TABLE OF CONTENTS When designing a pneumatic drive, there can be many objectives which usually lead to different choices of components:
minimum stroke time, i.e. maximum number of cycles per unit time,
optimal usage of compressed air,
minimum-size circuit members,
minimum component price,
standardisation to reduce the number of spare parts.
There is no simple guideline how to achieve an optimum design because the response of a drive is the result of a series connection of all components: a couple of sharp 90 elbows installed to "cosmetically enhance" the machine to improve its saleability can double the stroke time! And not only the static behaviour, i.e. the flow resistance or static friction, but also the dynamic behaviour has to be taken into account: charging and discharging of volumes, acceleration forces or speed-dependent friction. And the fact that almost all relations are non-linear does not make the task easier.
However, with today's sophisticated computers and advanced software packages there are very powerful tools available for the design and optimisation of pneumatic circuits. Important are sufficient knowledge of the process where the drive is installed and good models of the pneumatic components.
Although there are many books on pneumatics, only very few deal with circuit design and component sizing [1]. One exception is the study by Fleischer (1995). His final chapter and other results can be summarised as follows:
The performance time is the result of the interaction of all components: the total resistance of directional control valve, lines, flow control...
