Addressing Challenges of Machining Aluminum for Auto Sector

The increasing popularity of electric vehicles (EVs) is reshaping the automotive industry. The International Energy Agency’s (IEA) annual Global Electric Vehicle Outlook shows that more than 10 million electric cars were sold worldwide in 2022, and that sales are expected to grow by another 35% this year to reach 14 million. That’s why, to improve the efficiency and performance of EV components, manufacturers are turning to materials like aluminum. However, machining aluminum comes with its own set of challenges. In this article, you’ll read how innovative machine tool solutions can effectively address these obstacles.

Machining aluminum has always been a challenging task. Even today, the integration of silicon in aluminum structures and variations in strength and composition make it a complex material to work with. Alongside managing these challenges, automotive manufacturers must keep up with the rising demand for aluminum in EV components, manufacturing them efficiently while maintaining tight tolerances and superior quality.

To achieve these goals, innovative machining techniques are necessary. Dry machining, for example, is essential to avoid the buildup of coolant residue that could compromise the integrity of the components. Moreover, machining thin-walled aluminum components, such as those found in EV battery boxes, poses additional difficulties due to their delicate nature. 

Thin walls are susceptible to deformation, vibration and distortion during the machining process, potentially compromising the structural integrity of the components. To minimise the risk of workpiece deflection and tool chatter, careful selection of cutting tools, cutting speeds and feeds is crucial. Implementing efficient coolant systems and workholding techniques is also necessary to dissipate heat and provide stability, ensuring accurate and high-quality machining results.

Furthermore, EV components often feature long overhangs and extended reach lengths, which introduce further machining challenges. These characteristics result in increased tool deflection, vibration and reduced machining accuracy. Additionally, environmental challenges, such as diminishing resources, are pushing machine shops to find new ways to manufacture products. Purely relying on synthetic oils or dry machining may not be the best approach when working with aluminum. 

New Strategies 

Manufacturers must adopt various strategies to improve the manufacturing of EV components. Rigid workholding solutions, such as hydraulic fixtures or modular clamping systems, help minimize vibrations and ensure stability during machining operations. Using shorter and stiffer cutting tools, optimizing toolpath strategies and employing advanced machining technologies like adaptive control further enhance the machining process, reducing deflection and improving overall part quality.

Selecting the right tools is paramount. For instance, tool changers have weight restrictions that demand lightweight tooling solutions to maintain stability. as solution tools with internal features, like unique coolant channels, can be lightweight but also robust. Additionally, dampening technologies can enable effective vibration control to ensure precision machining even in challenging conditions.

In terms of milling technology, Sandvik Coromant's M5 family of completely indexable and adjustable 90-degree milling tools are advantageous over other solutions that rely on square shoulder technology or PCD coating inserts. Its M5B90 and CoroMill® 390 series of progressive rotary milling cutters have proven highly effective in milling thin-walled components. These cutters provide a radial progression that minimizes tool pressure, resulting in a burr-free finish even on walls as thin as 10 to 20 mm. 

By utilizing these tools, manufacturers can eliminate burring issues that could affect the quality and functionality of the final product. The tools provide cost savings and can deliver performance comparable to PCD technology. Additionally, advancements like diamond-like coatings (DLC) have further improved the performance of high-speed steel or carbide end mills, offering enhanced productivity.

Better Tapping 

Tapping plays a crucial role in machining aluminum components for the automotive industry. Aluminium’s soft and lightweight properties make it susceptible to thread damage. As a solution, tapping ensures precise and reliable threads, which is essential for securely fastening components like engine parts or chassis elements.

Accurate tapping guarantees the integrity and longevity of assembled parts, contributing to overall vehicle reliability. To this end, Sandvik Coromant offers a comprehensive range of tooling solutions to address specific machining needs, including its CoroTap® 100 range of straight flute taps that are optimized for short chipping ISO K, ISO N and ISO H materials.

A tool from this range, CoroTapTM 100-NM-M6x1, was put to the test against a competing tool to manufacture automotive covers — two separate tests were performed. Specifically, the application involved tapping 14 through and bling holes with a thread depth of 17mm into an ADT-4 workpiece, a light duty aluminium with a generally high silicon content of 9%. The CoroTapTM and competing tool were each put to work in a Brother S700 machining center and held in place by an ER rigid tap holder. 

The competing tool was run at a cutting speed (vc) of 38m/min and 2000 RPM. The CoroTapTM was run with the same cutting data, except a higher rotation speed of 2000 to 2500 RPM. KC 770T emulsion coolant was applied in both cases. 

In the end, the competing tool produced 36,000 holes in the ADT-4 workpiece and exhibited signs for wear and breakage. The CoroTapTM, on the other hand, produced 140,000 holes and only showed signs of wear, despite running at higher RPMs. This superior performance equated to a tool life increase of 390%, and cost savings of $12,000. By employing precise tapping techniques, manufacturers can ensure that automotive aluminum components meet stringent quality standards, ensuring safety and performance in the final product.

Transitioning to EVs

The future of the automotive industry is difficult to predict, as political influence and resource considerations play significant roles. While transitioning directly to EVs can be challenging for manufacturers, it is expected that hybrid vehicles will have a strong influence in the short term. Internal combustion engines (ICEs) will remain in use, albeit with reduced power, as mild hybrids gain popularity. 

In either case, the challenges of machining aluminum for automotive manufacturers will remain multifaceted, demanding innovative solutions to ensure efficient and high-quality production. Advanced tooling will remain crucial for unlocking benefits such as burr-free milling, increased productivity, and significant time and cost savings.

To find out more about Sandvik Coromant’s tooling solutions for machining aluminum, visit its website.