Complex Traction Inverter Part Manufacturing for Electric and Hybrid Vehicles

Project Introduction

As climate change poses a growing threat to our planet, industries worldwide are actively reshaping their energy structures to combat this issue. New energy vehicles are leading this trend in transportation.

WayKen, with decades of experience in CNC machining, has become a trusted partner in manufacturing automotive prototypes and components. Our strong reputation has attracted many customers and projects within the automotive industry.

This case study will introduce a custom traction inverter housing for electric and hybrid vehicles.

Inverter Housing Structure and Machining

This traction inverter housing has heat sink fins on the outside, mainly used to carry away the heat from the motor operation. The internal pocket of the housing has many deep holes for mounting brake components and batteries.

This is a low-volume project that involves producing 36 parts and is required to be delivered quickly. Overall there are more structural features and larger dimensions of 33*27*8.7cm, improve machining efficiency is a point during the manufacturing process.

After considering machine capacity, cutting efficiency, machining time, and cost, WayKen chose 3-axis CNC machining to produce them. These machines allow us to complete the housing parts by quick roughing and fine-cutting.

Machining Challenges and Their Solutions

After deciding on the process, let’s look at the machining challenges in this project and how WayKen solved them.

1. Side Deep Holes Machining

Upon reviewing the project drawings, we immediately noticed the deep holes highlighted in orange – critical features of this design.

There are two holes, labeled “in” and “out” which measure 11 cm in diameter and 106 cm in depth. They connect to an internal orange pocket of the housing, where cooling oil enters from the “in” side, removes heat generated by the system, and exits through the “out” side. For efficient cooling, the inner surface of these deep holes must have a smooth finish to allow the oil to flow freely.

However, achieving a high-quality finish on such deep holes is challenging. In common, CNC machines use an external water pipe to deliver coolant, which only manages to get about 30% of the coolant into the deep hole. This will results in high temperatures and debris buildup in the internal deep hole, negatively impacting the surface finish.

To address this, WayKen utilized machines equipped with a spindle liquid-cooling system. This system effectively delivers coolant directly into the deep hole. This approach not only clears debris to achieve the required depth but also maintains a lower temperature.

2. Managing Multiple Datum Planes and GD&T Requirements

The 2D drawing reveals the complexity of this project, with 7 datum planes labeled A through J. This design has specified over 50 GD&T requirements, including critical features like parallelism, flatness, and position tolerance.

For instance, the orange pocket, which channels coolant, demands precise flatness, finish, and parallelism of the housing’s end faces to prevent leaks. Similarly, the position of various holes is important for matching internal components; any misalignment could compromise the product’s performance and quality.

In that way, how does WayKen manage machining processes to ensure accuracy with so many GD&T requirements?

We followed these three key strategies:

• The geometric dimensions of the housing part are machined in a single setup aligned with their respective datum planes or holes.
• If single-setup machining isn’t possible, we use the datum planes or holes formed in the previous setup as reference points for the next setup.
• When the above methods aren’t feasible, we employ CNC machines equipped with probes to detect the necessary datum planes or holes. The machine then automatically adjusts machining parameters to maintain accuracy.

3. Dimensions and Quality Management

The drawing for this traction inverter housing project includes 267 marked dimensions, many of which require high precision GD&T. How WayKen will handle a low-volume project with such extensive dimensional and accuracy requirements?

Based on decades of manufacturing experience and a highly skilled team, WayKen meticulously controls the machining workflow. We determined the machining sequence and develop detailed SOP (Standard Operating Procedure) and SIP (Standard Inspection Procedure) documents. Then, the operators follow these documents closely, addressing any issues by consulting with the engineering team. We also often perform regular checks on dimensions and appearance during machining.

Additionally, we implement strict controls to manage non-conforming products, ensuring that only qualified products are delivered.

4. Inspection Challenges

As mentioned above, the traction inverter housing project includes many high-precision GD&T requirements, all of which must be inspected using a CMM. The inspection results are then shared with our customer.

Meeting these demands requires professional inspectors who can accurately follow specifications and expertly operate high-precision measuring equipment. At WayKen, we use Zeiss CMMs to meet our customers’ stringent requirements.

For this low-volume manufacturing traction inverter housing project, we first produced sample parts and provided a full FAI report to the customer. Once the machining process was verified and approved, we proceeded with the rest of the production. Before delivery, we inspected the housing parts according to the AQL sampling plan and shared these inspection reports with our customer.

Feedbacks and Expectations

We deeply appreciate our customer’s positive cooperation and open communication throughout the manufacturing of these complex traction inverter housings for electric and hybrid vehicles. Their feedback on machining and inspection details was invaluable. WayKen is also honored by the recognition of our quality.

If you have similar requirements or are looking for a reliable and experienced CNC machining manufacturer to handle your project, get in touch with us now!