AEMT - Association of Electrical and Mechanical Trades

25 April 2018
Nestech laminations stack up for the aftermarket
Roberto Movio’s interest in electrical engineering stems from his love of music (writes Thomas Marks, AEMT Secretary). From a young age he would be tinkering with effects peddles for his electric guitar, which drew him towards a degree in electronic engineering later in life at Udine University, Italy.
Rotor stacks of different sizes, assembled and machined to ensure tight tolerances. Such stacks can be welded, glued or riveted and have copper bars and glued permanent magnets. On request, the Company is able to provide rotors shafts.

His career has seen him work as a flight simulator technician for the Tornado aircraft with Thales Alenia, after which he built up over twenty years of experience in the sheet metal cutting industry for stator and rotor core stack laminations and assembly. 

It was at this point that Roberto came across the company PLD Collettori, while exhibiting at CWIEME in 2013. An instant friendship was made with company directors and brothers Luciano and Dino Pesavento. Roberto was ready to start making steps towards setting up his own company, and the Pesavento brothers realised the advantages in becoming partners with Roberto, whose experience neatly complimented their commutator business.

In 2017, Nestech srl was setup, and Roberto moved into PLD Collettori’s facility near Valdastico, with two additions to the works team for machining and assembly. 
Nestech has positioned themselves to offer laser cut laminations for poles, stators, rotor cores, linear motors, transformers, and stirrer stacks completed with windings, shafts, and fabricated housings if requested. Applications for Nestech’s products vary widely from prototype traction motors in the automotive industry to rotor/stator replacements in the repair industry. The choice for focusing on laser-cutting over stamping was clear to Roberto; he has placed himself within the one-off to small batch market, his main competition is from in house laser cutting equipment. There are very few laser cutting companies within Europe who also offer a completed stack ready for assembly. 

The company is young, but they already enjoy the use of a factory with an ISO 9001 quality management system and a 14001 environmental management system in place, thus meeting the requirements of high profile organisations in their client list such as Nottingham University and a major car manufacturer. 

With customers in the renewable energy sector and energy efficiency markets has led Roberto to reflect on his own social responsibility. He has taken great care to adopt sustainable practices not only in production, but also in respecting his workforce, his suppliers, and customers with equal measure. The flexibility of a small workforce means fulfilling these promises is easier than for larger organisations. 

Capabilities


Sharing PLD Collettori’s workshop equipment means Nestech can manage products from a 200mm to 2000mm diameter with lengths up to 3000mm. The facility is also advantageously placed within the engineering belt of Italy stretching inland from Venice. Strategic partnerships have been made with skilled locals, meaning Nestech can also supply pole and stator stacks complete with windings.

Roberto has carefully curated a range of high quality, cutting-edge, suppliers from his contacts within the sector for producing his laser cut laminations. Utilising PLD Collettori’s 3D CAD department allows the company to work with customers to produce accurate drawings, and his expertise in the latest technologies means customers can rely upon his advice for material composition, and assembly options. 

For the repair market, Nestech can reverse-engineer rotor and stator stacks, although original documentation offering dimensions and material grades is important to get an exact replica. If, however, the specification is to enhance the apparatus’s speed or efficiency, then by drawing on Nestech’s extensive experience, a solution can be developed with more modern insulation and material grades, improving the mechanical properties of the replacement product.

Once the final design has been signed-off – the CAD drawings are sent to their laser cutters, while Nestech’s technicians start work on the jigs required to hold the laminations together for pressing.

Backlack bonding

There are many ways in which the laminations can be insulated, stacked and pressed together. A current technology trend in the last few years is a varnish bonding called “backlack”. The technique significantly improves the mechanical strength and magnetic flux of the finished product over past techniques such as crimping, riveting, or welding. 
An insulating and bonding varnish is applied to both sides of the silicon steel lamination before cutting. Once assembled into a stack using a bespoke jig, pressure is applied and the product baked in the oven at 200oC to form a strong insulated bond. The resulting stack provides many improvements such as:

  • A stiffness which means the stack can be easily, and accurately machined to tight tolerances, and stator segments can withstand heavier loads than usual without deforming.
  • Compared to crimping or welded seams, the improved insulation of backlack bonding overcomes short circuits, which can be caused during welding, leading to better magnetic properties and less losses as a result.
  • A tight bonding between laminations minimises vibrations and noise.
  • The laminations don’t breathe under temperature variations, so corrosion is prevented.
Although a superb technology, backlack is not always desirable. For instance, in larger sheets, or for complex laminations with a small surface area to glue, it is still preferable to weld, bolt or rivet the laminations together. 

Once pressed, the stacks will require machining to the final dimensions and are prepared for any further requested work. Before shipping, a dielectric or flash test checks the completed stack for sound assembly, guaranteeing a quality product on delivery.

What’s in the pipeline? 


The Nestech partnership is in its early stages and there is still plenty of work on building business. Whether the PLD Collettori and Nestech will combine to offer their services together or separate as Nestech grows more independent is too early to say. For the time being, the symbiotic relationship has really helped propel Nestech into success. Nestech is developing customers in the UK, as well as with universities and electric motor research and development centres. If you have a motor design that needs prototyping, or a need to enhance a machine with a new stator/rotor, then Roberto will gladly help you through the process.

Media

In this story: Nestech SRL
Via Cavallara 18, 36040 Valdastico (VI), , Italy
0039 0445 745072
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