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Ultrasonic cleaner


#1

Hi all, I recently purchased and ultrasonic cleaner. Even though I am
mostly pleased with it, there is a problem which has baffled me.
After taking out highly polished silver items. I find very fine
scratches on the surface. I have to replosh and try again. Usually I
leave work in for about ten minutes in warm water. Does anyone have
any ideas why this should happen and what I can do about it. Richard


#2

I hope you’re not just placing your piece on the bottom of the
ultrasonicthat will scrtach the piece and ultimately damge your
ultrasonic The pieces need to be suspended in the soltitioj, via a
rack of some sort

Wayne


#3
    Hi all, I recently purchased and ultrasonic cleaner. Even
though I am mostly pleased with it, there is a problem which has
baffled me. After taking out highly polished silver items. I find
very fine scratches on the surface. I have to replosh and try
again. Usually I leave work in for about ten minutes in warm water.
Does anyone have any ideas why this should happen and what I can do
about it. Richard 

Richard, I find that I can use a tweezers to hold the item in the
ultrasonic for 20 seconds to get it clean after buffing. If the
liquid in the ultrasonic cleaner has been used alot it is my theory
that little particles of buffing compound or whatever are thrown up
agaist the item being cleaned and mar the surface so unless I have
pristine liquid in the cleaner I don’t leave the items in very long. Annette


#4

When using the ultrasonic cleaner, it is important to keep the pieces
from rubbing up against each other, as the vibration will cause them
to scratch each other andthe pieces should never touch the sides or
bottom of the tank.Also, silver has a tendency to be etched by the
ultrasonic waves, so polished silver shouldn’t be left in one
position in the ultrasonic for a long period of time. I would be
surprised if this was happening in just ten minutes, though. If it is
the etching effect, the surface will have a frosty white star-like
pattern. I don’t think your problem is from the etching effect, but
just thought you might like to know in case you ever encounter this
problem. When I worked in a production shop, I had one project that
involved polishing hundreds of pieces which had a flat surface that
had to be perfect. I made a special rack for the pieces out of
plastic coated wire so they would not touch each other. I also soaked
the pieces for a while in the hot ultrasonic solution before turning
on the ultrasonic function. One other thing to consider is that
drying the piece with by rubbing it with paper towel will put fine
scratches on the piece. Hope this helps so that you can avoid tedious
repolishing.

Natasha Wozniak


#5
    Hi all, I recently purchased and ultrasonic cleaner. Even
though I am mostly pleased with it, there is a problem which has
baffled me. After taking out highly polished silver items. I find
very fine scratches on the surface. I have to replosh and try
again. Usually I leave work in for about ten minutes in warm water.
Does anyone have any ideas why this should happen and what I can do
about it. Richard 

Richard, If the lines are not straight then it could be the sonic
etching the surface. This happens if the item is left in for a long
time.

Even on the most aggressive sonics it would take more than an hour
at high temperatures. Different cleaning solutions can slow this
down or speed it up. If the solution is cold you could run it for
6-8 hours before this happens.

Several years ago while I worked at Rio a company named Brassler who
makes burs had them make anodized aluminum bur blocks mainly for the
Dental industry. I had to test them in ultrasonics to determine how
long it takes to start etching the surface at different temperatures
and different solutions and with different makes of sonics.

All the brands we tested will etch through the anodizing at elevated
temperatures.

Some other possibilities aRe:

Don’t place anything on the bottom of the tank. Suspend everything
above it.

Don’t place several items in a jar, beaker, tray together where they
can vibrate against each other.

Your solution has too much ammonia in it. High concentrations of
ammonia in the sonic tank will turn to acid when the sonic is
running. If you are using an ammoniated solution try one without the
ammonia.

Maybe the item had the scratches on it to begin with an were hidden
by the polishing compound.

For more on the proper way to use an ultrasonic go to our web site
at www.mpgrepair.com and follow the link ‘tech notes’ which is about
half way down the page.

If I can be of any further help email or call.

Ken Kotoski
MPG Repair
www.mpgrepair.com
1-877-262-2185


#6
  Does anyone have any ideas why this should happen and what I can
do about it. 

Cast silver, especially, will do this, especially with a more
powerful cleaner, and clean solution. It will do it less after youve
used the cleaner all day and the solution is now full of polishing
compound, since all those particles of compound are then each
absorbing some energy… What happens is that ultrasonic energy is
concentrated at defects in the surface. Usually this is just dirt,
but silver is soft enough that when that occurs at surface porosity
or pits, it can start to actually attack the metal. The classic
test of whether an ultrasonic is working right is to suspect a piece
of aluminum foil therein for a minute or two. when removed, it will
be full of holes punched through the foil by the cleaner’s energy.
Both this, and the effect of the cleaner, are graphic illustrations
of just how powerful these machines are. but with silver, cast
silver especially is often just a little too soft to fully withstand
an ultrasonic for very long. The solution is that you’re leaving
the items in for way too long. try ten to fifteen seconds, not ten
minutes. and use the solution really hot. The temperature doesn’t
increase the aggressive action upon the metal, but it lets the
cleaner remove the polish compound a lot faster, minimizing the time
required.

Peter Rowe


#7
   Richard, If the lines are not straight then it could be the
sonic etching the surface. This happens if the item is left in for
a long time. Even on the most aggressive sonics it would take more
than an hour at high temperatures. Different cleaning solutions can
slow this down or speed it up. If the solution is cold you could
run it for 6-8 hours before this happens. 

Ken, I’ll dispute those statements, with regard to etching on CAST
silver items. Items fabricated from rolled or drawn metal usually has
much less of a problem, but silver castings often have at least micro
porosity going on, and the pores concentrate the ultrasonic energy I
think, or perhaps it’s just that cast silver is just that much softer
or something. the streaks DO tend to originate at defects in the
metal, wandering away from them randomly. It does NOT take extreme
temps, or very long times. Almost every ultrasonic I’ve ever used,
that had a built in heater, and was of sufficient quality and power
to be considered a professional level machine suited for use by
jewelers, even small ones, would easily cause wavey white streaks here
and there on some cast silver items, usually within a time span of
only a few minutes, something like five or ten minutes, just as
Richard described. The model E bransons, the ones with about a
gallon size tank and seperate transducer? Those will do it in less
than five minutes, even with an only lukewarm solution. In all these
cases, the solution is just a standard commercially sold jewelry
cleaner or perhaps BCR, a solution formulated for removing polish
compounds. And usually, there’s at least some suspended compound
already in the solution, which should absorb some of that power, but
the steaking can still occur. Note that not all pieces will do it.
Items that spent a bunch of time in a tumbler with steel shot, for
example have had their surfaces compacted and burnished enough they
become much more resistant to this effect. And some castings are
apparently just good enough, dense enough, that they don’t have
problems either.

Peter Rowe


#8

No I am not putting my work in the bottom of the cleaner. The
instructions state very clearly that this would seriously damage the
cleaner. I use the cleaner mostly for removing polishing compound. I
am beginning to realise that the tiny particles of abrasive compound
are rubbing against the polished surface of the work and creating
tiny scratch marks. This means I need to change the fluid every time
it gets at all dirty. Seems wasteful on cleaning fluid!

Richard


#9
I  am beginning to realise that the tiny particles of abrasive
compound are rubbing against 

Richard, only the very finely divided compounds, like rouge, stay
suspended in the cleaning liquid. The coarser stuff forms a mud on
the bottom of the cleaner. Letting the liquid get dirty from
accumulated polish compound does have an effect, but it’s a reduction
in cleaning efficiency, not scratching of the work. Ultrasonics
clean as well as they do because the sound waves are being driven
through the liquid at a slightly faster speed than the liquid
actually can sustain, which causes the liquid to literally fracture
and break apart from the retreating waves. Think “suction” on a
small area, creating a little vacuum bubble, and you’re on the right
track. This happens not so much in the main body of clean liquid, but
instead at any boundary or “flaw”. In short, it happens wherever the
liquid meets something, including the dirt you’re trying to clean off.
This concentrating of what are called cavitation bubbles at
surfaces, especially dirty ones, or at and around any small particle
the solution contacts, is what makes the machines work so well: the
energy gets concentrated just where it’s most needed, at the dirt.
However, this doesn’t stop happening just because the dirt has been
pulled/pushed away off the metal. So suspended particles of rouge in
your solution end up just absorbing some of the energy of the
ultrasonic cleaner, which would otherwise still be available to clean
your work. So as the cleaner gets more and more full of dirt, it’s
cleaning energy drops off quickly. It’s still plenty powerful,
though, with most cleaners, to keep right on doing the job well
enough, even with quite a bit of compound suspended in it. In our
shop, where we have a guy polishing all our work full time, the
ultrasonic is almost always running, and usually with the latest batch
of finished polished work therein. By the end of the day, the
solution, which is usually changed daily, though sometimes it skips
a day, is pretty full of compound. The work still gets cleaned
just fine, and isn’t scratched by the suspended compound. Be sure
to clean off coarse compounds before rouging the work, especially
with very soft metals like silver. And be sure the work is not in
contact with other work, or with things like metal hooks or
strainers, or the like. And if you use a steam cleaner, be sure to
flush it out with a good mineral deposit remover now and then. I’ve
seen steam cleaners with so much deposited minerals in the tanks that
the steam was carrying a finely divided mist of that stuff right
along with it, in effect turing it into a combination steam cleaner
and slight sandblaster. It’s subtle, and you might not immediatly
realize that the steamer is causing dull spots at the same time as
it’s doing it’s job…

Peter Rowe


#10

Peter is really correct as usual.

Any surface defect either pits or microcracks will focus the
ultrasonic energy and enlarge the defect. microporosity and
invisible cracks are very possible in castings. Silver would be
pretty susceptible to these defects. Porosity would be due mostly to
oxygen pick up and cracking due to the part design and cooling
rate. Jesse


#11

Hi Richard, You might try soaking the pieces in (or spraying them
with) ammonia and a little dish soap, then rinshing them prior to
putting them in the ultrasonic. This will remove the vast majority
of the polishing compound prior to the ultra. The problem otherwise
is that the compounds (and the rougher compounds from your tripoli,
for example) will always be floating around in your fluid, and will
be working against your finer rouge compound finish.

The other option is to put your items into baby food jars to put
them in your ultra, and each of the baby food jars (or whatever type
of glass jar) would have either new fluid or fluid specific to the
compound you just used. The ultra would then be filled with a neutral
fluid, and that fluid would never come into contact with your piece
or the contaminating compounds.

Good luck!
Karen Goeller
@Karen_Goeller


#12
 This concentrating of what are called cavitation bubbles at
surfaces, especially dirty ones, or at and around any small
particle the solution contacts 

Peter, This is not true.

There are no ‘cavitation bubbles’. Any bubbles that are visible in
the solution are trapped gasses and impede the ultrasonics
effectiveness. In some sonics you may be able to see lines of
cavitation were the sonic waves collide and create a distortion in
the solution that looks like bubbles. These are not true bubbles.

There is no concentrating of ultrasonic waves. The waves are sound
waves which are uniform when created and when a part of this wave
hits an object it then can bounce off or be absorbed or be
dissipated.

It isn’t concentrated. There is no mechanism to do the
concentrating.

Next you said:

 if you use a steam cleaner, be sure to flush it out with a good
mineral deposit remover now and then

This is not the only way and not the best way to remove build-up in
steam cleaners. Blow downs are the best way to remove the sediments.
Blow downs are what all the manufacturers recommend.

The additives were developed because many people don’t read
instructions on equipment or they don’t/can’t provide the
appropriate plumbing for the blow downs.

Adding chemicals to your steamer is not as good for your steamer in
the long run as blow downs are.

At MPG Repair we repair hundreds of steam cleaners and sonics every
year. We see the effects of what people do with their machines.

For professional answers to your equipment questions feel free to
email or call us at MPG Repair.

Ken Kotoski
MPG Repair
www.mpgrepair.com
1-877-262-2185


#13
I find very fine scratches on the surface. I have to replosh and
try again. Usually I leave work in for about ten minutes in warm
water. Does anyone have any ideas why this should happen and what I
can do about it. 

Hi Richard, First, the jewelry cannot be placed on the bottom of the
ultrasonic… this will mar the surface. If you are using the really
small ultrasonic machines, and you are hanging the jewelry in the
tank properly, then, you might want to leave it in the hot solution
( about 140 oF ) for 5 minutes without turning on the ultrasonic
transducer… this will serve to loosen the polishing compound.
after the 5 minute period, turn on the ultrasonic tansducer and
agitate the piece slightly … You should see the compound explode of
the piece within the first few seconds… then , rinse the item in
cold water and you should be all done.

We use very powerful ultrasonics that will etch/marr the surface if
we leave the transducer on for more than 2 minutes… so we found
that allowing the jewelry to “soak” in the hot cleaning solution
before using the ultrasonic transducer works perfectly… It is
important to realize that it takes a bit of time for the solution to
soak into the dirt and grime and that using the ultrasonic
transducer right away does not allow the solution to work it’s magic
of loosening the compound first …it will work well and correctly
if the item is allowed to “soak” first… and it works well on the
small machine we have also. Best Wishes, Daniel Grandi

We do casting/ finishing and a whiole lot more for designers,
jewelers and people in the trade. contact: sales@racecarjewelry.com


#14
       Peter, This is not true. There are no 'cavitation bubbles'.
... It isn't concentrated.  There is no mechanism to do the
concentrating. 

Ken,

My understanding, apparently incorrect, has always been that the
sound waves traveled through the solution until they hit some sort of
discontinuity, such as a particle or surface, and at that interface
between the liquid and the solid, cavitation bubbles would form, and
that it was the high speed expansion and contraction of these
invisiblly sized bubbles that was responsible for the highly
effective cleaning action. I didn’t mean that energy was more
concentrated at such surfaces, only that at such surfaces the
cavitation effect was taking place, and so only there was the sound
energy being converted into the mechanical scrubbing of the
cavitation bubbles… But if this is totally wrong, then Thank you
for correcting me. I don’t actually recall where I first read that
info…

     if you use a steam cleaner, be sure to flush it out with a
good mineral deposit remover now and then This is not the only way
and not the best way to remove build-up in steam cleaners. Blow
downs are the best way to remove the sediments. Blow downs are what
all the manufacturers recommend. 

True enough. I wrote the former paragraph kinda quickly, thinking
mostly of the effect the sediments can have on ones work when they get
that out of control. Blow down cleaning for some reason, just totally
escaped my fingers when I typed that. I DO know better. Again,
thanks for correcting.

   For professional answers to your equipment questions feel free
to email or call us at MPG Repair. 

That brings up an interesting subject. I happen to have, sitting in
the basement, an old Bransonic half gallon sized ultrasonic. It
doesn’t run. It’s owner was gonna just chuck it. If picked it up
thinking it must be repairable. Have you got any guess as to what
percentage of these things are repairable, and what average costs
might be? I’m just trying to get a guestimate before deciding
whether it’s worth paying the postage to send it to you. The tank
seems fine, but cosmetically, the rest of it’s been obviously used
for some time, with peeling paint, etc.

Cheers

Peter Rowe


#15

Ultrasonics rely on the principle of induced cavitation which is
the formation of small bubbles and there collapse on a surface.
Cavitation damage can be a major problem in handling fluids that are
at on near their boiling points. My experience with cavitation
damage is mostly with cryogenic pumps and boiler feed pumps and
pressure reductions of high pressure fluids, not cleaning but the
methology is is the same. Pit formation and crack enlargement
does occur. Here are a few descriptions of the cleaning
application of cavitation produced by ultrasonics:

http://www.ultrasonics.com
http://www.pmrsystems.com/page13.html 
http://www.natclo.com/dp/ultra.html

Jesse


#16
 I happen to have, sitting in the basement, an old Bransonic half
gallon sized ultrasonic.  It doesn't run. It's owner was gonna just
chuck it.  If picked it up thinking it must be repairable. Have you
got any guess as to what percentage of these things are repairable,
and what average costs might be?  I'm just trying to get a
guestimate before deciding whether it's worth paying the postage to
send it to you.  The tank seems fine, but cosmetically, the rest of
it's been obviously used for some time, with peeling paint, etc. 

Peter, From what you describe there is no way to tell if it can be
repaired or how much.

It’s kind of like me saying I have a diamond in my hand and it’s a
little dirty but can you tell me what it’s worth?

The paint is just a cosmetic thing and I have seen some very abused
units that were repairable.

The only thing I can say about your unit is unless you know exactly
what components are bad I can’t say if it’s worth repairing. If you
don’t know what’s wrong then the only way for me to give a price
would be for you to send it. Our estimates are always free and we
pay return ground shipping on all repaired items.

We repair all jewelry equipment and sell new and used tools and
equipment.

If you want to discuss the unit further email or call us toll free
at 1-877-262-2185. Ken Kotoski MPG Repair www.mpgrepair.com
1-877-262-2185


#17

For those that refuse to believe in ultrasonic cleaning theory, I
offer this site by Branson explaining how cavitation and overlapping
waves work in their ultrasonic cleaners.

http://www.processequip.thomasregister.com/olc/processequip/howworks.htm

Any care for a little crow?

Bruce D. Holmgrain
JACMBJ


#18

An even better description of ultrasonic cleaning can be found @
http://www.pmrsystems.com/contents.html

Bruce D. Holmgrain
JACMBJ


#19

Here is an article on ultrasonic cleaning units .

http://www.bluewaveinc.com/reprint.htm

Cleaning solutions for various materials are listed:

For jewelry type metals this confirms my use of conventional liquid
automatic dishwashing detergents. You don’t need much. Low
concentrations are best.

Cleaners use 20 to 80 KHZ. 40 KHZ is typical.

Medical diagnostics work in the Meg Hz range 10- 20 MHZ. Some
devices (lithotriptors) to break up kidney stones may be using
about 30 Mhz pulses.

Early units immersed the patient in a tub with an very strong focused
beam. Curent ones use a gell type fluid without body immersion. These
are even used on infants.

There are also units using a catheter where the transducer is
placed directly on the stone to cause it to fracture.

Ultrasonic systems replace Xray imaging since they do not utilize
damaging ionizing radiation.

jesse