero leakage.
EV Battery Tray Component Comparison
| Component | Material | Bore Ø (mm) | Bore Length (mm) | Tolerance | Drilling Method | Vc (m/min) | f (mm/rev) | Surface Finish (µm) | Key Requirement |
|---|---|---|---|---|---|---|---|---|---|
| Serpentine cooling channel | Al 6061/6063 | 6–15 | 1000–2500 | Position +/-0.2 mm; Ra < 0.8 | Gun drilling | 200–300 | 0.06–0.12 | < 0.8 | Zero leakage at 5 bar |
| Module mounting hole | Al 6061/6082 | 6–12 | 3–5 (thin wall) | Position +/-0.05 mm | CNC drilling | 100–200 | 0.04–0.08 | < 1.6 | No burr on underside |
| Cross-member bore | Al 6061 extrusions | 10–30 | 200–600 | Position +/-0.5 mm | Gun drilling | 200–300 | 0.06–0.12 | < 1.6 | Intersecting webbing |
| Cooling port connector | Al 6061/316L | 8–20 | 20–50 | H8; Ra < 1.6 | Gun drilling | 200–300 (Al) | 0.05–0.10 | < 1.6 | O-ring seal surface |
| Seal/EMI groove | Al 6061 | 3–6 | 2000–6000 | Depth +/-0.05 mm | Groove milling | 100–200 | 0.04–0.08 | < 0.8 | Continuous groove path |
FAQ
How are EV battery tray cooling channels drilled and sealed to prevent coolant leakage? The cooling channels are gun-drilled as straight-through bores from the side faces of the aluminium tray, then connected into a serpentine circuit by cross-drilling and plugging the channel ends (the cross-drilled ends are sealed by interference-fit aluminium plugs with 0.02–0.05 mm press-fit tolerance, or by threaded plugs with Loctite sealant). The channels are pressure-tested at 1.5× the operating pressure (5 bar for most EV battery cooling systems) for 10 minutes with zero leakage.
What positional tolerance is required for battery module mounting holes on thin-wall aluminium trays? The positional tolerance for module mounting holes is +/-0.05 mm to ensure that the battery modules (each weighing 10–30 kg) align with the threaded inserts in the tray.
How are cross-member bores drilled through extruded aluminium webbing? Battery tray structural cross-members are aluminium extrusions with internal webbing (thin walls that form the cross-section). Cross-bores drilled through the member must intersect the webbing without tearing or deforming it. The gun drill must cut through each web with a feed reduction of 50% at each web intersection to prevent the drill from deflecting or tearing the thin web.
What surface finish is required for cooling plate connector port bores for O-ring seals? The surface finish for connector port bores that seal with O-rings is Ra < 1.6 µm (per ISO 3601 for static O-ring seal surfaces). The bore is gun-drilled at Vc = 200–300 m/min, f = 0.05–0.10 mm/rev for aluminium, then the seal surface is burnished if the Ra exceeds 1.6 µm.
How is the battery housing perimeter seal groove machined to maintain the IP67 water ingress rating? The perimeter seal groove (for the liquid gasket or compression seal that seals the battery cover to the tray) is machined on a 5-axis CNC machining centre using a carbide end mill. The groove depth must be within +/-0.05 mm to maintain the correct compression of the seal. The groove path is continuous around the full perimeter of the tray (4–8 m total length).
The information provided in this article is for general informational purposes only. Data and recommendations are based on published research and industry experience as of 2026.