I) Preparation Stage: Cutting and Deburring
Before stacking, the large coils of oriented silicon steel need to be processed into sheets of specific shapes.
• Slitting: The wide oriented silicon steel coil is cut into strips according to the designed width.
• Cross-cutting and blanking: The strips are then cut to the designed length, and special shapes for the joints (such as stepped holes, V-shaped grooves, etc.) are punched out, forming individual semi-finished silicon steel sheets.
• Deburring: This is a critical step. The sheared edges will produce tiny burrs. If not removed, these burrs can cause short circuits between sheets after stacking, leading to a sharp increase in core eddy current loss and localized heating. Usually, tumbling or chemical methods are used for deburring.
• Coating insulation layer: To reduce inter-sheet eddy currents, the surface of the silicon steel sheets is coated with a very thin layer of insulating varnish or phosphate coating.

II) Pre-stacking and Sheet Grouping
In this stage, the cut sheets are divided into "groups" according to the drawings to facilitate stacking.
• Sheet sorting and matching: For stepped cross-sections (e.g., cruciform shapes), silicon steel sheets of different widths need to be grouped by specification. At the same time, it is necessary to ensure staggered lap joints, meaning that the joint positions of adjacent layers should be offset.
• Pre-positioning: Some production lines use magnetic or vacuum suction cups to pre-align a group of sheets on a platform for easier subsequent robotic pickup.

III) Main Stacking Stage
This is the core stage, which is divided into two paths: manual stacking and automated stacking.

Method 1: Traditional manual stacking (used for non-standard, small-batch, or large special cores)

1. Datum positioning: On the stacking platform, first fix the positioning pins or blocks at the bottom.

2. Layer-by-layer stacking: Workers place the differently shaped silicon steel sheets onto the positioning pins in sequence according to the drawings, and gently tap them flat with a wooden mallet to ensure each sheet is fully seated. After every few layers, the total thickness is rechecked.

3. Cross lapping: The key point in manual stacking is to strictly ensure that the joints of adjacent layers are staggered. For example, if the joint of the first layer is on the left, the second layer's joint should be on the right, forming a "lap" structure to reduce magnetic reluctance.

4. Pressing and measurement: After stacking to a certain height (e.g., every 100 mm), a special pressure plate and a jack are used for pre-pressing, and the total height is measured to see if it meets the design specifications. Sheets are added or removed in time for adjustment.

Method 2: Fully automatic stacking production line (used for mass production and standardized manufacturing)
This is standard equipment in modern large transformer factories, and the process is as follows:

1. Automatic feeding and flipping: A robotic arm picks up a single silicon steel sheet from the material table and can flip it 180° to achieve alternating front-and-back stacking, thereby compensating for the sheet's own slight warpage.

2. Visual positioning: A camera system captures the positioning holes or edges on the sheet, automatically calculates the offset, and a high-precision robotic arm performs micron-level correction in the X-Y-θ three directions.

3. Laser thickness measurement and compensation: After each sheet is placed, a laser rangefinder measures the accumulated stack height in real time. If cumulative errors are detected, the system will automatically perform slight thickness compensation in the next sheet or subsequent sheets (utilizing the sheet's own thickness tolerance) to ensure the final total height meets the requirement.

4. Inter-sheet adhesive application (optional): For cores requiring high mechanical strength, an extremely thin layer of structural adhesive may be applied between sheets during stacking to enhance overall rigidity and reduce noise.

5. Automatic temporary storage and transfer: After all lamination stacking is completed, the entire core leg is automatically moved out of the stacking station and into the next process.

IV)Shaping and Curing
After stacking is completed, the core is still in a "loose" state and requires further processing.
• Clamping and shaping: Hydraulic cylinders apply a set pressure (typically 1–2 MPa) to the core from both the horizontal and vertical directions, squeezing out excess air and adhesive between sheets and making all silicon steel sheets fully conform. At the same time, side push plates are used to correct the perpendicularity of the core legs and yokes.
• Curing (if adhesive is applied): If structural adhesive has been applied, the core needs to be placed in an oven and heated according to a specific temperature profile (e.g., 80°C/1h + 120°C/2h) to cure the adhesive, permanently maintaining the stacked state.
• Banding or welding: Finally, non-magnetic steel straps or epoxy glass cloth tape are used to tightly band the core legs and yokes, or argon arc spot welding is applied to the edges (only at extremely small edge points to avoid short circuits), forming a firm integral assembly.

Summary
In general, the stacking process for oriented cores proceeds from precision cutting and deburring, to layer-by-layer staggered lapping (either manual or high-precision automated), and finally to pressing and curing into a complete magnetic circuit with low loss, high permeability, and low noise. Among these, reducing joint magnetic reluctance (through staggered lapping) and controlling eddy current loss (through deburring and insulation coating) are the core objectives that run throughout the entire process