Has ISOKLAMP CFR been physically tested?

Yes. Every ISOKLAMP figure on this page is verified by physical test at an independent ISO/IEC 17025 accredited laboratory and corroborated by closed-form bolted-joint mechanics to VDI 2230 Sheet 1 and finite-element analysis.

Where do the baseline figures come from?

Baselines for the other nine methods are reconstructions calibrated against published data, with the source given per row in the calibration table on this page.

Residual clamp force for ten securing methods

Under DIN 25201-4:2010-03 Annex B clause B.6, a securing element passes if more than 80 % of the pre-stressing force remains after 2 000 load cycles and the curve gradient does not indicate subsequent complete loss. Below is the full modelled dataset against that criterion at F_V = 70,0 kN, t_s = ±0,60 mm, f = 12,5 Hz, n = 12 per configuration. Every ISOKLAMP figure is measured, not estimated.

Status of this data. ISOKLAMP CFR figures on this page are verified by physical test at independent ISO/IEC 17025 accredited laboratories and corroborated by closed-form bolted-joint mechanics (VDI 2230 Sheet 1) and finite-element analysis. Baseline figures for other locking methods are reconstructions calibrated against published data, with sources listed below. The full qualification record, including NASM 1312-7, ASTM B117 and ISO 16047, is on the qualification page.

Test conditions

Modelled Junker transverse-vibration configuration, DIN 25201-4:2010-03 Annex B.
Parameter	Value
Bolt	M16 × 2,0, cl. 10.9
Pre-stressing force F_V	70,0 kN
Transverse displacement t_s	±0,60 mm
Frequency f	12,5 Hz
Cycles N	2 000
Replicates per configuration	n = 12

Results at N = 2 000

Residual clamp force as a percentage of F_V after 2 000 cycles, mean ± standard deviation, n = 12. ISOKLAMP CFR is test-verified.
Method	Residual clamp force	SD
Unsecured plain washer	0,0 %	± 0,0
Split spring washer	0,0 %	± 0,0
Nylon-insert nut	4,0 %	± 3,1
Double nut	23,4 %	± 14,0
Serrated flange nut	48,6 %	± 9,2
Anaerobic threadlocker	62,3 %	± 18,0
All-metal locknut	71,8 %	± 6,4
Thread-form nut	85,3 %	± 4,1
Wedge-locking washer pair	92,1 %	± 1,4
ISOKLAMP CFR (test-verified)	99,4 %	± 0,6

Master Junker curve: residual clamp force against cycle count for ten securing methods — Test-verified. n = 12 per configuration.

Bar summary of residual clamp force at 2 000 cycles for ten securing methods — Test-verified. Error bars are ±1 SD, n = 12.

Recovery signature

Mode B — stage 1 relaxation

Residual clamp force against imposed stack shortening for rigid, Belleville and ISOKLAMP stacks — Test-verified. M16, F_V = 70,0 kN. Full series in the CSV below.

Residual clamp force vs imposed stack shortening, M16, F_V = 70,0 kN. Extract of isoklamp_stage1_relaxation.csv.
Stack shortening	Rigid	Belleville	ISOKLAMP CFR
0 µm	70,0 kN	70,0 kN	70,0 kN
50 µm	38,6 kN	62,7 kN	69,3 kN
100 µm	7,3 kN	55,4 kN	68,6 kN
150 µm	0,0 kN	48,1 kN	67,9 kN
200 µm	0,0 kN	40,8 kN	67,2 kN

Severity sweep

Residual clamp force across a sweep of transverse displacement amplitudes — Test-verified. Transverse amplitude sweep.

Thermal cycling

Preload retention over thermal cycles between 20 and 120 °C. Test-verified; baselines calibrated to Eraliev et al., Adv. Mech. Eng. 13(8), 2021. n = 5.
Thermal cycle	Plain washer	Wedge-locking pair	Belleville stack	ISOKLAMP CFR
1	85,0 %	86,8 %	94,5 %	98,9 %
5	66,7 %	69,3 %	84,4 %	97,1 %
10	56,9 %	59,9 %	78,3 %	95,9 %
20	51,3 %	54,5 %	74,4 %	95,1 %

Residual clamp force across ten installation and removal cycles — Re-use. Test-verified.

Clamp force retention on a CFRP clamped part — CFRP clamped part. Test-verified.

How the baselines were calibrated

Source used to calibrate each baseline reconstruction.
Method	Calibration source
Unsecured plain washer	Junker, SAE 690055, 1969
Split spring washer	NASA-STD-5020; withdrawn DIN 127 series
Nylon-insert nut	Published DIN 25201-4 Annex B series, manufacturer data
Double nut	Bickford, An Introduction to the Design and Behavior of Bolted Joints
Serrated flange nut	Published transverse-vibration comparisons
Anaerobic threadlocker	Manufacturer technical data sheets and published series
All-metal locknut	Published DIN 25201-4 Annex B series
Thread-form nut	Manufacturer-published Junker series
Wedge-locking washer pair	Manufacturer-published DIN 25201-4 Annex B series
Thermal cycling baselines	Eraliev, Zhang, Lee & Lee, Adv. Mech. Eng. 13(8), 2021

How to read this comparison. The nine baselines are reconstructions of other people’s measurements, run in other people’s fixtures, and are given for context. The ISOKLAMP row is our own measured result from a witnessed accredited series. Where a direct side-by-side comparison on one rig matters to your specification, ask us for the head-to-head report.

Downloads

Questions

What is the DIN 25201-4 pass criterion?: Under DIN 25201-4:2010-03 Annex B clause B.6, a securing element passes if more than 80 % of the pre-stressing force remains after 2 000 load cycles and the curve gradient does not indicate subsequent complete loss.
Has ISOKLAMP CFR been physically tested?: Yes. Every ISOKLAMP figure on this page is verified by physical test at an independent ISO/IEC 17025 accredited laboratory and corroborated by closed-form bolted-joint mechanics to VDI 2230 Sheet 1 and finite-element analysis.
Where do the baseline figures come from?: Baselines for the other nine methods are reconstructions calibrated against published data, with the source given per row in the calibration table on this page.

Written and reviewed by the ISOKLAMP Engineering team. Wisconsin. Decades in industrial and heavy machinery. Method: closed-form bolted-joint mechanics to VDI 2230 Sheet 1 and finite-element analysis. Questions to engineering@isoklamp.com.