Brief Analysis for Performance and Application Range of Automotive Welding glue

With the development of automobiles, people's pursuit is not only at the level of the means of transport, but more pursuit of their driving performance. The overall vehicle comfort is mainly reflected in the body's excellent sealing and waterproofing, shock absorption and noise reduction and NVH performance. Based on this, the body-in-white of the welding shop should carry out the necessary gluing process in the local area during the welding process, and at the same time, the performance, use and use of different types of glues are standardized and tested to meet the above performance requirements.

In order to ensure the performance of the body's sealing, shockproof, noise reduction and improve the comfort of the vehicle, the body needs to be glued. The body glue is divided into welding glue and coating glue. There are six main types of glue used in the welding shop: hemming rubber, expansion rubber, spot welding sealant, vibration isolating film, metal structural adhesive and bypass sealant, mainly distributed in the side wall, engine compartment, top cover and door cover. And other areas. This article mainly describes the performance, use, and location of the rubber for welding.

Performance and application range of automotive welding glue

1. Folding edge glue

Folding adhesive is a heat-curing, flexible one-component paste adhesive with epoxy resin as base material. It has good flow resistance, no corrosive gas release when heated, good corrosion resistance, no solvent. And PVC, with good adhesion to oil-coated steel and galvanized layer.

Folding edge glue is mainly used for the edging of the door, hood and trunk lid outer panel. Its main function is to increase the connection between the edging and the connecting sheet metal, improve the overall rigidity, waterproof, dustproof, rustproof and dustproof.

2. Expansion adhesive

The solvent-free reactive adhesive (sealant) which is made of synthetic rubber as a base material can be transported by a high pressure pump at room temperature, chemically crosslinked at 140 ° C or higher, and the cured product has high flexibility. It also has good adhesion to oil-based steel sheets and has good sag resistance. It does not require pre-gelation or pre-cure and is flush-resistant to prevent the effects of aqueous cleaners and pretreatment agents used in automotive production lines.

The expansion rubber is mainly used between the inner and outer panels such as the hood, the trunk lid, the top cover and the door to reduce the vibration and noise in the driving and improve the comfort of the whole vehicle. 

3. Spot welding sealant

Spot welding sealant is a solvent-free reactive adhesive based on rubber. It has high viscosity at room temperature and becomes a rubber elastomer after heat curing. It has excellent sealing and waterproof leakage performance. It is pumped by high pressure at room temperature, has good adhesion to oily steel plate, and has good sag resistance. The curing temperature is from 140 ° C to 210 ° C. The cured product has flexibility and good vibration. It is leak-tight and is not easily peeled off under low temperature conditions.

Spot welding sealant is mainly used in the front wall, side wall, floor, etc. The main function is to prevent water and gas from penetrating into the cab from below the floor or from the engine compartment.

4. Isolated film

The isolating film is mainly used for large outer plate parts such as the outer door panel and the side outer panel, and the expansion ratio ranges from 100% to 300%. The main function is to enhance the rigidity of the outer panel of the door and achieve the effect of vibration reduction.

5. Metal structure glue

The metal structural adhesive is mainly used for the sealing connection between the outer plate member and the outer plate reinforcing member, and is used for replacing the spot welding in the case where the outer plate surface is not allowed to have solder joints or poor weldability, so the bonding strength is required to be high, belonging to the structure Glue.

6. Bypass sealant

There are some closed box reinforcement beam structures on the side wall of the body-in-white after welding, so-called “bypass cavity structure”, such as A, B, C columns, sills, front and side walls. In addition to the noise outside the vehicle, in addition to engine noise, exhaust pipe noise, wind noise and tire noise, high-speed airflow is generated in these cavities when the car is driving at high speed. High-speed airflow usually causes two major problems: First, due to the uneven cavity, the tube resistance is large, causing friction between the high-speed airflow and the cavity obstacle, thereby forming a vortex at the cavity wall, and finally generating turbulent airflow noise; Second, the turbulent airflow causes the cavity sheet metal to resonate, creating resonant noise. At the same time, the bypass cavity is like the resonance box of the instrument, which will cause the resonance of the cavity noise and amplify the noise. Therefore, the "bypass noise" caused by the cavity must be taken seriously. At present, sealing technology is used to seal the cavity is an ideal method to solve the bypass noise problem.

Gluing equipment

At present, the all of slightly larger newly built automobile factory almost have equipment for gluing. The efficiency is high and the utilization rate of the glue is also high. Sometimes robots are used for automatic gluing, which is only used in workshops with high automation rates.

Conclusion

The welding gluing process is a very important part of the automobile body-in-white manufacturing process. With the improvement of the body manufacturing level and people's requirements for car comfort, the variety, performance, process specifications and rubberizing equipment of the welding body are positive continuous optimization and improvement to meet the body's shock absorption and noise reduction and NVH requirements.

Spderbond polyamide hot melt adhesive is very suitable for automobiles, Flex+ series could work as structure glue, LPM series could be used for cables and electronics, Tuff series is suitable for filters, Flex and ExA is good at bonding automotive interiors.

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