Ask Dr. Dave

RSS

I have worked with companies that manufacture superglue and polyurethane glue, both of which are single-component, no-mix adhesives. Superglue, which is the common term for cyanoacrylate adhesive, has been around for about 60 years. In contrast, the polyurethanes are about 20 years old in the retail market and somewhat older in professional woodworking. I admit to using both types of adhesive regularly.

I realize that the meter/mix equipment can be a major inconvenience. Adhesives come in two forms, namely two component or one component. Two-component adhesives are mainly epoxies, reactive acrylics, or polyurethanes.

You have a wide range of structural adhesive possibilities here. Normally, you require an adhesive that has been toughened with a rubber for this. Very rigid, quite brittle adhesives have been successful, however.

Numerous technologies and patents cover debondable structural adhesives. For your small parts, however, I can suggest a few simple alternatives.

Adhesives have become prevalent in solar applications to replace mechanical fasteners and welding.

Surfactants are widely used in a range of adhesives and sealants, primarily to promote the wetting of surfaces to promote adhesion. Unfortunately, some of them have been found to have suspect toxicity profiles or environmental issues.

Solvent-based adhesives were traditionally attractive systems for both industrial users and consumers. They are low-cost systems that dry quickly and frequently give high performance, particularly on plastics where the solvents soften or dissolve the surface layers.

We assemble steel panels with welding and screws. Can we replace these with an adhesive?

It may be a one- or two-part system. We need temperature resistance up to 500˚C, and the adhesive will be applied to fill small gaps in a hot mild steel structure. The required initial setting time is 5 min.

You don’t indicate which substrate is on the outside, and this does make a difference in the possible choice of adhesive. Epoxy adhesives were traditionally used for this application, but they should be used with care as they may be too rigid.