Abstract: Apparatus for laser welding a first metal part (1) to a second metal part (2), which apparatus comprises: a laser (3) which emits a laser beam (6) in the form of laser pulses (21), a scanner (4) for moving the laser beam (6) with respect to a metal surface (7) of the first metal part (1), an objective lens (5) which focuses the laser beam (6) onto the metal surface (7), and a controller (12) which controls the scanner (4) such that it moves the laser beam (6) with respect to the metal surface (7) to a plurality of focussed spots (16), characterised in that the apparatus focuses the laser pulses (21) with a spot size (34) and a pulse fluence (36) that causes the formation of a plurality of melt pools (19) in the first metal part (1) and heat stakes (17) in the second metal part (2), each heat stake (17) extends from a different one of the melt pools (19) and has a distal end (101), and the controller (12) spaces the focussed spots (16) apart by a distance (18) that is small enough to cause the melt pools (19)

Abstract: A weld (3) between a first material (1) and a second material (2), the first material (1) being a first metallic material, and the second material (2) being a second metallic material, the weld (3) has a width (4) between 0.5 mm and 7 mm, the weld (3) comprises at least one microweld (8), the microweld (8) forms a welding pattern (5) defined parallel to a surface (6) of the first material (1), and the microweld (8) has a characteristic feature size (7) of between 20 ?m and 400 um.

Abstract: Apparatus for laser welding a first metal part (1) to a second metal part (2), which apparatus comprises: a laser (3) which emits a laser beam (6) in the form of laser pulses (21), a scanner (4) for moving the laser beam (6) with respect to a metal surface (7) of the first metal part (1), an objective lens (5) which focuses the laser beam (6) onto the metal surface (7), and a controller (12) which controls the scanner (4) such that it moves the laser beam (6) with respect to the metal surface (7) to a plurality of focussed spots (16), characterised in that the apparatus focuses the laser pulses (21) with a spot size (34) and a pulse fluence (36) that causes the formation of a plurality of melt pools (19) in the first metal part (1) and heat stakes (17) in the second metal part (2), each heat stake (17) extends from a different one of the melt pools (19) and has a distal end (101), and the controller (12) spaces the focussed spots (16) apart by a distance (18) that is small enough to cause the melt pools (19)

Abstract: A method of working metal in which molten metal particles are ejected from, for example, a welding electrode or from a metal workpiece being cut or drilled. The ejected molten metal particles are caused to pass through a contact region in which they make contact with a cryogen, for example, liquid nitrogen or solid carbon dioxide. The contact renders the particles non-adherent to any adjacent surface to which the particles would otherwise adhere. Alternatively, the adjacent surface may be cooled by contact with a cryogen so as to render the particles non-adherent thereto.

Abstract: In a method of cleaning metal surfaces to be welded together, at least one jet carrying particles of solid carbon dioxide is caused to come into contact with the surfaces, where the solid carbon dioxide is allowed to sublime at the surfaces. The jet is formed by passing a stream of pressurised liquid carbon dioxide through a nozzle under pressure.

Abstract: A method of working metal in which molten metal particles are ejected from, for example, a welding electrode or from a metal workpiece being cut or drilled. The ejected molten metal particles are caused to pass through a contact region in which they make contact with a cryogen, for example, liquid nitrogen or solid carbon dioxide. The contact renders the particles non-adherent to any adjacent surface to which the particles would otherwise adhere. Alternatively, the adjacent surface may be cooled by contact with a cryogen so as to render the particles non-adherent thereto.

Abstract: In a method of cleaning metal surfaces to be welded together, at least one jet carrying particles of solid carbon dioxide is caused to come into contact with the surfaces, where the solid carbon dioxide is allowed to sublime at the surfaces. The jet is formed by passing a stream of pressurised liquid carbon dioxide through a nozzle under pressure.

Abstract: A method of friction stir welding together at least two metallic workpieces, including the step of applying at or adjacent a heated welding zone a cryogen in the form of at least one jet. The cryogen may be solid carbon dioxide. The workpieces may be of aluminium or an aluminium alloy.