Manufacturer of filling machines is using the precision movement capabilities of rodless pneumatic cylinders for handing delicate liquids that can froth or foam in an instant.
RCS Filling Machines has harnessed the precision movement capabilities of rodless pneumatic cylinders for handing delicate liquids that can froth or foam in an instant. Manufacturers of soaps, detergents and the many other products that can foam-up have to take particular care when it comes to the final packaging or filling stage of their manufacturing operation. Many turn to Nottingham's RCS Filling to develop bespoke machines that allow them to maintain production speeds yet be confident of successful filling.

The basic technique employed by RCS is to keep the dispensing nozzle just below the surface of the liquid as it fills the drum.

This is done using a rodless cylinder made by Hoerbiger-Origa to raise the nozzle at a precisely regulated speed.

In use, empty drums are delivered to the filling station, usually by conveyor, and the rodless cylinder lowers the filling nozzle into the drum to a point just above its bottom.

Delivery begins slowly, but once the nozzle is immersed in liquid it can speed up.

If the nozzle were to stay in a static position back pressure would soon build up and slow down delivery.

Therefore the nozzle begins to retract at a rate proportional to the delivery flow such that it always remains just below the surface.

Normally the drum is cylindrical, so the rate of retraction is a steady speed, relatively easy for RCS to set up.

This can be achieved with an open loop control algorithm, although RCS prefer to close the loop using a load cell to constantly weigh the amount of liquid that has been delivered and convert this into an exact determination of the level in the drum.

However, if the drum is of a profiled shape the rate of the rise in level is non-linear and either a specific control algorithm has to be developed or the level monitored in real time.

In either case RCS has to be confident that the Origa cylinder can accurately maintain position.

Once filling is complete the nozzle has to retract fully to allow capping to proceed to complete the cycle.

'Typically we will insert the nozzle rapidly, raise it slowly during filling, then complete the final retraction at high speed,' explains RCS technical director Stuart Margetson.

'It is quite a demanding duty cycle in a tough environment and operation may well be 24x7'.

'We use the Origa cylinder because it was the original rodless and has an enviable track record.' The Origa has three other major advantages appreciated by RCS's designers.

Its robust design allows it to be used as a structural element of the machine, reducing the amount of support engineering needed considerably.

The design is identical for all sizes from the smallest 16mm bore to the largest 48mm, which means RCS can use the same design details for all their machines regardless of overall size.

Finally the stroke length is infinitely variable up to 3m as standard, again rationalising machine design for RCS.

Pneumatic actuation is critical for RCS because many times the working environment is Zone 1 or Zone 2 explosive, where sparks from electrically driven actuators could be disastrous.

Hoerbiger-Origa pneumatic cylinders satisfy the demands of today's Atex regulations for explosive atmospheres, and equivalent regulations in other territories.

Some RCS machines have multiple nozzles for simultaneously filling a number of drums, and in others the nozzles have to be able to index in X and Y directions to fill drums on pallets.

Such machines will typically use several Origa cylinders to provide the necessary three dimensional movements.