Switch to

16. May 2019

Quantification of chip and cut behaviour of basic rubber

In this work a new laboratory test equipment is presented, that allows for the definition of suitable load conditions (force, rotational speed, impact incidence). The Instrumented Chip & Cut Analyzer (ICCA) collects all relevant data during the test. Using a mathematical algorithm, realistic and reliable answers on CC behaviour of the rubber are derived from the measurements.

Classifier “P” vs. normal force and varied rotational speed for SBR

Classifier “P” vs. normal force and varied rotational speed for SBR

Quantification of chip and cut behaviour of basic rubber (NR, SBR)
R. Kipscholl, R. Stoček
RFP Rubber Fibres Plastics 02|2019

Tyre treads are exposed to rolling and sliding impacts which lead to damages, known as chip and cut (CC) effects. Reliable prediction of the CC behaviour of new tyre tread compounds is very difficult without field testing. The traditional CC test methods used in laboratories employ simple devices, where loading conditions cannot be applied sufficiently and reproducibly. In this work a new laboratory test equipment is presented that allows for the definition of suitable load conditions (force, rotational speed, impact incidence). The Instrumented Chip & Cut Analyzer (ICCA) produces wear patterns like the ones observed on surfaces of tyre treads that have been operated in the field for a while. The relevant data are collected during the test. Using a mathematical algorithm, realistic and reliable answers on CC behaviour of the rubber are derived from the measurements in a short time with very little effort.

The traditional CC test methods used in laboratories employ simple devices, where loading conditions cannot be applied sufficiently and reproducibly. Only the sample weight loss and the damaging total energy are provided as results after the test, which is not sufficient to describe the complexity of CC phenomenon [3]. That is the reason why the reliable prediction of CC behaviour is very difficult without field experiments. Therefore, it becomes necessary to perform time and cost consuming development programs involving iterative tyre building and field testing of new candidates for tread compounds. A recently launched laboratory test equipment, the Instrumented Chip & Cut Analyzer (ICCA) manufactured by Coesfeld GmbH & Co. KG, Germany, allows the definition of suitable load conditions (force, rotational speed, impact incidence). It produces wear patterns as those observed on surfaces of tyre treads that have been operated in the field for a while. The relevant data values are collected during the test. Using a mathematical algorithm, realistic and reliable answers on CC behaviour of the rubber are derived from the measurements in a short time with very little effort.

The capability of the new laboratory test method employing the ICCA to determine the CC resistance is shown on carbon black reinforced compounds based on NR and SBR. Speed and loads were varied over a wide range. The measuring results evidence a very high sensitivity of this laboratory appliance. This rubber impact testing approach allows to quantify the CC behaviour using a new classifier “P” which is the reciprocal equivalent to CC resistance. According to the P-value determined in the tests, NR ranks higher than SBR regarding CC resistance at higher applied loading, whereas for lower applied loadings an inverse ranking has been determined. This ranking matches the ranking of known crack growth resistance of the analysed rubbers. Thus, the methodology and equipment provide a successful tool to investigate the durability of rubber compounds used for tyre tread rubber in the laboratory already.

Citation
R. Kipscholl, R. Stoček, RFP Rubber Fibres Plastics, 02|2019, 88-91

https://www.gupta-verlag.com/magazines/rfp-rubber-fibres-plastics-international/02-2019

 

Write a comment on this article now