Experimental analysis of tribological behaviour of advanced composite spools used in commercial pneumatic spool valves

• Tribological conditions inside a pneumatic valve are presented in detail.
• Friction behaviour of several composite pneumatic valve spools is analysed.The experimental approach is used for determination of the friction forces.
• Static and dynamic friction forces are analysed in detail. Friction force curves as a function of spool velocity are analysed in detail.
• The composite spool with the best friction characteristics is defined.

In this paper, we present the study of the tribological conditions inside a pneumatic valve. The main goal is to analyse the friction behaviour of new pneumatic valve spools made of advanced composite materials in detail by using the experimental approach. The spools are intended to be used without any lubricant in the valve, therefore experimental tests are carried out in dry working conditions. On the basis of the measured force curves the static and dynamic friction forces are determined as well as the friction forces depended on the spool velocity. Finally, the spool with the best friction characteristics, the minimal friction forces, is defined. Also, the machinability of the composite spools is considered.