Larry;
I have had quite a few inquiries about this subject. I come from a Diecast
background. I've been building molds my entire life and now I'm too old to
get a real job. The company I worked for previously is the biggest
independent diecaster in the USA Top Diecast Co ( a real nice bunch of
people). With them I had my first experiences with the 3M Tartan ( now 3D
Keltool) 20 yrs ago or so, doing mostly Diecast. It appears everyone in the
Diecast industry has the same problem getting manufacturing equivelent
prototype parts. They all tell me that the investment cast parts which they
can get do not have the same mechanical properties and cannot be used for
certifications. I have attempted to do pourings of Zamak 3 zinc into high
temperature silicone molds. Fusion Engineering shares a building with a zinc
diecaster so I have an endless supply of molten zinc. I was attempting to
mold very thin walled highly detailed prototypes for a product which I cannot
describe. They wanted it in magnesium but the prototypes could be zinc which
is much safer to work with. Needless to say we were unable to pour acceptable
parts. the zinc freezes to quickly even in silicone. I did however learn a
great deal from the experience (mostly how to treat burns and what not to
ever try again). What we did learn is that metals have to be injected at
great speed thus requiring an injection molding machine ( I already knew that
but I had to try it anyway). We did however figure out a way to make zinc,
magnesium, or aluminum short run parts inexpensively by utilizing our 3D
Keltool process. What our customers do is, most Diecasters have standardized
moldbases on their shelves that they use for tryouts and quick change
applications, usually one for each size range. Lets say the pocket size is
1.5 x 3 x 6. they have all the runners and spreaders installed already at a
standardized location. What they then do is order Keltool inserts from us. If
it is a real low volume we eliminate all the holes and core pins they can be
drilled later. If there are any slides required we eliminate them also and
CNC machine the details in later. We then build very simple keltool cavities
made right to the finished dimensions (no finishing stock anywhere) so the
inserts can be immediatly dropped into the die shoe. We grow the runner fan
and overflows right into the keltool blocks sometimes we even include the
ejector pin holes so the only machining required is the tapped holes to hold
the blocks down in the pocket. This process seems to be working very well.
Either us or any 3D keltool supplier (hi Brad) can supply these types of
cavities in about 10 days. the cost is around $30 per cubic inch and a some
change (excluding SLA masters and Engineering of course) Cavities to fit the
above size 1.5 x 3 x 6 will cost $2600 dollars we couldn't care less what
your part looks like. It can be simple, complex its all the same to us if it
fits within those blocks its $2600 bucks. If we have to Engineer the parting
lines and model the blocks then grow the SLA cavities and cores this usually
comes out to a similar amount, less if the part is simpler. Of course If you
can supply a master part with the part shrinkage and the .006 Keltool
shrinkage we can jam it into a lump of clay to form the parting lines. This
will cost you a little less but its a pain and not as accurate. We prefer the
CAD method. We can work with any type masters not just SLA.
I would expect in aluminum you can get maybe 300-500 good parts with the
quality deminishing thereafter (heat checks). In magnesium maybe a thousand.
In zinc we have one that has over 30,000 shots and its still going strong we
guaranteed it for 50 thousand ( I still have my fingers crossed). These are
all of course un-heat-treated A6 keltool material. You could probably get
many more if you heat treat the cavities and treat the cavities with a
ferritic nitrocarborizing process (maybe as much as 10 fold). Currently the
size limits are about 5 x 6 x 9 for any single blocks but they can be jammed
together for larger parts. The published accuracy of the 3D keltool cavities
is +/- .002inch / per inch. None of this is new technology or even high tech.
All this has been around for 20 some years (pre-dates RP ) so it is out of
favor these days. The only new twist is the ability to make the SLA master
cavities complete and ready to go in a day or so thanks to our friends at 3D
who have been quietly perfecting their technology so it can be used in the
mainstream manufacturing environment. I'm really pumped on what we will be
able to do in the future as all this develops even more. But lets not forget
the tried and proven past in our zeal for high technology, which in my
opinion many of us are way too hyped upon (myself included).
Good luck
Bob Morton
In a message dated 9/10/99 5:09:37 PM Central Daylight Time,
lblasch@opw-fc.com writes:
<< First I checked the RP-ML Archives and I found a few leads, but I am
looking for current data.
I am looking for sources that can make me Aluminum and Zinc/Aluminum
castings from rp masters with plaster or silicone molds to replicate
die cast parts. I am attempting to create "Manufacturing Process
Equivalent" parts for agency certification testing.
If you can suggest another way to produce die castings without costly
tooling, I would like to hear from you.
Thanks in advance,
Larry Blasch
Design Engineer
OPW Fueling Components
Cincinnati, OH 45240-5003
Voice: (513) 870-3356
Fax: (513) 874-1231
e-mail: lblasch@opw-fc.com
>>
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