Ultrasonic Case Cleaning — What’s the Optimal Dwell Time?
If you’ve read our feature story on Ultrasonic Cleaning by Jason Baney, you’ve seen the remarkable results that can be achieved with this method. Ultrasonic cleaning has many advantages over traditional tumbling methods of case cleaning. There is no dust or media residue to remove from the brass, and when done right, the cases come out clean and shiney, inside and out, even the primer pockets.
In its Benchtalk Archives, Brownell’s has an excellent article discussing Ultrasonic Case Cleaning. Brownell’s staff compares results, with measured dwell times from 5 to 75 minutes, using both Mpro-7 and HCS 200 cleaning solutions. Tests are performed with once-fired and 5X-fired Tactical 20 (Tac20) cases, as well as once-fired .260 Rem Cases. The article also compares the results from ultrasonic cleaning vs. tumbling in walnut media. Below are Brownell’s results for Tac20 cases with the HCS 200 (non-acidic solution). Go to Brownell’s article for MPro7 results and Rem 260 results.
|HCS 200 Cleaning Solution Test
Procedure — Solution was de-gassed for 15 minutes, then 63 Tac20 cases were placed in a single layer, in stainless steel mesh basket. The temperature of the starting solution was 102° F. When the cases were removed the temperature was 110° F.
Once-Fired Tactical Twenty Cases (HCS 200) — Observations
Five-Times Fired Tac20 Cases — Observations
How Does Ultrasonic Cleaning Work?
The Brownell’s article explains: “Ultrasonic cleaning uses high-frequency sound waves (generally between 20-80 kHz) to remove a variety of contaminants from objects immersed in a liquid. The result of these high-frequency sound waves is a process called cavitation. These high frequency bursts of ultrasonic energy produce a three-dimensional wave of alternating positive and negative pressure areas as the sound wave passes through the solution. During negative pressure, microscopic cavitation bubbles form and will continue to grown until they reach resonant size. As the positive sound wave passes, the pressure rises rapidly and implodes these tiny bubbles. Before these minuscule bubbles implode they store a tremendous amount of energy. These bubbles can be as hot as 10,000 degrees and have as much as 50,000 lbs per square inch of pressure. This sounds alarming, but you have to remember that these bubbles are microscopic in nature and pose no harm to anything, unless you are a carbon /powder residue deposit on a cartridge case!
When this cavitation bubble implodes near your brass case, it transforms the bubble into a jet about 1/10th of its size. This jet of energy can travel as fast as 400 km/hour. At 43 kHz, as is the frequency for our L & R HCS 200 ultrasonic cleaner, this is happening 43,000 times per second. This micro-burst of extreme energy is responsible for removing contaminants from the surface of your cartridge brass. Ultrasonic cleaning can reach into crevices and inaccessible areas and remove surface debris that can’t be cleaned by any other process.”
Photos and quotes © 2007-2010, Brownells®, Inc. All Rights Reserved, Used with Permission.
- UltraSonic Update — Brownell's Tests Cleaning Solutions
- Ultrasonic Case Cleaning–Tech Tips
- Two Tips for Better Ultrasonic Cleaning
- Ultrasonic Case Cleaning — How to Get Better Results
- TECH TIP: Citranox Solution for Ultrasonic Case Cleaning