Magnetic Assemblies

Assembly Tube Protection

Precision Magtech cooperated with a company in Italy offers a unique tube protection solution for permanent magnet assembly. This technological solution is used, among other applications, for mechanically fix the magnets on rotors for electric motors in a more effective, rapid and reliable manner. It can be used directly on automatic production lines to significantly reduce costs and production times for permanent magnet motors.

The heat shrink tube is fitted on the rotor, with the magnets already in position, then closed via a jet of hot air.
This results in strong adhesion, even for high-speed engines.

At the same time, it provides resistance to thermal shock, generated by a motor in continuous use.

This solution has also the function of protecting the magnets from corrosion and breakage.

Thanks to Its powerful mechanical closure and component compaction, it can also provide a reduction in motor noise.
The reduced and constant thickness of the tube wall (0.12 - 0.20 mm) does not influence the magnetic flux of the magnets, allowing designers to achieve safer solutions and optimal performance.

The current tubes diameters available range from 2 to 150mm.

Thermal resistance of over 180°C, together with excellent resistance to chemical substances, means it can be used in various application fields, even in difficult working conditions.

Positioning and the retraction/thermoforming cycle are immediate (5-10 seconds at approx. 150°C), facilitating extensive use, also in automatic production lines in the home appliance and automotive fields.

Magnetic Rotor Tube

In recent years brushless motors have come to represent an important innovation in the field of electric motors. Through the introduction of permanent magnets made with alloys containing rare earths such as Neodymium and Iron Boron, despite their small size, these motors are able to develop 50% more torque than conventional motors of the same size.

Moreover, brushless motors enable a reduction in energy consumption, have higher speeds, require less maintenance, dissipate heat better, have a lower moment of inertia, can be overloaded and are more reliable.

SPM (surface permanent magnet) brushless motors also have an inertia that is 20-30% lower than IPM (interior permanent magnet) brushless motors and their only real drawback was their increased cost.

This higher cost was due to the complexity of fastening the magnets and the difficulty in automating fixing of the permanent magnets externally to the rotor, also due to the fact that they are made of a material that cannot be welded.

It must be stressed that, unlike more costly steel or brass rings, our spiral-wound tube also covers and protects the ends of the magnets, which are also subject to corrosion and which, if chipped, can cause the motor to seize.
In motors that use annular magnets obtained by compression molding of Nd-Fe-B with the addition of thermosetting resins (plasto ferrite), our tube also protects the magnet from corrosion, in view of the fragile nature of the alloys used, preventing the motor from seizing.

The special polyester used reaches the point of maximum hardness upon completing the heat-shrinking process, thereby guaranteeing an excellent mechanical seal.
The spiral-wound polyester film is perfectly suited to this application, also due to the fact that brushless motors usually do not operate at very high temperatures, as the majority of permanent magnets would become de-magnetized. Our tube is used at operating temperatures of around 130-135°C, with peaks of up to 155°C.

The fact that the tube is perfectly round also guarantees balancing of the rotor.
This special tube has internal diameters ranging from 15 to 85 mm; thicknesses are very low and vary from 100 to 250 microns.
Even after heat-shrinking, the tube does not interfere with the air gap and with the magnetic flux of the motor, allowing it to achieve the maximum performance for which it was designed.
This simple, rapid and efficient solution is patented and has already been well and successfully received throughout the world by many leading companies in the field, after years of rigorous stress testing.

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

The Tubes technical department is at your service to listen to your needs and offer made-to-measure innovative solutions.

Tube Heat Shink on Rotor

Noise Reduction for Motors

SOLUTION FOR REDUCING NOISE IN ELECTRIC MOTORS

For over 20 years, Tubes has offered a unique solution for reducing the noise of electric motors by several decibels.

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.

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

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

It has the following functions:

1. Reducing rotor noise by several decibels
2. Protecting the magnets from dust, increasing the life of the motor
3. Compacting the surface of the rotor housing the slots, obtaining balancing of the rotor

This high tech tube is produced using the spiral-wound technique, and has no overlap.

In the 1990s our customers asked us to find a solution to the obsolete flattened 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).

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.

Tubes Size supplied and prices

The maximum inside diameter we can produce is around 145 -150 mm for the Tubes, so Rotor outer diameters are 145-150mm.

The polyester tubes can stand till 20.000 RPM for rotors diameter around 50 mm.