Plastic film extrusion machines have been equipped with Baumüller motors and converters for the Spanish manufacturer Jumarsol.
High-torque motors are steadily outpacing conventional gearbox motors when it comes to extrusion technology applications. Their compact design, in particular, is proving to be especially advantageous for machinery manufacturers. In spite of their small size, high-torque motors deliver the performance of geared motors while being more energy-efficient. They can be integrated into existing machine concepts or arranged side by side without difficulty. This increases the power density of the machine because less packaging space is required and less production area is utilised.
High-torque motors as direct drives
Moreover, high-torque motors are suitable for use as a sophisticated direct drive solution. Instead of the technically more complex gearbox solution, more and more users are turning to direct drives because they eliminate high-maintenance transmission components such as belts and toothed gears, for example. As a result, time-consuming and costly maintenance intervals can be reduced, thereby increasing availability of the extrusion equipment significantly. More significant are the energy cost benefits of switching from motor-gearbox solutions to direct drives. The elimination of wear-prone mechanical components in the drive significantly reduces friction losses in the system, thus affecting the energy balance positively – a decisive factor in times of rising fuel prices.
The DST high-torque motors developed by Baumüller fulfil these requirements for energy consumption. When used as direct drives, they exhibit optimum efficiency at the operating point. Thus, they enable an extremely efficient energy conversion since additional losses due to mechanical transmission elements are avoided. These efficiencies are even higher under partial load, resulting in optimised energy consumption over the entire operating range.
Suitability for blown film extrusion process
DST motors are well-suited for a variety of industrial applications – and not just due to their high efficiencies. Their high overload capability and favourable moments of inertia are sought after, in particular, for applications with stringent positioning and synchronous operation requirements. Such an application is the production of industrial plastic film using the blown extrusion process, in which multiple layers of thermoplastics must often be placed one on top of the other with maximum precision.
The special requirements of extrusion technology are also fulfilled by the DST motors of Baumüller in another respect: the motor series features an optional integrated thrust bearing. The reason for this is the amount of recoil forces that occur during extrusion. When the raw material is pressed out of the extruders, enormous pressure is exerted on the piece of machinery behind them. These pressure forces are supported by a thrust bearing integrated in the drive, eliminating the need for machine manufacturers to install a thrust bearing separately.
Application example – Film production at Jumarsol
The advantages of the high-torque motors in terms of performance and energy balance have convinced Brazilian machine manufacturer Carnevalli to equip its Polaris Magnum series blown film equipment with the innovative DST technology of Baumüller. The powerful DST motors ensure that plastic granules are introduced through a funnel into the feeder area of the equipment and then conveyed through the extruder – all with the maximum degree of accuracy. Melting and mixing follow next. The melted raw material is then pressed through a tubular die. This produces a type of plastic tube, which is inflated with air and thus cooled. The intensity and temperature of the cooling air dictates the width and strength of the film. Finally, the cooled film tube is laid flat and wound.
Spanish packaging manufacturer Jumarsol is operating several blown film machines made by Carnevalli and is enthusiastic about the immediate benefits gained from use of the technology. “Since we started using machines with high-torque motors to produce trash bags, we have seen our energy consumption drop by about 25%,” stated Jose Juan Aparicio, owner of the Valencia based company headquartered in Valencia. He is committed to further close cooperation with Baumüller: “We currently have 30 production lines and operate three shifts around the clock. The use of energy-efficient direct drive technology will pay back in a matter of months.”
For more information contact Bradley Douglas, Motion Tronic, +27 (0)31 701 1620, [email protected], www.motiontronic.co.za
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