The Definition of Precision Cleaning
February 27, 2019
The term “Precision Cleaning” describes processes that require a clearly defined maximum allowable level of particle, film or impurity contamination on the surfaces to be cleaned. Usually precision cleaning is performed with reference to a standard, such as a particle count or film contamination. Ordinary cleaning means that a substantial amount of the contaminants on the surface of the parts to be cleaned is removed but doesn’t specify how much may remain. Precision cleaning cleans until the targets for the remaining contamination are reached.
Why Precision Cleaning is Important
Industries that include aerospace, medical, pharmaceutical and electronics use precision cleaning standards in their manufacturing processes. Coating metal parts, plating components, cleaning tools prior to disinfection and cleaning silicon prior to diffusion all require high standards of cleanliness. If a part to be coated against corrosion or plated for appearance is not clean enough, the coating or plating may peel off. If a medical tool still has dirt in cracks or crevices, the disinfectant may not be effective. If a silicon wafer has particles adhering to it during a diffusion process, the diffusion may be uneven and the integrated circuit being manufactured may not work.
Precision cleaning means that an inspection of the part that has been cleaned can verify that the remaining level of contamination is within the allowed tolerances. Parts may be inspected microscopically and surfaces scanned to see if contaminating films or particles are present. The precision cleaning process pre-supposes that cleaning is highly controllable, even over the entire surface of the part, and complete in removing all contamination. The remaining number of particles and films must be insignificantly small.
How Precision Cleaning is Carried Out
There are many cleaning methods that can be used for precision cleaning but most have severe drawbacks. Cleaning with chemicals and solvents is widely used but the chemicals are expensive and special facilities are required for storage and handling because many of the chemicals are toxic, corrosive and health hazards. Disposal of the waste chemicals is becoming more difficult and expensive as environmental standards are tightened.
Manual cleaning with brushes, water jets and rinses is an option but is very time-consuming and labor-intensive. If the brushes are too stiff or the handling too rough, the surface of the object to be cleaned may be scratched or the object damaged. Other kinds of mechanical cleaning such as blasting with water or abrasives have similar problems. In addition, none of the mechanical cleaning solutions adequately clean inside holes and crevices where contaminants often collect.
Cleaning with ultrasonic cleaners addresses all these issues and offers a complete cleaning solution for precision cleaning needs. The cleaning method can be controlled precisely and different frequencies can handle different contamination and types of parts. Cleaning is rapid and complete, with only trace contamination left anywhere on the cleaned surfaces.
How Ultrasonic Cleaning Works
Industrial ultrasonic cleaners produce high-frequency sound waves at specified power levels in water or in a cleaning solution containing a mild detergent. The parts to be cleaned are submerged and the ultrasonic waves dislodge dirt and contamination from surfaces. For heavy contaminants on robust parts, lower frequencies provide intensive cleaning action while delicate parts can be cleaned gently at higher frequencies.
The ultrasonic waves penetrate wherever there is cleaning solution and deliver an even, complete cleaning action. Ultrasonic cleaning is especially effective for parts with crevices or complex shapes because even dead end holes are cleaned completely.
Kaijo offers a complete line of ultrasonic cleaning systems and components for precision cleaning applications. The company is a leading ultrasonic equipment manufacturer and can provide expert advice on ultrasonic cleaners to be used in specific applications that require precision cleaning.