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Monday, May 29, 2023

Charged EVs | Bonding, sealing and potting as key applied sciences for battery manufacturing

The transformation course of within the automotive trade attributable to digitalization and electrification brings with it quite a few new necessities for manufacturing expertise. For producers of programs for dishing out potting supplies, liquid seals, adhesive beads, or thermal conductive pastes, this opens up quite a few new fields of software. 

Adhesive bonding is a confirmed becoming a member of expertise within the automotive trade. The added worth of bonded joints is immense as a result of they not solely carry out the perform of becoming a member of, but in addition defend towards exterior influences and guarantee security. Properties which might be particularly demand for battery manufacturing.

Bonding and potting battery cells

Battery cells are available a wide range of codecs. Presently essentially the most used battery cell codecs are the cylindrical, the prismatic and the skinny pouch format. What all of them have in widespread is that they have to be linked by electrically insulating adhesives. Two element polyurethane thermal conductive adhesives with excessive thermal conductivity are sometimes used. The best problem with these supplies is a excessive viscosity A element and a really low viscosity B element, in addition to mixing ratios of as much as 100:5. Correct and constant mixing is crucial for the fabric to have the ability to attain its optimum properties. As well as, the A element is normally processed from 55gln (200l) drums on account of excessive materials consumption.  Optimizing materials extraction from the drum and the bottom doable lack of materials when altering are important right here.

In dynamic mixing, reactive resins with massive viscosity variations could be blended.

Cylindrical cells, additionally known as spherical cells, are sometimes encapsulated on account of their geometry. On the one hand, this serves to repair the cells in place; then again, self-leveling adhesives supply wonderful warmth dissipation, shock absorption and elevated crash stability. As well as, air pockets between the person cells can reliably be excluded. The potting resin is crammed straight into the product by a dishing out head (1C, 2C static, 2C dynamic). Subsequently, curing takes place by way of time, temperature, UV or humidity. Since battery cells can’t be potted underneath vacuum, it is very important have a dishing out course of that’s optimally developed for the element and the potting materials used. Ideally, that is decided upfront in lab trials on the Know-how Middle earlier than it’s utilized to the sequence manufacturing machine. The benefit of lab trails is that data on element optimization and sensible expertise could be offered throughout the product growth part. 

Velocity-dependent metering for demanding element geometries

The person battery cells are tightly organized to type a so-called module. Frames are sometimes used to connect and stabilize the cylindrical battery cells. The method that must be solved is how you can join the person battery cells to the body. The advanced element geometry entails a dishing out line with quite a few corners and modifications of path. The problem for the dishing out system is to use the identical quantity of adhesive at each level, even when the dishing out velocity varies. This may be solved by the bdtronic in-house developed speed-dependent dishing out known as speedUP®, which intelligently hyperlinks and controls the velocity of the axis actions and the dishing out price. Lengthy straight sections are disbursed at excessive velocity and significant curves at low velocity. The result’s a big discount in general cycle time. This expertise can be used for bonding and sealing of housings or casings with polyurethane, epoxy or silicone supplies with quick curing occasions.

Video speedUP for static and dynamic mixing.

To realize the very best adhesion with long-term stability, the battery cells are pretreated with plasma to activate and clear the floor earlier than the adhesive is utilized. Treating plastic and steel surfaces with plasma improves their capacity to bond to an adhesive in a number of methods. It removes natural contaminants that may impair adhesion and etches the floor of the plastic on the microscopic stage. This considerably improves the mechanical energy of the bonded joint. Final however not least, plasma prompts the floor of the plastic, making it extra wettable and extra more likely to react with an adhesive. This ensures long-lasting adhesion to wash, polar surfaces with out residues.

Efficient warmth dissipation

The battery modules generate vitality within the type of warmth throughout operation. That is dissipated by making use of thermally conductive supplies between the battery module and the aluminum warmth sink to stop overheating. Thermally conductive liquid hole fillers are designed for computerized dishing out in high-volume manufacturing. They provide wonderful thermal and mechanical properties and place just about no stress on elements throughout meeting. As a result of these supplies are liquid, they are often freely disbursed in virtually any desired sample or form, permitting excessive flexibility in manufacturing and design. To realize the thermally conductivity wanted in these functions, these pastes comprise a considerable amount of abrasive thermally conductive fillers. In comparison with different pump programs, eccentric screw pumps supply a number of benefits on account of their sturdy and low-wear expertise: because of the steady and volumetric pumping, strain fluctuations are prevented in order to not stress the fabric. This prevents sedimentation and separation, a standard drawback particularly with silicone-based warmth switch supplies.

Lab trials are important for outlining the optimum dishing out parameter

Thermally conductive supplies are normally utilized in a contour after which pressed between the becoming a member of companions, however they can be processed utilizing an injection course of. A course of was developed by bdtronic for an automotive producer through which the extremely abrasive hole filler is injected at low strain into the housing of a battery module in order to not injury the delicate pouch cells. The hole between the battery and the housing base is crammed utterly and with out air bubbles. Particular consideration also needs to be paid to the fabric preparation system. On the one hand, air pockets have to be reliably prevented throughout pail or drum changeover. Alternatively, materials extraction from the pail or drum have to be maximal. Thermally conductive supplies are utilized in massive portions and acquisition and waste elimination prices are excessive. A detailed take a look at the entire price of possession (TCO) exhibits that investing in dependable materials preparation results in excessive financial savings in operating prices in a short while.

Housing bonding and sealing

The battery housings are sometimes put in within the automobile flooring. To guard this housing from dust, mud, and moisture, they’re closed with a liquid seal. Sealing is an efficient dishing out technique for shielding elements from exterior influences by making a barrier. A normally extremely viscous and thixotropic sealant is utilized to the elements in response to a predetermined two- or three-dimensional contour. The rheology of liquid sealants, mixed with the built- in adhesion promoter, helps make sure that the cured sealant bead stays in place and maintains its predetermined profile and measurement.

The sealant or adhesive have to be metered very exactly and completely matched to the robotic motion. Inconsistent software can result in leaks and errors. Particular consideration have to be paid to the beginning/cease level of the bead. Eccentric screw pumps are based mostly on the endless-piston precept and permit steady and uninterrupted metering, making them ideally suited for this software. Along with static mixing, a dynamic mixing system is used for functions the place mixing high quality is necessary and materials properties are demanding, resembling a large mixing ratio, brief pot lives, and the place there are massive variations in viscosity between the bottom and catalyst.

bdtronic provides options for dishing out, warmth staking, plasma and impregnation functions for all necessary elements of electrical automobiles. Contact for extra data: gross, T +1 918 250 – 6496 or go to  

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