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Vacum casting vs. centrifugal casting


#1

Hello

I would like to know what is the difference between vacum casting
systems and centrifugal casting systems.

Someone told me that with a centrifugal system you will have higher
levels of detail than with a vacum system, is that true? Thanks

Ruslan, C.A.
Av. Paez, C.C. Central,
Planta Alta, Local 65
Tel: +58 255 6641327
Fax: +58 255 6237097
Acarigua - Venezuela
@Ruslan


#2

Ruslan

Vaccuum is generally and usually better than Centrifugal. However
you could have loss of details for many reasons. 1. Investment,
Sprue, Insufficient Power, Leaky gaskets etc.

Contact Daniel Grandi on our forum. sales@racecarjewelry.com

Regards
Kenneth Singh
karat46@aol.com


#3

Ruslan,

Hopefully one of our professional casters will respond with their
views on this question. I don’t do it ‘professionally’ but did do
production casting for a few years and continue to teach it and cast
for my own uses.

In my experience, centrifugal casting gives a more dense cast while
vacum casting provides more detail.

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut2


#4

Ruslan:

I do both and do not find that to be true, I have two Centrifugal
casting machines and a perforated vacuum system, I have a small
Neycraft caster that has been a fixture in my shop since 1984. I love
it if I have a small flask with a small load like 2 or three rings in
a 2 x 2 in. flask 1 or 2 rings, it will accommodate a flask up to 4 x
4 inch. I have a Centrifugal caster from Swest(sure am sorry they
sold out) that is about 15 years old that will take up to a 4 X 7
inch flask it was only intended for up to 4x6 but a 7 inch will fit
nicely. Uses standard Kerr/Vigor springs, and my Vacuum system, which
I love but the flasks are expensive, Vacuum is far far safer than
centrifugal systems as a rule, my little Neycraft being the exception
to the rule. The bowl or tub revolves at the same speed as the flask
so if any metal does get thrown out or you get a break in the end of
the flask, the metal doesn’t have the tendency to splash out of the
safety tub. My vacuum system will accommodate up to a 5x7 in flask.
The worst part is learning when and how fast to pour the metal when
vacuum casting, I do believe that the molecular density may be
slightly more compact with Centrifugal, but have no scientific data
to back that statement. The trade off is there is normally less
porosity with perforated vacuum cast items. I have never noticed any
appreciable difference in detail either way if my flask and metal
temps were on target. Vacuum assist is a whole different creature. I
tried it and never had that great of success, I tried using waxweb,
and various other vent gimmicks but never was happy with the results.
I do think the learning/coordination curve is harder for vacuum but
in the end, once you have developed the timing the results are worth
the effort.

Kenneth Ferrell
www.shadras.com


#5

I have used nothing but vacuum casting for 30 years. I have cast
every size and detail part with this system without problems.

There are probably as many people who will say centrifugal casting
will give the most detail as there are who will say vacuum casting
will give the most detail.

I have seen spiders that were cast by both centrifugal and vacuum
processes. There was no lack of detail in the spiders cast either
way. Our intuition may make us feel centrifugal casting gives
greater details because the metal is forced into the mold.

I have had some buckles and conchos cast for me by a centrifugal
caster. Most of the items I had cast this way had what I call
stretch marks which could not be polished away. I believe either
method will give you the detail you want once you master the
process. The decision between using either method of casting will
boil down to finances available for buying equipment, safety and the
size of castings you wish to produce. Centrifugal equipment my be
the least expensive way to go but it will limit the size of castings
you can produce.

Some thoughts: If you invest in a vacuum pump to vacuum you
investment you will have the major portion of the equipment you will
need for vacuum casting. Vacuum casting will allow you to pour more
metal into much bigger flasks than you can with the centrifugal
process.

I believe that vacuum casting with an electric melt furnace provides
a more consistent metal and flask temperature at the pour. The
flask is at a known temperature when it is removed form the oven.
The flask will not have enough time to cool before the metal is
poured therefore the temperature of the flask at pour is known. The
thermocouple of the electro melt will give the relative temperature
of the metal when it is poured. Corrections can be made before the
next pour If there is a problem in the casting caused by improper
temperature of the flask and metal.

I don’t believe, unless you use a high end centrifugal casting
system, you can obtain the same temperature consistency with
centrifugal casting using a torch to melt the metal as you can with
a vacuum system and electro melt furnace. With a centrifugal system
the flask temperature may cool or be heated by the torch before
pouring the metal. The temperature of the metal heated by a torch
is unknown and not consistent between melts.

Kenneth Ferrell made many good points in his post. He has
experience with both types of casting.

Thats my 2 cents and more,

Lee Epperson