Progressive blanking is particularly well-suited to the production of large series as it enables savings in the production costs of the single pieces. It enables the use of multi-impression dies which, by optimising the use of the raw materials, guarantees further savings.
When Corpack dies are used, the laminations are stacked during the blanking phase. These production runs are carried out using high speed presses with tonnage of up to 600 t and a range of dies covering diameters of up to 600 mm.
Compound blanking is suitable for medium-sized series or in cases where especially strict tolerances are required with respect to the dimensional characteristics of the stator and rotor laminations.
This technology is used both to produce finished laminations and semi-finished discs to be completed with single notching technology.
Presses up to 600 tons are used and a range of dies covering diameters of up to 1,240 mm.
Single notching is especially well-suited to the production of small series or large-size laminations. Thanks to the fast set-up times, production is extremely flexible.
The presses, from 2 to 20 tons, can be either manual or automatic. Euroslot has built up a large assortment of stator and/or rotor slot-type single notching dies which are at the disposal of design engineers to develop electrical machines, while minimising the costs of investment in tooling.
Ideal for sampling, prototypes or very small series, as it does not involve any tooling costs.
It is possible to manufacture products from steel sheets with maximum dimensions of 1,250 × 2,500 mm and thicknesses from 0.2 up to 20 mm.
The Group has an important heat treatment facility for semi-finished blanked steel laminations, which uses continuous-cycle furnaces.
The treatment involves two main phases: annealing, the purpose of which is to reduce magnetic leaks and increase permeability through the decarburization and enlarging of the grain; bluing, a lamination insulation treatment obtained through the creation of a special iron oxide surface layer.
Assembling of lamination stacks
The technology most widely used by the Group to assemble stacks is TIG, MIG, Plasma or Laser welding.
Backlack technology involves the use of magnetic sheet steel insulated with a thermosetting polymer which when exposed to temperatures of approx. 220°C, reacts causing the laminations to stick together. This is the best technology available in terms of electrical performance and strength of the finished stack.
STAPLING AND RIVETING
These methods are generally used for assembling stacks of small-to-medium dimensions.
Slinky technology is used to produce rotor or stator packs by rolling up a pre-blanked strip. It is particularly suitable when conventional blanking would not allow the use of the internal part of the disc.
In the car industry, the main application is to produce stator cores for alternators.
Euro Group has five Slinky production lines in Europe and two in Mexico.
Additional work processes
The Group manufactures die cast rotors in diameters ranging from 17 mm up to 425 mm with a maximum injection capacity of 60 Kg of aluminium per rotor. The alloys typically used are aluminium 99.7% and Silumin.
This operation can either be carried out cold or with a delta of temperature, using rotor pre-heating furnaces and liquid nitrogen for cooling the shafts. The existing tooling enables the insertion of shafts of even 3,000 mm in length.
Rotors with shafts can be supplied already balanced. The machine currently in operation has the capacity to balance pieces from 1 to 50 kg in weight, with diameters of up to 450mm and lengths from 130 mm to 800 mm.
Some companies of the Group are equipped to carry out turning operations on assembled stacks having diameters of up to 1,300 mm and lengths of up to 2,500 mm.
DESIGN ENGINEERING AND R&D
A network of CAD/CAM work stations is dedicated to the design engineering of the dies and to the integrated management of the numerical control machine tools.
A research and development centre, integrated with the companies of the group, proposes innovative solutions both relative to the dies and to their applications in the lamination blanking and lamination stacking processes.
The range of numerical control machine tools includes, among other things, a substantial number of horizontal and vertical machining centres, some of which are palletised, with which the steel plates and components of the dies are machined.
All the important seats and holes of the plates and components are finished with the aid of high precision planetary grinders: the unit of measure for the machining tolerances, positioning and repeatability is the micron.
ELECTRICAL DISCHARGE MACHINING
A large number of electrical discharge machining and wire electrical discharge machines are used for the machining of the steel and carbide components of the dies. Many of these machines have been robotised both to increase productive efficiency and in order to obtain a more reliable product from the quality standpoint.
The rapid evolution of electrical discharge technology accelerates the obsolescence of these machines which are, therefore, subject to being continuously replaced with new models.
ASSEMBLING AND TESTING OF THE DIES
Once machining has been completed, all the various components and plates of the dies are sent to the assembling department where expert tool makers proceed to assemble them.
There is also a quality control department equipped with high precision three-dimensional measuring machines.