What should be done to corners where two bends intersect to prevent cracking?

To prevent cracking at the corners where two bends intersect, drilling relief holes is an effective method. This practice alleviates stress concentrations that occur at the intersection of bends, which is a common area for material failure due to the high levels of stress that can build up there during bending operations.

When bends are made, especially in metals, it can be difficult for the material to properly deform at the sharp interior angle created by the intersection. By adding relief holes, you essentially create pathways for stress to dissipate, thus reducing the likelihood of cracking or fracture occurring during or after the bending process.

Other methods might not effectively address the stress concentrations that lead to cracks. For instance, polishing the edges may enhance visual quality but does not fundamentally alter the stress dynamics at the intersection. Applying a protective coating can help prevent corrosion but does not address mechanical stress issues. Heating the corner might allow for easier bending but could compromise material integrity and also does not mitigate stress concentrations. Therefore, drilling relief holes is a best practice in metal fabrication to ensure durability and structural integrity at critical junctions.