Lock washers are specialized fastening devices engineered to provide positive locking action within bolted joints. Placed beneath nut faces or bolt heads, lock washers increase friction, resist axial/radial stresses, and mitigate joint loosening or fluid leakage caused by operational vibration. As a premier lock washers manufacturer, supplier, and exporter in India, Intact360 Fasteners manufactures high-performance lock washers engineered to satisfy rigorous international industrial specifications.
Lock washers are categorized into 3 primary engineering types: External Tooth Lock Washers, Internal Tooth Lock Washers, and Helical Split Lock Washers. Selecting the appropriate tooth configuration or split geometry ensures optimal joint security across machinery, wheel hubs, electrical housings, and structural assemblies.
- External Tooth Lock Washers (DIN 6798 Type A): Feature outer teeth that bite into mating surfaces to resist heavy compressional and rotational forces.
- Internal Tooth Lock Washers (DIN 6798 Type J): Feature inner diameter teeth designed for shallow-headed fasteners, preventing snagging while resisting axial/radial stresses.
- Helical Split Lock Washers (DIN 127): Feature a split outer diameter that expands under compression to grip fastener heads under initial clamping tension.
External Tooth vs Internal Tooth Lock Washers
Tooth-type lock washers utilize twisted prongs or teeth that bite into both the fastener head and the mating substrate surface during torquing. The orientation of these teeth dictates their application:
1. External Tooth Lock Washers
Designed with alternating teeth protruding along their outer circumference, external tooth lock washers offer maximum torsional resistance. When tightened, the external teeth dig firmly into the mating surface to withstand heavy compressional forces. They are commonly used on machine parts, shafts, shipping containers, wheel hubs, and electrical ground connections where large bolt heads are present.
2. Internal Tooth Lock Washers
Internal tooth lock washers feature teeth arranged along their inside diameter. Engineered specifically for shallow-headed fasteners or small-diameter screws, the internal teeth form an interference fit with the material, resisting both axial and radial forces. Because the teeth remain concealed under the screw head, they prevent snagging and improve load-carrying capacity in wood, plastic-to-metal assemblies, and electrical enclosures.
Helical Split Lock Washers & Joint Reliability Mechanics
Helical split lock washers (also known as spring lock washers or snap rings) feature a cut split on their outer diameter. When tightened under load, the split ends flatten and expand to apply spring tension against the fastener head.
Understanding Split Washer Performance
While split lock washers have historically been used to prevent bolts from loosening, experimental engineering tests indicate that once a bolt loses its initial clamping torque, a split washer alone may offer limited resistance against dynamic self-loosening. For high-vibration applications subject to severe dynamic stress, Intact360 recommends specifying DIN 6798 Serrated Tooth Washers or Wedge Lock Washers alongside proper bolt preloading to ensure total joint integrity.
Technical Specifications & Standard Compliance
| Lock Washer Category | International Standard | Raw Material Options | Primary Mechanical Function |
|---|---|---|---|
| External Tooth Lock Washers | DIN 6798 Type A / ASME B18.21.1 | Spring Steel, SS 304/316, Bronze | Outer teeth bite into surface to resist torque |
| Internal Tooth Lock Washers | DIN 6798 Type J / ASME B18.21.1 | Spring Steel C67S, SS 304/316 | Concealed inner teeth resist axial/radial stress |
| Helical Split Lock Washers | DIN 127 / ASME B18.21.1 | Spring Steel, Stainless Steel 304/316 | Applies initial spring tension under bolt head |
| Serrated Lock Washers | DIN 6798 / DIN 6797 | 51CrV4, SS 316, Carbon Steel | High-vibration anti-loosening bite action |
To protect locking teeth and spring edges against environmental degradation, Intact360 applies specialized surface platings including Zinc Electroplating, Hot Dip Galvanizing (HDG), Black Oxide, Phosphating, Cadmium Plating, Molykote dry film lubricants, and PTFE/Xylan protective coatings.
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Industrial Lock Washers Technical FAQ
Why choose Intact360 as your lock washers manufacturer?
What is the primary function of a lock washer?
How do external tooth lock washers work?
What are internal tooth lock washers best suited for?
What are split lock washers?
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