Difficulties in machining automotive aluminum alloy motor housings

As electric drive systems continue to advance, the motor housing has shifted from a supporting role to becoming the “invisible protagonist” that significantly influences a vehicle’s overall energy efficiency and reliability. The market demands lighter, thinner, and more precise machining solutions that can be implemented quickly. Companies that can effectively manage thin-wall deformation, achieve precision in bearing holes, and ensure high surface quality all in one process will gain a competitive edge.

 

01. Machining Processes and Solutions

The aluminum alloy motor housing used in new energy vehicles is a crucial structural component of the drive system, and its machining quality has a direct impact on motor efficiency, noise, vibration, and the overall reliability of the vehicle. Due to its material properties—specifically, its low elastic modulus and tendency for tools to stick—and its precision structural characteristics, such as thin walls and a high-precision hole system, the machining process encounters several technical challenges.

The machining processes involved include rough and finish milling of reference surfaces, which utilizes integral PCD (polycrystalline diamond) face milling cutters. Additionally, the processes encompass thin-wall milling, drilling, composite reaming, multi-stage boring for small holes, precision boring of bearing holes, and root groove machining with non-standard PCD end mills and composite forming end mills.

 

02. Workpiece Machining Challenges:

Thin-Walled Deformation and Machining Challenges:

- Tolerance Issues: The bearing hole has an H6 tolerance, which complicates the machining process.
- Cutting Conditions: Intermittent cutting is required, specifically for the cooling water channel opening, which contributes to tool chatter.
- Surface Quality: The adhesion of aluminum alloy to the tool results in surface roughness greater than Ra > 0.8μm, leading to scratches on the machined surface.
- Cost-Efficiency: The cost of PCD tools is high, and the overall pass rate for multi-process operations is only 70%.

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 03. The Method Used by Xiwei

 

Thin-Wall Deformation Control

- Utilize PCD (Polycrystalline Diamond) milling cutters with an unequal tooth pitch at high speeds (vc ≥ 1500 m/min) and a small cutting depth (≤ 0.5 mm). This approach helps reduce cutting forces, prevent vibrations, and avoid deformation of the workpiece.
- Employ a micro-adjustable precision boring tool fitted with an anti-vibration boring bar to eliminate tool chatter.
- Use PCD inserts that feature chip-breaking grooves on the back rake face to ensure effective chip breaking and improve the quality of the machined surface.
- Implement composite boring tools or combined drill-bore tools to consolidate multiple machining steps into a single operation. This not only enhances efficiency but also improves the quality of the workpiece, raising the pass rate to over 98%.

 

04. Machining Examples and Conclusions

 

Part Name: Drive Motor Housing Specifications:

- Part Material: ADC12
- Machine Tool: Vertical Machining Center (BBT40 tool holder)
- Cooling Method: Internal cooling of the machine tool
- Processing Type: Precision milling of reference surfaces, along with composite drilling and reaming

Tools Used:

1. Integral Burr-Free Internal Coolant PCD End Mill:

– Model: CVNP90-063R10-P22 (PCD φ63 face mill)
– Cutting Parameters:
– Cutting Speed (vc): 1900 m/min
– Depth of Cut (ap): 0.1 mm
– Feed Rate (fz): 0.08 mm/tooth

 

2. PCD Composite Internal Coolant Drill-Reamer:

– Specifications: D8.7 x 4 x D9 (0.015, 0.012) x 18 x 45° x 110
– Cutting Parameters:
– Cutting Speed (vc): 1000 m/min
– Depth of Cut (ap): 8.7 mm
– Feed Rate (fz): 0.08 mm/tooth

This revised version maintains clarity while providing the necessary details about the specifications and machining processes involved.

 

05. Tool Advantages and Effects

The integral burr-free PCD end mill enhances machining efficiency by six times compared to a carbide face mill and increases tool life by five times. It achieves a surface roughness of Ra 0.5 μm, which is an improvement over the previous Ra 0.8 μm. Additionally, it resolves vibration issues and produces a burr-free finish after machining.

The PCD composite drill-reamer consolidates two to three previous operations into a single pass. This results in a two to three times increase in efficiency. Thanks to the use of PCD inserts, tool life is extended by over five times, leading to a 50% reduction in overall machining costs.

 

As global awareness of environmental protection increases and emission regulations become more stringent, new energy vehicles have emerged as a vital part of China’s developing industries, entering a phase of rapid growth. During this industrial transformation, the manufacturing process of electric drive assemblies is facing new challenges—particularly regarding the motor housing, which is a core component. The machining accuracy of the housing’s inner circle directly impacts the motor’s energy efficiency, operational stability, and overall lifespan, making this process crucial for the quality of new energy vehicle power systems.

To address the evolving demands of the industry, Zhengzuan has innovatively adapted established machining solutions from traditional automobile manufacturing. They have developed and launched an upgraded tooling solution specifically designed to meet the unique process requirements of new energy vehicle components. By thoroughly analyzing customer production line machining scenarios—focusing on optimizing cutting parameters, enhancing tool life, and controlling surface quality—and utilizing their precision tools, Zhengzuan aligns technical innovation with process needs. This approach aids customers in overcoming efficiency bottlenecks and quality challenges in motor housing machining.

 

01. Inner Circle Machining Solution for New Energy Motor Housings — Zhengzuan PCD Guide Boring Tool

- Guide-strip structure ensures tool accuracy and stability;
- High-precision machining reduces processing errors;
- Excellent surface finish quality;
- Flexible tool design with strong adaptability.

 

02. Processing Challenges

- High precision requirements;
- Balancing processing efficiency and accuracy;
- Difficulty in machining hole diameters, with excessive tool weight;
- High tool complexity;
- Prone to tool vibration, deviation, and wear.

03. Product Advantages

- The guide bar structure effectively stabilizes the tool, reducing vibration and improving surface quality;
- Ensures precision and stability while being compatible with more machine tool environments;
- Tools have good wear resistance and rigidity, easily handling internal circle machining;
- Lightweight tool design supports efficient custom machining;
- Replaceable blades extend tool life, reducing cost and increasing efficiency;
- Custom tool design and regrinding services available.

04. Application Cases

 

 

05. Machining Results

The surface has no scratches, the hole openings are smooth, and there are no burrs at the exits;
Finishing ensures accuracy and surface quality, with a hole wall roughness of Ra < 0.8;
The tools are stable, with no significant wear on the cutting edges under 30x magnification;

 

 

If you want to know more or inquiry, please feel free to contact info@anebon.com
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