304 Stainless Steel Serrated Lock Washer Internal External Tooth for Automotive Earthing Anti Loosening

304 Stainless Steel Serrated Lock Washer Internal / External Tooth for Automotive Earthing & Anti-Loosening

Material: 304 Stainless Steel
Standard Reference: GB861.1 Internal Tooth, GB862.1 External Tooth, Combined Internal & External Tooth Lock Washer
Important Note: These serrated washers are for EARTHING / BONDING and medium vibration auxiliary anti-loosening only. NOT for critical high load safety fasteners such as suspension, brake, steering, wheel hub and engine main bolts.

External Tooth Serrated Washer

Core advantages:
Long tooth arm provides strong biting force. Outer serrations break through paint, electrophoretic coating and powder coating reliably for low-resistance metal contact. Better anti-vibration performance. Larger bonding contact area.

Automotive application scenarios:

• Vehicle body earthing & bonding points, battery negative ground lugs

• ECU, control unit housing bonding, EV high voltage accessory shielding ground

• Motor housing, electronic water pump, cooling fan auxiliary brackets

• Wiring harness mounting brackets, underbody splash guard brackets, fog lamp and license plate brackets

• Amplifier and audio system ground terminals

Constraints: Outer serrations will leave indentation marks on sheet metal. Not suitable for visible decorative surfaces. Requires sufficient radial clearance around bolt head.
Matching fastener: Hex head bolts, large flange nuts

Internal Tooth Serrated Washer

Core advantages:
Serrations face inward and hide under screw head. Compact outer dimension, no exposed teeth after tightening. No obvious surface marks on visible areas. Save radial installation space.

Automotive application scenarios:

• Dashboard internal electronic modules, PCB board fixing

• Door control modules, small sensor housings inside cabin

• ADAS camera, millimeter wave radar housing fixation

• Interior metal frame and small latch mechanism assembly

• Compact aluminum alloy component bonding with limited installation space

Constraints: Shorter tooth arm, weaker anti-loosening and earthing performance compared with external tooth type.
Matching fastener: Pan head screw, button head screw, small diameter round head screw

Combined Internal & External Tooth Serrated Washer

Core advantages:
Serrations on both sides. Double biting effect. Best anti-vibration and bonding performance among three types.

Automotive application scenarios:

• Inverter housing, BMS housing, high power relay base

• EV power distribution unit PDU shell bonding points

• Auxiliary mounting points with continuous medium to strong vibration

Clear Non-Recommended Positions (Critical Safety Reminder)

Do NOT use serrated lock washers at below positions:

• Suspension arm, steering knuckle, brake caliper, wheel hub, half shaft

• Engine main connecting bolts

• Hardened thick high strength steel plates (teeth cannot bite into surface)

• Chrome plated, high gloss decorative trim parts

• Fasteners already fitted with serrated flange bolts or pre-applied thread locker

Quick Selection Guide

FAQ

Q1: Can these washers replace spring lock washers?

A1: No. Serrated washers work by surface biting for earthing and anti rotation. Spring washers rely on spring tension. Their working principles are different.

Q2: Can I use them on brake parts?

A2: Not recommended. Serrations may flatten under heavy impact load and cause loosening. Automotive safety critical joints require professional anti loosening solutions such as thread locker, double nuts or serrated flange bolts.