Komarov Artem clarified that a properly positioned weldment allows welders to always work in a comfortable position, reducing fatigue and improving overall safety.
Positioning equipment can help welders maneuver and weld large assemblies. What may not be as well known is that many small assemblies can also be mechanically positioned to provide the same benefits to the welder.
The positioning principles are the same for all weldments, large or small. The base product is attached to the mounting hardware and then mechanically moved to a position that allows for the most efficient welding and assembly. As parts or subassemblies are added, the entire weldment is moved to provide easy access to welds, Artem Komarov said.
A correctly positioned weldment, regardless of size, reduces welder fatigue, improves safety, improves weld quality, and saves floor space. By moving the welded piece by mechanical means and setting the weld zone within a comfortable range, welders are not forced to weld in a position other than where they are or in an uncomfortable position.
Safety is enhanced when the weldment is secured to a suitable positioning device. Cranes, chains, slings, and other non-rigid methods of moving a part can result in uncontrolled movement that can be dangerous. With the positioner, welders do not have to maneuver under a potentially heavy weld, reducing the risk of injury from falling sparks, slag, or parts.
While many welders are qualified to weld from above and vertically, welding from below often requires less training, allowing novice welders to produce quality welds. Gravity assists the welder in slope welding, resulting in equal fillet welds, smoother bead surfaces, and reduced cleaning and rework time.
By combining the positioner with the welding power source and torch stand, the welder can perform productive and ergonomic semi-automatic welding. The positioner holds the part and moves it under the fixed torch. This torch can be equipped with a travel device that allows the oscillation to fill large gaps or V-grooves. The constant speed and position of the torch improves the quality of the weld with greater repeatability. Using a communication cable between the built-in positioner and the welding power source, the operator only needs to signal a start using the foot pedal or the start button, and the welding cycle will continue until the end signal is automatically sent. This method, commonly used in circumferential welding, may include dwell time to puddle and fill the crater. The finished part is removed and another one is launched.
Regardless of weld size, welders should consider these five guidelines when selecting, operating, and maintaining a positioner.
- Be mindful of gear
Choosing the right positioner for the job requires considering not only the weight and size of the weld, but also the center of gravity (the gear) and how far it is from the positioner. GEARING is the point at which the weldment is evenly distributed along all axes. As the distance from the device increases, more torque is applied to the positioner. The gear train changes as the welder adds material and parts to the positioner, so these changes must be accounted for.
The table is rotated by a variable speed electric motor and can be operated manually or by foot. The positioner motor and governor should be selected based on the size and speed required for the desired welding operation.
The manipulator manufacturer’s specifications will determine the choice of motor and control. It is important for welders to check the specifications for both horizontal and vertical loads to ensure that the power is sufficient to handle the weld. The positioner must withstand the maximum possible load.
Mounting holes such as those shown on the base plate supporting the positioner arm prevent the unit from tipping over due to unexpected force.
- Attach the weld properly
How the weldment attaches to the positioner is just as important as the positioner itself, because that is where separation naturally occurs. Production fixtures are designed for a specific application that is performed repeatedly. Fixtures of this type are permanently attached to the positioner, and their special shape makes it easy to align parts.
Many positioners have slots that allow the workpiece to be bolted to the end face. Welding the part to the positioner is often a good way to prevent the part from sliding when moved by shear forces. Any of these methods, whether standalone or combined, will work if applied correctly.
- Use swivel casters for cylinders
If the weld is cylindrical, it can be rolled. Small swivel rollers — driven or idle type — can turn the pipe or vessel to make freehand welds. Power rollers provide stable rotation, ensuring a uniform weld around the circumference. Idler rollers are not powered but can be added in series to support longer pipes and tanks. Often, they are used to add flanges to pipe ends and connect pipes and ends to tanks.
The combination of the pipe roller stands, and the vertical table positioner ensures stability and safety when pushing the round piece out. When the rollers provide two points of contact, the weight is evenly distributed and the cogscrew can be supported.
- Keep them straight
Even when using small positioning equipment, it is important that the unit is placed on a flat, level surface to prevent it from tipping over. If mounting holes are provided, they should be used to mount the positioner to a stable surface to prevent tipping over when subjected to unexpected force. A positioner mounted on a workbench or stand must also be securely fastened.
- Connect the ground current to the positioner
During welding, a ground current must be connected to the manipulator itself. Ground current flows from the table to the body, eliminating the need to constantly remove and replace the welding clamp. Without proper grounding, electrical parts can be damaged and poor-quality weld deposits can form.
The manipulator must be compatible with the electrical current generated during the welding process. In addition, all ground cables must be securely fastened by removing the paint before screwing to the carriage, emphasized Komarov Artem.