DIN 440 Round Hole Flat Washers - ISO 7094 Flat Washers, Extra Wide Series, Product Class C

Round hole flat washers, defined in the DIN 440 standard published by the German Standardization Institute (DIN), are large diameter flat round washers with round holes, generally used as wooden structures. The round hole allows standard bolts to pass through the center hole withstanding an increasing load on the bearing surface under the bolt head.

Similarly, the ISO 7094 standard published by the International Standards Organization (ISO) describes the characteristics of extra-large series, product class C flat washers in 100 HV hardness class, with nominal sizes ranging from 5 mm to 36 mm (nominal thread diameters) (ISO 7094 Flat washers). - Extra wide range - Product class C). The following types of stamps are considered suitable for wooden structures:

• С product class hex bolts and screws with property classes up to (inclusive) 6.8
• Hex nuts of product class С in property classes up to (inclusive) 6

If dimensions other than those listed in this standard are required, they must comply with the requirements described in the ISO 887 standard.

The requirements for round hole flat washers are listed in the DIN 440 standard under the following headings:

• Mechanical properties of stainless steel for round hole flat washers
• Chemical composition of stainless steel for flat washers with round holes
• Mechanical properties of steel for flat washers with round holes
• Chemical composition of steel for flat washers with round holes

The use of austenitic group stainless steel is as follows:

• Steel of strength class 50, A1, A2, is used for soft, cold worked, turned and soft pressed fasteners.
• Steel of strength class 70, A2, A4, cold worked, is used for normal strength fasteners.
• Strength class 80, A2, A4 steel, extreme cold worked, high strength, special applications.

Our organization, among the numerous tests, measurements, analyses, and evaluations it provides for businesses in various sectors, also offers testing services for flat washers with round holes according to the DIN 440 standard and for flat washers (extra wide series, product class C) according to the ISO 7094 standard, with its trained and expert staff and advanced technological equipment.