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Small investment castings - cost?

bastarddsm

Aluminum
Joined
Feb 18, 2014
Location
Southern Illinois University
Thinking about working on a project with my dad reproducing some muscle car parts, have one part in particular we want to work on - trunk lock bezel. They are a chrome plated diecast part that is hard to come by for some cars. I want to make them from stainless to avoid the chrome plating step and make a more durable longer lasting part. I'm sure with the right machines it could be machined from solid, but I don't have those machines. I'd like to do a casting, then machine the features that need machined,and polish it.

Any idea on a ballpark per piece cost get something like this done? Qty is 25 - 100. Is investment casting the right method? I don't have a 3d model yet - I'd like to get an idea before I waste time making a model to find out it's too expensive.

lock.JPG
 
Get an accurate estimate of the volume and weight of the stainless steel part. Then find a local dental lab and talk to them to see if they can do a piece that size. Dental labs routinely make small stainless steel investment castings and are certainly used to small quantity jobs, because every bridge or partial is unique. You will have to provide the wax models for each part you want cast. The lab or a manufacturing jeweler or an actual investment foundry can help with information on rubber or machined aluminum molds for making numerous wax models of a single item. Jewelers do not do stainless steel, but do know how to make duplicate wax patterns. Maybe there is a way to use a 3D printer to make wax models, but the printers I have seen work very slowly. Foundries are able to cast multiple items at once by connecting many small models with wax rods/wire into a sort of tree array. That keeps costs down.

Investment casting does involve some skilled hand work to prepare the wax model and attach sprues and runners, so it is not going to be a cheap process. Then the castings have to have all those sprues and runners carefully cut off, again a hand process.

Larry
 
Some dentists (not dental labs) now have handheld 3D scanner wands and minature 5D milling machines, together with special suites of the necessary software, to make inlays and crowns from unfused ceramic blanks. After milling, the ceramic is fired in a minature oven, right in the dentist's office. Once they grind out the necessary recess in your tooth, the whole scanning, milling, firing, installation and trimming process can take less than an hour. I have had the crown for an implant and an inlay done with this process, the inlay just this morning!

So, the day of stainless dental castings is (just now) beginning to fade away. Larry is correct, though, if you have wax masters, a dental lab can probably do the work. It will depend on the size (max dimensions and total mass) of the castings you need, as dental labs are naturally specialized to do work the size of a tooth.

You definitely want to talk to your foundry/lab about multiples, because there will be hundreds of dollars of per-run cost. The only way to get per-part costs down is to do lots of parts in a single run.
 
Thinking about working on a project with my dad reproducing some muscle car parts, have one part in particular we want to work on - trunk lock bezel. They are a chrome plated diecast part that is hard to come by for some cars. I want to make them from stainless to avoid the chrome plating step and make a more durable longer lasting part.
You know, the people who mess with old cars are not stupid. They can tell the difference between zinc and stainless. If they wanted a more durable longer lasting part, they could buy a new Mustang GT.
 
Unless you are talking about a model car part, your part is too large for a dental lab

You can take a rubber mold off of an existing part, go from there to waxes and a casting.

There will be some shrinkage in the process.

Stainless steel will not have the same appearance as chrome plate, actually chrome over nickel

plate
 
You know, I did not ask for your opinion on the usefulness of this endeavor.


when asking for and getting free advice don't too be too uppity.

Put Dental or Medical into it and price just went up 10x. Why not ask the people who'll know for sure - send a quote request to a foundry that does this. There are a lots businesses doing this, search "investment casting". Looks like there are some in Illinois

investment casting in illinois - Google Search
 
About 20 years ago I had some gears cast out of aluminum. The per part cost wasn’t that bad. Most of the cost was in having the mold made. These were done by sand casting which I know is different than investment casting. The foundry I used did an amazing job on these gears. They actually looked like they were machined as opposed to cast.


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A free text search for casting stainless steel and this popped:


Stainless Steel Castings | Avalon Precision Metalsmiths

As a drag racer and hot rod enthusiast I understand your desire to pursue a better part. Anyone who has tried restoring a 60-70’s car knows a lot of re pop parts are sh$t. It is a good thing you are at least exploring offering a better part than OEM. Us car people spend stupid money on silly parts because it makes us happy. You certainly don’t go into the car hobby to become rich! How do you make a small fortune in drag racing? Start with a large fortune and go racing![emoji3]


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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
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
 
Yes, investment masters can be 3D printed. The print material isn't wax, but a soft plastic designed to burn out clean and leave no ash in the cavity. Any of the 3D printing services that cater to the jewelry trade should offer "burn-out material."

You might check with Shapeways, shapewayscom They will run parts in burn-out material and also job out the casting, for one stop shopping. Unfortunately they don't list stainless as an option, but do list brass, which could then be plated after polishing for an even better match to the original finish.

Yes, 3D printing of masters is going to be expensive, but on the other hand it will be easy to tweak the size if the first parts don't shrink to the right size.

Dennis
 
Am I missing something? I have no practical experience, but couldn't a live tool cnc lathe and a buff get you 99% of the way there? The only feature I see that's a problem is the square bottom key slot in the face. Or is there more going on internally that we don't see?
 
Hi wheels17:
You wrote:
"Am I missing something?"

Yeah, you missed this bit from the OP:
" I'm sure with the right machines it could be machined from solid, but I don't have those machines."

I agree with you...if the OP had the equipment, it's an obvious way forward.
So the question becomes "will it be cheaper to hire a machine shop or a casting house?"​

I think the jury's still out on that one.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
 
Thinking about working on a project with my dad reproducing some muscle car parts, have one part in particular we want to work on - trunk lock bezel. They are a chrome plated diecast part that is hard to come by for some cars. I want to make them from stainless to avoid the chrome plating step and make a more durable longer lasting part. I'm sure with the right machines it could be machined from solid, but I don't have those machines. I'd like to do a casting, then machine the features that need machined,and polish it.

Any idea on a ballpark per piece cost get something like this done? Qty is 25 - 100. Is investment casting the right method? I don't have a 3d model yet - I'd like to get an idea before I waste time making a model to find out it's too expensive.

View attachment 310521

Here's a link to a company that worked with me on a low volume part less than two years ago:

Stainless Foundry You might want select one of their sales people as they are pretty savvy on the casting process: Stainless Foundry

And probably stating the obvious but without a drawing/print at the very least not much is gonna happen.

And....Someone else mentioned about 3D printing the wax. Something to investigate at least to prototype your product.

Good luck on your part!
 
Thinking more about the subject. Investment foundries like to use silicon bronze. Silicon bronze has a low surface tension and high fluidity, it pours well and clean. Make your part in silicon bronze, polish and plate the part.
 
Search to see if a new product is patent protected if you intend to sell it.

But a very good thread. I would like to know the figures. who might run a short run, and cost of steel or iron short-run casting.

like if one had an off-patent wheel guard or few-up part...with having a pattern in hand.
 
Thinking more about the subject. Investment foundries like to use silicon bronze. Silicon bronze has a low surface tension and high fluidity, it pours well and clean. Make your part in silicon bronze, polish and plate the part.

I agree, silicone bronze, aluminum, or the OEM type pot metal will be much cheaper to cast than stainless. Then plate with chrome.
 
Marcus,

Have you played with the BASF ultrafuse 316 material? You can use it on pretty much any decent 3D filament-based plastic printer (we had some issues with nozzle clogging, but got it figured out). Basically print over sized (they tell you exactly what factor to use), send out for debinding and sintering (our material came with "coupons" for processing a couple of batches of parts), and parts show back up in a box.

We checked the porosity and mechanical strength as-sintered. It was decent, maybe a couple percent porosity and tensile strength better than 50% of normal 316. We sent some parts out for HIP'ing and both properties were improved (at an increased cost, of course).

Anyway, "cheap" way for anyone to get into metal 3D printing.
 
Making 3D printed waxes isn't expensive if you do it your self.

A half way decent 3D printer is approx $299.

a 750g reel of filament from Polymaker (one of the better 3D filament suppliers) is $49.99 from Amazon. There's likely cheaper filament availible.

https://www.amazon.com/Polymaker-PolyCast-Filament-Designed-Investment/dp/B08PHGBMK6

So for an investment of no more than $350 you can be making plastic impressions for investment casting.

One issue you might run into is that a lot of foundries have become ISO compliant, so the days were you could walk in with some waxes, pay cash and get cheap parts are gone. I used to get parts cast locally, I supplied the waxes, paid cash, and waited until the caster fit it in with another job. Those days (at least around here)are gone.
 








 
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