Ask Dr. Dave
Question: We need an adhesive for sticking a diamond onto a conical iron stick without applying heat. We also need a chemical remover for the adhesive; again, no heat can be used. After the diamond is attached to the stick, it will be cut (using another diamond) and then must be removed. The adhesive bond should be very rigid and not breakable unless the remover is used.
Answer: There are several adhesive types that could be used for bonding the diamond, including anaerobics and epoxies. These would give you a very rigid system; however they are thermoset systems that are very difficult to remove without heat. I would suggest that you look at an industrial-grade, high-performance cyanoacrylate adhesive. One of the types that are toughened with elastomers should give you outstanding adhesion, and it will be rigid but tough. One of the properties associated with cyanoacrylates is that, while they are often considered to be true structural adhesives, they are non-crosslinked thermoplastic systems that can be removed with organic solvents. Your supplier will be able to offer you alternative solvents so you can choose one that will meet your internal company policies concerning toxicity, flammability, etc.
Question: I want to glue some Mylar sheet (5 mils thick) to a smooth steel circular rim. The diameter of this circle is about 36 inches. The rim has a minor diameter of about 1/2-inch. The bond zone should be somewhat flexible. What adhesives would you suggest for this job?
Answer: Many adhesives will bond Mylar polyester to steel. A toughened cyanoacrylate would almost certainly work, but might be too expensive for the large bond area. However, because of the flexibility required in the finished assembly, you should consider either a reactive acrylic or a thermoset polyurethane for this application. Both should give you strong bonds, with the reactive acrylic probably giving you higher tensile shear strength, but the polyurethane providing more flexibility.