1. What is ultrasound:
Ultrasound refers to sound waves that are invisible to the human ear. A normal person's hearing can hear 16-20 kHz (KHZ) sound waves, a sound wave below 16 kHz is called an infrasound or a subsonic wave, and a sound wave exceeding 20 kHz is called an ultrasonic wave.
2. Ultrasonic generation:
The two main parameters of ultrasound:
Power density: p = transmission power (W) / emission area (cm2); usually p ≥ 0.3w / cm2.
The ultrasonic wave propagating in the liquid can clean the dirt on the surface of the object. The principle can be explained by the phenomenon of “cavitation”: when the ultrasonic wave propagates in the liquid to a pressure of one atmosphere, the power density is 0.35 w/cm 2 . At this time, the peak of the ultrasonic wave pressure can reach the vacuum or the negative pressure, but in fact no negative pressure exists, so a large force is generated in the liquid, and the liquid molecules are pulled into a cavity and a cavitation nucleus. This cavity is very close to the vacuum, which ruptures when the ultrasonic pressure is reversed to the maximum, and the strong impact due to the rupture strikes the dirt on the surface of the object. This shock wave phenomenon caused by the cracking of numerous small cavitation bubbles is called the "cavitation" phenomenon.
3. The cavitation effect of ultrasound
Ultrasonic cleaning effect and related parameters:
a. Cleaning media:
Ultrasonic cleaning generally involves two cleaning agents: a chemical cleaner and a water-based cleaner. The cleaning medium is a chemical action, and the ultrasonic cleaning is a physical action, and the two functions are combined to thoroughly and thoroughly clean the object.
b. Power density:
The higher the power density of the ultrasonic wave, the stronger the cavitation effect, and the faster the speed, the better the cleaning effect. For precise, high-surface finish objects, prolonged high-power density cleaning can cause "cavitation" corrosion on the surface of the object.
c. Ultrasonic frequency:
The lower the ultrasonic frequency, the easier it is to create cavitation in the liquid and the stronger the effect. When the frequency is high, the ultrasonic direction is strong, which is suitable for fine object cleaning.
d. Generally speaking, the ultrasonic effect is best when the ultrasonic wave is 30oС~40oС. The higher the temperature of the cleaning agent, the more significant the effect.
Generally, when the ultrasonic cleaning is actually applied, the operating temperature of 30oС~60oС is used.
4. Ultrasonic cleaning features:
"Ultrasonic cleaning process technology" refers to the use of ultrasonic cavitation to impact and peel off the dirt on the surface of the object to achieve cleaning purposes. It has the characteristics of high cleaning cleanliness and fast cleaning. Especially for blind holes and various geometric objects, there are unique cleaning effects that cannot be achieved by other cleaning methods.
5. Comparison of ultrasonic cleaning and other cleaning methods:
Cleaning method: % residual residue
Blow cleaning 86
Immersion cleaning 70
Vapor cleaning 65
Brush cleaning 8
Ultrasonic cleaning 0-0.5