Minac brings precise induction preheating to robotic welding
Polish automation specialist Robopartner Welding Systems needed a controllable way to preheat aluminium tubes before welding. By integrating an ENRX Minac into its robotic welding cell, the company has introduced precise, repeatable induction preheating into an automated welding process.
When preheating becomes part of an automated welding process, the heating method needs to be just as precise and adaptable as the welding itself. For Robopartner, a Polish supplier of robotic welding cells, this led to a new solution based on the Minac mobile induction heating system.
Robopartner designs and builds the RoboArc series of robotic welding cells for MIG/MAG, TIG and special processes, working alongside partners such as KUKA and Fronius. The company recently took delivery of its first Minac 6/10 SM Twin, which is being integrated into a robotic welding cell for preheating aluminium tubes before welding.
Aluminium can be challenging to weld because of its high thermal conductivity, which causes heat to spread rapidly away from the weld zone. For thick aluminium sections, preheating may be required by the welding procedure to ensure that the material reaches and maintains the necessary temperature for the welding process. In this application, the system brings the tubes to approximately 120°C before welding starts. A Minac system is also used to maintain the required interpass temperature during welding.
Precision and safety
‘We needed a heat source that our robotic cell could control, and the ENRX Minac fits perfectly,’ says Technical Manager Kacper Gnot of Robopartner.
The company had previously tested flame heating as a possible solution but found that it was not suitable for integration into a robotic welding environment. An open flame is more difficult to control and reproduce consistently from part to part. It also introduces an open flame and gas supply into an automated production environment, creating additional safety and integration considerations.
With the Minac, preheating becomes a controlled step in the automated sequence. Induction generates heat directly in the tube, without an open flame or contact with the workpiece. This makes it considerably easier to integrate preheating into the robotic cell and control the process consistently.
Designed for automation
ENRX specifically designs the compact Minac unit with automated applications in mind. A key advantage is the handheld transformer (HHT), which can be mounted on a robot arm, allowing the equipment to be integrated into automated production lines. The HHT is connected by flexible, water-cooled cables and can be fitted with different coil designs to suit the application.
‘This gives us the flexibility we need to integrate the heating equipment into our automated cells,’ Gnot explains. ‘The result is better on four fronts: faster cycle time, better weld quality, a safer cell, and a process that is fully automated.’
Communication capabilities were another important factor. The Minac supports several communication and control options, and Robopartner selected PROFINET to communicate with the robotic cell's control system. This allows preheating to be incorporated into the automated sequence alongside the other operations.
COMPACT AND FLEXIBLE: Space is tight in a robotic cell, and the compact Minac is designed for integration. Its handheld transformer is connected by flexible cables, allowing the heating head to be positioned exactly where it is needed.
ENRX Sales Manager Michał Wranik (left) and Technical Manager Kacper Gnot of Robopartner.
Local support makes a difference
Local support also played a role in why the company chose induction equipment from ENRX.
‘ENRX Poland is located quite close to Robopartner, so we're able to provide local service,’ says Sales Manager Michał Wranik. ‘Additionally, we have Polish programmers at ENRX in Norway who are able to support the integration and communication aspects of the project. We know from experience that being able to pick up the phone and speak to ENRX in Polish when they have a question is something that matters to customers. The language barrier should never become a project barrier.’
A first step
This is the first Robopartner application using Minac, but it is not expected to be the last. The company is already considering the technology for other projects.
The solution was presented jointly by ENRX and Robopartner at a recent Fronius welding show, where visitors showed strong interest in the possibility of combining robotic welding with automatic, precise preheating.
‘Visitors were positively surprised that it is possible to build such a robotic cell with automatic and precise preheating,’ says Wranik.
The project demonstrates how induction preheating can be integrated directly into an automated welding process, providing controlled and repeatable preheating without the practical limitations of flame heating. For Robopartner, it is also a step towards fully automated welding operations, with heating and temperature control incorporated into the same production sequence.
Why is preheating required when welding thick aluminium sections?
Aluminium has high thermal conductivity, meaning it rapidly transfers heat away from the weld zone. This is particularly challenging when welding thick sections, which have a large thermal mass and can absorb considerable amounts of heat.
Depending on the alloy, material thickness and welding procedure, preheating may be necessary to bring the material to the specified starting temperature and help maintain suitable conditions throughout welding.
Preheating can help to:
- Compensate for high thermal conductivity: Reduce the amount of heat drawn away from the weld zone, helping establish the required welding conditions.
- Reduce temperature differences: Bring the component closer to a uniform temperature, helping manage thermal gradients.
- Remove surface moisture: Help eliminate moisture that could otherwise contribute to hydrogen-related porosity. Proper surface cleaning remains essential.
- Balance heat across uneven sections: Help compensate for differences in thermal mass when joining components of different thicknesses.
Temperature control matters
Aluminium must not be overheated. The appropriate preheat and interpass temperatures depend on the alloy, material thickness and approved welding procedure. Excessive heating can permanently damage the mechanical properties of heat-treatable aluminium alloys.
For the Robopartner application, the target preheating temperature is approximately 120°C, reached in about 70 seconds. The Minac system also maintains the required interpass temperature during welding.