MICRODOSING

BAGGED PRODUCTS <25 KG

After the macro-ingredient are dosed, it is necessary to dose all minor ingredients, which can be numerous. 
In order to automate this type of dosing process, it is important to consider some important issues:

DOSING ACCURACY. It often refers to ‘sensitive’ products, i.e. products which are essential to formulate the recipe but can be harmful to the consumer’s health in case of over- and underdosage. 
The required accuracy is generally in the order of +/- 1 <2%; given that the amounts being dosed are usually small, this value    corresponds to a few grams. For instance, it is fairly simple to dose +/- 1% 10 kilograms (+/- 100 grams), however, it is far more    complicated to dose 1 kilogram with the same accuracy (+/- 10 grams). 
Further difficulties arise when it is necessary to dose the same ingredient in quantities, which are sometimes really different, according the recipe being executed. 
A great deal of attention must be devoted not only to the configuration of the dosing tool, but also to that of the weighing hopper. 
EXECUTION TIME OF THE WHOLE RECIPE. All ‘Macro’, ‘Micro’ and, if appropriate, ‘Nano’ ingredients generally converge into a mixing device which makes the blend homogeneous enough to be processed in the actual production.
Production plants are becoming progressively efficient every day; therefore, dosing times and cycles are becoming increasingly    shorter.     
CRISTIANO TORRE Company has solved these problems effectively and is able to offer a wide range of technical solutions that will perfectly adapt to the characteristics of the ingredients and the amounts to be dosed. 

SCHEMATIC EXAMPLE OF A MICRODOSING SYSTEM

1. METAL SUPPORT STRUCTURE

Fully bolted steel structure manufactured with cold formed welded structural hollow sections UNI 10219. The metal structure has been conceived to form a work platform for operators. Hot dip galvanized surface finish EN ISO 1461. Supply is always accompanied by a structural calculation report drawn up according to Eurocode 3 standards. For economic reasons, it is possible to provide technical drawings of each single component in addition to the calculation report, so that components can be produced by local suppliers. 
The work platform is completed by a security gate to enable the introduction of pallets with the bagged ingredients

 

2. BAG EMPTYING HOPPER

3. SUCTION INLET

It avoids the inevitable pollution which is produced when bags containing powdery ingredients are emptied. The hopper is equipped with a suction inlet connected to a centralized system or a self-contained suction filter. In the case of a centralized system, every bag emptier is equipped with a butterfly suction shut-off valve which opens together with the cover lid. 

4. BUFFER TANK

The function of this container is to feed the dosing, batch by batch, without interruptions. The ideal capacity of the tank is the amount needed to form all batches during a shift, in order to minimize any manual interventions of operators. This option is not always viable due to the available height and it is therefore necessary to opt for a maximum capacity compatible with the available space. The tank, its bag emptiers and the dosing tool can be mounted on load cells, which enable occasional software verification testing on the dosage performed. As it is necessary to dose poorly-flowing products, the tank is equipped with flat bottoms and a motorized crown extractor. 

6. EXHAUST SHUT-OFF BUTTERFLY VALVE

This valve closes the discharge of the dosing screw when reaching the required weight during the finishing phase. The valve prevents an accidental fall of the product (due to vibrations or other causes), which would affect the weighing accuracy. Interapp construction.  Standardized sizes ISO PN6. Cast iron body, sealing gasket made of white FDA approved EPDM rubber, stainless steel disc. Double-acting electro-pneumatic actuator.

7. WEIGHING HOPPER

Stainless steel construction with polished internal surface to facilitate the flow of powdery products during the unloading stage. Three OIML approved stainless steel load cells. Flexible insulation during loading and unloading guaranteed by a double coated flat sheet with 0.4 mm thickness. Automatic monitoring of weighing efficiency by means of test weights.

8. ACCESS HATCH

Wide internal access opening for inspection and cleaning. Tool-free opening and closing. Perfect internal flatness without any product retention points. Watertight. Magnetically coded limit switch signals when the lid is in place.

9. DOUBLE BUTTERFLY VALVE BETWEEN THE WEIGHING AND THE SERVICE HOPPERS

FDA approved, hermetically sealed valves for food uses, for unloading of the weighed product and perfect insulation of the weighing process from interferences caused by the pneumatic conveying.

10. SERVICE HOPPER

It is installed below the weighing hopper in order to receive the content which falls directly from the latter. By means of a rotary valve, it feeds the pneumatic circuit which transfers the whole batch to the destination point. The function of the equipment, whose useful capacity must be equal to that of the weighing equipment, is to separate the weighing and service functions so as to accelerate the recipe execution time. During the dosing process the system will convey the ingredients and be available to receive the subsequent batch which is ready in the upper hopper. In practice, once the system is fully operational, transfer time will be practically eliminated, as this process and the dosing process will be performed simultaneously. Moreover, the dosing process will not be affected by any leaks from the rotary valve thanks to the double butterfly valve located between the two hoppers. 

11. BATCH LOADING GROUP ON PNEUMATIC CIRCUIT FOR TRANSFER TO DESTINATION POINT

The loading and dosing of the product through the air stream of the pneumatic transport is performed by means of a rotary valve processed mechanically with ultra-fine tolerance. Nickel plated ductile iron body. Stainless steel rotor with bevel blades. Control by means of Sew Eurodrive gear motor. Entirely stainless steel piping injector. 

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