Technical Casting Traditional Parts from Rapid Prototype Parts?

I have stuff 3D printed in 316SS for work. For small items it isn't stupid money. If you want to recreate an unobtainable part or do a one off piece direct to metal it'll give you a finish comparable to casting. ....still will need to clean it up but you can print geometry that could not be easily machined or cast.

 

Has this thread been linked to here? http://www.jalopyjournal.com/forum/threads/making-a-671-blower.636663/

 

Well THAT'S insane!

 

we have a few scanners and printers here at my work,
used mostly for modeling for construction preplanning but there seems to be a bit of experimentation to study what it is actually capable of and useful for

when I get rich I will buy a scanner and printer, in the mean time they can do all the r&d so I know what to buy.

 

Yes you can. I'm the guy from the linked article above on building the 671 supercharger. We use our printer to actually mass produce quite a few of our products. Our front and rear plates are actually 3D printed tooling that we superglue to a wood board and made castings out of.

There are 3 methods of production that you can use to make metal castings from plastic 3D printed parts. 2 of the three are mass production and the last is best for special one off parts.

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Terminology:
Master - Also called a Tooling Master. It is a hardcopy of the part you which to produce. They are usually CNC cut or 3D printed to be near perfect. They are the template that is used to make a pattern. Masters are always produced at a scale of 1.0104 or 1.0208 to compensate for metal shrinkage.

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Number One: Flatback pattern

A flatback castings is any casting that you could sit on a flat surface and all the draft angles follow the same direction. requirements for a flatback are;

All angles draft the same way. If you don't know what draft is, here's a video
No offset or complex parting lines. Refer to video above if you're unfamiliar with the terminology.
No pockets that would result in negative draft from the pulling face.



Examples of parts like this would be blower front and rear bearing plates, fuel block off plates, idler brackets. With parts like these, literally all you have to do is print out the master, glue it to a board, add your gating and make some molds. This is the cheapest version of production and can yield lots of castings, pricing typically runs $200-$1000 depending on the size of the part. We have produced hundreds of blower plates with minimal wear on the tooling. (ABS plastic tooling)


Number Two: Matchplate Pattern

Matchplate patterns are actually a two part process. One, you print your master which is then used to make a cast aluminum pattern from your 3D printed part. We outsource our matchplates to a company in Ohio that is a dedicated matchplate company. Note that flatback parts can also be matchplates if you need your pattern to be made of aluminum instead of plastic. It's an increase in tool life at the cost of money. Refer to the video linked earlier to see a matchplate(the intake pattern is a matchplate).

Matchplates have no set requirements but they are very well suited for what flatbacks are not capable of, and that is if your part has offset parting lines or open pockets inside of your casting. Here is a 471 carb adapter I'm currently working on that can be matchplated. While this does have a flat parting line, this part can not be a flatback as it has a pocket in the center with negative draft on the bottom side.



Other examples of parts like this would be a blower gear cover, 2x4 carb plate, 3 deuce carb plates, curved door hands.

Pricing for matchplates run anywhere from $1200-$10,000 depending on complexity.


Number Three: Investment Casting

Investment casting is pretty much the exact same process as a matchplate but with one big difference. Instead of taking the master and creating an aluminum pattern, you actually create your mold from the master, burn out all the 3D printed plastic(destroying the master), then you are left with a hollowed out mold that you can pour molten metal into, creating your casting.

Here's a video of just that.



Now you might be thinking, "Dzuari, why do investment casting if you only get one casting and destroy the master? why not just make a matchplate and mass produce the part?"

Two reasons, complexity and price. Those two words are actually synonyms in the manufacturing world but with the new advent of 3D printing technology, we can now produce fantastically complex castings that 30 years ago, where completely impossible to make. Now for the laymen and guys just looking to repop an old part that is no longer sold anywhere, a one off investment casting is the way to go verse a matchplate that could be a couple grand. A 3D printed part that's the size of your hand would cost anywhere from $30-$150 bucks for the plastic master. Then you just pay for the investment casting labor and you have yourself a casting. We currently do not do or outsource any investment casting so i can't give you an idea on price but there are company's out there that do this process.

Here are some examples of parts that would be impossible to produce, even as one offs, without 3D printed investment casting.








This is actually a 3D printed mold. Instead of printing out the plastic and investment casting it. The printer uses glue and green sand to create a hollow mold that you just pour metal into. Hoosier Pattern in Indiana has one of these machines. I think it cost them either 500k or 1Mil, can't remember though.





Here is a video of the machine working




Currently the manufacturing industries is still warming up to the idea of 3D printing and has yet to fully utilize the capabilities of creating these extremely complex parts. Currently, most parts like the pictures above are purely decorational and non functioning but as cost go down on printers and demands continues for more and more efficient and light weight parts one day your radiator or intake will look less like this




And more like this. And yes, that is a real casting of a radiator/heat exchanger. I think it goes on an aircraft or something

 

Explain set back...

 

Moving the engine to the rear LOL

 

Really some amazing progress in the casting business

 

I was a owner of a small aluminum foundry during the 1980's and 1990's that was destroyed in a tornado in the early 2000's. A customer approached me with a pattern that was generated by a then new 3d printer and was curious as to if it could be used as a casting pattern. I mounted it to a match plate on the part line and jolt-squeezed a mold green sand. It vibrated out of the sand very cleanly and a casting was poured from the mold. Of course the shrink factor was not factored into the pattern as the customer was interested in using it as a show and tell for a prospective product. When they had determined that it did have prospect they decided to have a metal part cast to perform tests on. They had the part redone and I casted many samples from that pattern and had it until my building was destroyed. If the pattern can be mounted to a match plate and vibrated out of the sand, the pattern needs very little to no draft to get it out of the sand. The vibrator basically moves the pattern and increases the size of the mold making it possible to with draw it from the molding sand. I don't remember what the layer thickness was but with the sand I was using (180 AFS) it did show the lines which were carefully sanded out of the pattern. The production castings were produced in a cast iron permanent mold on a small tilt casting machine in my shop by the thousands. Very tight flasks and very close mold pins are required to do this class of work without draft. Draft allows the pattern to be drawn from the sand by hand as the pattern cannot be drawn consistently straight up especially with a part that is over a inch in height. Of course you can do this all in no bake binders too which I have used but my experience was in green sand. When I draw a pattern in AutoCAD I use a factor of 1.05 (12.187/12.000) to all dimensions and usually 1* to 2* draft per side for a loose pattern green sand mold (no match plate). After over 25 years of foundry that has always gotten me close to the required dimension casting in 319 and 356 alloys.

Greg

 

This is exactly what we do for our plastic prototypes at work.

We don't cast them, though. It is off to the mill after that.

 

When I was looking into casting my adapter covers (see avatar) I checked into a company called ExOne that does 3D printing in sand with a glue binder. It was .19 cents per square inch at the time. They can also create a cast pattern by using the double shrink when upsizing the part. That way the part that comes out has the proper shrink and can be used as the new pattern and mounted to a board for green sand casting. This is a good way to do rapid prototyping because you don't have to keep paying them to make new sand molds every time.

I did not end up using them to do my pattern but instead took a splash off of an original part and added some to the outer edge and attached it to a board. I then had it smoothed off with bondo and painted. I need to add some more to the edge because I run out of material in the turning process in the lathe. If I had the money I would have them make the master casting pattern. They are cost effective for rapid prototyping and making master casting patterns. The larger the quantity the less cost effective it is and better to have a casting pattern.

Here is a link to them. http://www.exone.com/Services/3D-Printing-Services/Parts-On-Demand

 

I bought a Makerbot digitizer to scan items and then make 3D prints of them. The Makerbot is a PIECE OF SHIT!!!! Every scan, rather the items is flat, round, shiny, dark, all different lighting environments, etc. look like an amoeba...My advise is to steer clear of the Makerbot-

 

I used a 3D printed pattern for my AVIATOR panel. I just cleaned up the panel with 3M glazing filler and sanded it all with 80-180-220. It was relatively easy, and I plan to do it again with more designs!

 

Having just purchased a new CNC mill a few months back, I have since rarely seen a need for my 3D printer. It was cool at first because it at least allowed you to create an object with little effort. It was however very problematic and finicky, and you rarely got a good print the first time, it usually took several. And for long print times of 5-6 hours or longer, you just held your breath to make sure you didn't have any hiccups that would kill the print in the final minutes of printing. For doing investment castings as shown above, it would definitely have advantages over milling a part, but I have since just unplugged my printer and mill all my patterns and cores. Its faster and the surface finish requires hardly any sanding to get it slick.
Cost being a factor, the really high end printers should provide better expectations for a better print quality. Mine listed for $1799. And while it does yield better parts than some of the bigger name brands, it still doesn't suit my expectations compared to milling my patterns. So I probably wouldn't ever buy another one unless the finished product quality improved dramatically and the success rate also improved greatly. With my CNC mill, I can get 100% quality and success every time.