In our different articles we focused mainly on the washing phase of the metal components, by analysing different themes linked to the type of detergents and / or solvents used, to the indicators important to evaluate the quality of the washing cycles and the solutions developed by FIRBIMATIC for particular sectors such as the medical one.
But another important stage of the washing cycle of metal and industrial components is the drying phase which has an impact on:
- The quality of the final cleaning result;
- The duration of the metal component washing cycle;
- The costs associated with each washing cycle.
Poor drying, especially when using aqueous detergents, is mainly responsible for altering the surface of the metals since small quantities of contaminant residues remain attached .
Here is the link to read our article on how to protect your washing systems from corrosion!
Similarly in solvent washing systems, partial or incomplete drying favors the surface formation of an adhering film which over time tends to crumble making the component unsuitable for the purpose and negatively impacting the downstream processes.
Perfect drying of metal components surface is a key prerequisite for successful phases such as coating, bonding or welding.
The most used drying methods in metal cleaning machines
The drying method that can fully satisfy the needs of the customer is the one that is able to assure:
- Completely dry components;
- Low energy consumption;
- A recovery of the detergent residues removed from the part;
- High performance
It is therefore important to choose the method that allows the complete drying of the metal parts without altering or damaging them.
Among the drying methods offered by the market we can find: the conventional drying method with light blowing, the forced air drying method with high pressure blower, the drying method by vacuum drying and, finally, the condensation drying method.
CONVENTIONAL DRYING METHOD
The conventional drying method is characterized by its simplicity, energy consumption reduction , mainly in aqueous systems, and by its intensity.
Drying phase takes place by exploiting the intrinsic heat of the components after they have been heated in the previous washing phase: by introducing a large amount of dry and fresh cold air in the chamber the evaporation automatically occurs.
Excess air is then conveyed outside through an exhaust flow.
The conventional drying method is particularly suitable for components with a smooth, rough surface without fine or deep holes and with good thermal conductivity.
FORCED AIR DRYING
The forced air drying method with hot air, makes sure the liquid present on the surface of the components evaporates through a large-scale adjustable air flow.
Usually this method requires a complete drying phase of more than three minutes due to the excessive presence of water.
This happens in particular when the parts are arranged in the washing phase in bulk or when they have a fine finish which increases the treated surface.
VACUUM DRYING DRYING
The drying method is used both in solvent and aqueous cleaning machines since it allows a complete and quick drying also of geometrically challenging metal parts .
The metal parts are inserted in a dryer where the solvent boiling temperature on the parts is lowered by pressure reduction . Residual liquid solvent immediately evaporates.
This method may require excessive energy consumption if the components do not have an adequate mass, so in these specific cases it is more convenient to combine the use of hot air and vacuum drying, or heating the components before the drying phase.
FIRBIMATIC uses vacuum drying in its hermetically sealed solvent degreasing machines, where the entire washing cycle takes place completely under vacuum.
Click on the link and find out more details on the washing cycle typical of FIRBIMATIC hermetically sealed solvent degreasing systems!
Finally, the last method is that of drying by condensation using heat pumps that allow quick, safe drying times and low energy consumption.
In this case, the temperature used to dry the surface of the components is between 20 and 90 degrees depending on the metal parts treated.
The extremely dry unsaturated air is blown onto the components through a closed circuit which allows to quickly eliminate the liquid: the air is therefore cooled, the water condenses and the droplets that form leave the system.
The cooled air is then heated again to the predetermined process temperature and returned to the drying chamber.
The condensation drying method can also be implemented in downstream processes through a separate module or alternatively used to cool the components.
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