Disc-Lock Washers

Disc-Lock Washer

Disc-Lock Washers

Disc-Lock Washers
Disc-Lock Washer

What is the Disc-Lock Washer?

The Disc-Lock Washer is a heavy duty structural self-locking product, which prevents loosening caused by shock or vibration in high stress applications.

It out-performs all other types of loose, washered, threaded or pinned systems and is probably the most effective locking device for maintaining joint integrity in the world.

The Disc-Lock Washer is not only a vibration-proof locking device, but also a heavy duty, structural device, recommended for the most stressful applications.

How does the Disc-Lock Washer work?

Unlike conventional washers, the Disc-Lock Washer consists of two washer-shaped pieces which are preassembled (glued pairs – new stock only) and which have inclined cams on one side and a series of ridges on the other. On installation the two cam sides are mated together and placed between the nut and the joint material. Under vibration the nut will attempt to rotate loose but, as the angle of the cams is greater than the pitch angle of the thread on the bolt, the interlocking cams and the non-slip ridges of the Disc-Lock Washer work together to create a jamming effect. This effect prevents loosening and further locks the assembly, thereby maintaining joint integrity




Disc-Lock Washers used in pipeline

Disc-Lock Washers used in steel mill

Disc-Lock Washers used in VOLTZ transgun

Who uses the Disc-Lock Washer?

Industries and machinery which use Disc-Lock Washers include:

  • Automotive industries (cars, trucks, buses and coaches)
  • Compressors
  • Cranes
  • Farm Equipment
  • Foundries
  • Go-kart Racing
  • Heavy Equipment Manufacturers (road and construction)
  • Logging Equipment
  • Marine Installations
  • Military
  • Mining
  • Oil Drilling Rigs (On and Off shore)
  • Pile Hammers
  • Pipelines
  • Public Utilities
  • Quarrying
  • Rail Engineering
  • Rapid Transit Systems
  • Refineries
  • Rock Hammers
  • Steel Mills

Disc-Lock Safety Washer Specification

Dimentional Chart:

Disk-Lock Washer Diagram

100-01* 6 3/16* 5 .203 .401 .080 5.15 10.18 2.03
101-01* 6 1/4* 6 .262 .495 .127 6.66 12.57 3.22
102-01* 8 5/16* 8 .326 .628 .142 8.28 15.95 3.60
103-01* 8 3/8* 10 .409 .705 .160 10.38 17.90 4.06
104-01* 10 7/16 11 .450 .880 .135 11.43 22.35 3.33
105-01* 10 1/2* 12 .510 .937 .166 12.95 23.82 4.22
106-01* 10 9/16 14 .572 1.128 .127 14.53 28.65 3.23
107-01* 12 5/8* 16 .651 1.247 .188 16.53 31.67 4.79
108-01* 14 3/4 20 .820 1.381 .242 20.82 35.08 6.15
109-01* 14 7/8 22 .883 1.470 .268 22.44 37.34 6.80
110-01* 16 1 24 1.015 1.626 .256 25.78 41.30 6.50
111-01* 12 1-1/8 27 1.140 1.715 .240 28.96 43.56 6.10
112-01* 12 1-1/4 30 1.275 1.875 .265 32.39 47.63 6.73
117-01* 12 1-3/8 36 1.430 2.196 .230 36.32 55.78 5.84
113-01* 12 1-1/2 38 1.523 2.196 .230 38.68 55.78 5.84

*For orders of stainless steel parts, add "SS" to the beginning of the order number.
**Weight and thickness of pairs will vary slightly with gauge of metal.
*These sizes are available in pairs and are plated in A.S.T.M B633-98, Class 2, Trivalent Chromate, Blue to comply with RoHS, WEEE and ELV European directives and are sold in pairs.
*These sizes are available glued and coated with Delta Protekt which complies with RoHS and ELV directives.

  • Manufactured in 1010 carbon steel and case hardened to 40/55 on the Rockwell C scale to a depth of 0.13mm (0.005”)
  • Also manufactured in stainless steel (316) up to size16mm (5/8”)
  • Zinc plated to A.S.T.M. B633-85 and baked to prevent hydrogen embrittlement. (Disc-Lock Washers are not suitable for hot dip galvanizing.)
  • All new stock from 2012 coated with Delta Protekt (colour – silver matte).  Minimum 600 hours of salt spray.
  • Each lot is micro-hardness tested after heat treatment
  • Can be used with Grade 2,5,8 and even stronger bolts


Disc-Lock Washers are sold in pairs. These pairs may be glued together for easier installation. However, due to circumstances beyond our control some washers may become separated during shipping and handling. This does not affect the operation of the washer and these washers should not be returned as defective.

Disc-Lock Washer - Installation Procedure

  1. To install the Disc-Lock Washer, simply mate the cams of the two pieces together and place between the nut and the joint material.
    Disc-Lock Washer Installation Step 1
  2. As the nut is tightened, one half of the Disc-Lock Washer is seated to the joint material and the other to the nut.
    Disc-Lock Washer Installation Step 2
  3. When the bolt elongates due to vibration and shock, the nut will attempt to rotate loose. As one half of the Disc-Lock Washer tries to rotate with the nut, the interlocking cams work against each other. This will increase/maintain the preload and further lock the assembly.
    Disc-Lock Washer Installation Step 3
  4. As the bolt contracts, the inclined planes of the cams cause the nut to rotate back to its original position.
    Disc-Lock Washer Installation Step 4
  5. In common with most fastening devices, Disc-Lock Washers should only be used against flat, relatively smooth metal surfaces.
  6. If the joint material is not metal, the Disc-Lock Washer may be used by securing a metal plate to the joint material in such a manner that the metal plate will not rotate.
  7. As with all fasteners, Disc-Lock Washers should be re-examined before re-using.
  8. An air-gun can be used when installing and removing Disc-Lock Washers

Frequently Asked Questons - DISC-LOCK Washer

  • Who developed the Disc-Lock Washer?
    The Disc-Lock Washer was developed by Disc-Lock International, California, USA.
  • Where are Disc-Lock Washers manufactured?
    Washers are manufactured in California and Taiwan.
  • How does the Disc-Lock Washer work?
    The Disc-Lock principle consists of two washer shaped pieces that have inclined cams on one side and a series of ridges on the other. The greater the rise angle of the Disc-Lock cams along with the non-slip ridges work together to prevent loosening caused by shock and vibration.  The result is a fastening system that is vibration proof according to Military Standards*.

    United States Military MIL-STD-1312, Test 7. Vibration Test Results data available upon request to info@disc-lock.co.uk
  • What are the chances of a fastener loosening if Disc-Lock Washers are fitted?
    None.  When applied and installed properly Disc-Lock Washers will ensure the fastener remains secure.
  • Can Disc-Lock Washers be used under the head of cap screws in blind hole applications?
  • Can Disc-Lock Washers be re-used?
  • Does a fastener fitted with a Disc-Lock Washer require a different torque setting from conventional washers?
    No, just use the recommended handbook torque.
  • In what sizes is the Disc-Lock Washer available?
    Fifteen sizes ranging from 5mm to 38mm in metric and from 3/16 to 1-1/2” in imperial.
  • What material is used in the manufacture of Disc-Lock Washers?
    Standard Disc-Lock Washers are made from 1010 Carbon Steel. Disc-Lock also stocks washers manufactured in 316 stainless steel – from 5mm to 16mm or 3/16 to 5/8” inclusive. Disc-Lock can also make special, exotic materials on a custom basis.
  • Does the Disc-Lock Washer have a special coating?
    Standard coatings are as follows:  Zinc plated per A.S.T.M B633-98, Trivalent Chromate (NO Hexavalent Chrome) and baked to prevent hydrogen embrittlement. (Disc-Lock Washers are not suitable for hot dip galvanising)
  • Are Disc-Lock Washers susceptible to hydrogen embrittlement?
    No, as they are baked after coating.
  • Is the Disc-Lock Washer corrosions resistant?
    No, the standard Disc-Lock Washer is not corrosion resistant.  However, our stainless steel washers are corrosion resistant.
  • Is the Disc-Lock Washer heat-treated?
    Yes, they are case hardened to between 40 to 50 on the Rockwell C scale, in a rotary furnace, in a carbon nitrite environment.
  • What is the maximum temperature in which Disc-Lock Washers can be used?
    Standard Disc-Lock Washers (made from 1010 carbon steel and case hardened) can be used for applications in environments up to a maximum temperature of 300° Fahrenheit.

    Stainless Steel Disc-Lock Washers can be used for applications in environments up to a maximum temperature of 1,150° Fahrenheit.

    Note:  To convert Celsius into Fahrenheit multiply C degrees x 1.8 and add 32.  Eg.  500° Celsius = 932° Fahrenheit  (500 x 1.8 = 900 + 32 = 932)
  • Is the heat treat hardness of Disc-Lock Washers checked?
    Yes, by micro hardness testing at independent testing laboratories.
  • Are lot numbers for checking on quality control maintained?
  • Will the Disc-Lock Washer save maintenance time?
    Yes, nuts and bolts fitted with Disc-Lock Washers do not require retightening.
  • In which type of applications have Disc-Lock Washers performed successfully?
    Disc-Lock Washers have out-performed all other types of loose, washered, threaded or pinned systems in a wide range of high stress, corrosive and vibration sensitive applications including heavy equipment, bus and truck fleets, oil drilling rigs, public utilities, railroads, logging and mining equipment, pipelines, military and many more.
  • How is the Disc-Lock Washer fitted?
    Simply mate the cams together and place between the nut and the joint material.
  • Do you need a torque wrench when fitting Disc-Lock Washers?
  • Can an air-gun be used when fitting Disc-Lock Washers?
  • Is the Disc-Lock Washer patented world-wide?