Ultrasonic Cleaning of Sensitive Metals

Ultrasonic cleaning can be applied to a wide range of metals such as aluminum, stainless steel, and titanium to name a few. But what happens when those surfaces are highly sensitive and require specialized care?

Because aluminum is such a soft metal, it is susceptible to the cavitation implosions that ultrasound cleaning produces. The cavitation bubbles can actually scar and slightly etch away the top surface, leaving what looks like star bursts. Couple this with a polished chrome finish, and the scarring looks even more pronounced in comparison.

Forgiato wheels found on Ferraris, Lamborghinis, and other luxury speed cars are often cleaned via ultrasonics because of their sensitivity.

To protect this very delicate finish, a few alterations to the general ultrasonic cleaning process must be implemented:

1. Reduce the temperature of the ultrasonic bath to no more than 130°F;
2. Use a reduced pH ultrasonic soap with aluminum buffers;
3. Don’t leave the parts in the bath for as long as you normally would when cleaning other metallic items; and;
4. Adjust your ultrasonic washer to operate at a higher frequency. Washing the item while alternating between a standard frequency (40 kHz) and a higher frequency (68 kHz – 170 kHz) will give you the best of both worlds — thorough, yet gentle, cleaning.

These modifications will help clean your parts without inflicting visible damage.

Case in point… Forgiato wheels found on Ferraris, Lamborghinis, and other luxury speed cars are often cleaned via ultrasonics because of their sensitivity. In order to get the most efficient cleaning possible without damage to the pristine surface; a mix of 40 kHz and 170 kHz is commonly used. This coupled with a tightly controlled bath temperature, and just the right length of time, produces a clean custom rim. Finished with a quick dip in a hot reverse osmosis bath and you are ready on race day!