The deciding factor for the weld seam and the surface quality during friction stir welding is the control of the process parameters, chief among them is the contact pressure. This is reported back through the sensors in the welding head to the machine and process control system.

This together with the individual axes of the lead machine represents a force control circuit. Different weld depths on a component can be realized with just one FSW tool type enabled by dynamic adjustments of the weld depth during the welding process. In addition, the hallmark exit cavity (negative of the friction pin) at the end of FSW seams, can be significantly reduced.

Highlights:

• Rotational speed up to 8000 rpm
• Force-controlled process via high precision sensors
• Integrated Tilt axis of 0 – 5°
• Chuck for multi-part FSW tools
• Pneumatic chucking for quick tool change
• Variable setting of the welding depth (optional)

DynaSTIR Friction Stir Welding Tool Technology

When considering which friction tool to employ, there are two choices: the original one piece (monolithic) design and the modern multi-part friction tool. Grenzebach specializes in the development and fabrication of multi-part friction tools based on a stationary shoulder design. Friction pin and shoulder materials, as-well-as the tool geometry, are individually adapted for diverse customer applications to ensure the best possible seam and seam surface quality.

Highlights:

• High quality seam surface (usually no refinishing necessary) 
• Significantly reduced process forces compared to monolithic tools
• Highly dynamic welding enabled by non-rotating tool shoulder 
• Separate parameterization of the friction pin and the shoulder possible (i.e. the stirring and compression processes can be adjusted independently of each other)
• Shoulder geometry does not have to be rotationally symmetrical. Special shapes such as tailored blank or fillet weld shoulders are also possible
• Extended durability through the use of high quality materials
• Lower heat input  
• Enables the use of the process for thin sheet application with material thicknesses < 1.0 mm 
• Independent replacement of friction pin and shoulder possible

The compact 4-Axis-machines DSM1400 & DSM2400 have been specially developed for FSW-process requirements. The focus during the development of these machines was geared
towards dynamic and precise process control as well as an intuitive control and operating concept.

HYDROPOL® Machine bed – Specially designed for very high static rigidity, low dynamic flexibility and deformation in steel-covered polymer concrete.

4-Axis-portal system – Designed for high axis dynamics and precise line guidance. The integrated C-axis allows the welding head to rotate by 360° both clockwise and counter-clockwise and thus is much more dynamic for joining complex path trajectories with narrow radii.

• Portal-traversing speed: Up to 13 m/min
• Welding speed: Up to 3 m/min
• Working range: DSM1400 1400 x 1000 x 400 mm and DSM2400 1400 x 2400 x 400 mm
• Max. axial force (Portal): 8000 N
• Process accuracy: +/-0.1 mm

Machine and process control – With the IndraMotion MTX control by Bosch Rexroth, Grenzebach relies on well proven CNC control technology and combines this with innovative
FSW process control. The machine and process programming is made easier via FSW CAD/CAM programming software.

In terms of cycle time, the rapid loading and unloading of components is just as important as the dynamics and speed of the welding machine. Modular, expandable, automatic feeding systems allow for simultaneous welding and loading / unloading of work pieces outside of the machine. The loading and unloading of components can be done manually by the operator with the help of a manipulator or an indoor crane, or fully automated.

The pivoting control panel with a 21 inch touch panel allows the operator to keep an eye on all welding parameters and machine data at a glance. A handheld controller is provided to manually control the axes. The large window in the front allows maximum visibility into the work space for the best supervision of the welding process. Optionally, you can follow the welding process at the control station via a camera integrated into the welding head.

Heavy assemblies and devices can be moved easily in and out of the machine with the help of an indoor crane. The machine is open at the top and the protective door at the front of the
machine is sufficiently large to ensure accessibility to the entire working area.

At the back of the machine, the service and maintenance personnel have easy access to the control hardware and  the central power supply.