Hi All:
I read this thread with interest and perked up my ears when dental labs were first mentioned as a source for investment castings. (I used to be a dentist so I know the subject).
There are a couple of misconceptions worth addressing.
First, partial denture frameworks are not cast from stainless steel, they are cast from cobalt chrome which is harder than a woodpecker's lips and therefore expensive to work with.(think high 40's RC and fairly brittle)
It's also expensive to buy and expensive to cast because it needs a special refractory investment and has a higher melt temperature and lower density than gold which is what dental labs cast routinely.
(The fluidity, high density and comparatively low melt temperature is what makes gold easy to cast accurately, and the biocompatibility and ductility is what makes it attractive for dental restorations)
The whole process of making a partial denture framework is completely different from the process used to make a commercial investment cast part...a refractory model of the patient's teeth and gums is poured, a technician custom waxes the framework up by hand using plastic patterns of the individual bits that go into the framework, then the whole thing is sprued and gated and buried in more refractory investment.
It's then burned out and cast.
Only one part is cast at a time, and the whole works is devested, trimmed, polished, then the teeth are put onto it.
Back in my day, this was expensive...a completed partial denture was fifteen hundred bucks give or take.
The prices haven't improved since then.
So knock the idea out of your head that you can get a dental lab to make these for you.
A commercial investment casting house can work with stainless steels of all kinds, and can make these for you.
The problem is making the waxes.
Traditionally a metal mold was made and the waxes were shot just like injection molded plastic parts are produced, then they were assembled on a sprue, invested and cast.
The mold cost about like a prototype plastic injection mold costs...twenty grand at a guess for what I can see of the OP's parts.
Nowadays all that cost can be circumvented by 3D printing the waxes, but as has been pointed out, the cost per wax is higher because the 3D printing is so slow.
Another alternative is to get the parts 3D metal printed.
There are several competitors in the market, the most common is direct metal laser melting...EOS is the most widely known and used system, but there are others.
A new system has just come on the market and show exceptional promise...it is the Rapidia system which uses sintering to consolidate a green printed part made from a water soluble metal paste that's 3D printed just like a filament printer does, and it has similar resolution.
For low volumes these are an acceptable and lower cost way to get a metal part that is about equivalent to an investment cast part...not as good for consistency and detail in stainless as die cast part, but workable for many things and much cheaper for small volumes of parts.
That's where I would look first.
Cheers
Marcus
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