Bonding or welding metals? The benefits and drawbacks

What kind of metals are used in the vehicle manufacturing sector?

Different types of metals are used in the vehicle manufacturing sector, such as treated steels, untreated steels, stainless steel and aluminum structures. Stainless steel is used in the bodywork and vehicle manufacturing industry because of its high stability in multiple areas. Aluminum, of various qualities, is indispensable in the industry for achieving weight reduction. 

These different metals are attached to each other or to other materials. Bonding a window to the metal chassis of a bus or fixing a sandwich panel inside an aluminum profile are examples.

1. Uniform distribution of forces

When an adhesive is used to bond metal, the tension is uniformly distributed across the connection. This is in contrast to other joining techniques, in which the tension is concentrated at the connecting points. This peak tension creates a local load and a less durable bond.

2. Efficient

The adhesive-to-metal application process is faster than the application process of other joining techniques, such as using screws or welding. Furthermore, in many cases adhesives are suitable for bonding as well as for sealing seams, joints and overlaps. This therefore eliminates an extra sealing step.

3. Esthetic benefits

Bonding metals also yields benefits in terms of the vehicle's appearance. This is because the bond is invisible in the exterior. MS polymer adhesives adhere to virtually any surface, which results in a large freedom of choice of materials. Furthermore, elastic MS polymer adhesives are easy to paint over and provide for a smooth surface in comparison to nuts and bolts.

4. Protection against corrosion

An elastic adhesive that also seals furthermore provides extra protection against various forms of corrosion. Contact corrosion can occur when two metals with a potential difference come into contact with each other. The use of adhesive, instead of screws, for example, creates a non-electrically conductive barrier between the two different metals and prevents contact corrosion.

1. The type of metal

Depending on the type of metal to be bonded, pretreatment may be required to ensure a proper bond. For example, raw aluminum often requires pretreatment, while, normally speaking, anodized aluminum can be bonded without needing any extra pretreatment.

2. Cleaning and pretreatment

In certain cases, pretreatment with a cleaning agent or activator is sufficient. Under more severe conditions, specific primers are recommended to create a durable bond.