Side-by-Side Comparison
Washers & Retaining Rings
Flat Washers vs. Lock Washers
Comparing 2 standards across 18 specifications. 18 key differences identified.
Comparing:
Flat Washers
Lock Washers
Standard flat washers distribute fastener clamp load and prevent surface embedding, standardized under DIN 125 (ISO 7089 Form A metric without chamfer) and ASME B18.22.1 (Type A Narrow, Regular, and Wide series in imperial sizes).
Lock washers resist bolt loosening under vibration through spring preload and mechanical biting, standardized under DIN 127 (helical split spring washers), DIN 6798 (internal/external serrated tooth star washers), and DIN 2093 (Belleville conical spring discs).
Specification Comparison Table
18 Parameters| Parameter / Spec | ||
|---|---|---|
|
Governing Standards
|
DIN 125 Form A (ISO 7089) / ASME B18.22.1 Type A | DIN 127 Form B / DIN 6798 / DIN 2093 / ASME B18.21.1 |
|
M3 Flat Washer
|
ID: 3.2 mm | OD: 7.0 mm | Thickness: 0.5 mm | — |
|
M4 Flat Washer
|
ID: 4.3 mm | OD: 9.0 mm | Thickness: 0.8 mm | — |
|
M5 Flat Washer
|
ID: 5.3 mm | OD: 10.0 mm | Thickness: 1.0 mm | — |
|
M6 Flat Washer
|
ID: 6.4 mm | OD: 12.0 mm | Thickness: 1.6 mm | — |
|
M8 Flat Washer
|
ID: 8.4 mm | OD: 16.0 mm | Thickness: 1.6 mm | — |
|
M10 Flat Washer
|
ID: 10.5 mm | OD: 20.0 mm | Thickness: 2.0 mm | — |
|
M12 Flat Washer
|
ID: 13.0 mm | OD: 24.0 mm | Thickness: 2.5 mm | — |
|
1/4" ASME Type A
|
ID: 0.281 in (7.1 mm) | OD: 0.625 in (15.9 mm) | Thickness: 0.065 in (1.65 mm) | — |
|
3/8" ASME Type A
|
ID: 0.406 in (10.3 mm) | OD: 0.812 in (20.6 mm) | Thickness: 0.065 in (1.65 mm) | — |
|
1/2" ASME Type A
|
ID: 0.531 in (13.5 mm) | OD: 1.062 in (27.0 mm) | Thickness: 0.095 in (2.41 mm) | — |
|
Helical Split Washer Mechanism
|
— | Spring tension + sharp trapezoidal edges that bite into mating surfaces under counter-rotation |
|
M6 DIN 127 Split Lock Washer
|
— | ID: 6.1 mm | OD: 11.8 mm | Thickness (s): 1.6 mm | Uncompressed Free Height: ~3.2 mm |
|
M8 DIN 127 Split Lock Washer
|
— | ID: 8.1 mm | OD: 14.8 mm | Thickness (s): 2.0 mm | Uncompressed Free Height: ~4.0 mm |
|
M10 DIN 127 Split Lock Washer
|
— | ID: 10.2 mm | OD: 18.1 mm | Thickness (s): 2.2 mm | Uncompressed Free Height: ~4.4 mm |
|
M12 DIN 127 Split Lock Washer
|
— | ID: 12.2 mm | OD: 21.1 mm | Thickness (s): 2.5 mm | Uncompressed Free Height: ~5.0 mm |
|
Belleville Disc Spring (DIN 2093)
|
— | Conical shape maintains thousands of pounds of preload over high thermal expansion cycles |
|
Serrated Tooth Star Washer (DIN 6798)
|
— | Multiple teeth bite through paint/anodizing to ensure electrical bonding and ground continuity |