How
to Size an Ultrasonic Tank
1. Determine your
largest part size [L x W x H]
2. Determine the number of parts you wish to clean at one time. [ parts
per-hour, day, week.]
3. Allow 1/2"Space between Parts for good circulation of cleaning
fluid [ one layer deep]
4. Determine the lay out size of the total # of parts to be cleaned at
one time
5. Allow 1/2" space on all sides of parts between parts and side of
tank
6. Allow a minimum of 2" liquid over and 4" under
your parts.
7. Allow 2" freeboard on tank [ distance from top of tank to water
level]
This would be the minimum size tank that you would need. If you
intend to clean many loads per day, you would need about 6" depth
under your parts
Gallon Capacity of an Ultrasonic Tank
To figure gallon capacity, multiply L x W x H [- 2" for
freeboard on height ]and divide by 231.This = gallons. Freeboard is the
distance from the lip of the tank to the surface of the water. 2"
minimum should be allowed in any tank to prevent spillage.
Weight of the Cleaning Solution
To calculate the weight of the cleaning solution [ water] multiply
gallons by 8.4 lbs
[10gal x. 8.4 lbs per gallon = 84
pounds]
Determining the Cleaning Process
General Cleaning: Light industrial cleaning, small instruments,
small parts that are not
particularly dirty, i.e. dental instruments,
are usually cleaned in a table top tank with a rinse in DI
water afterwards.
Ultrasonic Power: 50-70 watts per gallon. at 40-68 kHz frequencyIndustrial Cleaning: Large heavy parts, oil and grease to be
removed, surface to be clean
for painting or plating operations, parts
may have blind holes etc. Clean in ultrasonic tank
followed by a spray
rinse and an ultrasonic rinse.
Ultrasonic Power: 70-100 watts per gallon at 20,40-68 kHz
frequency.
Semiconductor / Medical / Optics / Electronics: Printed
circuit boards, Semiconductor wafers, Body implant able parts, optical,
laser components etc. These must be very clean requiring several stages
of cleaning at increasingly higher frequencies combined with spray
rinses and ultrasonic rinses during the process.
Ultrasonic Power: 100 to 150 watts per gallon at 40-68-170 kHz
frequency.
Determine the amount of Ultrasonic Power
The amount of ultrasonic power should always be calculated in
Watts / Average not Watts / Peak. Watts average is what the entire
system draws when it is working. Watts peak is the power required on
start up and is always higher.
Choosing A Cleaning Chemical
The most common solution is water with a detergent. This will clean
most parts. If you are cleaning an epoxy or other material that is not
affected by water, you must use a solvent solution. there are 3 types of
detergents;
1. Alkaline; for removal of oils, grease and particulates,
where a caustic type detergent will not hurt the part.
2. Neutral PH Detergent; for use with metals that will react to
acidic or alkaline detergents.
3. Acidic Detergents; for removal of rust and scale,
4. Solvents: Solvents are usually used at full strength, be very careful
in using solvents in an ultrasonic tank,
Never use
flammable solvents in an ultrasonic tank. This could create
an explosion
and cause severe damage. Consult with your ultrasonic company before.
using solvents. A specially designed ultrasonic tank enclosed in a
stainless steel hood with a fire protection System is required to use
flammable
solvents directly in an ultrasonic tank.
Heat
Almost all ultrasonic cleaning works better with heat. The
ideal operating temperature of an ultrasonic bath is 80% of the boiling
point of the solution. The best temperature to use in a cleaning
solution depends on several criteria.
1. Can you part take the temperature of the solution? Be careful not
to overheat your part beyond its maximum temperature rating.
2. Can the detergent operate efficiently at this temperature?
Some detergents will break down at elevated temperatures and become inefficient.
Check with the detergent manufacturer for specific information.
3. In a water based solution the best temperature is in the range of
80% of the boiling point of the solution. [ assuming water as the
solution.]
4. Solvents are different and you should consult the manufacture for
specific temperature ranges.5. For an ultrasonic tank to heat up in an hour or less it takes
about 80 watts per gallon of heat dependent on initial water temperature
and evaporation.
Basic Types of Ultrasonic Cleaning Systems
1. A single Tank cleaning system:
A single tank cleaning system is most often used when only a small
number of parts are cleaned. It is important to remember that you should
use an industrial grade ultrasonic cleaning system, not one of the
standard table top types. Most table top systems are very lightly
constructed and have small transducers, with the generator, tank and
heater in the same shell. These systems are used primarily for cleaning
small parts, once or twice a day. They are not designed to provide high throughput or a high end clean part.
Industrial Table Top Tanks always have the generator as a separate
unit, this prevents damage by the heat generated in the ultrasonic tank
and allows more room for larger transducers on the tank bottom.
Single industrial table top tanks can be set up to clean parts as
well as a multiple tank system at far less cost. Of course there is no
free lunch. A single tank system requires a manual cleaning procedure
with full operator attendance. Another restriction is that you are
limited by the size of a table top to smaller loads, especially if you
are using a multiple beaker cleaning system where 3 or 4 beakers are
placed in a holder and filled with cleaning and rinsing solutions. The
parts are manually transferred from one beaker to another.
Single tank systems are ideal for low volume, lab type or prototype
cleaning lines.
2. Industrial Single Tank Cleaning Systems
Large single tank floor mount ultrasonic cleaning tanks can be used
for in line cleaning of parts in plating or industrial cleaning
applications, there is no limit to the size of the tank.
3. Multi Tank Cleaning Systems
A multi tank cleaning system consist of an ultrasonic detergent
tank, spray rinse tank, and an ultrasonic rinse tank, at the minimum. Additional
stations such as multiple, detergent and spray
rinse tanks, ultrasonic
rinse tanks can be added to the basic system for quicker throughput and higher cleanliness levels. With multiple tanks you can process a lot of
parts fast and still maintain a high level of cleanliness. Usually these
systems have many automated features such as auto fill, drain,
filtration, DI water heaters, etc..The exact configuration of the system
should be worked out between you and the manufacturer.
Automation
Automation in a cleaning system eliminates the inconsistency
in process. By automating your cleaning system parts will always be
cleaned in the same manner from lot to lot. Choosing an automation
system is a decision that will be worked out between you and the manufacturer.
Work Fixtures
Work fixtures or baskets are always required to hold parts. Never put
parts directly on the bottom of an ultrasonic tank. In choosing work
fixtures be sure that you have enough separation, between parts for a
good flow of the cleaning and rinsing solutions. Make sure that the
material of the work fixture is compatible with ultrasonics. It is a
good idea to send parts to the cleaning system manufacturer and let them
decide on a work fixture. |
