DIN 125 Flat Washer Form B

One of the most common types of fasteners and hardware is the flat washer manufactured to the German standard DIN 125. It is a flat metal disc with a round hole in the center for installing a fastening element.

Washers of this type are used with various categories of fasteners — screws, bolts, threaded studs, pins, and others. By placing a washer under the head of a screw or under a nut, the contact area with the material is increased, reducing pressure accordingly. This helps avoid cracks and other damage to the material.

Manufacturing features and closest equivalents

Form B provides for a chamfer — a beveled edge for ease of use. Chamfered washers are made of high-strength carbon steel; other materials may also be used for their production. Steel requires corrosion protection, so it is provided with a zinc coating applied by galvanic, thermal spray, or hot-dip methods.

For increased corrosion resistance, washers are made of A2 and A4 grade stainless steel — this material withstands prolonged exposure to moisture and chemically aggressive substances. Washers are also produced from non-ferrous metals and their alloys: they can be made of brass, copper, aluminium. Special plastic washers are used for the most reliable corrosion protection.

DIN 125 standard washers have the following features:

• Products of this type are suitable for use with fasteners having a nominal thread diameter from M1 to M90. They are produced in a wide range of sizes, which makes it possible to select a suitable product.
• The inner diameter of the metal product ranges from 1.1 to 93 mm.
• The thickness of the fastening element can range from 0.3 to 12 mm.

Equivalent fasteners are manufactured in accordance with the Russian standard GOST 11371-78 and the international standard ISO 7089-90.

Applications of washers

This type of fastening product is in demand in virtually all branches of mechanical engineering: machine tool building, automotive manufacturing, instrument engineering, and others. Products of this type are used when joining various components of mechanisms and assemblies, and they are suitable for protecting thin-sheet materials from damage.

Washers have high resistance to deformation, so they can be used with fasteners having property class 10.9 and 12.9. A wide selection of sizes makes it possible to select a fastening element for any parts. When used with nuts, two washers may be applied, and if the screw is fully recessed into the material, only one washer is used.

d	d₁	d₂	h
M1.7	1.8	4.5	0.3
M2	2.2	5	0.3
M2.3	2.5	6	0.5
M2.5	2.7	6	0.5
M2.6	2.8	7	0.5
M3	3.2	7	0.5
M3.5	3.7	8	0.5
M4	4.3	9	0.8
M5	5.3	10	1
M6	6.4	12	1.6
M8	8.4	16	1.6
M10	10.5	20	2
M12	13	24	2.5
M14	15	28	2.5
M16	17	30	3
M18	19	34	3
M20	21	37	3
M22	23	39	3
M24	25	44	4
M27	28	50	4
M30	31	56	4
M33	34	60	5