Welding Process Classification based on degree of Mechanization
Welding processes are usually classified by the degree of mechanization by the code (E.g. ASME Section IX or AWS D1.1) and standards ( e.g. ISO 9817, ISO 15614-1). This classification is basically founded on the manual efforts put by the welder or operator during the welding processes.
The classification is based on the various parameters such as movement of welding torch, feeding of electrode or filler wire, and the handling of the workpiece. There are four main types of welding processes based on this classification:
- Manual Welding
- Semi-automatic Welding
- Fully-mechanised or Machine Welding
- Automatic Welding
Manual welding is designated as (m) according to ‘DIN-1910: Welding and allied processes – Vocabulary – Part 100: Metal welding processes’ or DIN EN 14610:2005. In Manual Welding operation, the complete welding operation is controlled by the hand during the welding. The feeding & guidance of the electrode, travel of the torch, and the handling of the workpiece. SMAW or stick welding is an example of a manual welding operation as shown in the below picture. Semi-automatic variants of the SMAW are also available such as spring tension SMAW welding although their applications are very limited.
In semi-automatic welding operation, the welding torch or gun movement is manually controlled by the welder but the electrode feed is automatic & the workpiece is handled manually. For example, in MIG-MAG or FCAW welding. The welder only moves the torch during the welding and the welding wire is fed automatically from the wire feeder connected to the welding machine. So, the welder is only responsible for the torch movement and workpiece handling. An example of a semi-automatic process is shown in the below picture.
Fully-mechanised or Machine Welding
In mechanised welding, the welding current, welding voltage and welding speed parameters are set to fixed values via the controls (torch movement, workpiece movement and wirefeed) on the welding machine without the manual movement by the welder. Similarly, the machine welding is defined as the type of welding where the welding operators control the welding via the controls (by adjusting torch movement, workpiece movement and wirefeed via buttons) on welding machine. Hence, the welder or operator do not engage in manual handling of welding torch & wire feed. The example of machine welding or fully mechanized welding is Submerged Arc Welding where welder controls welding torch movement & wire feed via machine buttons.
The mechanized welding equipment controls the following variables:
- Initiation and control of the welding arc,
- Feeding the welding electrode wire into the arc, and
- Control of movement and travel speed along the joint.
welding variable, as uniform speed and weld direction during operation are vital for quality welds. Quality also depends on how rigidly the welding carriage is held to the track because excessive vibration or dimensional variation can adversely affect the wire tip position.
GMAW as well FCAW can be fully mechanized conditional to setting up special purposes machine called SPM, where the torch movement is synchronized with the welding machine and controlled by electonic buttons. They are very useful for mass production where torch is fixed on a lathe and circular seams are welded. Other welding systems are used in pipe line welding using special purpose welding machine using GMAW and FCAW processes.
Robotic welding is type of welding where torch movement, wire feed as well as workpiece handling are automated. The welding operator use the machine controls to control all the welding parameters. In robotic welding, the welding parameters are programmed in the machine and can be recalled for later stage. The handling of the welding parts is automated too and no manual operation is involved. A summary of main parameters that defines the degee of welding automation is given in the below picture.