The Electric Materials Company manufactures AC Rotors in a state of the art production facility for many of the major mass transit systems around the world.
Through the use of custom manufactured tooling and dedicated equipment our experienced staff produces AC rotors of the highest quality. From the initial stacking operation for the core through to the final dynamic balance operation, all steps are subjected to very stringent monitoring as part of our ISO 9001:2008 Quality Control Plan.
Following is a brief synopsis of the manufacturing method used to produce our complete AC rotors:
First the core is stacked utilizing custom fixturing which produces a built up core of precise uniformity and trueness. Chemically cleaned rotor bars are then inserted into the core and mounted on the shaft. Then a series of machining and inspection steps prepare the rotor for the end connector brazing process.
Induction brazing is utilized to join the bars and end rings together. This manufacturing method produces a far superior connection than torch brazing. The brazing operations take place in one of our two computer-controlled induction brazing machines. During the brazing operation, precise non-contact temperature monitoring equipment continuously sends data to the computers which control and adjust the brazing process for uniform temperature control around the circumference of the ring. The process time for the brazing operation is relatively quick which is beneficial in maintaining desired metallurgical properties of both the end rings and bars. This produces the highest quality braze joint possible providing exceptional electrical and mechanical performance.
AC Motor Components
We specialize in the supply of copper components for the repair of AC rotors in the field. We invite you to send us your engineering drawings or bar and ring samples for evaluation. Our laboratory is equipped to quickly analyze the chemical composition of your product and our engineers will offer the exact copper alloy to achieve optimal performance. Proper matching of alloy composition & chemistry is critical to achieve the desired motor performance.
Copper Rotor Bars
As a copper mill our vertical integration enables us to produce the key conductive elements of the rotor assembly in-house. Our copper mill produces the rotor bars from initial cast billet production through the extrusion and draw processes. We monitor and control the chemical, mechanical and dimensional properties of the material through each step of manufacturing. Finally the rotor bars are cut to length per customer specifications. Small lot quantities are available which reduces the project overall cost and ensures a quick turn-around.
Copper End Rings
The copper end rings are a very critical component in the construction of a quality AC rotor. The rings must be mechanically capable of withstanding the high motor RPM’s and severe duty conditions often seen in traction motor applications. Many of our end rings are centrifugally cast in our foundry and then machined to precise dimensional tolerances. The centrifugal casting process produces an exceptionally pure alloy free from impurities, oxygen, porosity, inclusions and provides a very refined grain structure which exceeds the strength of static cast rings. For motors with exceptionally high RPM’s we recommend our roll forged rings which provide superior mechanical strength.