Laser welding techniques

Heat conduction welding and keyhole (deep penetration) welding

Heat conduction welding is a laser welding method that features a low output. This makes for a penetration depth of no more than 1 to 2 mm. With the ability to handle a relatively wide power range, heat conduction welding can be adjusted to the ideal power level, and the shallow penetration makes it possible to weld materials that are susceptible to heat effects under optimal conditions.
This welding type is used for butt joints, lap joints, and other welding applications for thin plates, and can also be used for welding hermetic seals and other seals. Heat conduction welding is also suitable for volatile alloys such as magnesium and zinc, for which keyhole (deep penetration) welding is not suitable.

Keyhole welding (deep penetration welding) uses a high-output laser for high-speed welding. The narrow, deep penetration allows for uniform welding of internal structures. Because the heat-affected zone is small, distortion of the base material due to welding can be minimized.
This method is suitable for applications requiring deep penetration or when welding multiple base materials stacked together (including for butts, corners, Ts, laps, and flange joints).

Differences between heat conduction welding and keyhole (deep penetration) welding

	Heat conduction welding	Keyhole (deep penetration) welding
Tolerance	Accuracy required on both surfaces	Accuracy required only on one surface
Heat efficiency	Approx. 35%	Approx. 95%
Welding efficiency level	Low	High
Welding speed	Slow	Fast
Energy required for 1 mm seam	High	Low
Heat-based distortion	Slight distortion	Minimal distortion (less than heat conduction welding)
Seam size	Large	Small
Seam smoothness	Smooth	Rough

Remote laser welding

Remote laser welding is a welding method where the laser beam is controlled by a mirror and quick movements of the welded part for high productivity, production line flexibility, and cost-effectiveness.
The laser beam is controlled by a movable mirror (1) and a lens system (2). The lens system can be used to control the Z direction, and the movable mirror can be used to control the X and Y directions (3), enabling quick and accurate application of the laser beam to the welding area anywhere within the laser beam range (4).

Laser deposit welding

This method is also referred to as laser cladding or direct metal deposition. Welding involves the use of a filler material, with the surfaces of the filler material and the base material melting to form a metallurgical bond. Common filler materials are wire or metal powder. This method can be either automatic or manual depending on the application. Laser deposit welding can be used not only for joining but also for repairing weld surface defects, for manufacturing mesh-shaped components by forming weld beads, and for processing metal surfaces.