When stators and rotors are punched, the various process steps cause mechanical stress in the electrical sheet. This stress impairs the magnetic properties of the lamination stack. In addition to known causes of this deterioration, such as punch-stacking or punching, we also investigated the influence of the straightening of the lamination stack.
Driven by the trend towards increasingly complex geometries, the feed of lamination stack through the ever longer punching tools is essential for smooth and efficient (high number of strokes) production. Straightening, which “kneads” the strip flat, is an established process in this regard. Unfortunately, this worsens the magnetic properties, which is not at all what the developer of the electric motor had in mind.
To avoid such conflicting objectives, we are pressing ahead with our developments such as segmentation (no straightening required), bonding varnish (Backlack) (no punched stacking nubs and thus no short circuits between the laminations), BPS® technology (fully automated production of stator segments) EPS® technology (fast bonding of full stators and rotors).
“We make your motors better!”
Facts
- Straightening also degrades the magnetic properties
- SWD is advancing its technologies to resolve conflicting goals