Ditch the Torch and Use Induction Heat to Break Free Rusted Bolts

Re:Ditch the Torch and Use Induction Heat to Break Free Rust... by millebe on Sunday May 05, 2024 @02:01PM (#40266813)

This wouldn’t work. The primary reason heating and cooling bolts works for their removal is because they expand anisotropically due to constraints and then shrink uniformly. If you remove a bolt in this way and measure it with a micrometer, you will find the cross section has permanently narrowed and the bolt has permanently elongated, an ever so slight amount.

Assuming you managed to install a preheated bolt, it would become looser as it cooled down.

[ Parent | on HN ]

Re:Ditch the Torch and Use Induction Heat to Break Free Rust... by millebe on Sunday May 05, 2024 @02:07PM (#40266863)

Now if you tried this with a hot bolt and equally hot nut, the bolt would contract along its length, but the threads would get looser so it’d probably still be a net loss for clamping load.

Rivets, on the other hand, are commonly heated and forged so that both ends have a head, and then as they cool the clamping load increases. This was very common a hundred years ago, but my understanding is that bolted joints provide a more predictable clamping load and that is why they are so dominant today.

[ Parent | on HN ]