Introduction
As EV battery systems become more powerful and energy-dense, thermal management is critical. Liquid cooling plates (also called cold plates or thermal plates) ensure that battery modules operate at safe temperatures by efficiently removing heat.
However, not all cooling plates are manufactured the same way.
Small variations in channel geometry, flatness, sealing quality, or machining strategy can lead to major performance issues.
This guide explains what EV engineers, purchasing teams, and technical managers must evaluate before placing an order.
1. Types of Liquid Cooling Plates (and Which One You Need)
Cooling plates generally fall into three categories:
1）CNC-Machined Cooling Plates
➤ Aluminum monoblock design
➤ Channels fully machined
➤ Excellent heat transfer and precision
➤ Ideal for prototypes and high-performance EV packs
2）Bonded Cooling Plates
➤ Two aluminum sheets bonded together
➤ Good for high-volume production
➤ Lower cost, but depends on bonding quality
➤ Used in ESS, commercial EVs, and moderate-load applications
3）Friction-Stir Welded (FSW) Cooling Plates
➤ Extremely strong weld
➤ Supports complex channel patterns
➤ Ideal for durability-focused applications
Which type should you choose?
- Prototypes → CNC
- Cost-sensitive volume production → Bonded
- Heavy-duty EV systems → FSW
2. Key Performance Factors in Cooling Plate Design
Cooling plate performance largely depends on channel design and machining accuracy.
Critical design features include:
➤ Channel shape (U-shape, serpentine, multi-path)
➤ Channel depth and width
➤ Inlet/outlet connector angle
➤ Internal corner radii
➤ Flow uniformity across the module
➤ Structural strength under pressure
Channel geometry directly affects:
➤ Heat transfer
➤ Flow resistance
➤ Operating lifespan
If the design is not optimized, you may face hot spots, poor cooling uniformity, or structural failure.
3. Machining Precision: The Most Important Quality Factor
EV cooling plates require tight tolerances, especially for sealing surfaces and internal channels.
Engineers should check the following:
➤ Channel depth tolerance stability
➤ Wall thickness between channels
➤ Flatness of the top/bottom surfaces
➤ Surface roughness inside channels
➤ Uniformity across long parts
➤ Avoiding micro-burrs that block coolant flow
A high-quality supplier will:
➤ Use 3-axis/5-axis CNC machines
➤ Provide channel-depth measurement reports
➤ Inspect sealing surfaces using CMM
4. Sealing Methods and Common Failure Points
Liquid cooling plates must be fully leak-proof under pressure.
Different sealing methods introduce different risks.
Common sealing methods:
➤ O-ring sealing
➤ Gasket sealing
➤ Adhesive bonding
➤ Welded sealing
Typical failure points:
➤ Uneven sealing surface machining
➤ Incorrect groove depth or width
➤ Rising burrs after machining
➤ Pressure deformation during operation
➤ Insufficient bonding strength
Important:
Even a 0.05–0.1 mm deviation in flatness can lead to leakage.
5. Material Selection: Why Aluminum Matters
Cooling plates are generally made from:
➤ 6061 aluminum — ideal for CNC machining
➤ 3003 aluminum — ideal for bonding
➤ 6063 aluminum — extrusion-based plates
➤ ADC12 / A380 — die-cast cooling housings
The material you choose affects:
➤ Thermal conductivity
➤ Weldability
➤ Flatness after machining
➤ Compatibility with anodizing
➤ Corrosion resistance
ESS applications often prioritize corrosion resistance, while high-performance EV applications focus on heat transfer.
6. Surface Finishing: Improving Cooling Plate Reliability
Cooling plates often require surface finishing to protect against corrosion and improve sealing performance.
Recommended finishes:
➤ Anodizing (Type II) — corrosion resistance
➤ Hard anodizing (Type III) — improved durability
➤ Passivation — enhances surface stability
➤ Laser marking — traceability
Buyers should confirm:
➤ Color consistency
➤ Dimensional changes after finishing
➤ No warping after anodizing
7. What EV Buyers Should Review Before Ordering
Before selecting a supplier, confirm they can provide:
➤ DFM review for channel geometry
➤ Engineering suggestions for improving flow efficiency
➤ CMM reports for sealing surfaces
➤ Pressure/leak testing capability
➤ Material certification (Al 6061/3003/etc.)
➤ Prototype → mass-production transition ability
Red Flags 🚩
Avoid suppliers who:
➤ Cannot explain their machining strategy
➤ Do not provide inspection reports
➤ Refuse to do leak/pressure testing
➤ Offer unrealistically low costs without explaining the process
Conclusion
Liquid cooling plates play a critical role in battery safety and thermal balance.
By understanding the manufacturing process—and knowing what to check before ordering—EV engineers and buyers can greatly reduce risks, improve performance, and ensure long-term reliability.
Well-designed cooling plates depend on a combination of engineering, machining accuracy, material selection, and thorough QC.
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