DIN 128 A Split
Spring Washers, Curved Form A
Manufacturer Mumbai
What Is a DIN 128 A Curved Spring Washer
DIN 128 covers two washer profiles under the same standard, distinguished as Form A and Form B. Form A is the plain curved version — a split ring bent into one smooth, even curve, without the additional twist that gives Form B its two distinct high points. Fitted under a bolt head or nut, that curve compresses flatter as the fastener is torqued down, and the residual spring tension it retains at final torque helps resist a small amount of loosening from vibration or thermal cycling over time.
It’s functionally very close to a DIN 137 A curved spring washer, and the two are frequently specified somewhat interchangeably. Form A is generally the right choice over the twisted Form B where the application’s vibration and loosening risk is modest, and the simpler, purely spring-based construction is all that’s needed — reserving Form B’s added edge bite for joints where a bit more anti-loosening margin is worth the small extra cost.
Akbar Fasteners Pvt. Ltd. manufactures DIN 128 A spring washers in-house at our Mumbai facility, under ISO 9001:2015, with full mill test documentation, and exports this range to over 50 countries.
Where DIN 128 A Split Spring Washers, Curved Form A Genuinely Earn Their Place
Continuous Spring Tension
The curved profile retains residual spring force at final torque, helping resist loosening from light vibration and thermal cycling.
Simple, Economical Construction
A single-curve stamped profile that’s straightforward to manufacture in volume for general-duty fastening applications.
Full Dimension Reference
A published inner and outer diameter chart lets you match the correct washer to your bolt size and application.
Wide Material & Finish Choice
Spring steel and stainless steel available across the full size range, in bulk quantities for OEM and general assembly needs.
DIN 128 A Spring Washer Dimension Chart
Standard nominal dimensions by bolt size — inner diameter (d1) should match your bolt or screw diameter with standard clearance, and outer diameter (d2) should clear the bearing surface it seats against. Free height and spring rate vary by material temper and are confirmed against your torque and load requirement at quotation.
| Bolt Size (d) | Inner Dia. (d1) | Outer Dia. (d2) | Thickness (s) | Free Height |
|---|---|---|---|---|
| M3 | 3.1 mm | 5.9 mm | 0.5 mm | 0.9 mm |
| M4 | 4.1 mm | 7.6 mm | 0.6 mm | 1.1 mm |
| M5 | 5.1 mm | 9.2 mm | 0.7 mm | 1.3 mm |
| M6 | 6.1 mm | 11.8 mm | 1.0 mm | 1.8 mm |
| M8 | 8.2 mm | 14.8 mm | 1.2 mm | 2.2 mm |
| M10 | 10.2 mm | 18.1 mm | 1.6 mm | 2.8 mm |
| M12 | 12.2 mm | 21.1 mm | 2.0 mm | 3.4 mm |
| M16 | 16.3 mm | 27.4 mm | 2.5 mm | 4.2 mm |
| M20 | 20.4 mm | 33.8 mm | 3.0 mm | 5.0 mm |
Figures shown are representative reference values for quick planning purposes; free height and spring rate are matched to your specific torque and vibration requirement at quotation. Please confirm exact dimensions against the current DIN 128 standard document or your engineering drawing, and request our certified dimensional data sheet, before finalizing a purchase order.
Spring Washer Product Range
Split Spring Washers, Curved Form A
Plain curved anti-loosening spring washers in spring steel and stainless steel, M3 to M20.
DIN 128 BSplit Spring Washers, Waved Form B
Twisted-profile counterpart with added edge bite, covered under the same DIN 128 standard.
DIN 137 ACurved Spring Washers, Form A
Closely related curved spring washer standard with a similar anti-loosening function.
DIN 137 BWave Spring Washers, Form B
Closely related wave spring washer standard alongside DIN 128.
DIN 128 A Technical Overview
Available Materials
- Spring Steel Standard Offering
- Stainless Steel A2 / A4 on Request
- Phosphor Bronze Non-Magnetic Applications
- Surface Finish Zinc Plated / Bright / Passivated
- Custom Material To Specification
Hardness & Spring Rate
- Surface Hardness ~42–52 HRC
- Spring Rate Matched to Bolt Size
- Form Plain Curve, Form A
- Load Data Confirmed at Quotation
- Testing MTC / NABL on Request
Available Dimensions
- Bolt Size M3 – M20
- Custom Sizes To Drawing on Request
- Standard Reference DIN 128 A
- Thickness Range 0.5 – 3.0 mm
- Packaging Loose / Boxed / Bulk
Application Areas
Wherever a light, economical spring washer is enough to help resist loosening.
General Machinery Assembly
requiring vibration resistance
Automotive & Two-Wheeler Assembly
fastening applications
Appliance & Electrical Assembly
consumer and industrial goods
Agricultural Equipment
fastening under vibration
Furniture & Cabinet Hardware
fastening assemblies
Packaging Machinery
guard panel fastening
Electronics Enclosures
for equipment housings
General OEM Assembly
volume manufacturing
Standard Export Documentation
Prepared as standard practice for every spring washer shipment.
Mill Test Certificate (MTC)
Material composition and hardness verification for every production batch.
Certificate of Conformance
Confirms the shipment matches the purchase order specification, size, and form in full.
Certificate of Origin (COO)
Confirms India as country of manufacture for destination customs purposes.
Commercial Invoice & Packing List
Itemized value, Incoterm, and detailed carton/weight breakdown for customs clearance.
Dimensional Data Sheet
Certified inner/outer diameter and free height data against DIN 128 A available on request before order confirmation.
Bill of Lading
Ocean or air freight shipping document confirming carrier, mode, and consignee details.
Internationally Recognised Standards Coverage
Related Fastener Grades & Standards
DIN 128 B Split Spring Washers
Twisted-profile counterpart with added edge bite, covered under the same DIN 128 standard.
View DIN 128 B →DIN 137 A Spring Washers
Closely related curved spring washer standard with a similar anti-loosening function.
View DIN 137 A →DIN 93 Tab Washers
Bendable locking washers offering a physical, verifiable safety locking mechanism.
View DIN 93 →Top Nickel Fasteners Manufacturer
See our full in-house nickel alloy manufacturing and documentation capability.
View Manufacturer Page →Send Us Your
Bolt Size & Quantity
Tell us your bolt size, material preference, and quantity — we’ll confirm the correct DIN 128 A specification and issue a certified dimensional data sheet with your quote. Akbar Fasteners Pvt. Ltd. responds within 24 hours.
Sales: +91 724 0000 733 · Support: +91 800 9315 333 · sales@akbarfasteners.in