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Technical stainless steel shot impingement on sterling


#1

Hello out there, I found this at finishing.com. Thought all of you
with the expertise could help this gentleman. Jake at Nikolas.

Our SSshot from our main supplier has been impinging the surface of
our sterling jewelry. The shot is a combo/mixture of shapes -
spheres,ballcones,enlongated speres,and pins of 302 stainless steel.
We use it in a vibratory bowl tumbler. The first thing I did was to
remove the pins. This helped a good deal. Then I added a bit more than
recommended burnishing solution and made the solution w/ less water.
Again this helped a bit more. The result here is mild impingement and
still the shot has difficulty reaching the recesed areas of the
design. The size of parts which comprise this steel shot mix are
large. a sphere = 4mm

Q. Would using smaller pieces of shot 2mm spheres or instance, reduce
the texturing produced by the steel?

Q. Is the problem not only the size, but the weight of the shot? What
about the hardness?

John Humphries
New Orleans, Louisiana, USA


#2

The only action you have already done that I do not agree with is to
reduce the water, on the contrary, I would strongly recommend to
increase it so you can reduce the sliding action of the shot. In some
tumblers you can reduce the rotation speed and this will certanly help
at the only cost of having a longer burnishing cycle. Have you ever
tried using warm water? some folks assure this has helped to obtain a
brighter finish.

David C. Duhne
DIAMANTEX, Mexico


#3
    Our SSshot from our main supplier has been impinging the
surface of our sterling jewelry. The shot is a combo/mixture of
shapes - spheres,ballcones,enlongated speres,and pins of 302
stainless steel. We use it in a vibratory bowl tumbler. 

Hi John, Can you adjust the amplitude of your tumbler? It may be
vibrating too violently for what you’re trying to achieve, especially
with soft silver castings. I use mixed Stainless Steel Shot including
pins and don’t have a problem tumbling silver. Of course, I adjusted
my amplitude down through initial testing.

I use a Raytech 25 vibratory tumbler with a donut shaped bowl. I run
about 40 lbs of mixed stainless shot and have the amplitude set short
of medium.

HTH,
Donna


#4

This is a trick that I use to correct the problem of orange peel or
impingement on annealed sterling. This process work hardens the
sterling, with the steel, then uses the abrasive to smooth the
surface, then burnishes the pieces. It works very well, but it is a
bit of a nuisance.

First run the castings or chains or whatever in a rotary tumbler with
your steel shot with appropriate liquid for about an hour or two.

Next, run the items for 6 to 8 hours in a medium abrasive such as
Rio’s clean cut aqua cones. I do this is a TV-25 with flow thru
rinse.

Then run in the steel shot again for about 2 hours- I prefer the
rotary tumbler as before.

If the work is sort of flat or with planishing marks, I finish the
pieces in a dry medium of green buff with 25% wood pegs in a
vibratory tumbler for 24 to 36 hours. This effectively buffs the
sterling - resulting in a beautiful bright finish.

There is another way to polish that you might try too. First run in
your abrasive media, then in the dry media, skipping the steel
altogether. That works especially well on gold anticlastic work,
probably because it is already work hardened from the forming
process.

You are correct to remove any pins from the steel shot mix. Pins are
only used in finishing deep detail. I almost never add pins to my
shot.

Judy Hoch, G.G.
@Judy_Hoch
www.marstal.com