Product Summary

Longze Wedge Lock Washers (DIN 25201) are high-end self-locking fasteners engineered to prevent bolt loosening even under the most severe vibrations and dynamic loads.

Manufactured in Yongnian, China, our wedge lock system utilizes "tension instead of friction" to secure bolted joints. Consisting of a pre-assembled pair of washers with cams on

the inside and radial teeth on the outside, Longze washers create a wedge effect that ensures the bolt remains pre-loaded. Whether for railway tracks, mining equipment, or wind turbine towers, our wedge lock washers provide a fail-safe solution where standard spring washers fail.

• ✔ Wedge-Effect Security: The cam angle ($\alpha$) is larger than the bolt thread pitch angle ($\beta$). Any attempt by the bolt to rotate loose increases the tension, effectively self-locking the joint.

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• ✔ Vibration-Proof Reliability: Extensively tested on Junker vibration rigs to maintain pre-load where nylon-insert nuts and standard washers lose 100% of their tension.

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• ✔ Reusable Engineering: High-grade alloy steel construction allows these washers to be reused multiple times without losing their locking function or damaging the mating surfaces.

• Standards: DIN 25201-4, NL Series (Standard & Large OD).

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• Size Range: M3 to M130 (Metric) | #5 to 5" (Imperial).

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• Material Grade: Alloy Steel (Through-Hardened) | Stainless Steel 316 (A4).

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• Surface Hardness: ≥ 465 HV1 (Steel) | ≥ 520 HV0.05 (SS316 Surface Hardened).

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• Surface Finish: Delta Protekt / Zinc Flake Coating (Chrome-free), Plain.

Mechanical Properties & Material Standards

• Matching the steel grade to the structural requirements of the transmission line.

• Material Grade	Surface Hardness	Core Hardness	Tensile Strength	Environmental Suitability
  Alloy Steel	≥ 465 HV	420 - 480 HV	High-Tensile	General Machinery / Rail
  SS316 (A4)	≥ 520 HV	200 - 300 HV	Moderate	Chemical / Offshore
  254 SMO	≥ 550 HV	240 - 320 HV	Extreme	Saltwater / Subsea

Standard Cross Arm Dimensions

• Common angle steel configurations for standard utility pole mounting.

• Thread Size (D)	Inner Dia (di)	Outer Dia (do)	Thickness (T)	Max Torque (Grade 10.9)
  M10	10.7 mm	16.6 mm	2.5 mm	70 Nm
  M12	13.0 mm	19.5 mm	2.5 mm	120 Nm
  M16	17.0 mm	25.4 mm	3.4 mm	290 Nm
  M20	21.4 mm	30.7 mm	3.4 mm	570 Nm

 

Galvanizing & Corrosion Resistance

• Ensuring 30+ years of service life in corrosive environments.

• Surface Treatment	Process	Salt Spray Test	Best Application	Hardness Retention
  Zinc Flake	Delta Protekt	600 - 1000 Hours	Infrastructure / Rail	Excellent
  SS316 Surface Hard	Diffusion	1000+ Hours	Marine / Coastal	Excellent
  Plain (Steel)	Heat Treated	< 12 Hours	Oil-Immersed Engines	Maximum

Avoid Pitfalls:

• Insufficient Hardness: If the washer is softer than the bolt (Grade 8.8/10.9), the teeth won't "bite" and the wedge effect fails. Longze steel washers are through-hardened to ≥ 465 HV, ensuring they are harder than a Grade 12.9 bolt.

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• Incorrect Installation: The two washers must be installed "Cam-to-Cam". We supply them pre-glued in pairs to ensure they are never installed incorrectly on-site.

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• Lubrication Sensitivity: While wedge lock washers work with lubricants, the torque-to-tension ratio changes. Longze provides detailed torque charts for both dry and lubricated conditions to ensure 100% pre-load accuracy.

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Perfect Fit Assembly:

• Large OD (SP Series): For use on painted surfaces, soft materials (aluminum), or oversized holes, we recommend our Large OD Wedge Washers to distribute the clamping force.

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• Counter-Bore Fit: Our washers are precision-machined to fit within standard counter-bore diameters, making them a direct upgrade for standard spring or flat washers.

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Quality Control & Logistics:

• ISO 9001 Certified: 5-step QC including Junker Vibration Testing (Sample-based), Hardness Spectrum Analysis, and Digital Cam-Angle Verification.

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• Sea-Worthy Packaging: Pre-glued pairs are packed in sealed inner boxes (e.g., 100 or 200 pairs), then secured in reinforced master cartons for export from our Yongnian hub.

• Q: Can I use these with locking nuts? A: It is unnecessary. The wedge lock washer is a superior locking mechanism on its own. Using both may interfere with the tension-based locking principle.

• Q: Do these damage the surface of the part? A: The radial teeth must grip the surface to work. While this leaves a small indentation, it is the proof that the joint is securely locked.