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Which positioner is ideal for different cylindrical structures?

Technology, Positioners

The recent growth of offshore renewable energy applications and the changes in the tanks, trucks and trailers industry, brought new handling challenges to the industrial world, that is now facing increasingly larger and more complex structures.

Thus, with this paradigm shift, manufacturers are now asking: “which is the ideal positioner for my part?”

The answer is  never straightforward, but we can say that the first thing to do is to analyze the variety and type of production:

  • How many models do we have?
  • Do we want to handle simple cylindrical structures like wind towers? Or do we want to handle tanks or even more complex tubular geometries such as jackets for monopiles or for oil platforms?
  • What are the processes where these systems will be integrated? Welding, painting, pickling, ...?


Since the wind towers’ surface is mostly smooth, turning rolls (also known as roller beds) are usually the best option. Loading and unloading is easy, and setup is somewhat short.
There are several types of turning rolls:

  • Fixed Turning Rolls

    The diameter adjustment is manual, so fixed turning rolls are ideal for when we work always with the same model. It is also usually a more economic option.
  • Self-Aligning Turning Rolls

    The self-aligning turning rolls option has an automatic adjustment to the diameter of the structure. The part's own weight and dimensions force the rolls to move and accommodate the tower which ends up in an optimal centered support position.
  • Fit-Up Turning Rolls

    In this case, through a hydraulic system, it is also possible to adjust the height of the fit-up turning rolls. This is especially used when we have two shells and we want to weld them together. For this operation we must guarantee the best possible contact for the welding and, to do so, it is often necessary to also adjust the height.

Important information:

  • When the turning rolls are integrated in more invasive processes (for example painting or metallization), some modifications needs to be made, in order to guarantee, not only the functioning of the equipment itself, but, above all, the safety of the workstation.
  • The turning rolls can be motorized in translation to move them within the factory (with the use of rails).


Despite many manufacturers use traditional turning rolls for surface treatment, Motofil has developed special positioners for painting. In these positioners, the handling of the part is done without external contact, which results in a more effective painting process, with less need for corrections.


Due to the irregular geometry of this components, turning rolls are not a viable option, so manufacturers end up using lathe positioners. These positioners can be prepared for a manual operation or be integrated in a robotic welding installation.

  • Manual Operation

    Unlike the turning rolls, these positioners have a coupling system at the ends and are equipped with a motorized lifting movement. This motorization allows a more ergonomic position for the operator, as it allows him to load the part at a low height from the ground and lift it according to his needs to carry out the welding.
  • Robotized Installations

    The main difference from the manual positioners, is that all movements are servo-controlled to guarantee a good collaboration with the robot. It is important to note that there may be an adjustment to the length of the positioners when moving the counterpoint. This adjustment can be motorized or manual.


Although cylindrical, some structures have a highly complex geometry, such as jackets. Here, to ensure that the robots can access the joints, it is necessary to be able to manipulate the part in 5 axes. Our main solution for this challenge is the use of orbital positioners and a robot in an optimal position, which usually means that he is "hanging" in a gantry with freedom of movement in X, Y, Z.
This combination not always guarantee that welding is possible, but it is the most flexible solution that best match the challenge of welding parts with such difficult access requirements.


Besides what was described in this article, there are many other factors that conditions the choice of a handling system (production volume, budget, manufacturing process, factory layout, ...). In the end, the best approach is to look at the challenge and discuss the best solution with an industrial machine manufacturer, like Motofil.


/ N/D