Dosing system for the passivation of aluminium parts
DRIZZLING Drizzling is a dosing system developed by ALIT for the passivation of aluminum parts. Similarly to other materials, aluminum surfaces must be treated to be durable over time, as they are naturally subject to oxidation and corrosion. In the specific case of aluminum, various surface treatment processes can fulfil this purpose. One of the most significant and widespread is certainly coating, which is the last (but not least) step of a chemical process that includes several intermediate stages in which parts are degreased, deoxidized, and passivated. This is where ALIT TECHNOLOGIES’ Drizzling dosing system can make a difference. Combined with chrome-free chemicals, such as ALFICOAT 748/3, developed by Alufinish GmbH with nanotechnology components, it guarantees excellent passivation results in terms of both corrosion resistance and paint adhesion.
HOW IT WORKS Drizzling consists of a dosing panel for automatically managing the demineralized water coming from a feed tank and the amount of passivating chemical product, in order to apply an optimally concentrated solution on the material to be treated. The use of special atomizing nozzles and compressed air enables it to produce and evenly distribute a light mist of chrome-free solution.
ADVANTAGES • no need for a recirculating passivation tank: thanks to the low volume of solution sprayed onto the workpieces, a tank is no longer required to collect the solution for continuous recovery and re-spraying; • ever-clean solution: thanks to the reduced volumes of atomized solution, the Drizzling system allows using an ever-fresh, “disposable” solution; • no disposal of passivating solutions due to their ageing; • ever-fresh, contaminant-free solution; • possibility of converting chromate conversion coating lines to chrome-free lines easily and with guaranteed success; • minimum space requirements, as the demineralized water feeding tank can be installed outside the line, if a process tank cannot be used. Moreover, the system only features one spraying bar with a minimum footprint of about 30 cm in length, which can be easily mounted within an existing tunnel.
KEY COMPONENTS DEMINERALIZED WATER SUPPLY
DISTRIBUTION SYSTEM
• Demineralized water tank
• Flow adjustment and control of the water-product
• Demineralized water level control in the tank
solution for each sector of the spraying bar
DOSING SYSTEM WITH PLC
SPRAYING BAR
• Flow and conductivity control of incoming
• For tunnel heights of 2 to 8 meters • Electronic flow control of the water-product
demineralized water • Conductivity control of the mixed solution
solution for each nozzle (OPTIONAL)
(indirect concentration measurement) • Product level control in the drum
PLC
DEMINERALIZED WATER FLOW
CONDUCTIVITY CONTROL OF THE INCOMING DEMINERALIZED WATER
FLOW ADJUSTMENT AND CONTROL OF THE WATER-PRODUCT SOLUTION
CONDUCTIVITY CONTROL OF THE MIXED SOLUTION
ALARMS • minimum level alarm in the demineralized water tank • alarm in case the conductivity of the incoming demineralized water is too high • alarm in case the incoming demineralized water flow is too low • alarm in case the conductivity of the water-product solution lies outside the optimal range • minimum level alarm in the drum containing the product to be dosed • alarm in case the outlet flow is too low for each nozzle (OPTIONAL), if a nozzle is clogged
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Information is provided based on our best knowledge and awareness at the time of printing and it reflects our experience in our laboratory and in practice. This information should only be considered as a recommendation to be adapted to any specific needs. Since the use of our products and systems is not subject to our influence, we cannot offer any type of guarantee or insurance.
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