Helium Mass Spectrometry for Micro Leak Detection in Battery Envelopes
Inline helium mass spectrometry detects sub-micron battery envelope leaks down to 10-8 mbar l/s, preventing moisture-induced HF corrosion and solvent loss.
Cylindrical Crimp Seal
Meaning
Mechanical compression joints secure the open end of a metallic canister around a top cap assembly using a polymer gasket. In round cell production, a cylindrical crimp seal prevents electrolyte leakage and maintains internal pressure. This closure process involves radial and axial compression of the steel can wall against the plastic seal ring, creating an airtight joint that supports safety vents.
Sourcing specifications dictate the precise force profiles and dimensional tolerances of this mechanical joint because it represents the primary barrier against the leakage of toxic materials during lifetime operation.
Mechanical Deformation
Crimping machines apply precise force to deform the upper edge of the steel can inward. This crimping action compresses the plastic gasket beyond its elastic limit to fill all micro-cavities along the metallic interface. Consistent tooling alignment prevents uneven stress distribution that could lead to micro-fractures in the protective nickel coating.
Material Performance
The gasket material must resist degradation from contact with volatile organic solvents and corrosive salts. Polybutylene terephthalate or specialized polymers maintain their elastic recovery over long temperature ranges. When these materials degrade, the joint loses compression and leaks appear.
Quality Assessment
Visual inspection and dimensional checks verify the final crimp height and diameter against engineering drawings. Force-displacement monitoring during the squeezing process identifies tool wear or material variations. Pack assemblers reject cells with inconsistent crimps to ensure uniform contact resistance and safety.