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Detecting EV Leaks the Sensible Way — Repurposing

By Inficon Contributed Article

Recycling leak-detection equipment provides savings

Leak testing may occur in-line or off-line. (Provided by INFICON)

Automakers and their suppliers will invest billions of dollars on manufacturing and assembly operations to meet a growing demand for electric and hybrid-electric vehicles over the next 10 years.

In the process, some manufacturers are finding that they can save considerable time and money by recycling equipment previously used to produce parts for internal-combustion vehicles in making electric vehicle-related components.

Leak testing critical components to help improve quality and reduce warranty costs today is an important part of the production process. These tests will become even more important as the industry transitions to electric vehicles (EVs).

EV sensors and other electronics, for example, are much more sensitive and require tighter tolerances than components in vehicles powered by internal combustion engines. EV leak-detection systems will need to meet much more stringent performance requirements, according to Thomas Parker, INFICON’s North American automotive sales manager. They also must be adapted for changes in the vehicle’s structural design, material usage and key drivetrain systems.

Silver Lining

Some manufacturers are finding that they will not have to buy entirely new leak detection systems. Automakers and component suppliers are learning that they can save significant time and money by repurposing—and modifying—existing ICE (internal combustion engine) equipment for EV applications.

The reutilization of robotic leak-detection systems can cut costs by as much as two-thirds. An all-new system can cost $500,000 up to $1 million or more so the savings can be substantial.

Working with KUKA, INFICON is a company that has taken the lead in developing repurposed automotive leak-detection systems in North America. Chip Darling, a technical specialist leader for KUKA’s Product Performance group in Michigan, noted that recycling benefits can extend beyond the cost of a base test stand. Additional savings would come from reusing gantries, machining lines and other equipment and floorspace.

“Companies want to make the most of what they already have,” Darling said.

“But of course, there has to be a solid business case. Our job is to find the best solution and present the facts to our customers.”

Planning to Repurpose

The first step when switching a leak-detection system to an EV program is to conduct a process capabilities study, including a detailed analysis of equipment, vehicle design specifications and leak-test requirements.

“Companies need to know what their current leak detection system is capable of and compare that to requirements for the new program in terms of test sensitivity, speed and repeatability,” Parker said. “An EV may need a lower leak rate, faster cycle time or different measurement certainty for the metrology.”

An engineering study will determine what can be reused and what changes will be needed. Everything from new vacuum pumps and larger chambers to different seal tooling or additional processing steps will need to be considered. A robotic leak-detection system will include a test stand and subsystems such as a programmable logic controller, tracer-gas vacuum-handling unit and test instrumentation. All of these can be retrofitted to varying degrees.

Modifications can either be made directly at the manufacturing plant or offsite by the test-unit supplier depending on the size and complexity of the system. The job itself can take anywhere from a few hours to several months.

After the equipment is updated, tests are conducted on prototype EV parts to prove the new equipment performs as intended. This means detecting leaks within specified time limits and demonstrating that the process and measurements are repeatable.

Switching a Test System

INFICON and KUKA teamed up to work on the installation of their first retrofitted EV leak test system in late 2020. The repurposed unit is being used at a transmission plant in Michigan that is switching from a traditional automatic gearbox to a one-speed unit.

Due to higher operating temperatures, EV gearboxes have internal glycol-water cooling circuits that are not found on automatic ICE transmissions. “An EV’s fluids, sensors and pressure rates all demand lower leak rates,” Parker said. “Problems that aren’t found through proper leak testing during the manufacturing process easily can lead to costly and much more serious problems once a vehicle is in service.”

KUKA’s retrofitted transmission test system required modified seal tooling and extensive changes to the vacuum handling chamber, due in part to changes made to the center motor housing. Only minor changes were needed for the existing control system and INFICON’s LDS 3000 helium leak detector.

Although there are less than half as many cavities to test in the new EV gearbox, the layout is more challenging because the openings for the electric driver and controller are adjacent, Darling said. “We have to check for external leakage from each cavity on its own, as well as for internal leakage between them. The stakes are also higher. An external oil leak in an automatic transmission may result in a warranty issue, but the premature failure of an EV control unit can be catastrophic.”

The testing changes for the new repurposed system were relatively straightforward, but they required a lot of replumbing and a new process sequence. KUKA completed the update for the EV transmission program in about 12 weeks at one of its facilities in Michigan.

INFICON’s Thomas Parker reviews settings for recently repurposed leak-detection system (Provided by INFICON)

Learning Curve

Hardware changes are the easy part of the repurposing process. The bigger challenge is transforming manufacturing cultures and getting people to accept that an EV gearbox is different than a multiple-speed automatic, Parker says.

“There’s a real learning curve involved in switching to EV component testing,” he noted. “Everything leaks differently. We educate customers on leak-rate theory and how aluminum-porosity leaks are different compared to mechanical-fastener or welded-joint leaks. It takes time, but eventually there is an ‘aha moment’ when the customer realizes that a cast-aluminum-housing porosity leak is different than a weld leak or rotating-seal leak.”

There also are teachable moments for helium-based leak testing. Helium systems are ideal for EV components which have leak-rate tolerances that are as much as 30 percent tighter. Companies are finding that they can’t meet the tighter demands of an EV gearbox with pressure decay or air-testing systems. A cost-saving option is to blend helium with air. The mixture is not as precise as pure helium, but it’s more economical. INFICON’s LDS 3000, for example, can detect both gases.

“Advanced test systems also can be integrated into emerging Industry 4.0 modules,” Parker said. “Leak detection can provide important data to help companies identify potential quality issues and make more informed decisions.” INFICON, for example, offers flexible bus modules and device-specific connectivity. That capability can be added during the repurposing process, which allows information to be shared with production equipment and operators to quickly identify potential problems and make changes on the fly.

“The more data you have available, the better it can be used,” Parker added. “Leak testing is well-suited for Industry 4.0.”

Transition to EV Gaining Momentum

The transition to electrified drivetrains, which is well underway in Asia and Europe, also is gaining momentum in North America.

EV sales in the U.S. are expected to nearly double in 2021 to account for 3.5 percent of the new-vehicle market, up from last year’s record of 1.8 percent. EV market share is projected to hit 10 percent by 2025 and continue to grow through the end of the decade.

Parker predicted that repurposed leak-detection equipment will follow a similar growth path. There currently is a potential for more than 100 systems to be retrofitted in North America and 1,000 globally.

“Right now, it’s all about being cost effective and getting up to speed quickly,” he concluded.

Edited by Industry Report Editor Bill Koenig from material supplied by INFICON

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