1- Special tolerance requirements for key parts

In the manufacturing of EV battery trays and Liquid Cooling Energy Storage Battery Pack Enclosure， the tolerance control of key connection surfaces and interfaces directly affects the sealing, heat dissipation efficiency and assembly accuracy.

a. Liquid cooling plate installation surface

The liquid cooling plate is the core component of the battery thermal management system. The flatness of its installation surface directly affects the sealing of the coolant flow channel. If the flatness is out of tolerance, it will cause uneven compression of the silicone gasket, causing local leakage or increased thermal resistance.

b. Welding seam misalignment

The battery tray often uses an aluminum alloy welding structure. Welding seam misalignment will cause stress concentration and reduce fatigue life. Especially for scenarios with high requirements for Battery Pack Enclosure airtightness (such as IP67), misalignment must be strictly controlled.

c. Battery module positioning hole

The positioning hole is used to accurately fix the battery module. Excessive tolerance will cause module misalignment, causing electrical connection failure or mechanical vibration risks.

d. Fixing bolt hole position

The bolt hole is used to connect the Battery Pack Enclosure to the chassis. Position deviation will cause assembly stress and even cause bolt breakage.

e. Battery Pack Enclosure edge straightness

The Battery Pack Enclosure edge straightness affects the assembly of the upper and lower covers and the IP protection level, especially for laser-welded enclosures, where the edge needs to be used as a reference for laser head tracking.

2-The impact of dimensional tolerance on manufacturing efficiency

The impact of dimensional tolerance on manufacturing efficiency is mainly reflected in its balance between processing flow, cost control and product quality. Reasonable tolerance design can not only ensure product function, but also optimize production rhythm. The impact of reasonable control of dimensional tolerance on manufacturing efficiency is mainly reflected in the following aspects:

a. Balance between processing accuracy and production cost

· Although strict dimensional tolerance can improve sealing and assembly accuracy, high-precision processing equipment and complex processes are required, which significantly increases equipment investment and processing time.

· Excessive pursuit of accuracy may lead to increased processing costs. Strict tolerances need to be set in key functional parts, and tolerances should be appropriately relaxed in non-critical areas to reduce costs.

b. Control of rework rate and scrap rate

· Reasonable tolerance design can reduce rework caused by dimensional deviation.

· Welding deformation is the main problem in battery tray manufacturing. The use of CMT cold welding process can optimize heat input, reduce deformation after welding, and shorten the rework cycle.

c. Modular and standardized production

· Through standardized components, tolerance requirements are concentrated on local replaceable parts, reducing the overall processing difficulty.

· Standardized tolerance design can also support multi-model compatibility and reduce the need for customized processing.

3-Industry standards and practical applications of flatness control

For new energy vehicle battery trays, industry standards have strict requirements:

a. Flatness standard: The flatness of the liquid cooling plate installation surface must be ≤0.2mm, the flatness of the bottom support plate must be ≤0.5mm/m², and the flatness error of the frame after welding must be ≤0.8mm6.

b. Manufacturing process optimization: CNC precision milling, CMT cold welding and vibration aging treatment (VSR), combined with laser interferometer online detection, reduce the risk of deformation.

c. Material selection: It is recommended to use high-strength aluminum alloys such as 6061, with a yield strength of ≥1180MPa, taking into account both lightweight and structural stability.

4- Tolerance adjustment strategy driven by materials and processes

a. Material innovation drives lightweighting

Using lightweight high-strength aluminum alloys (such as 6061) and composite materials (silicon carbide reinforced aluminum matrix), combined with anodizing and insulating coating, to achieve 30% weight reduction and improve corrosion resistance, adapting to the heat dissipation requirements of liquid cooling systems.

b. Process collaboration improves manufacturing accuracy

One-piece extrusion molding + stir friction welding (FSW) reduces the number of welds, CMT cold welding and laser welding control thermal deformation.

c. Simulation detection closed loop to ensure reliability

CAE simulation optimizes the layout of reinforcement ribs, laser scanning and helium leak detection technology realize full process monitoring, modular design is compatible with ±5mm tolerance, reducing costs and increasing efficiency.

We will regularly update you on technologies and information related to thermal design and lightweighting, sharing them for your reference. Thank you for your attention to Walmate.