DIN 137A Curved Spring Washer — A2 Stainless Steel (SUS304), Whitened & Passivated

FULLERKREG DIN 137A curved spring washers are manufactured to DIN 137 Type A standard in A2 stainless steel (SUS304 / 1.4301 / 0Cr18Ni9) with a whitened and passivated surface finish. DIN 137 Type A is a curved (dished) spring washer with a larger outer diameter than DIN 128A, providing greater spring travel and higher load capacity for the same bolt size. The curved profile generates axial spring force when compressed, compensating for joint relaxation and maintaining bolt tension without sharp edges or surface marking. A2 stainless steel provides excellent general corrosion resistance, non-magnetic properties, and food-safe compliance.

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Product Highlights

• Standard: DIN 137 Type A (Curved Spring Washer)
• Material: A2 Stainless Steel (SUS304 / 1.4301 / 0Cr18Ni9)
• Surface Treatment: Whitened & Passivated
• Size Range: M3 – M36
• Profile: Type A — Curved / dished (larger OD than DIN 128A, greater spring travel)
• Function: Axial spring force — anti-loosening, joint relaxation compensation, no surface marking
• Non-magnetic, non-sparking
• RoHS & REACH Compliant

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Dimensional Specifications — DIN 137 Type A (Curved), A2 Stainless

All dimensions in millimeters (mm). Per DIN 137 Type A.

Nominal Size	For Bolt	d1 min	d2 max	h min	h max	s (thickness)
3	M3	3.2	7.5	0.8	1.2	0.5
4	M4	4.3	9.5	1.0	1.4	0.6
5	M5	5.3	11.5	1.2	1.7	0.8
6	M6	6.4	14.0	1.5	2.1	1.0
8	M8	8.4	18.0	2.0	2.8	1.2
10	M10	10.5	22.0	2.5	3.5	1.5
12	M12	13.0	26.0	3.0	4.2	1.8
14	M14	15.0	30.0	3.5	4.9	2.0
16	M16	17.0	34.0	4.0	5.6	2.5
20	M20	21.0	42.0	5.0	7.0	3.0
24	M24	25.0	50.0	6.0	8.4	3.5
30	M30	31.0	62.0	7.5	10.5	4.0
36	M36	37.0	74.0	9.0	12.6	5.0

All dimensions in mm per DIN 137 Type A. s = material thickness; h = free height (curved profile height). Please verify with your engineering team for critical applications.

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DIN 137A vs. DIN 128A — Key Differences

Feature	DIN 137 Type A	DIN 128 Type A
Profile	Curved / dished	Curved / single arc
Outer diameter	Larger OD for same bolt size	Smaller OD
Spring travel	Greater	Standard
Load capacity	Higher (larger bearing area)	Standard
Typical use	Higher load applications, larger bearing area needed	Cheese head & pan head screws
Size range	M3–M36	M2–M36

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Material & Mechanical Properties — A2 Stainless Steel (SUS304)

Property	Value
Material Grade	A2 / SUS304 / 1.4301 / 0Cr18Ni9
Cr Content	17.5 – 19.5%
Ni Content	8.0 – 10.5%
Surface Treatment	Whitened & Passivated
Magnetic	Non-magnetic (austenitic)
Operating Temperature	-196°C to +300°C
Corrosion Resistance	Excellent — atmospheric, fresh water, mild chemicals
RoHS / REACH	Compliant

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How DIN 137A Curved Spring Washers Work

• Curved / dished profile: The washer is formed into a curved dish shape. When compressed under bolt load, it acts as a spring maintaining axial clamping force as the joint settles
• Joint relaxation compensation: The spring-back force compensates for embedding losses and thermal expansion/contraction, keeping the bolt under consistent tension
• No surface marking: Smooth curved surface distributes load evenly without sharp edges — ideal for soft materials, coated surfaces, and anodized aluminum
• Larger bearing area: Greater OD vs. DIN 128A provides higher load capacity and better load distribution for the same bolt size

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Application Scenarios

• High-load bolted assemblies — larger OD provides greater spring force and bearing area
• Food & beverage processing equipment — A2 stainless, food-safe, easy to clean
• Medical & pharmaceutical equipment — non-magnetic, corrosion-free
• Electronics & precision instruments — non-magnetic, no surface damage
• Outdoor & architectural hardware — excellent atmospheric corrosion resistance
• Soft material assemblies — aluminum, plastic, coated surfaces where sharp edges must be avoided
• Thermal cycling applications — spring action compensates for expansion/contraction

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Product Photo Gallery

FULLERKREG DIN 137A Curved Spring Washer, A2 Stainless Steel:

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Why Choose FULLERKREG?

• 🏭 Direct manufacturer — factory in China, no middlemen
• 📐 Strict DIN dimensional control — 100% inspection on critical dimensions
• 🌍 Global export experience — serving distributors in Europe, North America, Southeast Asia
• 📦 Flexible MOQ — small trial orders and large bulk shipments both welcome
• 📋 Full documentation — material certs, RoHS declarations, test reports available
• ⚡ Fast lead times — standard sizes in stock, ready to ship

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Frequently Asked Questions

Q: What is DIN 137 Type A?
A: DIN 137 Type A is a curved (dished) spring washer with a larger outer diameter than DIN 128A for the same bolt size. When compressed, it acts as a spring to maintain axial clamping force and compensate for joint relaxation. No sharp edges — no surface marking.

Q: What is the difference between DIN 137A and DIN 128A?
A: DIN 137A has a larger outer diameter and greater spring travel than DIN 128A for the same bolt size, providing higher load capacity and better load distribution. DIN 128A is designed specifically for cheese head and pan head screws with a smaller OD.

Q: What is the difference between DIN 137A and DIN 137B?
A: DIN 137A is curved (single dished arc). DIN 137B is wavy (multiple corrugations). Both share the same outer dimensions but differ in profile and spring characteristics.

Q: Is A2 stainless steel food-safe?
A: Yes. A2 (SUS304) is widely used in food processing and pharmaceutical equipment. Non-toxic, easy to clean, resistant to most food-contact environments.

Q: Do you provide material test certificates?
A: Yes. Mill certificates, chemical composition reports, and dimensional inspection reports are available upon request.

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