Within a month of taking delivery of automated welding equipment to perform cold metal transfer (CMT) welding, Metalplus received no less than four orders from large industrial customers to repair a diverse range of machine components.
Metalplus’ acquisition of the state-of-the-art new equipment means it no longer has to subcontract out the specialised welding work CMT equipment performs.
“With CMT we can weld a 1mm thick sheet without distortion, so enabling us to do repairs on, typically, the thin-walled impellers of compressors and pumps, small diameter shafts, as well as applying hard-metal coatings to steam valves and other hard-wearing components requiring special protection against wear,” said Roman Mornau, Metalplus’ Divisional CEO.
The robotic welding system enables welding of complex three-dimensional shapes. “In addition to its special capability of performing very fine work without distortion, as well as its speed and accuracy, the CMT system has the further advantage of very low welding energy impact into the parent metal compared with conventional welding technologies,” Roman pointed out.
Within a month of putting the system into operation at its Robertsham, Johannesburg, workshop in mid-August, Metalplus was awarded the following contracts:
● repairing thin-walled stainless steel impellers of a multi-stage high pressure pump for a large local petrochemical company.
The CMT equipment comprises a six-axes robotic arm to precisely control the welding point, a two-axes manipulator to rotate and pivot items to be welded, and a computerised CMT welding machine.
“The robotic devices are synchronised and fully integrated into the computerised CMT welding machine – all controlled by a single user interface with relative ease of programming,” Roman said.
To achieve a low-temperature weld the CMT process uses an initial arc strike to create sufficient heat for the parent metal to be in solution, and then allows the filler material to form a droplet immediately above the welded area so that no further heat is transferred to the weld by the electric arc. “The droplet simply falls onto the molten surface of the component to be welded. This is repeated at specific increments that are programmed for the application to achieve the desired weld shape,” Roman explained.
If the work item is small it may be connected directly to the manipulator, but when a large component, such as a turbine rotor, has to be worked on then a universal joint is installed between the manipulator and the work piece to rotate the heavy rotor on rollers, with the ability to programme an optimum welding speed.
“Thanks to its flexibility, the system provides repair solutions for a multitude of applications,” Roman stated.
