AEMT - Association of Electrical and Mechanical Trades

25 April 2018
PLD Collettori Commutators – Copper, Steel, Mica and lots of experience!
Nestled in the foothills of the Italian Alpes just a 1 hour drive from Venice , sits the head office and workshops of two recent members to join the AEMT (writes Thomas Marks, AEMT Secretary). PLD Collettori produces commutators for the electric motor sector, and Nestech, a startup producing laser cut stack laminations for electric motors.

Background and Capability

Luciano Pesavento and his brother Dino acquired the 80’s formed Veneta Collettori company in 2002 along with their workshop assets and equipment based in Valdastico, Northern Italy. Placing their initials PLD before the company name to form the company of today. 

Luciano is the mechanical engineer of the two brothers. His strong points may not be English, however with many other English speakers in the company for the international market, this isn’t a problem. His entrepreneurial spirit, and acute understanding of mechanical engineering, inspired by his love of classic cars, means the company is thriving. Dino compliments his brother’s mechanical strengths as an electronic engineer and has the same passion for business. He now also manages his own carbon composites company called Carbonveneta, most likely inspired by working in their father’s construction company. 

When they bought the company, PLD’s customer base came purely from the Italian market. A major customer of theirs at the time was the manufacturer Ansaldo (now part of Nidec). The last 16 years has seen the brothers expand and invest wisely in innovation, engineering capabilities, and business (Nestech). The company now has major contracts with Trenitalia Transport group, and exports between 70-80% largely to the European market, as well as the Middle East and Turkey. They supply a full range of traction and industrial commutators from 250/800mm right up to the more bespoke 2000mm. 

Their small size, but multinational philosophy means they can offer a personalised service to manufacturing companies looking to find solutions through prototypes, engineering companies looking for replacement commutators for old equipment, or any bespoke design. 

With over 30 years of niche experience, PLD can be a welcome partner to draw knowledge and know-how from. Their expertise covers the range of technologies in use, calculating dynamic stresses, material selection, equipment design, assembly methods, and stabilization. An internal design department works with 3D CAD drawings to accurately produce a virtual design, which, when finalised, is also used to develop the jigs required for forming the commutators with great accuracy.

Incidentally, these jigs are also manufactured in house, contributing to their philosophy for quick-response-manufacturing. Combined with an inhouse copper drawing capability, means Luciano’s team can produce high quality commutators in-house, without the unpredictability and lead times from external suppliers. 

Creating Commutators

Variation in commutator designs, means the design and construction is a skilled task. Whether replacing a commutator like for like, or designing a bespoke dovetail, glass-banded, or steel shrunk design, their understanding of the manufacturing methods can help. 

When replacing a commutator like for like, it helps PLD if you have the original manufacturer’s certificate, drawings and dimensions. If these are not available, PLD can work with you to understand the application of the equipment and come to a suitable work specification for the grade of materials to be used. In addition to this, material grades, and modern manufacturing methods mean that mechanical strengths in the commutator can be improved. This might be required if the machine is to operate at higher speeds than originally specified.

The way the commutator bars and mica insulations (segment packs) are mounted onto the steel hub defines the type of commutator, all their methods are designed to apply considerable counter force to hold the bars together despite the high speed centrifugal forces. 

Dovetail or V-ring commutators are the most common method of mounting and are used in most applications. A V-shaped notch is cut in the front and back of the commutator bars. A corresponding V-shaped ring, insulated with mica, holds the commutator together. When clamped, tension forms between the bars and rings, drawing the commutator bars inwards. When designing this mounting method, an experienced designer allows enough bar height to accommodate the v-notch without weakening the bars. A shallow V-notch, designed incorrectly, will allow bars to lift in operation, which will lead to a failure. 

Glass-banded commutators
are lighter in weight and require less maintenance. The segment pack compression is retained on the exterior of the commutator by cured glass banding applied in grooves adjacent to the brush track. These banded commutators, which lack clamping, means they cannot be checked for tightness in the same way as the dovetail configuration. However, by tapping each segment and listening out for the ‘ring,’ ensures the bars have remained rigid. 

Steel shrink ring commutators are designed for extreme duty applications and can withstand rapid acceleration and high speeds. The technique for shrinking-on is more modern than that used for dovetailing. The copper alloy body, which is held together by glass banding, is shrunk into an insulated steel body to give a single compact piece. This can reach high rotational speeds, even for very long commutators.

Moulded commutators are typically smaller, less expensive, for high series production. The equipment is not usually repaired; which is why PLD Collettori do not produce them. 
Finally, before shipping the finished commutators, several quality checks are carried out resulting in an impressive 1.8 x 1000 production defect wastage. Checks include: testing of dimensions, insulation resistance with a dielectric or hipot test, commutator hardness (Brinnel Test), measuring resistance to mass, heat seasoning of the commutator through various operating cycles, and an over-speed centrifuge test. 

Next for PLD Collettori

PLD Collettori sits comfortably in a niche market, for which there is very little competition in Europe. Luciano takes great pride in the quality of the work they produce and hasn’t any concerns about the future of the DC Commutator sector. Although an aging technology, there is plenty of room for business in other countries. The repair industry is becoming a large revenue generator for the business now, so their joining the AEMT network comes at a strategic time. 

Luciano and Dino’s partnership with Roberto Movio and Nestech was formed after exhibiting at CWIEME in 2013. Roberto was representing a steel cutting company close to PLD Collettori’s booth. After getting to know one another better, they realised there was a clear synergy in their expertise and networks. To support Roberto in the startup of Nestech, has meant PLD can reduce their overheads by sharing equipment, and improve parts of their own steel lamination production. Where the expanding companies go in the future, is too early to say, but for now the synergies and co-operation between these two companies is working very well.  


In this story: PLD Collettori snc
Via Cavallara 18 , 36040 Valdastico (VI), , Italy
0039 0445 745097
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