NSK-KElectrically conductive connections
Areas of application
- Establishing an electrically conductive screw connection between conductive parts in order to achieve potential equalisation between components (Potential equalisation is often colloquially referred to as earthing).
- Functional reliability thanks to optimised residual spring properties to prevent slackening and loosening effects
Special features
- Suitable for application-specific, low preload forces
- Defined, constant coefficient of friction
- Increases the flexibility of the screw connection
- Locking element to prevent loosening & automatic unscrewing
- Standard-compliant according to SN 70076
Comparison of possible solutions for electrical connections (equipotentiality)
| Spring/profile Locking edge ring1 Spring washer2 with washer |
Contact disc (other manufacturers) |
Clamping disc (DIN6796) |
Lock washer SK-K |
NSK-K | |
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| Uniform contact pressure |
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| Defined / reproducible preload force (coefficient of friction) |
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| Compensation of slackening effects3 |
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| Installation effort and risk |
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| Promotes electrical conductivity |
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| One-piece threadlocking solution4 |
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| Dimensions comply with SN 70026 |
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| Acquisition costs compared to washer DIN 1255 |
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1
DIN 127, 128, 6905, 7980 ec.
2
DIN 137, 6904
3
based on VDI 2230, DIN 267-26
4
according to pr EN17976
5
same / higher / high
Technical information
| Spring steel C60 EN 1.1211 |
Stainless steel A41 EN 1.4401 |
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 | Min. 720h in the salt spray test (according to ISO 9227) |
PREN 27 | depending on material |
| Temperature range | -40°C to 150°C | -40°C to 150°C | depending on material |
| Screw quality | max. 8.8 | up to and including A4-80 |
depending on material |
| Dimension range | M4 - M12 | M4 -M12 | as required |
1
can also be used for stainless steel A2 screws, e.g. EN 1.4301 or EN 1.4310
Applications
How does equipotential bonding work?
Current flow during potential equalisation
The electrical current flows from or to the cable lug via the teeth of the contact washers with the connecting elements, the cable lug and the conductive counter layers
NSK-K Corresponds to SN 70076
Why do screw connections come loose?
How does an NSK-K 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
Spring characteristic curve, matched to:
- ≤ 8.8 Strength class (steel)
- A70 / A80 for stainless steel 1.4401
How are NSK-K tested?
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
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 steel (C60) with zinc flake
| NSK-K | Article No. | DI | DA | S | H | Width tooth m |
Height tooth n |
Weight/1.000 St. | Pcs. per unit | 3D Download | Request |
|---|---|---|---|---|---|---|---|---|---|---|---|
| NSK-K4 | 070710 | Ø 4.10+0.48 | Ø 8.20-0.40 | 1.00±0.03 | 1.30±0.20 | 1.20±0.10 | 0.20+0.20/-0.10 | 0,30 kg | 1.000 | Download | Add to request list |
| NSK-K5 | 070720 | Ø 5.10+0.48 | Ø 10.20-0.40 | 1.00±0.03 | 1.50±0.20 | 2.00±0.10 | 0.40+0.30/-0.10 | 0,43 kg | 1.000 | Download | Add to request list |
| NSK-K6 | 070730 | Ø 6.10+0.48 | Ø 12.20-0.40 | 1.20±0.04 | 1.90±0.20 | 2.00±0.20 | 0.40+0.30/-0.10 | 0,80 kg | 1.000 | Download | Add to request list |
| NSK-K8 | 070740 | Ø 8.20+0.58 | Ø 16.20-0.50 | 1.40±0.04 | 2.40±0.25 | 2.00±0.20 | 0.40+0.30/-0.10 | 1,60 kg | 1.000 | Download | Add to request list |
| NSK-K10 | 070750 | Ø 10.20+0.58 | Ø 20.25-0.50 | 1.60±0.04 | 2.75±0.25 | 2.00±0.20 | 0.40+0.30/-0.10 | 2,80 kg | 500 | Download | Add to request list |
| NSK-K12 | 070760 | Ø 12.40+0.58 | Ø 24.25-0.50 | 1.60±0.04 | 3.00±0.25 | 2.00±0.20 | 0.40+0.30/-0.10 | 4,00 kg | 500 | Download | Add to request list |
| NSK-K16 | 070780 | Ø 16.40+0.58 | Ø 32.30-0.62 | 2.50±0.06 | 5,00±0.30 | 2.00±0.20 | 0.40+0.30/-0.10 | 12,00 kg | 250 | Download | Add to request list |
Stainless steel A4 / 1.4401
| NSK-K | Article No. | DI | DA | S | H | Width tooth m |
Height tooth n |
Weight/1.000 St. | Pcs. per unit | 3D Download | Request |
|---|---|---|---|---|---|---|---|---|---|---|---|
| NSK-K4 | 076710 | Ø 4.10+0.48 | Ø 8.20-0.40 | 1.00±0.03 | 1.30±0.20 | 1.20±0.10 | 0.20+0.20/-0.10 | 0,30 kg | 1.000 | Download | Add to request list |
| NSK-K5 | 076720 | Ø 5.10+0.48 | Ø 10.20-0.40 | 1.00±0.03 | 1.50±0.20 | 2.00±0.10 | 0.40+0.30/-0.10 | 0,43 kg | 1.000 | Download | Add to request list |
| NSK-K6 | 076730 | Ø 6.10+0.48 | Ø 12.20-0.40 | 1.20±0.04 | 1.90±0.20 | 2.00±0.20 | 0.40+0.30/-0.10 | 0,80 kg | 1.000 | Download | Add to request list |
| NSK-K8 | 076740 | Ø 8.20+0.58 | Ø 16.20-0.50 | 1.40±0.04 | 2.40±0.25 | 2.00±0.20 | 0.40+0.30/-0.10 | 1,60 kg | 1.000 | Download | Add to request list |
| NSK-K10 | 076750 | Ø 10.20+0.58 | Ø 20.25-0.50 | 1.60±0.04 | 2.75±0.25 | 2.00±0.20 | 0.40+0.30/-0.10 | 2,80 kg | 500 | Download | Add to request list |
| NSK-K12 | 076760 | Ø 12.40+0.58 | Ø 24.25-0.50 | 1.60±0.04 | 3.00±0.25 | 2.00±0.20 | 0.40+0.30/-0.10 | 4,00 kg | 500 | Download | Add to request list |
| NSK-K16 | 076780 | Ø 16.40+0.58 | Ø 32.30-0.62 | 2.50±0.06 | 5,00±0.30 | 2.00±0.20 | 0.40+0.30/-0.10 | 12,00 kg | 250 | Download | Add to request list |
Technical changes reserved
Contact washers are used for establishing electroconductive connections (eg for earth and ground connections) of coated equipment parts with coating thicknesses of up to 100μm. See also SN 70093.
Contact washers are used for establishing electroconductive connections (eg for earth and ground connections) of coated equipment parts with coating thicknesses of up to 100μm. See also SN 70093.
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-K for electroconductive connections
Spring steel with zinc flake
| SK-K | Article No. | DI | DA | S | H | Width tooth m |
Height tooth n |
Weight/1.000 St. | Pcs. per unit | Request |
|---|---|---|---|---|---|---|---|---|---|---|
| SK-K4 | 090710 | Ø 4.10+0.48 | Ø 8.20-0.40 | 1.00±0.03 | 1.35-0.15 | 1.20±0.10 | 0.20+0.20/-0.10 | 0,30 kg | 1.000 | Add to request list |
| SK-K5 | 090720 | Ø 5.10+0.48 | Ø 10.20-0.40 | 1.00±0.03 | 1.50-0.25 | 2.00±0.10 | 0.40+0.30/-0.10 | 0,43 kg | 1.000 | Add to request list |
| SK-K6 | 090730 | Ø 6.10+0.48 | Ø 12.20-0.40 | 1.20±0.04 | 1.80-0.30 | 2.00±0.20 | 0.40+0.30/-0.10 | 0,80 kg | 1.000 | Add to request list |
| SK-K8 | 090740 | Ø 8.20+0.58 | Ø 16.20-0.50 | 1.40±0.04 | 2.40-0.45 | 2.00±0.20 | 0.40+0.30/-0.10 | 1,60 kg | 1.000 | Add to request list |
| SK-K10 | 090750 | Ø 10.20+0.58 | Ø 20.25-0.50 | 1.60±0.04 | 2.60-0.45 | 2.00±0.20 | 0.40+0.30/-0.10 | 2,80 kg | 500 | Add to request list |
| SK-K12 | 090760 | Ø 12.40+0.58 | Ø 24.25-0.50 | 1.60±0.04 | 2.60-0.45 | 2.00±0.20 | 0.40+0.30/-0.10 | 4,00 kg | 500 | Add to request list |
Stainless steel A4 / 1.4401
| SK-K | Article No. | DI | DA | S | H | Width tooth m |
Height tooth n |
Weight/1.000 St. | Pcs. per unit | Request |
|---|---|---|---|---|---|---|---|---|---|---|
| SK-K4 | 096710 | Ø 4.10+0.48 | Ø 8.20-0.40 | 1.00±0.03 | 1.35-0.15 | 1.20±0.10 | 0.20+0.20/-0.10 | 0,30 kg | 1.000 | Add to request list |
| SK-K5 | 096720 | Ø 5.10+0.48 | Ø 10.20-0.40 | 1.00±0.03 | 1.50-0.25 | 2.00±0.10 | 0.40+0.30/-0.10 | 0,43 kg | 1.000 | Add to request list |
| SK-K6 | 096730 | Ø 6.10+0.48 | Ø 12.20-0.40 | 1.20±0.04 | 1.80-0.30 | 2.00±0.20 | 0.40+0.30/-0.10 | 0,80 kg | 1.000 | Add to request list |
| SK-K8 | 096740 | Ø 8.20+0.58 | Ø 16.20-0.50 | 1.40±0.04 | 2.40-0.45 | 2.00±0.20 | 0.40+0.30/-0.10 | 1,60 kg | 1.000 | Add to request list |
| SK-K10 | 096750 | Ø 10.20+0.58 | Ø 20.25-0.50 | 1.60±0.04 | 2.60-0.45 | 2.00±0.20 | 0.40+0.30/-0.10 | 2,80 kg | 500 | Add to request list |
| SK-K12 | 096760 | Ø 12.40+0.58 | Ø 24.25-0.50 | 1.60±0.04 | 2.60-0.45 | 2.00±0.20 | 0.40+0.30/-0.10 | 4,00 kg | 500 | Add to request list |
Technical changes reserved
Contact washers are used for establishing electroconductive connections (eg for earth and ground connections) of coated equipment parts with coating thicknesses of up to 100μm. See also SN 70093.