Aluminum transformer strips (common grades include 1060, 1070, etc., mostly in O-state soft form) serve as the core conductive material for dry-type transformer windings. The precision of their manufacturing process and the rigor of quality control directly determine the transformer's energy consumption, insulation lifespan, and operational safety.

1. Core Production Process Flow

The production of aluminum transformer strips is a deep-processing chain that transforms high-purity aluminum ingots into precision strips. The process begins with smelting and casting, where high-purity aluminum with a content of over 99.6% is melted at 720°C to 760°C. Impurity levels of silicon, iron, copper, and others are strictly controlled through degassing and slag removal before being cast into flat ingots.  Next comes hot rolling and rough rolling, where the flat ingots are milled to remove oxide layers, heated, and undergo hot rough rolling for preliminary shaping, followed by multiple passes of cold rough rolling to achieve a specific thickness.  The critical stages of annealing and finishing follow, where O-state annealing (complete recrystallization annealing) eliminates work hardening, imparting high ductility (typically ≥20% elongation) and a soft texture to the material, facilitating subsequent coiling.  Precision slitting and edge trimming are core processes unique to transformer strips, involving high-precision longitudinal slitting of aluminum coils to the required width, along with mandatory edge chamfering (rounded corners/R-edges) to remove burrs. When necessary, interlayer paper padding is added to prevent scratches before packaging and storage.

II. Key Quality Control Points

1. Chemical Composition and Electrical Performance Control: Strict control of impurity elements is paramount. Although elements such as Si, Fe, and Cu can enhance strength, they significantly reduce conductivity. It is essential to ensure the resistivity is ≤0.028Ω·mm²/m (conductivity ≥61% IACS), which serves as the foundation for reducing transformer load losses.

2. Dimensional and Plate Flatness Precision: Thickness tolerance (e.g., ±0.03mm), width tolerance, and plate flatness (e.g., waviness, warping) must meet high precision requirements. Uneven thickness can lead to winding ampere-turn imbalance, while poor plate flatness may cause uneven interlayer gaps or collapse during winding.

3. Edge and Surface Quality: This is a critical area prone to issues. The edges must be smooth and free of burrs (with burr height typically required ≤0.015mm~0.03mm) to prevent arc discharge and interlayer insulation breakdown. The surface must be clean, scratch-free, oil-free, and free of oxidation spots to avoid compromising the adhesion and dielectric strength of the insulation varnish.

4. Mechanical Performance Stability: As an O-state material, it must ensure appropriate tensile strength (e.g., 60-95 MPa) and high elongation, avoiding breakage during automatic winding while maintaining good conformability for tight coiling.

In summary, the production of aluminum transformer strips is a combination of metallurgy and precision manufacturing. Only by precisely controlling the purity of smelting, the annealing hardness, and the edge trimming process can strips that meet the high standards of power systems be produced.