The quality of high-precision welding depends on strict preparatory work in advance. Any oversight in details may lead to the final precision not meeting the standard.

One: Workpiece accuracy control

The dimensional tolerance of the workpiece to be welded should be controlled within ±0.02 to 0.1mm (adjusted according to the scene), and the shape and position tolerances (such as flatness and perpendicularity) should be ≤0.05mm/m to avoid welding misalignment caused by the deviation of the workpiece itself.

The precision of bevel processing: The bevel Angle, the thickness of the blunt edge, and the gap must strictly comply with the design requirements (for example, the gap of the bevel in laser welding is usually ≤0.1mm). Precision processing equipment (such as slow wire cutting, laser cutting) should be used to ensure that the surface roughness Ra of the bevel is ≤3.2μm, avoiding burrs and oxide scale from affecting the fusion.

Cleanliness requirements

The area to be welded on the workpiece (including the bevel and the 50mm range around it) must be thoroughly cleaned of oil stains, oxide films, rust, moisture and other impurities. It is commonly wiped with alcohol or acetone or cleaned with ultrasonic waves. If necessary, acid washing and passivation (such as for stainless steel) should be carried out.

Welding materials (welding wire, welding rods, shielding gas) must be dry and free of impurities: the surface of the welding wire must not have oxide scale or oil stains, and the purity of the shielding gas (such as Ar, He) must be ≥99.99% (up to 99.999% in special scenarios) to prevent gas impurities from causing pores and inclusions.

Welding material matching

The composition of the welding wire/electrode should match that of the base material (for example, the same material welding wire should be used for stainless steel welding, and transitional filler materials should be selected for welding dissimilar materials), ensuring that the mechanical properties of the joint are consistent with or close to those of the base material.

The diameter accuracy of the filling material needs to be controlled (for example, the diameter tolerance of the fine wire TIG welding wire is ±0.02mm) to avoid unstable deposition due to diameter fluctuations.

Ii. Welding Equipment and Parameter Control

Equipment accuracy and parameter stability are the core guarantees for high-precision welding, directly affecting the shape of the molten pool, heat input and joint consistency.

Equipment accuracy requirements

Welding power supply: The stability of output current and voltage should be ≤±1%. During pulse welding, the error of pulse parameters (frequency, duty cycle) should be ≤±0.5% to ensure uniform heat input.

The positioning accuracy of the motion system welding robot or workbench should be ≤±0.02mm, and the repeat positioning accuracy should be ≤±0.01mm (such as the beam positioning accuracy of laser welding), to avoid the deviation of the welding trajectory.

Auxiliary system: The stability of the wire feeding speed of the wire feeding mechanism is ≤±2%, and the control accuracy of the protective gas flow is ±5%, ensuring the stability of the filling volume and protection effect.

Optimization of process parameters

Heat input control: For high-precision welding, heat input must be strictly limited (for example, the heat input for laser welding of thin-walled parts should be ≤50J/mm) to avoid dimensional deviations caused by thermal deformation. By adjusting parameters such as current, voltage, welding speed, and beam power (for laser welding), the fluctuation of the molten pool size (penetration depth and width) should be no more than ±0.05mm.

Welding sequence: For complex structures, a reasonable welding sequence should be designed (such as symmetrical welding and segmented stripping) to reduce overall deformation. For instance, circular welds are welded symmetrically and synchronously to prevent the center of the circle from shifting due to heating on one side.