Capillary Gap Tolerance
The maximum allowable gap between two metal parts to ensure a strong joint through capillary forces. Excessive gaps lead to lack of fusion.
Physicochemical mechanism of action
Capillary gap tolerance refers to the maximum allowable gap width between two metal parts to ensure a strong joint through capillary forces. These forces occur due to surface tension and water vapor entering the gap, bonding the parts together.
Metallurgical relevance & risks in welding
An excessive capillary gap tolerance leads to lack of fusion because the water vapor doesn't sufficiently penetrate the gap. This can result in poor joints and cracks in the filler metal. A gap that's too small, on the other hand, can cause overpressure and surface damage.
Workshop practice & instructions
The capillary gap tolerance should be precisely maintained to ensure optimal joints. A gap width of 0.1 to 0.2 mm is a good starting point. For special materials or high stress applications, the tolerance may be smaller (down to 0.05 mm). It's important to clean the filler metal before welding and keep the metal dry.