Pneumatics for bottling

16 February, 2018

The market for plant and machinery used in the bottling process is extensive, and Italy holds a prominent position in this sector. For pneumatic components to be fit for purpose in this market, they must be proven to be reliable and be able to operate at high speed in order to meet, and even exceed, required productivity levels. The choice of materials and treatments must be suitable for individual zones within a plant; for example, for areas where parts may be in contact with food or detergents. Today, applications are emerging that use electrical rather than pneumatic cylinders.

What is bottling?

When thinking of the bottling process, those who do not operate in this sector might imagine the situation represented in the opening drawing. Many people (me included) still like to breath in the vapours that come out of wine while decanting it into thoroughly cleaned bottles while relaxing in the fresh environment of their cellar. However, the industrial reality is very different; we generally deal with plants that are able to fill 3000 bottles per hour, and in the mineral water sector up to 90,000 bottles per hour.

This is a very wide and diversified world. Solutions are different depending on the treated fluid: wine, water, milk, beverages, juices or oil. Moreover, they are very different depending on the container: glass, polyethylene, aluminium or steel.

The bottling, or ‘filling’, is the central part of a series of very complex processes. These processes begin with the container production; for instance, the creation of the PET bottle. In certain cases, there is a sanitisation phase. This is followed by the real filling, closure with the cap, labelling and packaging. All these steps must be carried out in compliance with food safety criteria; in accordance with the certification rules of individual countries and in line with rigid quality control procedures.

Flexibility is another requisite that is increasingly requested; for example, flexibility is necessary to construct plants that can be reconfigured for different liquids. However, containers, too, can change in accordance with designers’ requirements and market expectations. In Italy can be found the headquarters of some of the largest manufacturers of bottling plants and machines in the world. Italy also houses hundreds, if not thousands, of small- and medium-sized companies that can design and produce the widest variety of machines or special sub-assemblies.

Components for bottling

Are the pneumatic components used in this sector different from those deployed elsewhere? Yes and no. We can also say ‘no’ because if a component has been designed to perform many millions of cycles without the need for maintenance, while also offering a high degree of reliability and being compliant with European and ISO standards, it is suitable for this sector as well as for others. However, we can also answer positively, because some characteristics are singular to this industry.

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.

The other air treatment group used in the bottling sector is ONE. While Syntesi is an example of modularity, ONE is, by contrast, an example of integration. It comprises a single body that encases all the typically functions; filter, condensate exhaust, pressure regulator, manual valve, electric valve, pre-start valve, gauge, pressure switch and four air outlets. It can be panel-mounted because all regulation or maintenance functions are on the front side.

Actuators: not only stainless steel

Let’s now look at actuators. In several machines, stainless steel actuators lead the way; both in terms of standard cylinders – for instance, in accordance with the ISO15552 regulation – and special tailor-made cylinders. In this regard, Metal Work can offer the competence of Alfa Meccanica Group, a specialist in the design and manufacture of special actuators made from various materials including AISI 304, AISI 316 and 316L steel.

Where stainless steel use is not compulsory it is possible to exploit specific, less expensive, solutions. In collaboration with Brescia Engineering University, Metal Work recently developed anti-corrosion ISO15552 cylinders. These products use aluminium alloys as their base material, with a set of successive surface treatments that increase their resistance to corrosion. Besides passing saline mist tests, these products have proven to withstand acid environments up to pH=2 and basic environments up to pH=12.

Of course, actuators used in the bottling sector are not only pneumatic. Apart from mechanic cam motions that are ideal for high speeds and granted sequences, several motions are electrically controlled. The following case example is worth mentioning: There is a growing trend for beverages containing whole piece of fruit, not only liquid. This has resulted in some challenges for the ‘filling’ systems because the density and the consistency of the product are not constant. They have then introduced some dispensers, in other words big syringes where the plunger is operated by an electrically controlled cylinder. In this way, it is possible to control the speed and the stroke of the plunger precisely, irrespective of the type of bottled fluid. Metal Work has supplied many of these actuators, electrical cylinders of the Elektro ISO15552 series. Concerning motors, it is possible to choose either stepping or brushless motors. When the cylinder is mounted on a rotary part of the machine, it can be convenient to use a motor equipped with integrated drive controlled by a fieldbus.

Conclusion

As explained, the pneumatics supplier is an important partner for machine manufacturers and must be able to design and supply components both as standard and as custom-made options. Only in this way can the performance and the reliability of plants be optimised. Bottling machines, pneumatic components and electrical actuators are good examples of sectors where Italian mastery stands out.

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