Home » DIN 128A Lock Washer Spring – 70# Steel Zinc

DIN 128A Lock Washer Spring – 70# Steel Zinc

DIN 128A Curved Spring Lock Washer — 70# Spring Steel, Zinc Plated

FULLERKREG DIN 128A curved spring lock washers are manufactured to DIN 128 Type A standard in 70# high-carbon spring steel (Grade 70, per GB/T 699) with mechanical zinc plating. DIN 128 Type A is a curved (single-coil) spring washer that generates axial spring force through its curved profile, providing anti-loosening performance with smooth, even load distribution — no sharp edges, no surface marking. The 70# spring steel achieves 40–50 HRC hardness after quench and temper, delivering superior spring force and fatigue resistance. Mechanical zinc plating provides enhanced corrosion protection without hydrogen embrittlement risk.

Note on zinc treatment: At 40–50 HRC, conventional electroplating introduces hydrogen embrittlement risk. FULLERKREG applies mechanical zinc plating (per GB/T 17460) — cold mechanical impact with no acid pickling, no electrical current, no hydrogen introduction.

Product Highlights

  • Standard: DIN 128 Type A (Curved Spring Lock Washer)
  • Material: 70# Spring Steel (Grade 70, GB/T 699)
  • Surface Treatment: Mechanical Zinc Plating (GB/T 17460) — no hydrogen embrittlement
  • Hardness: 40–50 HRC (392–513 HV) after quench & temper
  • Size Range: M2 – M36
  • Profile: Type A — Curved single-coil (not helical split, not wavy)
  • Corrosion Resistance: Enhanced — suitable for light outdoor and humid environments
  • RoHS & REACH Compliant

Dimensional Specifications — DIN 128 Type A (Curved), 70# Steel Zinc

All dimensions in millimeters (mm). Per DIN 128 Type A.

Nominal Size For Bolt d1 min d2 max h min h max s (thickness) b (width)
2 M2 2.1 4.4 0.70 1.10 0.6 0.9
2.3 M2.3 2.4 4.9 0.90 1.10 0.6 0.9
2.5 M2.5 2.6 5.1 0.90 1.10 0.6 1.0
2.6 M2.6 2.7 5.2 0.90 1.10 0.6 1.0
3 M3 3.1 6.2 1.10 1.30 0.7 1.3
3.5 M3.5 3.6 6.7 1.20 1.30 0.7 1.3
4 M4 4.1 7.6 1.20 1.40 0.8 1.5
5 M5 5.1 9.2 1.50 1.70 1.0 1.8
6 M6 6.1 11.8 2.00 2.20 1.3 2.5
8 M8 8.1 14.8 2.45 2.75 1.6 3.0
10 M10 10.2 18.1 2.85 3.35 1.8 3.5
12 M12 12.2 21.1 3.35 3.65 2.1 4.0
14 M14 14.2 24.1 3.90 4.30 2.4 4.5
16 M16 16.2 27.4 4.50 5.10 2.8 5.0
18 M18 18.2 26.4 4.50 5.10 2.8 5.0
20 M20 20.2 33.6 5.10 5.90 3.2 6.0
22 M22 22.5 35.9 5.10 5.90 3.2 6.0
24 M24 24.5 40.0 6.50 7.50 4.0 7.0
27 M27 27.5 43.0 6.50 7.50 4.0 7.0
30 M30 30.5 48.2 9.50 10.50 5.0 8.0
36 M36 36.5 58.2 10.30 11.30 6.0 10.0

All dimensions in mm per DIN 128 Type A. s = material thickness; b = ring width; h = free height (curved profile height).

Material Properties — 70# Spring Steel (GB/T 699)

Property Value
Material Grade 70# Spring Steel (Grade 70)
GB Standard GB/T 699, GB/T 4354
C Content 0.67 – 0.75%
Mn Content 0.50 – 0.80%
Heat Treatment Quench & Temper
Hardness 40 – 50 HRC (392 – 513 HV)
Tensile Strength 1275 MPa min.
Surface Treatment Mechanical Zinc Plating (GB/T 17460)
Coating Thickness 8 – 25 um
Operating Temperature -40°C to +120°C
RoHS / REACH Compliant

Chemical Composition — 70# Spring Steel (GB/T 699)

Element C Mn Si P max S max Cr max Ni max
Content % 0.67–0.75 0.50–0.80 0.17–0.37 0.035 0.035 0.25 0.25

DIN 128A vs. DIN 128B — Key Differences

Feature DIN 128 Type A (Curved) DIN 128 Type B (Wavy)
Profile Single curved arc Wavy / corrugated (multiple waves)
Contact Continuous curved contact Multi-point contact
Spring action Axial spring via single curve Distributed multi-wave spring force
Typical use Cheese head & pan head screws General bolted assemblies

Application Scenarios

  • Cheese head screw assemblies (DIN 84) — curved profile optimized for cheese head applications
  • Pan head screw assemblies (DIN 7985) — smooth curved profile, no surface marking
  • Heavy machinery & industrial equipment — high spring force with outdoor corrosion protection
  • Automotive manufacturing — chassis and underbody components exposed to moisture
  • Construction & steel structures — sheltered outdoor environments
  • Agricultural & mining equipment — high-vibration, humid conditions
  • Soft material assemblies — curved profile distributes load without sharp edge marking

Product Photo Gallery

FULLERKREG DIN 128A Curved Spring Lock Washer, 70# Spring Steel, Zinc Plated:

[ Photo 1 ] [ Photo 2 ] [ Photo 3 ] [ Photo 4 ]

Why Choose FULLERKREG?

  • 🏭 Direct manufacturer — factory in China, no middlemen
  • 📐 Strict DIN dimensional control — 100% inspection on critical dimensions and hardness
  • 🌍 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, hardness reports, RoHS declarations available
  • ⚡ Fast lead times — standard sizes in stock, ready to ship

Frequently Asked Questions

Q: What is DIN 128 Type A?
A: DIN 128 Type A is a curved spring lock washer. The ring is formed into a single curved arc. When compressed under bolt load, it acts as a spring maintaining axial clamping force. Unlike DIN 127B (helical split), it has no sharp edges and does not mark bearing surfaces.

Q: Why mechanical zinc plating for 70# spring steel?
A: At 40–50 HRC, conventional electroplating introduces hydrogen embrittlement risk during acid pickling. Mechanical zinc plating uses cold mechanical impact with no acid pickling or electrical current, eliminating this risk while providing 8–25 um zinc coating for enhanced corrosion protection.

Q: DIN 128A vs. DIN 128B — which to choose?
A: DIN 128A (curved) is designed for cheese head and pan head screws with a single smooth arc. DIN 128B (wavy) provides multi-point contact for general assemblies. Both share the same dimensions.

Q: Do you provide material test certificates?
A: Yes. Mill certificates, hardness reports, chemical composition reports, and RoHS declarations available upon request.

FULLERKREG Fasteners — Precision DIN Standard Fasteners, Direct from Manufacturer.
For wholesale inquiries, technical questions, or custom orders, please contact our sales team.

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