Countersunk External Tooth Serrated Conical Lock Washers

Xiaoguo® factory's Countersunk External Tooth Serrated Conical Lock Washers have a built‑in recessed shape. When you put them in, they sit level with or below the part surface, so the whole outer face ends up smooth and flat.

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Product Description

These Countersunk External Tooth Serrated Conical Lock Washers are cone‑shaped locking rings with a sunken profile and teeth around the outside edge. The sunken shape lets them fit right into recessed mounting holes, so the screw head ends up flush with or below the part surface. When you tighten the screw, the cone part pushes back with steady spring pressure, and the outer teeth bite into the base material. That keeps the fastener from coming loose when things vibrate or move under load.

Installation Guide

Here is the installation guide for the Countersunk External Tooth Serrated Conical Lock Washers. You can use it as a reference for your operation.

（1）Selection Specifications

Match the corresponding inner and outer diameters of the Countersunk External Tooth Serrated Conical Lock Washers with the specifications of the countersunk screws. The specifications must be consistent to avoid being too large or too small, which may affect the fit and anti-loosening effect.

（2）Installation direction (Key point)

Conical convex surface + outer tooth surface facing towards the screw head

Flat back surface should be tightly attached to the workpiece sheet metal surface

Do not install in the reverse direction. Installing in the reverse direction will lose the elastic pre-tightening and tooth surface locking functions.

Countersunk External Tooth Serrated Conical Lock Washers

Mon	φ2.5	φ3	φ3.5	φ4	φ5	φ6	φ8	φ10	φ12	φ14	φ 16
d min	2.7	3.2	3.7	4.3	5.3	6.4	8.4	10.5	13	15	17
d max	2.84	3.38	3.88	4.48	5.48	6.62	8.62	10.77	13.27	15.27	17.27
dc	5.1	6	7	8	9.8	11.8	15.3	19	23	26.2	30.2
h	0.2	0.2	0.25	0.25	0.3	0.4	0.4	0.5	0.5	0.6	0.6
Number of Number of teeth min	10	12	12	14	14	16	18	20	26	28	30

(3) Align the washer correctly

Slip the Countersunk External Tooth Serrated Conical Lock Washers onto the countersunk screw, then put the whole set into the mounting hole. The inner taper of the washer will align itself to fit the angle of the screw head.

(4) Hand‑tighten first

Start by turning the screw by hand. Keep it flat against the washer and make sure it's straight – no tilting.

(5) Tighten to standard torque

Use a wrench and tighten to the usual torque spec. Squeeze it just enough to flatten the cone a little so it gives some spring tension, and let the outer teeth bite gently into the surface.

(6) A couple of things to watch out for

Don't overtighten – Stick to the recommended torque. Don't use an impact wrench to hammer it down.

Never stack washers – Only use one per screw. Stacking them creates uneven pressure, bends the washer, and kills its locking ability.