Welding
Welding is a permanent metal-joining process that fuses two or more components using heat, pressure, or both, often with filler metal and shielding gas depending on the process. In manufacturing, welding creates structural assemblies such as frames, fixtures, and machine bases before CNC finish machining restores flatness, parallelism, and critical datums affected by weld shrinkage and the heat-affected zone.
On the shop floor, hybrid weld-and-machine work usually follows a weld-first, machine-later sequence. Fabricators burn in the assembly with extra stock on critical faces, then transfer it to the CNC after the weldment has stabilized or been stress-relieved. Welding changes geometry: heat creates a heat-affected zone and residual stress, and shrinkage during cooling can pull long members out of square, shift hole patterns, or bow a base plate. A machinist often has to skim-cut bearing pads, guide-rail lands, dowel holes, or sealing faces to restore flatness, parallelism, and location. Process choice shapes the workflow: MIG is common for structural fabrication, TIG for cleaner precision, laser for low heat input and automation, and friction stir welding where melting is undesirable. These can be CNC- or robot-driven, but the final skim cut brings the assembly back to print.
Is welding the same as CNC machining?
No. Welding is a joining process that fuses components with heat, pressure, or both, while CNC machining is a subtractive process that removes material to create precise geometry. They are complementary steps in a fabrication workflow.
What does 'CNC welding' mean?
CNC welding usually means the welding motion or sequence is controlled by a computer or robot, not that welding becomes a machining operation. It allows automated, repeatable weld paths and can be integrated with robotic positioning.
Why is the heat-affected zone important to machinists?
The heat-affected zone is the region next to the weld whose microstructure and properties change from thermal exposure. It matters because that change can affect distortion, strength, fatigue performance, and machinability near the joint, which is why finish machining after welding is often necessary.