Engineering: when a repair might be stronger than the parent material

Self-tutoring about engineering and repairs: the tutor mentions a scenario with a broken hinge.

I mention in my post from June 9, 2026 the potential bonding strength of super glue. Said bonding strength came in handy, impressively so, with a repair I made last week.

A few weeks back a plastic hinge for a window screen broke while I was closing it. The hinge is likely over thirty years old, and just as likely inconvenient to replace. I wondered: could it be glued back together? I put the pieces aside, not having time then to tackle it.

Last week, I came upon the pieces from the broken hinge again. On that occasion I had time to consider gluing the hinge back together, and decided to try.

I wanted the repair to be quick, so opted for super glue. I put on eye protection (which I always do when working with chemicals). I fetched a new 1mL tube of super glue – Stuck was the kind I used this time, I think.

The break was bad, with the hinge pin on either side being broken off from a stronger middle section. In turn I glued on one side, then the other – the second side took three tries before it would stick, for some reason. However, it finally did: the plastic hinge was back together. I went and did a ten-minute chore to allow the repair to strengthen.

The hinge was back together, but now I had to press it back in place, past two pressure tabs that would hold it there. The idea struck me that pressing that hinge through therein would surely test the strength of the repair. Moreover, access to the site was clumsy, which probably put more strain on the repaired hinge. Yet, it snapped into place, and held together!

Being that the repaired hinge survived the re-install, and works, I suspect it’s stronger now than just before it broke. Such can be the power of super glue:)