Stainless Steel Internal Tooth Lock Washers - Grade 202, 304, 316, A2, A2-70
Internal tooth lock washers have teeth on the inner edge which secure the bolt or screw by gripping its surface, thus preventing any loosening caused by vibration or shock. They prove to be especially handy in cases where the bolt head is smaller than the washer’s outer diameter, or when it’s necessary to conceal the teeth.
Technical Specifications – Internal Tooth Lock Washers
Below is a standard technical specification table for Internal Tooth Lock Washers (as per DIN 6798-J or ANSI B18.21.1):
| Washer Size (Nominal Bolt Size) | Inner Diameter (d) |
Outer Diameter (D) |
Thickness |
Number of Teeth |
Standard |
| M2 | 2.2 mm |
4.8 mm |
0.3 mm |
8–10 |
DIN 6798-J |
| M3 | 3.2 mm |
6.2 mm |
0.4 mm |
10–12 |
DIN 6798-J |
| M4 | 4.3 mm |
7.6 mm |
0.5 mm |
10–12 |
DIN 6798-J |
| M5 | 5.3 mm |
9.2 mm |
0.6 mm |
12–14 |
DIN 6798-J |
| M6 | 6.4 mm |
11.0 mm |
0.8 mm |
12–14 |
DIN 6798-J |
| M8 | 8.4 mm |
14.5 mm |
1.0 mm |
14–16 |
DIN 6798-J |
| M10 | 10.5 mm |
18.0 mm |
1.2 mm |
16–18 |
DIN 6798-J |
| M12 | 13.0 mm |
21.0 mm |
1.4 mm |
16–18 |
DIN 6798-J |
| M16 | 17.0 mm |
27.0 mm |
1.6 mm |
18–20 |
DIN 6798-J |
| M20 | 21.0 mm |
33.0 mm |
2.0 mm |
20–22 |
DIN 6798-J |
- Inward-Facing Teeth: Provide a firm grip around the bolt/screw shaft area.
- Locking Action: Teeth bite into mating surface to resist rotation.
- Flush Finish: Ideal for applications requiring a smooth outer edge.
- Anti-Vibration: Effectively prevents fastener loosening in dynamic environments.
- Carbon Steel (Zinc-Plated or Black Oxide)
- Stainless Steel (SS304 / SS316)
- Phosphor Bronze (for electrical applications)
- Smooth outer profile—safe for exposed surfaces
- Suitable for small head fasteners or countersunk screws
- Offers better aesthetics than external tooth versions
Material Comparison – Internal Tooth Lock Washers
Material |
Grade |
Corrosion Resistance |
Strength |
Magnetic |
Common Finish |
Applications |
| Carbon Steel | Low/Medium Carbon | Low | High | Yes | Zinc Plated / Black Oxide | General machinery, indoor applications |
| Stainless Steel | SS304 | High | Medium | Slight | Natural / Polished | Electronics, medical devices, automotive interiors |
| Stainless Steel | SS316 | Very High | Medium | No | Natural / Polished | Marine, chemical processing, corrosive environments |
| Phosphor Bronze | C51000, C54400 | Moderate to High | Medium | No | Natural / Tinned | Electrical assemblies, anti-sparking applications |
| Beryllium Copper | Alloy 25 | High | High | No | Natural | Aerospace, electronics, EMI shielding |
| Spring Steel | EN42J, SAE 1070 | Low to Moderate | Very High | Yes | Dacromet Coating | High-vibration, high- stress mechanical systems |
Internal Tooth Lock Washers feature multiple sharp, serrated teeth projecting inward from the inner edge of the washer. These teeth grip the bearing surface beneath the head of a screw or bolt to prevent loosening due to vibration or dynamic loads.
Material
Stainless Steel (304/316)
Thickness
2-8mm
Inner Diameter
2.2 mm - 21.0 mm
Outer Diameter
4.8 mm - 33.0 mm
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