Meaning
Precision manufacturing tolerances applied to foil shearing machinery limit metal overhang along cut edges of current collector foils. Effective burr height control keeps metallic projections on aluminum and copper current collectors below three micrometers. Excess edge deformation risks puncturing polyolefin separators during cell stacking or roll winding operations.
This process applies to rotary slitting and mechanical punching dies operating on bare or coated electrode strips.
Mechanics Of Formation
Shearing blade wear increases local plastic deformation before shear fracture occurs across the foil thickness. Improper clearance between upper and lower slitting knives creates high tensile drag that yields prominent metal burrs. Careful burr height control requires micro-inch blade alignment and controlled web tension during high-speed cutting.
Separator Puncture Risk
Sharp metallic projections standing proud of the electrode edge create concentrated mechanical stress against thin porous separators. Under compressive pressure inside prismatic or pouch cell stacks, metal burrs pierce through the ceramic separator layer over time. Direct contact between cathode and anode foils causes micro-short circuits that accelerate self-discharge rates.
Tooling Maintenance
Automated inline optical sensors scan edge profiles continuously to detect metal burr growth during high-speed web slitting. Machine operators perform preventative blade regrinding or cassette replacement when measured edge projections exceed established statistical limits. Strict burr height control extends cell service life by preventing internal insulation breaches.
