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These are 316L screws that often break inside. I’m looking for a solution – how can they be removed once they break inside, or what material should be used instead?
If it’s broken inside, find a way to weld a hex nut onto it and then tighten it. Is it possible to avoid using these flat-head hex bolts?
You can also drill holes in the broken bolt and then use a wire extractor to remove it. I’m not sure what the medium used in your device is, what its operating temperature is; the material of the bolts chosen needs to be considered carefully.
It looks like a filter! I mainly repair PTA equipment, and I often encounter this situation – it’s very difficult to deal with. I’ve tried everything mentioned above, but none of them seem to work very well. Regarding welding those nuts, it’s necessary to first weld a small layer on the broken screw; this makes it easier to weld the nut and also prevents the nut from not being positioned correctly when welded to the chassis ； If you need to drill holes in stripped screws, you must use an alloy drill bit; otherwise it’s almost impossible to do it. Then use a reverse taper bit to try to pull the screw out. It’s important to provide cooling during drilling. When using a reverse taper bit, it’s best to wait until the screw has returned to room temperature and to heat the surrounding area slightly – after all, it’s the principle of thermal expansion and contraction ； Just use the loosening fluid or something like that ； In cases like this, it’s likely that the bolts are not under the right stress. From that perspective, vibration and other issues can’t be addressed either. Given the strength and corrosion resistance of 316L, there aren’t many alternatives available
316L boasts relatively strong corrosion resistance, but its hardness is not that good. In your case, the FV520B material can be subjected to heat treatment, which helps to increase its hardness and effectively prevents breaking. Additionally, 520B has much better corrosion resistance than 316L!
All the methods mentioned upstairs don’t work; the wire extractor can’t be used because the threads inside get stuck there and prevent pulling. The only option is to use a drill to make a hole and then tighten it slowly
Apply plenty of butter before tightening each bolt, and after that, fill the hex keys with butter as well
Should we try using a different material, or switch to a round-head version with internal hex keys?
I’ve never seen it; I’m just guessing. If it keeps breaking down frequently, it’s probably a structural issue – the structure needs to be changed or improved. Is it caused by vibration? Extended bolt, with a lockout mechanism.