Focus position
The focus position is the vertical location of the narrowest beam cross-section in laser or electron beams relative to the workpiece surface. It largely determines penetration depth and bead geometry.
Physicochemical mechanism of action
The focus position is where laser or electron beams have their narrowest cross-section. This point lies near the workpiece surface and influences the beam's energy distribution.
Metallurgical relevance & welding risks
The focus position directly affects penetration depth and bead geometry. If it's too high, penetration can be too deep, resulting in a thin, fine weld profile—risking toughness and microstructure. If too low, penetration is too wide, making a thick, irregular bead—leading to distortion and defects like porosity or hot cracking.
Workshop practice & procedures
To hit the optimal focus position, position the beam so it has the smallest cross-section on the workpiece surface. You can do this by adjusting the focal point and beam distance. For laser welding, a focus position of about 1 to 2 mm is common; for electron beams, it's often between 0.5 and 1 mm. The exact value depends on the material, welding method, and specific requirements.