Pneumatics for bottling

16 February, 2018

Speed is required by several applications in this sector; for example, it is often requested to execute numerous changeovers within a second. Even more important than speed is the assurance that the changeover time will not vary after the machinery has been in use over a period of several years. Let us consider, for instance, a pneumatic solenoid valve that controls the motion of a cylinder. Say the valve opening time is10ms and the cylinder motion occurs in 50ms. The machine often doesn’t have time to complete a motion and, signalled by a sensor, to activate the successive phase. It is therefore necessary to plan ahead and to control the successive phase before the one currently in operation is accomplished.

At this stage, it is not so important whether the valve opening time is shorter or longer because it can be anticipated, but it is very important that time remains as constant as possible and is not influenced by the passing of years, by temperature or by the day of the week (for example, the possible symptoms of Monday morning syndrome when a machine is started up again after being idle for a certain period of time). Here, the experience of the manufacturer of pneumatic components comes into play. For example, Metal Work’s HDM and CM solenoid valve islands are modular assemblies that can contain a number of valves ranging from 1 to 64 and are available in different types with fittings for tubes from 4mm to 10 mm in diameter. The switchover time in the case of, for example, the monostable 5/2 valves is 8ms in operation and 33ms in reset.

A key benefit is that after 50 million cycles they only have variations of ±3ms. To achieve this result, Metal Work worked hard on the design, on the materials and especially on tribological aspects. The spool seals are of FKM/FPM, which is a material compatible with many oils and detergents. The spool is made of aluminium treated with chemical nickel-plating and machine-polished to achieve a high level of hardness (no wear) and low roughness (minimal friction).

The grease used required some of the most rigorous research activity. The type used for a number of years, called ‘high grip’, adheres to the treated surfaces without being transported by liquids and eventually entering the valve; no matter whether the liquids are water, detergents or even glycol. HDM and CM valve isles were designed 15 years ago, but over the years they have undergone numerous ameliorative modifications in order to enhance their reliability and, as explained, their functional constancy over time.

Pre-treatment of compressed air

The compressed air used in bottling plants must be adequately treated if the valves and actuators are to be protected adequately. Metal Work relies on five series of air treatment groups, what we refer to as FRL. Among them, our customers prefer two. Syntesi is a modular group, available in two sizes, with attachments from 1/8” to 1”. It stands out for its high performance in relation to its size, for its range completeness, for its flexibility and user-friendliness in configuring the groups with the various modules. For applications requiring very pure air, we offer a 5 µm filter module followed by a purifying module to retain oily particles, and finally an active carbon filter module to retain organic particles. Syntesi enjoyed such immediate market success that another Italian manufacturer decided to copy it almost integrally.