Washers · DIN 6798

M20 Serrated Lock Washers

A serrated lock washer in M20: this guide pulls the row from the standard, adds the assembly numbers an engineer actually uses, and links you straight to a quote.

M20 Dimensional Row (DIN 6798)

For size	Inner diameter d1 (mm)	Outer diameter d2 (mm)	Thickness h (mm)	Type	Reference standard
M20	21.0	33.0	1.5	Internal-tooth type A	DIN 6798 A/J

Spanner & Drive for M20 Serrated Lock Washers

Drive geometry for M20 Serrated Lock Washers is given by the row above; match the tool to the listed values.

Common Applications for M20 Serrated Lock Washers

M20 Serrated Lock Washers are commonly specified for high-load load-spreading on structural joints.

Installation Tips for M20 Serrated Lock Washers

At M20 the stretch in the bolt becomes the controlling factor — for critical joints, use angle-controlled or stretch-controlled tightening instead of pure torque.

Mating Parts for M20

A M20 flat washer pairs with a M20 bolt/screw and matching M20 nut.

When to Step Up or Down from M20

When the joint preload approaches the proof load of M20 class 8.8, step up to M24 class 8.8 (or move to M20 class 10.9). When the joint is over-specified, M16 often saves weight and cost without losing the safety margin.

Technical Drawing

Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.

Sends the selected values to the quote form below.

Request a Quote

Adjust the parameters in the drawing above and click "Request this configuration" to send the exact specification straight to this form.

Category Type Standard Thread size Material Finish

Dimensions & Specifications (DIN 6798)

For size	Inner diameter d1 (mm)	Outer diameter d2 (mm)	Thickness h (mm)	Type	Reference standard
M3	3.2	6.0	0.5	Internal-tooth type A	DIN 6798 A/J
M4	4.3	7.6	0.5	Internal-tooth type A	DIN 6798 A/J
M5	5.3	9.2	0.6	Internal-tooth type A	DIN 6798 A/J
M6	6.4	11.0	0.7	Internal-tooth type A	DIN 6798 A/J
M8	8.4	14.8	0.8	Internal-tooth type A	DIN 6798 A/J
M10	10.5	18.0	0.9	Internal-tooth type A	DIN 6798 A/J
M12	13.0	21.5	1.0	Internal-tooth type A	DIN 6798 A/J
M16	17.0	27.0	1.2	Internal-tooth type A	DIN 6798 A/J
M20	21.0	33.0	1.5	Internal-tooth type A	DIN 6798 A/J
M3	3.2	7.0	0.5	External-tooth type J	DIN 6798 A/J
M4	4.3	9.0	0.5	External-tooth type J	DIN 6798 A/J
M5	5.3	10.0	0.6	External-tooth type J	DIN 6798 A/J
M6	6.4	12.0	0.7	External-tooth type J	DIN 6798 A/J
M8	8.4	15.0	0.8	External-tooth type J	DIN 6798 A/J
M10	10.5	19.0	0.9	External-tooth type J	DIN 6798 A/J
M12	13.0	22.0	1.0	External-tooth type J	DIN 6798 A/J
M16	17.0	28.0	1.2	External-tooth type J	DIN 6798 A/J
M20	21.0	34.0	1.5	External-tooth type J	DIN 6798 A/J

Frequently Asked Questions

Which washer dimensions matter most for M20?

For a flat washer, the outside diameter (the bearing surface) and the thickness control how the load is spread under the head and how much elastic preload is preserved. The inside diameter must clear the bolt body but not be so large that the head bears mostly on the washer's outer rim.

What is the coarse-thread pitch of M20 for Serrated Lock Washers?

For M20 the standard coarse pitch is 2.5 mm — this is the value used for Serrated Lock Washers.

What clearance and tapping drill suit M20?

Use a 22 mm clearance hole (ISO 273 medium) for through-fixing, or a 17.5 mm tapping drill for a coarse M20 thread.

Should M20 Serrated Lock Washers be tightened by torque or by angle?

For critical structural joints at M20, angle-controlled or stretch-controlled tightening is more repeatable than pure torque — the friction scatter at large diameters can dominate the torque signal.

How do I request a quotation?

Use the technical drawing on this page to pick the exact configuration, then submit it with the quote form. We respond within one business day.