Automotive battery sealing for e-mobility: Adhesive and sealant application opportunities in battery module and battery pack manufacturing

At SM Klebetechnik, students have the chance to conduct practical research to complete their Bachelor’s or Master’s degree. This year, Tobias Palmen, an industrial engineering student specialising in technical sales in Mechanical Engineering at Aachen University of Applied Sciences, investigated “Gluing and sealing in battery module and battery pack manufacturing (e-mobility)” for his Bachelor’s thesis. In the course of this research in our in-house technical centre, a high-viscosity butyl was applied using our GX 78 screw spindle drum melter and the KP 81 pump application head during battery module and battery pack production. The tests confirm the practical suitability of our equipment:

Automotive battery sealing for use in e-mobility applications is an important processing step during production. Precise sealant application safeguards the interior of the battery pack from ambient conditions whilst also protecting passengers from gases or other toxins that the battery pack might otherwise release should it fail. Along with their air- and gas-sealing function, the butyl-based sealants used to seal the battery cover also provide high resistance to ambient effects such as salt, stone impacts or temperatures below the freezing point. Sealant viscosities of 1.5 – 3 million mPa*s are not uncommon. Despite their high viscosity, when applying these high-viscosity sealants, it is important to ensure uniform application in a reproducible process to achieve the sealing effect across the full sealing surface. Moreover, processing speeds and path feed rates of up to 400 mm/s are required in order to satisfy cycle times in the automotive industry.

SM Klebetechnik: Systems already meet a broad range of requirements in automotive battery sealing

Based on initial applications in the area of battery pack sealing, SM Klebetechnik optimised its equipment engineering for the specific requirements in this field. The result is a usage-oriented application solution that satisfies the broad range of automotive battery sealing requirements. SM Klebetechnik’s KP 81 pump application head with its gear pump built into the head has proven effective in applying butyl. The bead module makes it easy to change the application nozzle, thereby enabling different bead patterns. That means both round beads with diameters of up to 20 mm and also other bead geometries such as square or triangular beads are possible.

The integrated gear pump allows for a very short control system between nozzle discharge and pump. This, in turn, makes it possible to apply sealant precisely with minimal pressure fluctuations during application. Moreover, a front closing needle valve ensures clean start-stop action without stringing over the component.

To melt and pump high-viscosity sealants, drum melters for 20 or 200-litre packages are used in the most common applications. Along with the required melting capacity, the drum melter must also have a suitable ram force to achieve continuous mass flow and optimal pump inflow as well as filling level. Its screw spindle drive enables SM Klebetechnik’s GX 78 screw spindle drum melter to melt and pump these highly viscous materials in high discharge volumes. When processing hot butyl, the discharge volume of the screw spindle drum melter is six times greater than that of the pneumatic drum melter (107 kg/h versus 16.8 kg/h). This is due to both the ram force of up to 130,000 N and the high-capacity melting plate. These melting plates are characterised by a heating capacity of 19.5 kW and flow-optimised material guidance.

Kleb- und Dichtstoffapplikation in der Batteriemodul- und Batteriepackfertigung
Kleb- und Dichtstoffapplikation in der Batteriemodul- und Batteriepackfertigung

Technical centre testing confirms practical suitability

In the course of Bachelor’s thesis work, tests were conducted with a leading manufacturer of adhesives and sealants in the in-house technical centre of SM Klebetechnik. This involved using the KP 81 pump application head and the GX 78 drum melter to apply a bead of high-viscosity butyl. The testing confirmed the practical suitability of the equipment configuration, as did the feedback of the partner:

„The tests were conducted in the technical centre of SM Klebetechnik in Heinsberg, Germany. The company employs about 60 people and its size makes it a very flexible and active partner for us.

The 200-litre GX7882 screw spindle drum melter system was soon able to apply a perfect sealing seam without any problem. After adjusting the parameters, it also successfully applied sealant to a simulated section with a tight radius. By selecting various nozzles and fine-tuning further machine settings, the system essentially satisfied all requirements with regard to injection quantity, geometry, application rate, etc. This proves the overall suitability of the proposed system. SM Klebetechnik’s systems are already used in the automotive sector and we have agreed in principle to collaborate on future projects – to seal battery housing covers, for example.

We can also envision further collaboration on reactive hot-melt applications, such as gluing mica sheets to plastic battery housings.

The hot butyl test series shows that the application technology for  automotive battery sealing developed by SM Klebetechnik can also melt and pump very high-viscosity sealants in sufficient quantities, thereby satisfying customer requirements. In addition, the use of the KP 81 pump application head during subsequent bead application shows that the existing technology can also be used to apply this sealant. Bead diameter can be modified by using different nozzle diameters and varying the pump speed.

About SM-Klebetechnik

For more than 30 years, SM Klebetechnik has made a name for itself internationally in the development and construction of special machines and standard devices for processing adhesives and sealants.

Our machines for hot glue application and coating tasks are primarily and widely used in the automotive, mechanical engineering, graphic industry, adhesive tapes as well as in the furniture, construction, wood and textile industries. Our aggregates are also integrated in production plants at adhesive and sealant producers and compounders. In our certified, owner-managed company, over 60 employees work in the interests of our clients every day.