Locking Washers

These are used for locking a device and reducing the vibration. They reduce loosening by preventing unscrewing rotation of the fastening device; locking washers are usually also spring washers.

Spring washers, sometimes called disc springs, are a subtype of washers. They lend their mechanical capabilities to the unique profile of the material: when subject to a load, the irregularities of the washer compress with a proportionate resistance to return to their pre-deflected shape.

Spring washers are employed in applications where assemblies need a part to take up play, eliminate rattle, maintain assembly tension, compensate for expansion or contraction in materials after assembly, or to absorb intermittent shock loads and provide a controlled reaction under dynamic loads.

These washers are designed to be tightened to a required torque beneath an ordinary fastener. They exert a spring tension that keeps the fastener from vibrating loose. They are often attached to the nut side of the fastener.

Locking washers are available in a wide range such as spring washers, star washers, multi-tooth washers, disc spring washers, wave washers, taper washers, safety washers etc.

Spring Washers

Spring Washers Type A Square

DIN 7980 Product Code: D05

A Spring washer is a metal ring split at one point and bent into a helical shape. This helps the washer to exert a spring force between the fastener’s head and the surface. This keeps the washer firm against the substrate and the bolt thread hard against the nut or substrate thread, creating more friction and resistance to rotation.

A spring washer square has square ends at the split end. Provides much better resistance as compared to a plain washer.

Materials – Spring Steel, Titanium, SS-301 and SS-316
Size Range – M3 to M48

Spring Washers Type B Flat/ Split Lock Washers

DIN 127B Product Code: D06

The lock washer prevents nuts and bolts from turning, slipping and coming loose because of vibration and torque. The washer has sharp edges that dig into the nut as well as mounting surface in order to prevent rotation in the counter clockwise direction.
Spring Lock Washers are of many types, most common one being the helical split washer. A ring split at one point and bent into a helical shape. This causes the washer to exert a spring force between the fastener’s head and the substrate, which maintains the washer hard against the substrate and the bolt thread hard against the nut or substrate thread, creating more friction and resistance to rotation.

Materials: Spring Steel, Titanium, SS AISI 301 and AISI 316
Standards: IS 3063, DIN 127B
Size Range: M2 to M48

Split Spring Washers Curved

DIN 128B Product Code: D09

These are specialty spring lock washers – They are split metal rings that are bent into a curved (Type A) configuration.

Unlike standard split helical spring lock washers, the DIN 128 lock washers are non-directionally specific allowing the screw and or nut to be tightened in a clockwise or counter-clockwise manner.

When compressed by tightening the nut, the DIN 128 lock washer exert a spring force between the tightened bolt and the substrate creating frictional resistance to rotation. The lock is created by the friction the lock washer generates between the screw head and the base and between the threads.

Available in stainless steel AISI 301 and AISI 316 in sizes from M2 onwards.

Curved Spring Washers

DIN 137A Product Code: D16

Curved spring washers are uninterrupted formed disks in either a curved or waved configuration unlike standard split helical spring lock washers. They are often used to fit around curved surfaces such as the outside diameter of a pipe or tube. Curved spring washers are non-directional and allow the screw and or nut to be tightened in either a clockwise or counterclockwise manner.

When compressed by tightening the nut, the DIN 137 lock washers exert a spring force between the tightened bolt and the substrate creating frictional resistance to rotation.

Curved washers are excellent for applications with repeated cycles through a range of motion along with a lighter thrust load. The curved washer is often superior to a helical spring for maintaining tension on a cam action or similar application where very little height is available.

These washers are recommended for locking lightweight components onto soft materials and are often used to absorb axial end play.

Wave Spring Washers

DIN 137B Product Code: D17

These washers are recommended for locking lightweight components onto soft materials and where a higher torque is required. The wave spring washers in this range are particularly useful in applications requiring anti vibration characteristics.

Go to the Spring Washers page

Star – Tooth Washers

Star Washers Internal Type

DIN 6797J Product Code: D11

These are locking washers that form part of the serrated or toothed type of washers. They feature serrations or teeth that extend radially inward to bite into the bearing surface.
Their effectiveness is more evident on soft substrates such as plastics or Aluminium although they do resist rotation better than plain washers on harder surfaces. As per DIN 6797J

Materials
– Spring Steel
– SS AISI 304
– SS AISI 316. Available on request.

Star Washers External Type

DIN 6797A Product Code: D12

These are locking washers that form part of the serrated or toothed type of washers. They feature serrations or teeth that extend radially outward to bite into the bearing surface. Designed for use in providing increased locking force and torsional resistance.
Their effectiveness is more evident on soft substrates such as plastics or Aluminium although they do resist rotation better than plain washers on harder surfaces. As per DIN 6797A

Materials
– Spring Steel
– SS AISI 304
– SS AISI 316. Available on request.

Multi Tooth Washers – DIN 6798

A multi tooth washer increases frictional resistance and suitable for moving parts. The multi tooth lock washer works best with smaller screw heads. It is useful where a good grip is required but the teeth should not be visible as they affect the appearance of the product.

Metric DIN 6798 Serrated Lock Washers that are available in Form A (external serrations), Form J (Internal serrations) and Form V (conical for countersunk head screws). The teeth are superimposed on one another maximizing the friction between the surface of the substrate and fastener. The teeth bite into the surface of the substrate to oppose any loosening forces.

Multi Tooth Washers External – Type A

DIN 6798A Product Code: D13

Multi Tooth Washers External (Form A) have teeth on the outer edge the washer allowing for maximum contact on the biggest possible surface area.

Materials
– Spring Steel
– Stainless Steel AISI 304
– Stainless Steel AISI 316. Available on request

Multi Tooth Washers Internal – Type J

DIN 6798J Product Code: D14

Multi Tooth Washers Internal (Form J) have teeth that extend inward from the inside edge of the washer and are recommended when the head of the screw is smaller than the diameter washer or when the surface of the fastener is irregular or convex.

The multi tooth lock washer works best with smaller screws heads. It is useful where a good grip is required but the teeth should not be visible as they affect the appearance of the product. The internal teeth grip the screw head and are useful in preventing a backward motion.

Standard : DIN 6798J

Materials
– Spring Steel
– Stainless Steel AISI 304
– Stainless Steel AISI 316. Available on request.

Multi Tooth Washers CSK – Type V

DIN 6798A Product Code: D13

Multi Tooth Washers CSK (Form V) are conical in shape with teeth extending outwards and is used with countersunk head screws with a 90 degree countersink.

Materials
– Stainless Steel AISI 304
– Stainless Steel AISI 316. Available on request

Go to the Star Tooth Washers page

Disc Spring Washers

DIN 2093 Product Code: D18

Known by many different names, this non flat washer is a type of spring shaped like a washer. They have a slight conical shape which give the washers a spring characteristic which provide an axial force when deformed. These are among the most widely used tension generating washers. The washers enhance load or deflection values through stacking.

Disc Washers are loaded in the axial direction, either dynamically or statically. They offer well-developed solutions to many engineering problems. Through a unique combination of high force in a small space, the disc can be used single or arranged in stacks.

Conical Spring Washers

DIN 6796 Product Code: D20

A Conical spring washer designed to help prevent loosening of bolted joints under vibration. This type, manufactured to DIN 6796 has an inherent conical shape which can be loaded along its axis either statically or dynamically. It is also known as a Belleville washer, disc spring, coned-disc spring and cupped disc washer.

Conical washers hold tight where heat or vibration might shake standard washers loose and are known for their ability to provide the highest load bearing capacity and have a low deflection range.

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Safety and Conical Spring Washers

Serrated Safety Washers Type S – Schnorr Type

Safety washers were developed as a reliable and economic bolt locking device with the basic principle of a disc spring. This ingenious form combines the advantage of security through friction and mechanical locking. They are in the form of a disc spring but with a trapezoidal cross-section and serrations on both sides. The outer diameter is matched to the head diameter of the pan head and socket head cap screws.

Advantages

The cross section ensures locking effect at the outside diameter.
Due to the closed ring form, high degree of pretensioning is achieved.
Sliding surfaces allow tightening with damaging the mating surfaces.
High resistance to vibration due to positive locking of the serrations
Suitable for a wide range of screw/bolt heads minimizing stocks.

Afnor Contact Lock Washers – NF E-25 511

Contact Washers (also known as Rib Washer Single Side Serrated Washer) are Conical shaped Lock Washers formed with a ribbed or serrated top surface. The conical shape exerts locking force 360 degree around the underside of the screw head or nut by generating tension. The ribbed top surface further enhances the locking force and resists the torqued fastener connection potential for loosening under pressure and vibration. This is a single-sided toothed and non-slip locking washer, providing the designer the ability to secure wobble-prone screw effectively. It is particularly suitable for use on slot fasteners, dynamic cross-loaded to the screw connections and applications that require high biasing forces.

These washers are widely used in locomotives, appliances, elevators, electrical towers, medical machinery and electronic equipment.

Range available: Sizes – M3 to M20

Materials SS-304 / SS-316. As per NFE – 25511

Go to the Safety and Conical Spring Washers page