Silicon steel sheet processing into a transformer core, there are many things to pay attention to, covering the processing environment, silicon steel sheet characteristics, processing accuracy and other aspects, the following are the specific content:

Processing environment
Temperature and humidity: the temperature of the processing environment should be maintained at 15 ℃ -35 ℃, humidity in 40% -60% is more appropriate. The temperature is too high or too low may affect the physical properties of silicon steel sheet, resulting in increased processing difficulties; humidity is too high will make the silicon steel sheet surface rust, affecting the insulation properties and magnetic properties; humidity is too low may produce static electricity, adsorption of dust and other impurities.
Cleanliness: The processing place should be kept clean to avoid dust, oil and other impurities falling on the surface of silicon steel wafers. Impurities may damage the insulating layer of silicon steel wafers, increase the eddy current loss of the iron core, and reduce the efficiency of the transformer.

Silicon steel sheet characteristics
Material and performance: according to the use of transformer requirements and working conditions, select the appropriate grade and specifications of silicon steel sheet. Different grades of silicon steel sheet, its permeability, iron loss, thickness and other performance indicators are different. For example, for high-frequency transformers, should use thin specifications, low iron loss of high permeability silicon steel sheet.
Directionality: silicon steel sheet has magnetic anisotropy, along the rolling direction of the best magnetic properties. In the processing and stacking, should try to make the magnetic flux direction and silicon steel sheet rolling direction consistent, in order to give full play to its magnetic properties, reduce the magnetic resistance and iron loss.

Processing precision
Dimensional accuracy: the shear and punching dimensional accuracy of the silicon steel sheet directly affects the assembly quality and performance of the core. The deviation of the shear size should be controlled within ±0.1mm, and the burr height of the punched piece should not be more than 0.05mm, so as to ensure that the core is stacked tightly, reduce the air gap, and lower the magnetic resistance.
Flatness: The flatness of silicon steel sheet should be ensured during processing to avoid bending, twisting and other deformations. The flatness deviation of the silicon steel sheet should be no more than 0.2mm/m, otherwise it will lead to gaps in the core stacking, increase eddy current loss and affect the performance of the transformer.

Insulation treatment
Insulation material selection: according to the voltage level of the transformer and the use of the environment, select the appropriate insulation material. For low-voltage transformers, ordinary insulating paper can be used; for high-voltage transformers, it is necessary to use better performance of polyimide film and other insulating materials.
Insulation process control: in the insulation process, to strictly control the process parameters. For example, the impregnation time, temperature and concentration of insulating varnish and other parameters will affect the insulation effect. If the impregnation time is too short, the insulating varnish can not be fully penetrated; if the temperature is too high or the concentration is too large, the insulating varnish may be poorly cured, thus affecting the insulating performance.

Core stacking
Stacking order: Follow the correct stacking order, generally using staggered stacking, so that the seams of the two adjacent layers of silicon steel sheets are staggered each other, in order to reduce the air gap in the magnetic circuit and eddy current losses. For example, when stacking E-type and I-type silicon steel sheet, E-type sheet should be neatly arranged first, and then insert I-type sheet.
Stacking pressure: stacking pressure should be applied evenly and moderately, the pressure is too small will lead to iron core loose, affecting the mechanical strength and magnetic properties; pressure is too large may make the silicon steel sheet deformation, increasing iron losses. Generally speaking, the stacking pressure control in 1-3MPa is more appropriate.

Quality Inspection
Process testing: In the processing process, regular quality testing should be carried out to detect and correct problems in processing in a timely manner. For example, every processing of a certain number of silicon steel sheet, its size, flatness, burrs and other indicators should be tested.
Finished product testing: After the core processing is completed, comprehensive quality testing should be carried out, including appearance inspection, size measurement, magnetic performance test and insulation performance test. Only the iron core with all indexes meeting the design requirements can be put into use.