SK-ZCylinder head screws

Areas of application

  • Force-fit screw connections for static and dynamic transmission of the operating load via the braced components
  • Cheese head screws

Special features

  • Defined, constant coefficient of friction
  • Increases the flexibility of the screw connection
  • Locking element to prevent loosening & automatic unscrewing
NSK screw locking devices

Comparison of possible solutions for cylinder screw connections

  Spring/profile Locking edge ring1
Spring washer2 with washer		 Toothed disc
(DIN 6798 / 6907)		 Serrated lock washer
(DIN 6797/ 6906)		 Clamping disc
(DIN6796)		 Locking edge disc SK
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
State of the art5
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 Conformity with applicable standards / prerequisite for CE labelling

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 Cylindrical head bolts up to 8.8 Cylindrical head bolts up to A4-70
Dimension range M6 - M16 M6 - M16
1 can also be used for stainless steel A2 screws, e.g. EN 1.4301 or EN 1.4310

Anwendungsbereiche

Railway Industry
Elevators
Agricultural machinery
Mechanical engineering

Why do screw connections come loose?

How does an SK-Z 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 SK-Z 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

Spring steel (C60) with zinc flake

SK-Z Article No. DI DA S H Weight/1.000 St. Pcs. per unit 3D Download Request
SK-Z6 090630 Ø 6.10+0.48 Ø 9.90-0.36 1.40±0.10 1.60+0.20 0,50 kg 1.000 Download Add to request list
SK-Z8 090640 Ø 8.20+0.58 Ø 12.70-0.36 1.40±0.10 1.70+0.20 0,90 kg 1.000 Download Add to request list
SK-Z10 090650 Ø 10.20.0.58 Ø 16.10-0.36 1.60±0.10 2.00+0.20 1,50 kg 500 Download Add to request list
SK-Z12 090660 Ø 12.40+0.58 Ø 18.30-0.52 1.80±0.10 2.40+0.20 2,00 kg 500 Download Add to request list
SK-Z14 090670 Ø 14.40+0.58 Ø 21.40-0.52 2.40±0.10 2.90+0.20 3,70 kg 500 Download Add to request list
SK-Z16 090680 Ø 16.40+0.58 Ø 24.60-0.52 2.50±0.10 3.10+0.20 5,10 kg 500 Download Add to request list

Stainless steel A4 / 1.4401

SK-Z Article No. DI DA S H Weight/1.000 St. Pcs. per unit 3D Download Request
SK-Z6 096630 Ø 6.10+0.48 Ø 9.90-0.36 1.40±0.10 1.60+0.20 0,50 kg 1.000 Download Add to request list
SK-Z8 096640 Ø 8.20+0.58 Ø 12.70-0.36 1.40±0.10 1.70+0.20 0,90 kg 1.000 Download Add to request list
SK-Z10 096650 Ø 10.20.0.58 Ø 16.10-0.36 1.60±0.10 2.00+0.20 1,50 kg 500 Download Add to request list
SK-Z12 096660 Ø 12.40+0.58 Ø 18.30-0.52 1.80±0.10 2.40+0.20 2,00 kg 500 Download Add to request list
SK-Z14 096670 Ø 14.40+0.58 Ø 21.40-0.52 2.40±0.10 2.90+0.20 3,70 kg 500 Download Add to request list
SK-Z16 096680 Ø 16.40+0.58 Ø 24.60-0.52 2.50±0.10 3.10+0.20 5,10 kg 500 Download Add to request list
Technical changes reserved
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