Frictionmeter / RK

- RK -

Friction coefficient measuring unit RK
The frictionmeter ‚RK’ is a device which determines the coefficient of friction µ. The coefficient of friction µ is a measure of the frictional properties of a test specimen.

The device is used to examine the surface structure of thread guides and friction elements or the influence of different preparations on the running characteristics of POY, yarns, filaments, wires or other flexible materials.

Measuring priciple
A test specimen (thread or thin wire) is drawn over a friction body at a defined wrapping angle and a defined speed. During this operation the tensile force on the test thread is measured before and after the friction body. An increase in the tensile force (thread tension) is a measure of the coefficient of friction µ. µ is calculated according to the Eithelwein formula.
Friction factor measurement

The friction factor is measured at the contact points of two materials:

- Thread (or wire) against a solid body, such as ceramic or metal.
Any form of friction body can be used. Round friction bodies with diameters between 2 mm and 60 mm.

- Thread against thread.
In measuring the thread/thread friction factor the thread is wrapped around itself so that it forms a friction body at the contact points.

- Friction factor measurement on heated ceramic and steel friction body. - Stick-slip measurement (static friction measurement)

Stick-slip friction measurements are carried out at an extremely slow thread speed (approx. 1 mm/min !!). At this speed a constantly increasing force builds up in the test thread after it has passed the frictin body. This tensile force falls quite suddenly when the test thread gets into sliding friction (slip). The level of this self-buildingtensile force is a measurement of static friction.

The extremely low speed is generated and digitally displayed by the SS26 drawing-off device. The same measuring sensors and measuring arrangements are used as for friction factor measurement.

- Extraction equipment for taking up the drawn-off threads.

Evaluation per PC

The evaluation of a coefficient of friction µ measurement is done with the RK-WIN software . This software has been specially developed for the requirements of the friction factor and stick-slip measurements.It offers the graphical representation of the measurement sequence, a measuring report and lots more. An A/D converter card is also provided with the software package for installing in the PC.

Tensometric Win friction value measurement software RK-WIN


The friction value measurement software RK -WIN is used for the precise measurement of the coefficient of friction µ. It is adapted to our tried and tested frictionmeter RK and replaces the friction value measurement program RK PC 9400.

The software now uses the features of the Windows operating system, such as the clipboard, use of any printer, and simple operation using a mouse. Naturally, settings and projects, i.e. set scales andlabels, can be saved, activated and managed. In addition, the measurement screens may besaved in BMP format.The evaluation of the measurement can be seen directly in a continuously updated result block.

The measuring log is automatically copied to the clipboard.It can then easily be inserted in your word processing software.

Apart from the time driven measurement, which determines the friction coefficient µ at a pre - set measuring time, another interesting measuring option has been added:

the result driven measurement (automatic mode).

In this mode the measurement does not finish until the friction coefficient µ approaches a limiting value. The tolerance of the limiting value can be preset. The duration of the measuring process is therefore not predetermined at the start, but is rather dependent on the desired accuracy of the experimental result.


Data sheet:

Data sheet RK-WIN (Download)

Data sheet RK-Info (Download)

Data sheet RK-FHS200 (Download)

Data sheet RK-SS26 (Download)