NSK-SStrength classes < 8.8
Areas of application
- Force-fit screw connections for static and dynamic transmission of the operating load via the braced components with low strength classes below 8.8
- Ideal for the substitution of fasteners whose standards have been withdrawn:
- Serrated lock washers (DIN 6798)
- Spring washers / profile rings (DIN 127,128, 6905, 7980)
- Spring and profile discs (DIN 137, 6904)
- Toothed discs (DIN6797, 6906)
Special features
- Suitable for low preload forces
- Defined, constant coefficient of friction
- Increases the flexibility of the screw connection
- Special spring characteristics / optimum residual spring behaviour for strength classes < 8.8 (Characteristic spring curves shown in M-Design)
- Locking element to prevent loosening & automatic unscrewing
Comparison of possible solutions for stressed screw connections up to and including strength class 8.8
| Spring/profile Locking edge ring1 Spring washer2 with washer |
Toothed disc (DIN 6798 / 6907) |
Serrated lock washer (DIN 6797/ 6906) |
Clamping disc (DIN6796) |
Lock washer SK-S | NSK-S | |
|---|---|---|---|---|---|---|
| Damage to the counterclaims |
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| Defined / reproducible contact pressure (coefficient of friction) |
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| Improved compliance with short clamping lengths |
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| Compensation for slackening effects3 |
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| Compensation of loosening effects4 |
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| Acquisition costs compared to washer DIN 1255 |
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1
DIN 127, 128, 6905, 7980 etc.
2
DIN 137, 6904
3
based on VDI 2230, DIN 267-26
4
in accordance with DIN 65151 / DIN 25201 - 4
5
same / higher / high
Executions
| Spring steel C60 EN 1.1211 |
Stainless steel A41 EN 1.4401 |
|
|---|---|---|
| Hardness / Strength | ≥ 430 HV10 | ≥ 595 N/mm2 |
| Coating | Zinc flake coating | - |
| Corrosion protection | > 720h in the salt spray test (according to ISO 9227) | PREN 27 (related to base material) |
| Temperature range | -40°C to 150°C | -40°C to 150°C |
| Screw quality | < 8.8 | up to and including A4-70 |
| Dimension range | M4 - M12 | M4 - M12 |
1
can also be used for stainless steel A2 screws, e.g. EN 1.4301 or EN 1.4310
Applications
Why do screw connections come loose?
How does an NSK-S 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-S 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 8.8 (steel)
- A70 / A80 for stainless steel 1.4401
Friction coefficients are determined in accordance with DIN 16047
The decisive factors for a constant and defined coefficient of friction with low tolerance are
a.) the form of the connecting element
b.) the surface coating of the connecting element
Spring steel (C60) with zinc flake
| NSK-S | Article No. | DI | DA | S | H | Weight/1.000 St. | Pcs. per unit | 3D Download | Request |
|---|---|---|---|---|---|---|---|---|---|
| NSK-S4 | 070810 | Ø 4.10+0.48 | Ø 8.20-0.40 | 1.00±0.04 | 1.30±0.20 | 0,30 kg | 1.000 | Download | Add to request list |
| NSK-S5 | 070820 | Ø 5.10+0.48 | Ø 10.20-0.40 | 1.00±0.04 | 1.50±0.20 | 0,43 kg | 1.000 | Download | Add to request list |
| NSK-S6 | 070830 | Ø 6.10+0.48 | Ø 12.20-0.43 | 1.20±0.04 | 1.75±0.20 | 0,80 kg | 1.000 | Download | Add to request list |
| NSK-S8 | 070840 | Ø 8.20+0.58 | Ø 16.20-0.43 | 1.40±0.04 | 2.40±0.25 | 1,70 kg | 1.000 | Download | Add to request list |
| NSK-S10 | 070850 | Ø 10.20+0.58 | Ø 20.25-0.52 | 1.60±0.05 | 2.75±0.25 | 3,00 kg | 1.000 | Download | Add to request list |
| NSK-S12 | 070860 | Ø 12.40+0.58 | Ø 24.25-0.52 | 1.60±0.05 | 3.00±0.25 | 4,30 kg | 500 | Download | Add to request list |
Stainless steel A4 / 1.4401
| NSK-S | Article No. | DI | DA | S | H | Weight/1.000 St. | Pcs. per unit | 3D Download | Request |
|---|---|---|---|---|---|---|---|---|---|
| NSK-S4 | 076810 | Ø 4.10+0.48 | Ø 8.20-0.40 | 1.00±0.04 | 1.30±0.20 | 0,30 kg | 1.000 | Download | Add to request list |
| NSK-S5 | 076820 | Ø 5.10+0.48 | Ø 10.20-0.40 | 1.00±0.04 | 1.50±0.20 | 0,43 kg | 1.000 | Download | Add to request list |
| NSK-S6 | 076830 | Ø 6.10+0.48 | Ø 12.20-0.43 | 1.20±0.04 | 1.75±0.20 | 0,80 kg | 1.000 | Download | Add to request list |
| NSK-S8 | 076840 | Ø 8.20+0.58 | Ø 16.20-0.43 | 1.40±0.04 | 2.40±0.25 | 1,70 kg | 1.000 | Download | Add to request list |
| NSK-S10 | 076850 | Ø 10.20+0.58 | Ø 20.25-0.52 | 1.60±0.05 | 2.75±0.25 | 3,00 kg | 1.000 | Download | Add to request list |
| NSK-S12 | 076860 | Ø 12.40+0.58 | Ø 24.25-0.52 | 1.60±0.05 | 3.00±0.25 | 4,30 kg | 500 | Download | Add to request list |
Technical changes reserved
What is the difference between SK and NSK washers?
| Lock washer (SK Washer) |
New lock washer (NSK washer) |
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|---|---|---|
| State of development |
1990
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2007 cont.
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| Form |
Linear cross- section
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Angled or curved cross-section with bead
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| Compensation of loosening effects1 |
mainly given
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I.O.
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| Compensation of loosening effects2 |
not given (standard from 2005)
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I.O.
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| Fulfilment of the teckentrup product characteristics |
Manufacturer-dependent and to be verified in individual cases
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I.O.
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| Costs |
Identical NSK
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Identical SK
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1
according to DIN 65151 and, if applicable, DIN 25201 - 4 2021-11, depending on design with adapted parameters depending on strength class etc.
2
based on VDI 2230, DIN 267-26 2005-12
The SK washers are produced by different manufacturers worldwide and may have different functional properties with the same external appearance.
SK washer
NSK washer
SK-S (small) for strength classes < 8.8
Spring steel with zinc flake
| SK-S | Article No. | DI | DA | S | H | Weight/1.000 St. | Pcs. per unit | Request |
|---|---|---|---|---|---|---|---|---|
| SK-S4 | 090010 | Ø 4.10+0.48 | Ø 8.20-0.40 | 1.00±0.04 | 1.20+0.15 | 0,30 kg | 1.000 | Add to request list |
| SK-S5 | 090020 | Ø 5.10+0.48 | Ø 10.20-0.40 | 1.00±0.04 | 1.30+0.20 | 0,43 kg | 1.000 | Add to request list |
| SK-S6 | 090030 | Ø 6.10+0.48 | Ø 12.20-0.43 | 1.20±0.04 | 1.60+0.20 | 0,80 kg | 1.000 | Add to request list |
| SK-S8 | 090040 | Ø 8.20+0.58 | Ø 16.20-0.43 | 1.40±0.04 | 2.20+0.20 | 1,70 kg | 1.000 | Add to request list |
| SK-S10 | 090050 | Ø 10.20+0.58 | Ø 20.25-0.52 | 1.60±0.05 | 2.20+0.20 | 3,00 kg | 1.000 | Add to request list |
| SK-S12 | 090060 | Ø 12.40+0.58 | Ø 24.25-0.52 | 1.60±0.05 | 2.40+0.20 | 4,30 kg | 500 | Add to request list |
Stainless steel A4 / 1.4401
| SK-S | Article No. | DI | DA | S | H | Weight/1.000 St. | Pcs. per unit | Request |
|---|---|---|---|---|---|---|---|---|
| SK-S4 | 096010 | Ø 4.10+0.48 | Ø 8.20-0.40 | 1.00±0.04 | 1.20+0.15 | 0,30 kg | 1.000 | Add to request list |
| SK-S5 | 096020 | Ø 5.10+0.48 | Ø 10.20-0.40 | 1.00±0.04 | 1.30+0.20 | 0,43 kg | 1.000 | Add to request list |
| SK-S6 | 096030 | Ø 6.10+0.48 | Ø 12.20-0.43 | 1.20±0.04 | 1.60+0.20 | 0,80 kg | 1.000 | Add to request list |
| SK-S8 | 096040 | Ø 8.20+0.58 | Ø 16.20-0.43 | 1.40±0.04 | 2.20+0.20 | 1,70 kg | 1.000 | Add to request list |
| SK-S10 | 096050 | Ø 10.20+0.58 | Ø 20.25-0.52 | 1.60±0.05 | 2.20+0.20 | 3,00 kg | 1.000 | Add to request list |
| SK-S12 | 096060 | Ø 12.40+0.58 | Ø 24.25-0.52 | 1.60±0.05 | 2.40+0.20 | 4,30 kg | 500 | Add to request list |
Technical changes reserved