Using robots to promote electromobility and build safety valves for batteries

The boom in electromobility is also causing demand for batteries and the battery parts to skyrocket. Automotive supplier Hugo Benzing which is based in Korntal-Münchingen near Stuttgart and manufactures battery bursting discs, among other components, is feeling the effects of this. In the event of thermal overheating, the valves reduce the pressure in the battery, thus contributing significantly to the safety of electric cars. Valve production is challenging and highly synchronized – and therefore ideal for automation solutions.

Electromobility is on the rise. Electric cars run on electricity that can be produced from renewable energy sources, thus reducing CO2 emissions – an important step towards climate protection. The decision-makers at the medium-sized company Hugo Benzing GmbH & Co. KG in Korntal-Münchingen quickly recognized that the trend towards electric vehicles would be a lasting one. The world's leading manufacturer of safety elements also realized that their expertise would be useful for the construction of electric cars. Thus, the safety experts started developing bursting membranes and bursting discs for electric car batteries. The patented safety valves release pressure into the ambient air in the event of thermal overheating in the battery. They ensure the safety of the battery and therefore of the electric car by preventing a rise in pressure in the battery.

Focus on safety in the production process

To manufacture this vent valve for the battery of the electric car, constant quality controls are required throughout the production process in order to meet the safety requirements. The valve consists of three parts, which are assembled in an automated production cell at Benzing. "We initially built the valves by hand," recalls Managing Director Christian Benzing. However, it soon became clear that the demand from the automotive industry for these vent valves for electric cars would grow significantly.

At automotive supplier Hugo Benzing in Korntal-Münchingen, safety valves for the lithium batteries in electric cars are produced using an automated process.

"So we needed high quantities," says Benzing. The enormous increase in capacity could only be achieved with automation. What's more, the safety checks could now be standardized according to defined, programmed processes and using state-of-the-art technology. This is where the expertise of the mechanical engineering and automation company WAFIOS Tube Automation GmbH based in Simonswald in the Black Forest came into play.

Two million valves per year

"We received the order for the first automation cell in October 2019. The following year, it went into operation in Korntal," says Boris Kühn, Managing Director of WAFIOS Tube Automation, looking back on the early days of the automation cell. Since 2023, two largely identical cells have been in use, producing a total of two million valves per year. Six KUKA robots work together in each unit. The KR AGILUS robots assemble the vent valve out of three individual parts – a carrier part, a spring and a locking part.

Six KR AGILUS robots assemble the bursting discs for batteries in an automation cell.

The robots also swivel through 360 degrees. Precise calculations have been carried out to ensure that they do not collide during the work processes and these are programmed according to defined sequences. Transfer stations, where the individual robots set down and pick up the individual parts, are the key to this. Successive execution of pick-and-place tasks guarantees uninterrupted work in the cell.

Maximum precision is required when gripping the individual parts.

The cell is mobile thanks to its modular design

There are two reasons why the automation specialist chose KUKA robots for the Benzing order: first, WAFIOS Tube Automation has been a system partner of the Augsburg-based robot specialist since 2013, and second, Benzing had previously relied on KUKA for other automation processes and had very positive experiences with them. Numerous different processes are carried out at high speed in the seven by five meter cell. This called for a fast, precise and compact robot. The decision was made to go for a sextuplicate of the highly precise KR AGILUS for each cell - designed for extremely high working speeds. In addition to the robot being versatile, the entire system is also operationally mobile. It is not bound to a fixed location in the factory, but is rather mounted on three steel plates and can be relocated in its entirety in no time at all. "This was an important factor for us because production processes always need to be adapted. This mobile solution means we don't have any production downtime," says Christian Benzing.

Robots move the individual parts through the cell

The valves for the batteries in electric cars are manufactured at Benzing in a three-shift system. An employee initiates the automated production process by feeding the carrier parts into the system via a palletizing system. There, the KR AGILUS picks up a carrier part and transfers it to a light inspection point, where the inspection is performed by an image-processing camera. These cameras are an important part of the inspection process. After the carrier part, the spring which is also gauged before it is used, is fed in. Finally, the locking part is supplied and is also inspected. If a part is faulty, the KR AGILUS separates it out into a box provided for this purpose.

The individual parts are picked up and set down again precisely at transfer stations.

The machine operator can intervene at any time

Once all the components have been inspected, the robots transfer them to the assembly station. "There, they are welded using ultrasound - a high frequency," explains Dietmar Dengler, also Managing Director at WAFIOS Tube Automation. The resulting vapors are extracted to protect employees. A robot then transfers the welded parts to the deburring station, which removes the welding residue. Another test station is integrated at this point. If the finished component meets the requirements, it undergoes a leak test, which is carried out in a helium booth. "If everything is OK, the component is laser-inscribed and is good to go," says Dengler. Operators can also request individual components for inspection during the process if deemed necessary. Once all the automated production steps have been completed, the operator removes the completed safety valves.

Grippers demand maximum precision

The grippers used by the robots to pick up and set down the delicate individual parts proved to be a challenge. "The springs have six arms that bend if you hold them too tightly," explains Dengler. But the people at WAFIOS Tube Automation are familiar with these requirements for gripper tools and have therefore developed them for the assembly cell themselves. The comprehensive control system, which is used to operate the system and the six KR AGILUS robots via a single panel, was also developed in-house and has been used by customers for many years now. "The operators simply program the control system, they don't need to have any knowledge of robots," stresses Kühn.

Christian Benzing (center) opted for WAFIOS Tube Automation to implement the automation solution - together with Managing Directors Dietmar Dengler (left) and Boris Kühn (right)

To be the best supplier in this area, we need complete control of the process. We can only achieve this with automation.

Christian Benzing, Managing Director of Hugo Benzing GmbH & Co. KG

The employees at Hugo Benzing GmbH & Co. KG are pleased with the automation system. Thanks to their "robot colleagues", the employees have more resources for other production activities. Moreover, it would not make sense to manufacture the safety valves by hand due to the complexity of the assembly process, the numerous testing processes and the sharp increase in output. The company is therefore making a significant contribution to the continued proliferation of electric cars.