Battery Pack Sealing - EV Battery

Achieving a quality seal is critical for the performance and longevity of EV batteries and for protecting integral components from water intrusion and other harsh environmental conditions. 

EV batteries are subject to increasingly stringent performance and safety standards. Increasing the significance of a reliable and repeatable pack seal is critical to the performance, safety and longevity of the pack. The seal must meet design and regulatory compliance for enclosure standards, such as IP68, which means that the seal will protect against water intrusion, corrosion and outside contaminants. The pack must also meet design and regulatory safety standards to enhance vehicle safety and mitigate the risk of thermal propagation/runaway.  

In pack seal applications, a bead of material is robotically applied around the perimeter of the casing assembly using cure-in-place (CIP) gasketting or form-in-place (FIP) gasketting methods. CIPGs are dispensed and allowed to cure before assembly, creating a compression gasket in the pack seal joint. Alternatively, FIPGs are dispensed, assembled immediately and allowed to cure over time. Both gasketting methods provide improved cycle times and have better overall performance compared to traditional pre-formed gaskets. 

To meet the life cycle demands, materials continue to evolve for improved performance, compression and serviceability. Common material compounds include one or two-component silicones, polyurethane and butyls. 

The challenge in material application is maintaining proper control over dispensing parameters to ensure that the bead dimensions and uniformity are consistent throughout the dispense. A void or variation in the size of the bead can compromise sealing performance. In an FIP gasket, precision in bead volume is critical for ensuring a complete seal without over-applying. In a CIP gasket, the dispensed material becomes a compression gasket. Thus, uniform bead dimensions and proper knit line techniques are critical to successful sealing.

Bead placement, the correct volume of material, its flow rate and in the case of two-component materials, proper mix ratios are the most important factors in ensuring a quality bead. To ensure a durable and reliable seal, the application must be clean, precise and repeatable. 

We take a design-led approach in determining the ideal dispensing solution. Through our development labs, application expertise and material supplier partnerships, we can test and determine process parameters to deliver a solution that meets your application and production requirements. 

Graco understands the challenges of pack seal applications and has developed system solutions to ensure a reliable seal. Our portfolio of dispense equipment can solve the most common material application challenges in battery design and construction. From industry-proven pumps to custom meter, mix and dispense systems, we deliver dispensing solutions for reliable and consistent bead application.