Precision drying is an esoteric industrial process. Commonly found in the optical and metal-plating industries, precision drying is often used on in metal plating lines, on lenses and copier rolls.

Precision drying typically (and logically) follows an aggressive aqueous cleaning process. Aqueous bulk cleaning is used to removing plating chemicals, polishing agents and fingerprints. The drying process is used to remove the aqueous cleaners. The objective is to produce a perfectly clean finished surface, free of any spots or defects which might mar the surface.

Since the aqueous cleaners always have detergents, saponifiers or surfactants to boost the effectiveness of the cleaning process, simply using heat to boil away the water will leave the non-volatile additives on the surface of the part. Air knives and tumbling may also be used to dry components, but many fragile components can take neither the abuse or the heat of those drying mechanisms.

As the photo shows, one of the key problems is "water entrapment." Stampings, motor windings, filters, castings and machined parts often have irregular shapes, blind vias or tiny openings. When water gets into these tight spaces it will be very difficult to get the water out of them. This is because of (a) the surface tension of water and (b) water's high boiling point. In effect, the engineer is battling the inherent chemical characteristics of water. This is hard work. It's much easier simply to replace the water with Vertrel^®, which has the desired characteristics, and get the desired result without the water.

It's easy to clean and dry large components during a metal plating process. But when components are small, or have complex shapes in which the aqueous cleaners become entrapped, or are too fragile for mechanical drying, then aqueous cleaning starts to cause more problems than it solves. In this example, Vertrel^® will remove the water on these eyelets, cleaning them quickly, without spotting, and without a lot of wasted time or electricity.

Precision drying with Vertrel^® simplifies all of these issues for the following reasons:

• The Vertrel^® products are much, much heavier than water, with a typical density or specific gravity of 1.3 or so. Since water and Vertrel^® will not mix, the water floats on top of the solvent, just as oil floats on top of water, making removal easy.
• The Vertrel^® cleaners have a surface tension which is much lower than water -- they are "wetter" than water, to paraphrase an old TV commercial. This means Vertrel^® cleaners will easily go into and come out from tight spaces, displacing the water from those dark crevices. Solvent entrapment is never a problem with Vertrel^®.
• Lastly, the Vertrel^® cleaners boil at very low temperatures, so with the addition of a tiny bit of heat or a short wait, the Vertrel^® will boil away. Getting Vertrel^® off the parts is never a problem.

How does precision drying work with Vertrel^®? It's easy. Usually the only equipment required is a modified vapor degreaser. The most important modification is to add a beefed-up water separator, because obviously in the drying application the solvent sees much more water than in more traditional cleaning applications.

An important benefit is that the Vertrel^® fluids contain no chlorine, so they cannot "turn acid" like older solvents did. The older drying fluids required stabilizers to keep them from hydrolosizing the chlorine and turning into hydrochloric acid. This cannot happen with Vertrel^®.

Operationally, the process is a simple immersion of the parts in the liquid solvent (not the vapors) for a few moments. Often the parts are rotated in a basket or tumbled gently. The heavy solvent goes into all the tight spaces and floats the water out of those chambers. The water floats to the top of the degreaser where it is removed by the water separator. The parts are slowly removed from the machine and they come out clean, dry and spot-free.

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The Vertrel^® solvents are used by several manufacturers under non-disclosure agreements, so no case studies are available at this time.

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