A drawing just showed up in my email inbox that calls for a 10mm bend radius on Ø13mm rebar. That’s just about exactly 25% of the CRSI standard. For those of you who don’t work in metric, that’s a 3/4" bend diameter (because rebar bends are generally called out as diameter instead of radius) on a #4 bar (Ø1/2"). The standard is 6 x Ø, so 3".
You could bend it that tight, maybe, but not without seriously weakening it. Rebar is relatively brittle compared to common structural steel, and even that isn’t generally bent to a tighter radius than the material thickness.
That’s someone who doesn’t understand process. Has to be longer, bent and then cut to the desired length. Maybe he’s trying to avoid having to pay for the excess required plus the additional operations lol
We struggled with this at our factory. They didn’t like us putting the bend radius on drawings for sheet metal parts because they didn’t want to change the bend dies in the press brakes. The material was fracturing when they bent 7 or 10 ga steel with dies for 16ga.
Having them repair every fracturing that occured helped getting the point across about the need for specific radiuses. For some reason, dies breaking seemed “routine procedure” until we got the designed radiuses put in place.
Not repair. Get QC to reject those parts.
Typical brake press are “air bend”. Top die never bottom out on lower die. Top die have a typical 0.03" rad.
If you’re “corning” the bend then you could fracture.
For 7 and 10ga steel, something wrong with the process.
Repaired part will be weaker. Not all parts are allowed to be “repair”. The weld need to stress relieve and heat treat back to spec.
Not saying your parts need to go through that.
Of course it can be weaker. The original design can also be ‘stronger’ depending on what the reparation consists of.
The point was that having people fix their own errors lead us to figure out the real cause of the issue and then enforce proper procedure. Re-reading Mr. Capriotti’s reply made me notice the distinction between the two that you were trying to make. He’s working with gauge sheet metal, we’re working with thicker sheet metal (From 1/8" to 3"). Repairing fractured gauge sheet metal must be hell compared to repairing a 3/8" part that had fractures in it’s bends.
That and I don’t think welding a cracked rebar is legal, LOL
We (previous job) had to repair 12" thick plate because getting a new one will be costly and long time.
Still cut, machine weld-prep, weld all 12". Ultrasound inspection. Stress relieve. It’s a week work.
We make parts for CAT and other heavy equipment. All “repair” require approval.
Well we could put scarped part on the employee’s car and let them take it home LOL
Or show them the cost and take it out of their raise and bonus if they keep making same “mistake”.
We moved onto repairing cracked, fractured parts. So welding is the only way to repair.
Assuming a tight bend rebar could crack and the customer might just weld it.
