There have been many advancements in electric vehicle (EV) technology in the 21st century, making it one of the most prominent and eco-friendly options due to its efficient battery systems and low fuel costs.
The battery systems are encased in a battery housing, essential for protecting and optimizing the vehicle’s performance. This can be achieved by improving the thermal dissipation and durability of the casing. Automotive prototyping provides excellent production solutions to iterative housing designs and functional testing.
Battery housings require precise dimensions, so precision milling is the ideal method for this process due to its accuracy, material versatility, and excellent surface finishes.
After reading this article, you’ll have a thorough understanding of the technical and engineering outlook of the battery housing manufacturing process and requirements.
What Battery Components Require Precision Machining
Custom CNC milling is a precision machining process crucial in manufacturing battery housing components due to their complex shapes, tight tolerances, and functional requirements, which can be achieved by milling. Some parts that are typical examples of milling are mentioned below:
- Battery Housing Frames and Trays: Aluminum alloys make housing frames due to their strength-to-weight ratio and excellent structural integrity, which is crucial for the battery pack. The frames are lightweight and designed to withstand mechanical stresses, improving the vehicle’s range while maintaining strength.
- Cooling Plates and Channels: Cooling plates are used in battery packs to dissipate heat and optimize the performance of the batteries. The cooling plates have special channels carved for coolant to improve heat dissipation.
The dimensional accuracy of the channels produced using precision milling is beneficial for the cooling plates since it provides uniform heat dissipation, preventing thermal spikes that can degrade battery health. The channels are milled using high-speed specialized tools, preventing heat buildup during the process and providing dimensional accuracy.
- Connectors and Busbars: Precision milling is used for electrical connectors and busbars, which require precise geometries with a smooth surface finish for efficient power distribution. Furthermore, the finish minimizes electrical resistance.
Modern milling techniques, such as multi-axis CNC machining, increase versatility and enable complex connector shapes, crucial to high-voltage EV systems.
- Enclosures and Covers: High-precision milling is used to manufacture battery housing enclosures and covers with tight tolerances, providing an excellent seal that prevents exposure to environmental factors and moisture.
The high-precision milling process results in a lightweight design that provides exceptional sealing capabilities, which optimizes performance without compromising essential factors such as strength and durability.
Optimizing Material Removal For Lightweight Battery Housing Structures
Weight is a pivotal factor around which the EV design revolves; therefore, reducing the weight of a vehicle directly improves energy efficiency and range. Precision milling is ideal for making battery housing structures, as it can precisely remove excess material to achieve a lightweight and durable design.
Aluminum alloys that offer high strength-to-weight ratios and are corrosion-resistant are commonly used to make such components.
1. High-Speed Machining for Enhanced Efficiency
High-speed machining (HSM) uses a high RPM spindle paired with low-depth cutting that reduces the force required to cut, making it efficient at material removal with precision.HSM is effective for thin-walled aluminum structures, minimizing distortion and preventing heat buildup.
HSM can maintain consistency in high-volume production and can be further improved by high-durability tool coatings to improve tool life. Moreover, compared to traditional milling, HSM removes more material faster, increasing its efficiency and reducing production time.
2. Trochoidal Milling for Reduced Tool Stress
Trochoidal milling is a process where the milling tool follows a circular path to reduce tool engagement with the workpiece, reduce the cutting force, and prevent heat generation.
Trochoidal milling is suitable for making intricate geometries in battery housing as it provides a high-quality surface finish with enhanced performance. The process has minimal tool wear and a higher material removal rate in dry machining, making it a cost-effective production method.
3. Topology Optimization Integration
The topology optimization software is used to identify non-critical zones in battery housing designs. This means that it can be used to highlight unnecessary material in the design, which can be removed to reduce weight without compromising durability.
Manufacturers can significantly reduce the weight of components to increase the range and optimize the vehicle’s performance.
A design may go through various iterations to optimize material distribution before being precision-milled into the final product with the ideal geometry.
These advancements align with industry goals for extended vehicle range and reduced production costs.
Ensuring Dimensional Accuracy In Complex Battery Housing Geometries
EV battery housings have varying and complex geometries, which are dependent on the available space. For this reason, they require high dimensional accuracy and precision.
Precision milling using computer numerical control (CNC) systems is used to achieve tight tolerances, which are compatible with the automated assembly process.
Multi-axis CNC milling, such as 5-axis machining, allows you to create intricate features such as undercuts and curves in a single unified setup rather than multiple steps. This is crucial for minimizing setup errors and improving repeatability.
The following table outlines common dimensional accuracy challenges and how precision milling addresses them:
| Challenge | Description | Precision Milling Solution |
| Tight Tolerances for Assembly Alignment | Any deviation can result in misalignment, causing uneven load distribution | 5-axis CNC milling achieves tolerances of +/- 0.005 mm |
| Complex Geometries | Multi-angle machining can shape intricate designs but increases setup complexity. | Precision milling can process multiple features in a single setup |
| Thermal Distortion | For thin-walled battery housings, heat from machining and cutting can lead wrapping. | High-speed CNC milling with a low depth of cut can reduce heat generation |
| Imperfections | Surface defects can compromise water sealing of the battery enclosures. | CMMs and probes used in precision milling can compensate for errors using live machining feedback |
Coordinate measuring machines (CMMs) and laser scanning can be easily integrated with precision milling to verify dimensional compliance and accuracy post-machining, resulting in high-quality and consistent components. The techniques can detect micro-imperfections to ensure consistency.
Tooling advancements, such as actuating tools and auto-compensation boring heads, enhance accuracy and can adapt to real-time machining conditions to minimize vibration and thermal distortion.
Enhancing Surface Finish For Improved Thermal Management and Sealing
The surface finish of a battery housing is directly related to the battery’s performance, especially for thermal management and sealing applications. This means that a better surface finish will result in better heat dissipation and proper air-tight seals.
Precision milling produces a superior surface finish due to its computerized and optimized cutting parameters, such as low feed rates and high cutting speeds, which provide high dimensional accuracy.
Milling results in a flat and smooth uniform surface of the cooling plates and housing, allowing for a greater contact area with the heat sink material, improving the transfer efficiency
Precision milling of sealing surfaces prevents any air gaps, which is crucial for gasket seals to prevent moisture from entering and causing damage.
Modern milling tools are equipped with dampers that reduce chatter and vibration, resulting in a finer surface finish and reducing post-processing to lower production costs.
Conclusion
Precision milling is a highly versatile manufacturing process that enables the production of high-precision components. It is vital for EV battery housing manufacturing as it can overcome various challenges involved in battery housing manufacturing, from the frames to the busbars.
Precision milling ensures dimensional accuracy, which means it can adhere to the tightest requirements and produce a high-quality component that results in the highest performance.
Precision milling can produce EV battery systems with the most demanding requirements, which can range from structural integrity to thermal management.
Modern advancements in milling technologies, such as 3D-printed tools and topology optimization, have boosted efficiency and sustainability.
Precision milling is a highly versatile and efficient method to produce battery housings at a lower production cost while maintaining the highest quality of execution.
