The method referenced above incorporates ultrasonic cleaning technology—the key word being incorporates. Simply buying an ultrasonic cleaning tank with the mindset that they are all the same and setting it in the corner for the toolmakers to use will get us right back to where we started—solvent, rags and abrasives.

So what is an ultrasonic cleaner? An ultrasonic tank has a radiating diaphragm—usually the bottom of the tank, side of the tank or immersible assembly placed inside the tank. This diaphragm vibrates at an ultrasonic frequency—usually 20,000 to 40,000 cycles per second—which results in positive and negative pressure (or sound) waves being sent through the cleaning solution in the tank.

With the words “ultrasonic cleaning,” one would think it is the sound waves that provide the cleaning action. Actually, the intense and intricate cleaning agitation is due to millions of microscopic imploding bubbles that are created due to the pressure waves resulting from the ultrasonic vibration of the radiating diaphragm (or tank wall).

This process is known as cavitation. The amazing thing is that in a properly powered tank, these agitating bubbles happen everywhere throughout the bath and are non-directional. So by placing tools in the bath, all surfaces are scrubbed no matter their relation to the ultrasonic diaphragm—provided that the cleaning solution is in contact with the part. Additionally (and this is important), the pressure waves actually travel through the steel, and can therefore provide agitation in internal cavities—such as water lines.

As stated earlier, ultrasonic cleaning molds and components requires the correct process. You can have the best ultrasonic cleaning system the world offers, but use it with the wrong detergent and the results will be disappointing at best. When it comes to mold cleaning applications, the proper cleaning solution—used at the proper temperature—is as important as the equipment itself.

A successful ultrasonic cleaning process consists of three key elements:

Ultrasonic cleaning equipment properly sized and powered for the application.

Detergent suitable for the contaminant to be removed, the mold material being cleaned and performs well in an ultrasonic tank.

Correct operating temperature (180°F is often desired for mold cleaning applications).
If one of the above is out of sync, the process may not perform as desired and hand cleaning will again be the norm.

Timesavings
How much time can the correct ultrasonic cleaning process save? On average, take the time involved to PM a tool and cut it in half. Imagine disassembling a mold, loading all the cavity blocks, cores and ejector pins into the ultrasonic cleaning tank—come back in 20 minutes (after doing something productive), do a quick rinse and blow the residual moisture off with compressed air. How long would this have taken if cleaning by hand? Most likely hours, if not days … not to mention, the tools are cleaner than any human could have ever gotten them.

Complex, higher cavitation tools will save even more time. Consider the majority of time involved in a PM is cleaning—let’s say 70 percent. An ultrasonic cleaning process will not eliminate all of this time, there will be time loading the components into the basket, loading the basket in the tank, etc. But even if we were only 70 percent efficient here, the end result would be just shy of a 50-percent savings (70% of 70% = 49%).

A variety of ultrasonic tanks and systems are available in the marketplace—ranging from small tabletop models to large, completely automated multi-stage systems. Purchasing a tank or system is an important decision, and there are many factors to consider. Some of the more important things to consider are:

1) Equipment Design and Quality

2) Tank Size: Size and Quantity of Tooling to Be Cleaned

3) Cleaning Solutions and Rust Inhibitors

4) System Process Layout

5) Justification/Budget