Washers · DIN 6798 A
DIN 6798-A Star Washer
Accurate Fastners manufactures and supplies DIN 6798 A external-tooth serrated lock washers in stainless steel grades SS 304 and SS 316, covering the diameter range M4 to M24. Produced by cold forging, these washers are designed to resist loosening under vibration in a wide range of industrial assemblies.
- Standard
- DIN 6798 A
- Grades
- 304 / 316
- Size
- M4 – M24
- Length
- —
Verification note: Brochure prints the standard as "DIN 6978-A"; the external-tooth star washer standard is DIN 6798 A. Please confirm.
Overview
What is the DIN 6798-A Star Washer?
DIN 6798 A is a German standard that defines the geometry and dimensional requirements for external-tooth serrated lock washers. The 'A' designation within the DIN 6798 family specifies an external-tooth configuration, meaning the serrations radiate outward from the washer's outer edge. Accurate Fastners produces these components to this standard using a cold-forging process, which generally promotes dimensional consistency and surface integrity across the production run.
The washer's defining feature is its ring of angled teeth arranged around the outer circumference. When the fastener is tightened, these teeth bite simultaneously into the bearing face of the fastener head or nut above and the substrate surface below, creating multiple interlocking contact points. This mechanical engagement is what gives the serrated lock washer its resistance to rotational loosening, making it a common choice in assemblies subject to vibration or repeated thermal cycling.
Accurate Fastners has served industrial customers for 21 years from its base in Ahmedabad, Gujarat, supplying fasteners both locally and for international requirements. The DIN 6798 A star washer sits within a broader range that includes anchors, nuts, bolts, screws, thread bars and pipe clamps. The company's quality control team conducts checks during procurement and at the delivery stage, and products are manufactured from high-quality raw materials.
In Depth
Product description
Construction and Geometry
DIN 6798 A star washers are cold forged, a process that shapes the component under compressive force without removing material. This typically results in a dense, work-hardened structure with well-defined tooth profiles. The washer body is flat with a central bore sized to the nominal thread diameter, and the external teeth are formed at a precise angle so they spring slightly when the fastener is tightened.
The tooth geometry on an external-tooth washer concentrates clamping force at multiple small contact points distributed around the outer edge. The angled profile means the teeth resist backward rotation more than forward rotation, which is the directional behaviour intended to oppose loosening. Available from M4 through to M24, the washer dimensions scale proportionally so the tooth count and depth remain effective across the entire size range.
Functional Behaviour in an Assembly
During assembly, the star washer is placed between the fastener head and the mating surface. As torque is applied, the teeth embed into both contact faces, increasing friction and creating a mechanical interlock. The spring-back characteristic of the teeth also provides a degree of axial preload retention, helping maintain clamp load when minor settling or thermal movement occurs in the joint.
It is worth noting that serrated lock washers may mark soft substrates such as aluminium or coated surfaces. In such cases the suitability of the washer should be assessed against the surface finish requirements of the assembly. For harder substrates, including steel structural elements and cast components, the tooth engagement is generally effective at maintaining joint integrity under sustained dynamic loading.
How It Differs from Similar Washers
The DIN 6798 family includes both external-tooth (Type A) and internal-tooth (Type J) variants. The external-tooth configuration distributes its locking action over a larger diameter, making it commonly preferred where the bearing area is generous and maximum locking engagement per tooth is desired. Internal-tooth versions are more often used under small fastener heads where the teeth need to remain hidden beneath the head diameter.
Compared with a plain flat washer, the DIN 6798 A provides active locking rather than simply distributing load. Compared with a spring lock washer (DIN 127), the star washer offers a greater number of locking points but a lower individual tooth spring force. The choice between types typically depends on substrate hardness, surface finish sensitivity, vibration frequency and the specific assembly standard being followed.
Material & Grade
Material and grade information
- SS 304
- SS 316
DIN 6798 A star washers from Accurate Fastners are available in SS 304, an austenitic stainless steel that typically offers good corrosion resistance in mildly corrosive environments, along with useful mechanical strength for general industrial use. SS 304 is commonly selected for applications in food and beverage machinery, LED lighting structures and water purification equipment where exposure to moisture or cleaning agents is moderate and chloride levels are low.
SS 316 contains molybdenum, which is widely understood to improve resistance to chloride-induced pitting corrosion compared with SS 304. It may be the preferred choice in pharmaceutical machinery, marine-adjacent installations or any environment with elevated chloride exposure. Both grades are non-magnetic in the annealed condition and offer the general corrosion resistance characteristic of austenitic stainless steel. The appropriate grade for a specific application should be confirmed with the Accurate Fastners sales team.
Grades shown are those documented for this product in the Accurate Fastners brochure. General material notes are guidance only; confirm grade selection for your environment.
Technical Data
Technical specifications
| Product type | Washer – DIN 6798-A Star Washer |
|---|---|
| Material | Stainless steel |
| Material grade | SS 304, SS 316 |
| Applicable standard | DIN 6798 A |
| Nominal diameter / size | M4 – M24 |
| Head / form | External-tooth serrated lock washer |
| Manufacturing process | Cold forged |
Sizes
Available sizes
Documented size range
M4 – M24
Documented length range
Not applicable
Individual sizes within the documented range, thread pitches and lengths are confirmed at quotation stage.
Applications
Industrial applications
Water Purification Equipment
In RO water purifier assemblies, stainless steel lock washers may help maintain secure fastenings on pump housings and filter brackets exposed to continuous moisture and periodic vibration from pressurised flow.
Submersible Pump Assemblies
Submersible pump casings and motor end-cap joints can benefit from serrated lock washers to resist loosening caused by the vibration and hydraulic forces present during pump operation.
Solar Energy Mounting Structures
Solar panel racking systems use M-series fasteners exposed to wind-induced vibration and thermal cycling. A DIN 6798 A washer may assist in retaining clamp load across the bolted joints over time.
Food and Beverage Machinery
Stainless steel construction is commonly required in food processing equipment. SS 304 or SS 316 star washers may be used in mixer, conveyor and filling machine frames where hygiene and corrosion resistance are considerations.
Pharmaceutical Machinery Frames
Pharmaceutical production equipment often specifies stainless steel fasteners throughout. DIN 6798 A washers in SS 316 may suit bolted joints on machine frames and panels in clean-room or washdown environments.
Featured for: LED Lighting
Features & Selection
Features and selection considerations
Design features
External-Tooth Locking Design
Serrations around the outer circumference engage both the fastener bearing face and the substrate simultaneously, creating multiple interlocking contact points that resist rotational loosening under vibration.
Cold-Forged Production
The cold-forging process shapes each washer without material removal, generally producing a dense structure with well-formed, consistently angled teeth across the M4–M24 size range.
Stainless Steel Construction
Offered in SS 304 and SS 316, both austenitic grades that provide inherent corrosion resistance without surface coating, reducing the risk of coating damage affecting locking performance.
Broad Diameter Coverage
The M4 to M24 range accommodates a wide variety of bolted joint sizes, allowing one supplier to cover multiple fastener positions within the same assembly or product range.
DIN 6798 A Compliance
Produced to the DIN 6798 A standard, providing defined dimensional parameters for bore, outer diameter and tooth geometry to support repeatable assembly and interchangeability across procurement batches.
Before you order
Nominal Diameter and Bolt Compatibility
Select the washer to match the nominal thread diameter of the bolt or screw being used, from M4 to M24. Confirm that the washer's bore and outer diameter suit the bearing face of the fastener head and the clearance in the joint.
Grade Selection for the Environment
Choose SS 304 for general indoor or low-chloride environments and SS 316 where chloride exposure or aggressive cleaning agents are present. Discuss the operating environment with the Accurate Fastners sales team if uncertain which grade applies.
Substrate Surface Considerations
External-tooth star washers may mark or score soft or coated mating surfaces. Confirm that the substrate material and finish are compatible with tooth engagement before specifying DIN 6798 A washers in assemblies with anodised or painted components.
Quantity and Documentation Requirements
Provide estimated annual or project quantities when enquiring, as this assists with lead-time and batch planning. If quality documentation such as material test reports is required for your procurement process, specify this clearly at the enquiry stage.
FAQs
Frequently asked questions
What does the 'A' in DIN 6798 A signify?
The 'A' designates the external-tooth variant within the DIN 6798 standard family. External teeth radiate from the outer edge of the washer, distributing locking engagement over a wider diameter compared with the internal-tooth 'J' type.
Which stainless steel grades are available for these washers?
Accurate Fastners supplies DIN 6798 A star washers in SS 304 and SS 316. SS 304 suits general-purpose use, while SS 316's molybdenum content is typically associated with improved resistance to chloride corrosion. Confirm grade suitability with the sales team for your environment.
What diameter range is covered?
The DIN 6798 A star washers are available from M4 to M24. If you require sizes outside this range or have unusual dimensional requirements, contact Accurate Fastners directly to discuss whether alternative options are available.
Can these washers be used on coated or painted surfaces?
External-tooth serrated washers may score soft or coated substrates during tightening. Whether this is acceptable depends on the assembly's surface finish requirements. We recommend reviewing substrate compatibility before specifying these washers on anodised, painted or similarly finished components.
Do these washers comply with any Indian or British standards?
These washers are produced to DIN 6798 A. Accurate Fastners' broader fastener range may comply with IS, BS and DIN standards. For specific certification or standards documentation relevant to DIN 6798 A, please confirm requirements when placing an enquiry.
How can I request a quotation for DIN 6798 A star washers?
Submit your requirements—diameter, grade, quantity and any documentation needs—via the enquiry form on the website, by emailing export@accuratefastners.com, or by contacting Accurate Fastners on WhatsApp. The sales team will respond with pricing and lead-time details.
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