Standard Metric Flat Washer Sizes and Dimensions are shown in the following
table according to
ANSI B18.22M and ISO standards. Width, outer and inner diameter dimensions of a washer are shown in the table for standard metric washer sizes including M5, M6, M8 and M10.
Some important notes from the ANSI B18.22M:
- Two types of washers are specified in the ANSI standard, Soft and Hardened. Soft washers are generally used in low
strength applications to distribute bearing load, to
provide a uniform bearing surface, and to prevent
damage of the work surface. Hardened washers are intended primarily
for use in high-strength joints to minimize embedment,
to provide a uniform bearing surface, and to
bridge large clearance holes and slots.
Some important notes from the ISO standards:
An overview of suitable combinations of ISO metric plain (flat) washers and bolts, screws or nuts in respect of property (hardness)
classes and product grades is given in the following chart.
|
Washers |
Hardness class |
100 HV |
200 HV |
300 HV |
|
Product grade |
C |
A |
A |
|
Bolts, screws, nuts |
Product grade |
A |
no |
yes |
yes |
|
B |
no |
yes |
yes |
|
C |
yes |
no |
no |
|
Bolts, screws |
Property class |
≤ 6.8 |
yes |
yes |
yes |
|
8.8 |
no |
yes |
yes |
|
9.8, 10.9 |
no |
no |
yes |
|
12.9 |
no |
no |
no |
|
Nuts |
Property class |
≤ 6 |
yes |
yes |
yes |
|
8 |
no |
yes |
yes |
|
9, 10 |
no |
no |
yes |
|
12 |
no |
no |
no |
|
Case-hardened thread rolling screws |
yes |
yes |
yes |
|
Stainless - steel bolts, screws and nuts |
- |
yes |
- |
