Accurate dosing for small quantities

Source: StockAdobe.com

A new project of Visco Tec Asia at the end of 2019 was the application of a fragrance on top of feminine hygiene products. Before implementation, dosing tests were carried out for the customer. A “preeflow eco-spray” dispenser was employed for this. The aim of the tests was to check the dosing accuracy and repeatability of the dispenser for the small quantities. A particular challenge was to achieve precise results for various different products. Various quantities were to be tested for several products in the customer portfolio: 1.5, 1.8 and 2.5 mg per part – to allow flexible automated production. The in-depth dosing tests consistently demonstrated the accuracy and consistency of the small volumes required for the process. With the tested dispenser, the company is able to spray with less than 1 % deviation from the nominal value.

Test with customer product

The parts to be dispensed run in a roll form under the dispenser. The speed of the roll is over 1,500 parts per minute. At the final stage, the customer wants to apply a small amount of <1.6 mg of fragrance to each product. The material is gravity fed from a container suspended about 2.5 meters above the floor. The method used up to now could not precisely dose such a small volume in each part and had poor repeatability. In conclusion, the customer decided to purchase the newly tested dispenser to integrate it into the existing line.

Required accuracy and consistency achieved

The dosing tests proved that the customer required volume accuracy and consistency for product model could be achieved. In addition, the change from a pressure tank or gear pump tank, which was previously used, to product being fed by a gravity tank was convincing. An analogue signal with PLC now also makes it possible to link the speed of the production line with the flow rate of the dispenser. This means that the amount of liquid to be sprayed can be dynamically adjusted according to the speed of the roll.

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