Metal fastening with double-sided adhesive: the right solution for every surface

How can you assemble metals? Certainly, there are several methods to consider, from welding, to screws, to rivets, and so on. Certainly, given the great progress made in recent years in the field of adhesive technologies, the idea of gluing metals with double-sided adhesive should not be overlooked. These are structural or non-structural adhesives, for instance, or high-performance double-sided adhesive tapes. The opportunity is to glue metals together instantly and faster, without affecting the final aesthetic, without punctures, and without noisy processes. Not least of all, it must be noted, metals lend themselves very well to fastening, presenting a very high level of surface energy. The consequence of this peculiar property is to be able to count on the great effectiveness of the adhesives, much higher than what is possible to obtain, for example, with materials characterized by a much lower surface energy, such as plastics (other materials with a rather high level of surface energy, although lower than that of metals are, for example stone, glass, and ceramics). But, be careful: not all metals react in the same way to fastening solutions by means of adhesives and double-sided adhesive tapes.

The different types of metals

To make the most of the different adhesive solutions for fastening metals, it is best to know the differences between the different types of metal. First of all, let’s divide them into two groups: on the one hand, ferrous metals, on the other non-ferrous metals. In the first category we are all the steels, i.e., alloys of iron and carbon with a percentage of carbon below 2%, beyond which is cast iron. In this category are also different types of stainless steel, a peculiar steel with low carbon content and a minimum chromium percentage of 11%, obtaining a self-priming steel, therefore resistant to corrosion. In the other category are all non-ferrous metals, such as aluminium and copper alloys.

Depending on the type of processing required, metals from either category are chosen, considering the strength, workability, flexibility, weight, and other factors required each time, as well as the cost. It must be noted, however, that the properties of a metal can be modified with special industrial treatments: this detail, when discussing adhesive solutions for metals fastening, cannot be neglected.

Treatments to improve metals

While stainless steel does not require treatment to withstand corrosion and oxidation, simple steel requires special interventions. Aluminium itself is self-passivating, spontaneously forming an oxide layer on its surface.

In any case, there are different treatments for metals to increase resistance against corrosion, to improve mechanical performance, and obtain specific aesthetic results. Those looking for the best adhesive solutions for fastening metals should know that different treatments should lead to different choices in terms of strong double-sided adhesive tapes and metal glues. There is a long list of possible procedures, such as:

         ·         Electrochemical coatings

·         Galvanizing

·         Anodizing

·         Heat treatments

·         Thermochemical treatments

 There are other possible treatments, though they are less common.

The best metal adhesives, depending on the treatment

We have now outlined that, based on the metal material and the treatment to which the surface was exposed, it is necessary to choose different solutions for fastening metals. Let’s consider, for instance, heat treatment: if welding affects the metals which have undergone this treatment, the adhesives, from their part, do not compromise the surface in any way.

What about galvanization? This process coats the metal with a protective layer of zinc: the most used method is the hot bath. And, of course, galvanized steel – which resists corrosion and has lower costs than stainless steel – can be welded, but with all the issues deriving from the creation of toxic fumes: because of this, it is advisable to test the use of metal adhesives.

Another intervention used to improve the performance of metals is anodization, often used, for example, on aluminium. It is best to a make distinction, here: though normal anodized aluminium can be glued very easily using high-performance double-sided metal adhesive tapes, it should be noted that this is not taken for granted in the case of “colourful” anodized aluminium, i.e., sealed; in this scenario it is best to carry out tests beforehand.

And again, think of powder coating, a widely used industrial treatment. In this case, it is best to consider whether to proceed with gluing metals before or after the treatment, keeping in mind that there are adhesives for bare metal and adhesives designed to be used on powder-coated metal.

In short, gluing metals with adhesives, double-sided adhesives, and fastening systems is possible and very often extremely advantageous: what’s important is to choose the right adhesive product!