There are several variables that affect ultrasonic cleaning performance. Understanding and controlling these variables is key to maintaining process control. Knowing your tank’s control parameters and the variables that affect performance is paramount to maintaining and improving your process.
There are essentially six main variables that affect cleaning performance:
- Power Amplitude (excitation force per unit area)
- Tank Size and Geometry
- Location of parts
Out of these 6 variables the one most likely to bring down your cleaning process is power amplitude. The power amplitude decays as your tanks age. On tanks with variable power output, the cleaning force/area can be adjusted in order to maintain the same level of performance, but up to a limit. The power amplitude is the main variable that decays as a result of aging transducers. As the power degrades, the cleaning force/area drops proportionately. The Sonic Meter is specifically designed to sense and quantify changes in the resultant power amplitude.
Frequency is fixed. Tanks can have multiple transducers with different frequencies. The discrete frequencies can be “swept” from one frequency to another, but frequency is not variable. It is discrete and inherent to the transducer or transducer set.
Chemistry and Temperature
The chemistry and temperature both play key roles in cleaning force performance, and it is crucial that these are controlled and monitored for consistency. Both optimum temperature and chemistry promote efficient cavitation. Refer to your tank manufacturer and process guidelines when selecting temperature settings, degas time and solvent solutions.
Tank Size and Geometry
Tank size and location of transducers to the exterior of the tank play important roles in the pressure distribution of cavitation throughout the tank. In large tanks, sparsely populated transducers can create large volumes of low pressure. The tank’s geometry can also have a significant impact on the distribution of cavitational forces throughout the fluid volume. Filters, hangers, racks, non-symmetric tank volumes, voids and protrusions can cause standing waves to concentrate non-uniformly and at significantly varying amplitudes throughout the volume.
Location of Parts
The location of parts within the tank can play a significant role in the quality of cleaning. Using the Sonic Meter to map the tank’s pressure profile is extremely powerful not only in monitoring performance but also in determining locations and settings for optimal pressure amplitude. With the tank mapped, parts can be placed in the locations of specific pressure output.
Over time the tank’s ultrasonic transducer and the mechanical coupling to the tank degrade. In a high production environment this change can be noticeable in as little as 6 months for a new tank. Although this initial degradation may not be immediately measurable in the product, tracking this decay is critical to understanding the lower threshold of your process before performance degradation takes out your process control.
Carbon Ring Test
The non-quantitative method used in industry for checking the basic functionality of ultrasonic tanks is typically a carbon ring test. The test media is nothing more than a ceramic ring with a carbon coated surface. The ring is placed in the tank for a specified period. At the end of that period, the ring is removed and examined. There is an estimation made as to how much surface area of carbon has been removed. This is simply a qualitative go-no-go type of measurement for confirming basic operation.
How the Sonic Meter works
The power amplitude is quantified by measuring the fluid’s internal pressure. The Sonic Meter is the only meter on the market that can measure the internal cleaning forces. The Sonic Meter’s slender probe can pinpoint areas of optimum output or detect tank degradation after mapping the pressure profile. Employed in the meter’s construction are ultra-rugged state of the art electronics and sensing technology. The output of the meter is based on wide-band pressure sensing technology and high precision analog to digital filtering with constant reference signal monitoring. The piezo sensor is contained in a hermetically sealed and hardened stainless housing. This sensor’s sensitivity has been specifically tuned to work with tank cleaners operating between a few thousand Hertz to 500kHz. Displayed output is from 0-130psi. The bandwidth and sensitivity of our meter was designed to work with the most common cleaners on the market from dental cleaners to large volume industrial tanks.
The Sonic Meter provides two options for taking measurements:
- Real time reading (updates every 50msec), this option gives the instantaneous pressure output of the tank at a given position.
- Averaged reading, sample 1-40 readings at intervals of 10msec to 100sec. Ten samples at 1-sec intervals works for most applications. For both options there are user defined high/low limits. A visual alarm is displayed when a reading is out of range. This alarm will indicate if the reading is above or below the user-specified limits.
Please click Specifications to learn about the details of our high precision cavitation meter.