Chemically Etched Electrical (Silicon) Steel

• Burr-Free Rotors, Stators and Transformer Laminations
• Inexpensive Tooling
• No Annealing Needed

Silicon steel, also known as electrical steel, is a very low carbon alloy (less than .005%) that is used in motor and transformer laminations. It is characterized by lower core loss properties and higher magnetic permeability than carbon steels. There are a number of grades that include both grain-oriented and “NGO” (non-grain-oriented) versions. The standard thicknesses are .007, .014, .0185 and .025 inches. Silicon steels are often produced with an electrically insulating coating known as coreplate, which eliminates the need to interleave laminations with dielectric material.

For rotor and stator laminations used in electric motors, which can have demanding geometries and tolerances, photo etching is a productive and cost effective fabrication solution. Tooling costs for photo etching, compared to stamping, are very low; typically less than $300 and lead time for photo tooling is two days or less. Photo etching also eliminates the possibility of out-of-plane burrs, which can cause shorts in the lamination stack.

Although the traditional “I” and “U” laminations used in linear transformers are readily produced by stamping, there are many new transformer applications that require more demanding geometries that are best suited for photo etching. Like rotors and stators, unusually-shaped transformer lams can be readily produced by photo etching. Another advantage of photo etching is improved material utilization as many parts can be nested. Single die stamping does not allow this flexibility for oddly shaped parts.

Photo etching electrical steel also eliminates the need for post-stamping annealing since there is no cold working of the material.