My comments are preceeded y %%%%%%%%%
At 03:25 PM 6/23/99 +0100, you wrote:
>
>Tom,
>
>I understand you guys get involved with cast tooling. Are you a foundry or
>tool shop as well?
%%%%%%%%%%% We are two investment casting foundries, ferrous and nonferrous,
and are, therefore, in the injection molding business. We make most of our
own injection molds.
>
>I need some advice, but some background first. I've been in RP and RT for 8
>years and tried all sorts of things except cast metal tooling. I ran a RP
>bureaux until we went down in January. I am now with a reasonably sized
>toolroom and moulding operation trying to educate them into RT and not just
>production tooling. As you can imagine the first thought is "conventional"
>and not out of the box, leading to some frustrations! We do however run an
>EOS DMLS system for some inserts.
>
>Recently I came across the main casing for a car heating and ventilation
>system. All the main automotive manufacturers use them just repackaged to
>fit the space. Two mouldings circa 20 x 15 x 12 inch, fitting together and
>housing all the vents and flaps. Functional rather than aesthetic, PP plus
>20%talc.
>
>Customer needs maybe 200 for prototype testing. This thing pulls in just
>about every direction and thus in these numbers will be a series of loose
>inserts. However the stock removal to machine it is considerable. Our
>leadtimes are a joke as are our prices. So I got to thinking about cast
>tooling but finding a source of experience is not easy.
%%%%%%%%%%%%% We work nominally within a nine-inch cube. The largest RP
Tooled wax I've done is 8 x 2 x 2 with 0.1-inch walls. The RP Tool was CAD
designed around the customer's .stl to be two parts, A and B, with nominally
1/8-inch walls. Inclined holes in A and B and prototyped pins to fit the
holes were included to cause the halves to part in the correct direction
from one another. The injection port and gate was included in the design
also. Approximately four hours of straightening/tapping/surface finishing
were required to assemble the halves and make the mold useable for hand
injection molding of waxes. It takes about a weekfrom CAD designed. You can
infer a cost. Mold life is unlimited. You might want to try it for your
larger part. You'ld have to design your A and B in such away as to match
your available press frame, and following the above rules.
%%%%%%%%%%%%%% Another way for you to go would be SLA master, RTV mold, and
polyurethane vacuum cast. I can sugest peiople who can do that for you.
%%%%%%%%%%%%%%% Keep me posted on your progress.
>
>Can you comment? Practicality at this size? Masterpattern? Cost!!? Surface
>finish - would we need to polish? Accuracy? Material? Leadtime? Anything
>else?
>
>Tim Plunkett
>Rapid Product Development Director
>MH Group
>tim@plunkett.demon.co.uk
>
>
For more information about the rp-ml, see http://ltk.hut.fi/rp-ml/
This archive was generated by hypermail 2.1.2 : Tue Jun 05 2001 - 22:51:56 EEST