A vacuum filler is a machine used for filling pasty products."Verfahren und Vakuumfüller zum Abfüllen einer pastösen Masse" Retrieved August 8, 2012 The pasty products are moved with the aid of a vane cell feed system under a vacuum.
Objective
Levelling the weight of pre-packaged goods in the food sector, especially those involving viscous or pasty products, places extremely high demands on the reproducible accuracy of filling and portioning systems. In order to achieve this, technical and technological issues as well as product-specific characteristics have to be taken into account. In addition to the aforementioned factors, the requirements on the quality of an end product is a key issue when selecting or implementing a technical process solution. The development of vacuum filling machines has made it possible to fulfill both the technical and the quality-related requirements.
In the food sector, moving or transporting fluids is achieved with the aid of pump technology. Colloquially, this is known as filling or portioning. Various different types of pumps are used, depending on the type of filling products to be moved. Vacuum fillers with vane cell feed systems and vacuum feeding are commonly used for viscous products. The products are transported with the aid of a hopper with a feeding device, a vane cell feed system under a vacuum and appropriate volume expulsion in the pump housing. This is basically a volumetric feed principle, which means that a certain weight is defined via a volume. In addition to the vane cell feed systems,„Flügelzellenpumpe“ , Retrieved August 8, 2012 also known as rotary vane pumps, there are also screw feed systems with feed augers, toothed wheel feed systems and evacuated lifting cylinders. With all these systems, transportation is achieved via volume expulsion under a vacuum. Vacuum fillers are traditionally used in the meat processing industry as well as in other food sectors. They can also be found in some non-food sectors. Generally speaking, vacuum fillers can be used for filling pasty and compressible products.
History The first vacuum filler was developed in the early 1960s. The technology has been refined since then.
Requirements/effects The pumpability of viscous or pasty products has a key effect on the reliable function of a vacuum filler. Filling products in the food sector can be characterised with the aid of various different properties related to their pumpability (“fillability”). They are either physical characteristics that can be measured directly or they are sensory attributes.
Gas content/density The gas content is also called the “air content”. The air content of a fluid is the percentage share of air that enters the fluid during grinding/mixing processes. This can be measured using special apparatus and has a direct relationship to the density of a fluid. Compressibility The compressibility depends on the air content of a fluid. A high level of compressibility is linked to a high gas content in the fluid. Viscosity Viscosity is a measure of the consistency of a fluid. The higher the viscosity, the higher the consistency of the fluid is (it is less fluid); the lower the viscosity, the lower the consistency of it is (more fluid). Highly-viscous filling products in the food processing industry are primarily found in the meat, bakery products and convenience food sectors. These highly-viscous substances are commonly referred to as being “pasty”. The fluidity is the basic requirement for the pumpability of a fluid. The viscosity can also be determined using suitable rheological measuring apparatus. In the food sector, the viscosity is primarily dependent on the fluid content of the filling product. Temperature The temperature is a key factor for pumpability as it has a direct effect on the viscosity as well as on the product quality. Texture, fibrousness, dimensions of the inserts Specific sensory characteristics of a filling product have a significant effect on the assessment of the fillability and compliance with the precise weight. Weight accuracy With the help of modern filling technology in the food sector, accurate portioning with a difference of up to 1% in relation to the required volume of a portion can be achieved.
Mode of operation
The key element of a vacuum filler is the vacuum filling principle. The filling product is fed into the feed system mechanically via a hopper with actively driven feeding auger, as well as via vertical “vacuum suction”. Pre-evacuated cells of a vane cell feed system move underneath the hopper. The pressure difference relative to the ambient pressure (underpressure) caused by the evacuation ensures that the cells are filled with product. The feed system moves continuously, thus generating a continuous filling flow. The product is portioned by means of cyclic movements of the feed system. Each cell of the feed system has a particular volume. The portion is defined by the rotation distance of the rotor. The portioning volume is therefore set in the control system by multiplying the rotor's rotation distance by the number of the feed system cells within it. The portion weight must be determined in the control system via the portion volume parameter with the aid of scales.
Structure and technical requirements Vacuum fillers are primarily used in the food trade and in the food industry. Special criteria apply to the design of machines in the food sector due to specific hygiene standards and hygiene regulations. This includes, for example, ensuring that they are easy to dismantle, have level surfaces and seals that can be rinsed from the rear, no dead spaces, ergonomic shapes, a small range of parts and detectable materials/materials suitable for food use. Relatively aggressive ambient conditions, such as reactive detergents, reactive or abrasive filling media, intensive high-pressure cleaning and extreme ambient temperatures, are also faced.
Vacuum fillers are therefore made of a high proportion of stainless steel with a very robust design. Moving parts can be easily dismantled and can be cleaned individually. In addition to the mechanical or design-related issues, complex electronic components in a vacuum filler also have to be taken into account.
Vane cell feed system with hopper
The vane cell feed system mainly consists of a rigid pump housing with attached side plate that is fixed to the pivoting hopper, and a removable rotor with pump vanes and cam. Depending on the machine size there are various different sizes of vane cell feed systems with parts with appropriate dimensions. The hopper can be swivelled to clean and dismantle surfaces and parts that come into contact with filling product. The driven rotor with an appropriate number of slots is located in the pump housing, in which pump vanes form cells with defined volumes when the machine is closed, supported by the cam. Induced by the rotor movement when the machine is started, the cells move in the direction of the vane cell feed system outlet and therefore ensure that a defined product flow is achieved. The weight accuracy of a feed system is partially dependent upon the production precision of the parts and their degree of wear.
Vacuum system The cells are filled by evacuating the vane cell feed system. By applying a vacuum via a vacuum pump, the filling products are gently drawn out of the hopper into the feed system as soon as an evacuated cell moves underneath the hopper. The vacuum pump is protected by an integrated water separator. The level of vacuum can be set according to the filling product. In addition to the feed effect, the filling product is simultaneously evacuated to a certain extent (approx. 2–4 %). This means that the air content of the filling product decreases and the filling product becomes denser.
Feeding
The term feeding in the context of vacuum fillers refers to actively moving the filling media in the direction of the lower part of the hopper to support the vacuum approach within the hopper. Feeding is achieved by using moveable feeding augers with scrapers/rigid counter arms. The feeding auger is driven in synchronisation with the rotation of the rotors. Due to the special geometry of both augers and the parallel rotation movement, the filling product is moved vertically in the direction of the vane cell feed system. The required feed intensity depends on the viscosity of the media to be filled. Less active feed is needed with low-viscosity media than with high-viscosity product. There are therefore a variety of combinations or versions of the parts involved in the feeding process.
Machine base The machine base acts as the stand for a vacuum filler. For hygiene reasons, bases are made completely of stainless steel. The compact machine base is designed to ensure that it can be moved easily using lifting equipment.
Lifting device Lifting devices allow the hopper to be loaded using standard trolleys. They can either be fixed onto the vacuum filler or a mast type lifting device can be positioned separately next to the vacuum filler. Lifting devices can be driven hydraulically or electrically.
Control and drive systems
A computer-aided control system is required for operating the various functions associated with a vacuum filler. Usually, several drives are integrated into the vacuum fillers for the various different applications. With the most modern generations of vacuum fillers, the drives are implemented by means of servo motors and appropriate bus systems.
Sealing devices To produce individual portions from homogeneous product via a feed system, a “sealing device” is always required at the feed system outlet. This device separates portions and is controlled in synchronisation with the portion output. These devices could be linking devices for sausages, clippers for portionable sausages, dosing valves for tubs and cans, cutting devices for dough as well as forming equipment for dumplings.
Other feed system principles Generally speaking, vacuum fillers can be equipped with various different feed systems. However, in principle, the basic machine structure, with a hopper, vacuum system, feeding device, machine base, lifting device, control system and sealing device, is very similar. Depending on the application, each type of feed system has advantages and disadvantages.
Screw feed system with feed augers With a screw feed system, two counter-rotating screws form cells within a housing; they are moved in the direction of the pump when the screws are rotated. The filling product is again moved into the screw feed system with the aid of a vacuum and mechanical feeding devices. Toothed wheel feed system An outer toothed ring is driven, rotating an inner toothed wheel with it. The toothed wheels form cell segments as they move against each other. The cell content is transported through the toothing and it is then voided and ejected in the outlet area. Feeding via lifting cylinders Feeding via alternately moving lifting cylinders is the simplest feed system principle. The volume is defined by the geometry of the cylinders, and the portion size is determined by the number of strokes. Hopper vacuum systems The additional creation of a hopper vacuum is a variation of the vacuum filler concept. The vacuum system is enhanced with an additional vacuum pump, specially designed for the hopper. The hopper is closed and is connected to an upstream reservoir. The vacuum present in the hopper allows filling product to be drawn into the filling machine from the reservoir. The filling product is also intensively evacuated.
Range of applications Food Meat products Cooked, dry and boiled sausage (sausage meat) Dry and cooked cured products
Dairy products Butter Cream cheese and cream cheese-based products Curd Cheese spread products Yoghurt
Fish products Fish masses Caviar
Vegetable products Potato products
Bakery products Fruit bread