DIN 433 Small OD Flat Washers — A2 Stainless Steel (SUS304), Whitened & Passivated

FULLERKREG DIN 433 flat washers are manufactured from A2 stainless steel (SUS304) with a whitened and passivated surface finish. DIN 433 specifies a small outer diameter washer — the outer diameter is significantly smaller than DIN 125A for the same bolt size — designed specifically for use with countersunk (flat head) screws, socket head cap screws in counterbored holes, and applications where space constraints prevent the use of standard DIN 125A washers.

The reduced OD allows the washer to seat flush within counterbores and confined spaces while still providing load distribution under the screw head. A2 (SUS304) stainless steel provides excellent corrosion resistance for general outdoor, food-grade, and mildly corrosive environments.

Product Specifications

Standard	DIN 433 (Small OD flat washer)
Material	A2 Stainless Steel / SUS304 / 1.4301
Surface Finish	Whitened & Passivated
Size Range	M1.6 – M20
OD Characteristic	Small OD — significantly smaller than DIN 125A for same bolt size
Hardness	≤ 200 HV
Tensile Strength	≥ 500 MPa (A2-70)
Corrosion Resistance	Good — outdoor, food-grade, mild corrosive environments
Magnetic	Slightly magnetic after cold working
Recommended Use	Countersunk screws, socket head cap screws in counterbores, confined spaces
Related Standard	DIN 125A (standard OD)  |  DIN 9021 (large OD)  |  ISO 7092 (small washer series)

Product Gallery

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Dimensions — DIN 433

All dimensions in mm. Data verified against DIN 433 / ISO 7092 standard and reference specifications.

Nominal Size	d1 — Inner Ø (mm)	d2 — Outer Ø (mm)	h — Thickness (mm)
M1.6	1.7	3.5	0.3
M2	2.2	4.5	0.3
M2.5	2.7	5.0	0.5
M3	3.2	6.0	0.5
M3.5	3.7	7.0	0.5
M4	4.3	8.0	0.5
M5	5.3	9.0	1.0
M6	6.4	11.0	1.6
M8	8.4	15.0	1.6
M10	10.5	18.0	1.6
M12	13.0	20.0	2.0
M14	15.0	24.0	2.5
M16	17.0	27.0	2.5
M20	21.0	34.0	3.0

* d1 = inner diameter; d2 = outer diameter; h = thickness. All per DIN 433 / ISO 7092.

DIN 433 vs DIN 125A — Small OD vs Standard OD

Property	DIN 433 (This Product)	DIN 125A (Standard OD)
OD characteristic	Small — fits within counterbores	Standard — general purpose
M6 outer diameter	11.0 mm	12.0 mm
M8 outer diameter	15.0 mm	16.0 mm
M10 outer diameter	18.0 mm	20.0 mm
M12 outer diameter	20.0 mm	24.0 mm
Best for	Countersunk screws, counterbores, confined spaces	General fastening, load distribution
ISO equivalent	ISO 7092	ISO 7089

Material Properties — A2 / SUS304

Designation	A2 / SUS304 / 1.4301 / 0Cr18Ni9
Cr Content	17.5 – 19.5%
Ni Content	8.0 – 10.5%
Tensile Strength	≥ 500 MPa (annealed)
Hardness	≤ 200 HV
Density	7.93 g/cm³
Temperature Range	−50°C to +300°C
Magnetic	Slightly magnetic after cold working

Typical Applications

• 🔩 Countersunk (flat head) screws — the primary application: small OD fits within the countersink recess, allowing the screw to sit flush while the washer distributes load under the head
• 🔧 Socket head cap screws in counterbores — small OD fits within the counterbore diameter, providing load distribution without protruding beyond the bore
• 🧲 Confined space fastening — where standard DIN 125A OD is too large due to adjacent components, edges, or structural constraints
• 🏭 Precision machinery & instruments — small OD for clean, compact fastening in precision equipment and instruments
• 🍼 Food & pharmaceutical equipment — A2 stainless for hygienic, corrosion-resistant fastening in food processing and pharmaceutical machinery
• 🏠 Architectural & decorative fastening — compact, clean appearance for visible fastening in architectural hardware and decorative applications

FAQ

Q: What is the difference between DIN 433 and DIN 125A?
A: DIN 433 has a smaller outer diameter than DIN 125A for the same bolt size. For example, M10: DIN 433 d2 = 18 mm vs DIN 125A d2 = 20 mm. DIN 433 is designed for use with countersunk screws and in confined spaces where the standard DIN 125A OD is too large. Both have the same inner diameter for the same bolt size.

Q: What is the ISO equivalent of DIN 433?
A: DIN 433 is equivalent to ISO 7092 (small washer series). DIN 433 is the German national standard; ISO 7092 is the international equivalent.

Q: Can I use DIN 433 washers with standard hex bolts?
A: Yes. DIN 433 washers have the same inner diameter as DIN 125A for the same bolt size and can be used with any bolt or screw of the corresponding nominal diameter. The smaller OD simply provides a more compact bearing surface.

Q: Are A2 stainless DIN 433 washers suitable for outdoor use?
A: Yes. A2 (SUS304) provides good corrosion resistance for general outdoor, architectural, and mildly corrosive environments. For marine, coastal, or high-chloride environments, specify A4 (SUS316) washers.