Enhancing end-of-line testing to increase production efficiency and NVH performances

Streamlining motor manufacturing

Now more than ever, there are many aspects to consider when building a car. Imagine the different motor variants that need to be produced, not to mention the customization and innovation involved with such tasks. To meet these industry trends, automotive companies need to reduce costs and uphold manufacturing efficiency standards. These needs and pressures for car manufacturers to comply are caused by the high demands of mass customization, end-customer needs and wants and the ever-changing industry conventions.

“We strive to support our customers with maximum flexibility,” says Oscar Bertuzzo, laboratory manager at CEBI Motors. “We see that in the automotive market, there are many motor variants that need to be produced, while cost reduction has become a standard,” he adds.

CEBI Motors is a company with 45 years of experience in electromechanical manufacturing. It develop and produces direct current (DC) micromotors and gear motors for automotive comfort applications. These relate to the actuation and control of dedicated vehicle subsystems such as windows, doors, trunks and adjustable seats (the latest consisting of 85 percent of its business).

Each tier-one supplier and end application have different needs in terms of motor requirements (such as performance, comfort and cost). CEBI Motors aims to have a customer-centric approach based on customer specifications rather than on a fixed catalog. It considers this one of its main advantages concerning competition, but this approach comes with challenges.

A custom process to accommodate customer requests may require additional cost or development time compared to producing a component from a catalog. CEBI Motors quickly understood that it needed a standardized process to make sure it provided production efficiency and flexibility when responding to customer requests. To achieve this, CEBI Motors partnered with Siemens Digital Industries Software to use Simcenter™ Anovis™ hardware and software. Simcenter Anovis is part of the Siemens Xcelerator business platform of software, hardware and services.

Streamlining performance, such as revolutions per minute (rpm), torque and power, without increasing dimensions and production cost is a standard requirement for motor components. But automotive suppliers and original equipment manufacturers (OEMs) are increasingly becoming more concerned with the comfort aspect.

Understanding noise and vibration compliance

“The main challenges when building our products relate to noise and vibration and electromagnetic compliance,” says Bertuzzo. Modern cars have a lot of electronics and miss the masking effect of the combustion engine noise. This poses the challenge of meeting the requirements of a quiet motor with low electromagnetic disturbances.

The noise, vibration and harshness (NVH) aspects are critical as auto OEMs see the overall acoustic and vibration comfort as a key brand differentiator.

An end-of-line test is typically performed on the components at the end of the production/assembly line to confirm whether motors are noiseless. This test is performed by an acoustic expert and consists of a subjective assessment or an objective measurement that is compared against target values.

CEBI Motors initially adopted the first option, foreseeing a subjective evaluation of 100 percent production, or the totality of the motors produced. This was done to meet the stringent requirements on acoustic performances for its end customers, including emitted noise within 45 adjusted decibels (dBA), that are challenging to fulfill statistically during the development.

But the disadvantages of a subjective approach were clear. Multiple operators were needed at the same time to test all motors, which made it a resource-intensive task. Parallel end-of-line test stations were installed to support cycle time, resulting in extra costs. This proved to be an inefficient approach as it added additional time and cost to the production process.

On top of that, this process was not stable over time; it strongly depended on the expert performing the evaluation and the overall quality of the batch, which can change a lot depending on the manufacturing and assembly process.

The consequent risk was that the operator may discard a good motor from a batch just because they subjectively perceived it as less good than all the others. On the other hand, when analyzing a batch of motors with overall low NVH quality, the operator will sort out only a small percentage of those perceived as the loudest ones.

These lead to additional costs for CEBI Motors, being it the cost of scrapping products that are performing well or having recalls from its customers.

Because of these challenges, CEBI Motors decided to switch to an objective characterization of its motors. However, that switch also came with challenges.

Using a microphone to make an acoustic assessment can be unreliable due to the background noise in the production environment and requires dedicated processing to extract the needed parameters to confirm the quality of the motors.

The company tried many solutions for objective acoustic assessment, both with in-house and external software, but none satisfied its needs.

Using Simcenter Anovis to meet customers’ needs

“We felt the solution was to measure vibration only, but no software or hardware vendor wanted to take the risk to apply this idea in production,” says Bertuzzo. “Siemens was the only one that took up the challenge to use vibration tests to extract metrics usable for acoustic troubleshooting.”

Using Simcenter Anovis hardware and software helped CEBI motors meet customers’ needs. Thanks to its deep order processing functionalities, specifically related to motor analysis, it helped the CEBI Motors team create an easy workflow to analyze acoustic emissions based on vibration measurements.

Those are easier and faster to perform and do not require specific boundaries in terms of background noise.

Time and angle synchronous signal processing based on high-precision tachometer measurements are two unique metrics that are leveraged to gain a deep understanding of the motors’ acoustic performances.

CEBI Motors used Simcenter Anovis to provide a modular and adaptable solution and tailored it to its specific needs. The industrialization of the process was performed in close collaboration with CEBI Motors’ integrator The integrator took care of establishing proficient collaboration with Siemens engineers that installed the end-of-line testing hardware and software. This provided a suitable solution for CEBI Motors in terms of low implementation time and cost.

Using the flexible interface of Simcenter Anovis made it easier to fit the software and hardware in the specific application. It allowed CEBI Motors to adopt a systematic approach to the fault detection process.

This flexibility was required to include a customized approach to asynchronous testing. Parallel end-of-line test benches were foreseen to increase the capacity of the lines and support a short cycle time. But tests on different components must start independently to take advantage of this setup. Thanks to its customizable platform, the CEBI Motors team used Simcenter Anovis to support the start of the vibration measurements on multiple benches in an asynchronous way. This allowed the team to take advantage of the parallel lines to save testing time and increase the efficiency of the process.

CEBI Motors can now benefit from a more accurate process to objectively characterize its motors. This results in a more trustful assessment of its NVH performance and a more stable quality between batches. The advantages are clear: fewer suitable motors are scraped with an overall production cost reduction.

The end-of-line testing process is now also fully automated, drastically increasing the line’s overall efficiency. “We can remove one operator per shift over three shifts, which is a huge cost advantage for the company,” says Bertuzzo.

Looking at future applications

After finalizing the implementation of Simcenter Anovis on the existing production lines, CEBI Motors will deploy it to a recently completed line and plans to extend it to an additional plant.

Bertuzzo is excited about the added value and has a clear idea of the future benefits that using Simcenter Anovis will bring the company.

“Siemens software is so complete in motor analysis that I envision using the output of the acoustic tests to monitor and adjust our product parameters during production,” says Bertuzzo.

For small electric motors, the NVH performance is linked to pure design and the manufacturing and assembly processes. In this sense, adjusting the production parameters is critical to optimize noise emissions.

Using Simcenter Anovis provides a detailed description of the noise issues of the motors and can support CEBI Motors in relating each of those to a specific component or part of the production process. The root cause of the problem can be identified in near real-time to provide immediate feedback to the operators on what to change in the assembly process to improve the acoustic emissions.

“Our final goal is to avoid scraps, and using Simcenter Anovis can help us achieve that,“ says Bertuzzo, together with Negri and Alfieri, part of the CEBI Motors team involved in Simcenter Anovis application.

This will be particularly relevant for future products where CEBI Motors already sees a strong market push. More OEMs are requesting specific motors for autonomous vehicle (AV) applications. In autonomous cars, smart seats are expected to rotate by up to 180 degrees for the driver to switch from passive to active position and vice versa. This requires 20 to 30 percent more power in the motors, potentially affecting vibration and acoustics. CEBI Motors plans to continue using Simcenter Anovis to optimize designs and assembly processes to support it in engineering these new products in the future.