NSK-LStandard drillings & slotted hole fixings up to 12.9 strength classes

Areas of application

  • Highly stressed and high-strength bolted connections in accordance with VDI 2230-1
  • Force-fit, static and dynamic transmission of the operating load via the braced components
  • Strength classes 8.8 to 12.9 or A70 and A80
  • Circular hole and slotted hole connections
  • Effective even with limited installation space (See also NSK-B for larger installation spaces)

Special features

  • Suitable for high preload forces
  • Defined, Defined, constant friction coefficient
  • Increases the flexibility of the screw connection
  • Special spring characteristics / optimum residual spring behaviour for strength classes 10.9 and 12.9 (Characteristic spring curves shown in M-Design)
  • Locking element to prevent loosening & automatic unscrewing
  • Complies with standards DIN 267-26, DIN 25201-4, DIN EN 17976

Comparison of possible solutions for highly stressed and high-strength screw connections

  Spring/profile Locking edge ring1
Spring washer2 with washer
Wedge disc pairs
(flat design)
Wedge disc pairs
(conical design)
Clamping disc
(DIN6796)
NSK-L
Damage to the counterclaims
Defined / reproducible contact pressure (coefficient of friction)
Improved compliance with short clamping lengths
Compensation of slackening effects3
Compensation of loosening effects4
Acquisition costs compared to washer DIN 1255
1 DIN 127, 128, 6905, 7980 etc
2 DIN 137, 6904
3 according to VDI 2230, DIN 267-26
4 in accordance with DIN 65151 / DIN 25201- 4
5 same / higher / high

Technical Information

  Spring steel C60
EN 1.1211
Stainless steel A41
EN 1.4401
(in preparation)
Other materials EN 1.4547, EN 2.4819, EN 2.4668 (on request)
Hardness / Strength ≥ 430 HV10 ≥ 595 N/mm2 depending on material
Coating Zinc flake coating - -
Corrosion protection > 720h in the salt spray test (according to ISO 9227) PREN 27 (bezogen auf Grundwerkstoff) depending on material
Temperature range -40°C to 150°C -40°C to 150°C depending on material
Screw quality 8.8 - 12.9 up to and including
A4-80
depending on material
Dimension range M6 - M20 M6 - M20 as required
1 can also be used for stainless steel A2 screws, e.g. EN 1.4301 or EN 1.4310

Applications

Railway Industry
Elevators
Agricultural machinery
Mechanical engineering

Why do screw connections come loose?


How does an NSK-L work?

Force-locking effect with curved geometry matched to the preload force depending on the strength class.

  • Increases the flexibility of a bolted joint
  • Prevents slackening effects and supports the locking effect against selfacting loosening

Form locking effect due to the interlocking under the screw head or on the nut.

  • Supports the locking effect against selfacting loosening

How are NSK-L tested?

Minimum residual spring force test according to DIN 267-26
Force measurement, if the screw connection is relieved by 20μm (Technical specifications for conical spring steel washers for bolted joints)

Spring characteristic curve, matched to:

  • Strength class 10.9 and 12.9 (steel)
  • A80 for stainless steel 1.4401

Vibration test according to DIN 65151 & DIN 25201-4 Annex B.

  • Application-orientated testing on circular-holes and slotted holes
  • Internal testing equipment are verified by external institutes.

Pressure cone test  

Deflection tests

The functional properties and tests for slotted hole connections are not defined in standards. The tests, carried out by teckentrup SLI, are used for orientation.
The properties and testing methode for slotted hole connections must be specified by the user.

Spring steel (C60) with zinc flake

NSK-L Article No. DI DA S H Weight/1.000 St. Pcs. per unit 3D Download Request
NSK-L6 070230 Ø 6.10+0,48 Ø 14.20-0,43 2.40±0.04 3.10±0.20 2,13 kg 1.000 Download Add to request list
NSK-L8 070240 Ø 8.20+0.58 Ø 18.20-0.52 2.40±0.05 3.40±0.25 3,94 kg 1.000 Download Add to request list
NSK-L10 070250 Ø 10.20+0.58 Ø 22.25-0.52 2.80±0.06 3.70±0.25 6,83 kg 500 Download Add to request list
NSK-L12 070260 Ø 12.40+0.58 Ø 27.25-0.52 2.80±0.06 4.30±0.25 10,11 kg 500 Download Add to request list
NSK-L14 070270 Ø 14.40+0.58 Ø 30.25-0,52 3.50±0.06 4.70±0.25 15,27 kg 250 Download Add to request list
NSK-L16 070280 Ø 16.40+0.58 Ø 32.50-0.52 3.50±0.07 4.90±0.30 16,80 kg 250 Download Add to request list
NSK-L20 070300 Ø 21,00+0,58 Ø 40,00-0,52 4.00±0.07 6.00±0.30 28,58 kg 100 Download Add to request list

Stainless steel A4 / 1.4401 (Available from February 2025)

NSK-L Article No. DI DA S H Weight/1.000 St. Pcs. per unit 3D Download Anfrage
NSK-L6 076230 Ø 6.10+0,48 Ø 14.20-0,43 2.40±0.04 3.10±0.20 2,13 kg 1.000 Add to request list
NSK-L8 076240 Ø 8.20+0.58 Ø 18.20-0.52 2.40±0.05 3.40±0.25 3,94 kg 1.000 Add to request list
NSK-L10 076250 Ø 10.20+0.58 Ø 22.25-0.52 2.80±0.06 3.70±0.25 6,83 kg 500 Add to request list
NSK-L12 076260 Ø 12.40+0.58 Ø 27.25-0.52 2.80±0.06 4.30±0.25 10,11 kg 500 Add to request list
NSK-L14 076270 Ø 14.40+0.58 Ø 30.25-0,52 3.50±0.06 4.70±0.25 15,27 kg 250 Add to request list
NSK-L16 076280 Ø 16.40+0.58 Ø 32.50-0.52 3.50±0.07 4.90±0.30 16,80 kg 250 Add to request list
NSK-L20 076300 Ø 21,00+0,58 Ø 40,00-0,52 4.00±0.07 6.00±0.30 28,58 kg 100 Add to request list
Technical changes reserved
The securing effect of the NSK-B and NSK-L on slotted holes is verified using a wide range of test methods. The hole clearance in the transverse direction corresponds to normal holes (DIN EN 20273; tolerance class H 13, medium). Furthermore, slotted hole edges are always deburred. For your own applications, it is recommended that you carry out your own tests with specialised personnel.