For over 20 years, Politubes has offered a unique solution for reducing the noise by several decibels of universal electric motors caused by the rotors gaps when spinning at high rpm.

The special multilayer spiral-wound tube produced for this application is fitted over the rotor and heat-shrunk so that it takes the shape of the rotor, obtaining complete uniformity of its surface and a perfect roundness in order to preserve rotors balancing.

This compacting of the surface drastically reduces the noise caused by the rotor slots during rotation.

The tube is made using only heat-shrinkable Polyester designed specifically for electric purposes (Mylar HS UL nr E 93687).

The advantage using Polyester is its high mechanical resistance, even with very limited thicknesses (between 50 and 120 micron).

It has the following functions:

  1. Reducing rotor noise by several decibels.
  2. Protecting the magnets from dust and pollution, increasing the life of the motor.
  3. Avoiding that copper wires come out from rotors.
  4. Compacting the surface of the rotor housing the slots, obtaining balancing of the rotor.
  5. Thermal (class B) and dielectric (4 – 5 kV) insulation.

Our heat shrinkable polyester tubing also guarantees the double electrical insulation requested by IEC 60335-1 standard, allowing electric motors manufacturers to obtain VDE / UL / CCC certificates.

This high tech tube is produced using the spiral-wound technique, and has no overlap; spiral wound tubes is the only way to preserve a perfect roundness of the tubes and the rotors balancing.

In the 1990s our customers asked us to find a solution to the obsolete Lay-Flat tube with overlapping edges, as our tube must be perfectly round in order to guarantee balancing of the rotor (an essential feature in any motor).

As a matter of fact, the overlapping of layers in Lay-Flat sleeves was causing the lost of rotors balancing.

Therefore, the use of a multilayer spiral-wound tube ensures a higher dielectric strength and mechanical resistance.

The limited thickness means that the tube does not interfere with the gap and with the magnetic flux of the motor, even after heat-shrinking.

Due to completely automated insertion and to instant heat-shrinking of the tube on the rotor, the product adapts perfectly to automated production processes, as shown in the video above.

This tube can be cut to size or rewound in rolls with lengths of several hundreds of metres, in order to optimise logistics and reduce transport costs.

The adhesives, carefully selected during our forty years of experience, comply with all REACH and ROHS standards and ensure the films used maintain all their original properties.

The Politubes R&D center remains at your disposal should you require anything, and to work together to design tailored, innovative solutions.