Fasteners and Insulation Requirements in the New Energy Vehicle Sector
Mandatory Requirements for Dissimilar Metal Connections
Steel bolt + aluminum housing: Zinc-nickel / zinc-aluminum coating + insulating nylon flange washer, to block galvanic corrosion; new standards explicitly require potential difference ≤ 250 mV.
Application-Specific Assembly Specifications
Battery Pack — Aluminum Tray + Grade 10.9 / 12.9 Steel Bolts
Dual-layer chromium-free zinc-aluminum coating + glass-fiber nylon flange washer; alternating corrosion cycle ≥ 720 h.
Motor / E-Control Aluminum Housing Fasteners
Zinc-nickel 5–8 μm coating + integrated insulating washer; fine-pitch thread pairing to prevent aluminum hole fretting corrosion.
Chassis Subframe Aluminum Cast Bracket Connection Bolts
Zinc-nickel 8–12 μm heavy-duty coating, 1.5 mm thick nylon flange washer, mandatory for coastal-region vehicle models.