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 Post subject: Sand cast pattern
PostPosted: Sat Nov 15, 2014 10:10 pm 
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Joined: Sun Aug 16, 2009 3:17 am
Posts: 1041
Location: Baden-Baden Germany
Sand cast pattern made in a 3D printer . The magic new way to make patterns .Compare to use a cnc machine and a router , the printer can print any geometry in one go without turning the pattern to machine the back or the sides .This patterns are lightweight , because they are hollow inside with a for example honeycomb system . Very strong and hard . You can print any geometry you can imagine , fast cheap and accurate .


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 Post subject: Re: Sand cast pattern
PostPosted: Tue Nov 18, 2014 6:01 am 
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Joined: Sun Jan 12, 2014 7:16 am
Posts: 15
Or better still, miss out this step and print the sand directly to make the mould.
That's what can be done now.
Moulds can be made in several sections which are locked together before the molten metal is poured in.
Apparently very expensive at the moment, but like every bit of new technology the price will come down.


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 Post subject: Re: Sand cast pattern
PostPosted: Tue Nov 18, 2014 2:01 pm 
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Joined: Sun Aug 16, 2009 3:17 am
Posts: 1041
Location: Baden-Baden Germany
The machine to print sand big enough to make a crankcase is about 1 million € . The sand core for a crankcase about 500€ , but you can use it only one time . 400mm x 400mm normal printer is 6000€ . I went to the Euromold to look for possibilities .


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 Post subject: Re: Sand cast pattern
PostPosted: Wed Nov 19, 2014 12:52 am 
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Joined: Wed Aug 13, 2008 12:10 am
Posts: 334
When you go to the expense of having a printed sand pattern made, you also end up with a series of lines all over from the layered formation of the printed sand. You also only get one go with the mould, which is annoying if the metal failed to fill the cavity. The best way is to Cnc machine the pattern equipment in urethane tooling board- especially if you are making objects bigger than a main bearing cap.


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 Post subject: Re: Sand cast pattern
PostPosted: Wed Nov 19, 2014 2:16 am 
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Joined: Sun Aug 16, 2009 3:17 am
Posts: 1041
Location: Baden-Baden Germany
Normally companies use sand printed patterns if the castings are very complicated for aircraft and others . This is not in use for mass production .The sand patterns I looked at had no lines at all , surface was just perfect .German company building this printers and exhibited it last time at the euromold in Frankfurt .
CNC milling compared to printing . Printing makes no dust , no noise , no tool change , no tools at all , printing all sides in one go , no workpiece change to finish the back or sides , material is cheap , lightweight because honeycomb inside , very strong and hard .
How can you beat this ? I can print complete crankcases if I like in one go .


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 Post subject: Re: Sand cast pattern
PostPosted: Wed Nov 19, 2014 6:26 am 
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Joined: Sun Jan 12, 2014 7:16 am
Posts: 15
"I can print complete crankcases if I like in one go ."

You mean, assuming you have access to a printer big enough, print a plastic crankcase and then use it to make your sand patterns ?
Which are then used to make the actual metal crankcase ?

I understand there is software available to use when 3D printing that will calculate and make the allowances necessary for shrinkage etc.
Not sure who sells this but would be interested to know, even though I'd probably have to sell the house to pay for it.....


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 Post subject: Re: Sand cast pattern
PostPosted: Wed Nov 19, 2014 1:39 pm 
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Joined: Wed Aug 13, 2008 12:10 am
Posts: 334
I make use of 3d printing occasionally but only when it makes sense to do so. It is not the miracle tool that will make the world a better place- at least not until the technology improves and the costs come down dramatically.
I own a CNC machine that will work within an envelope of 2000 x 1000 x 350 mm that I use to make all my patterns in house. A 3d printer capable of building to that size will be in the region of 750000 euros where as a CNC machine is just about affordable for me without having to sell my wife and children to medical science.
To create the part that you illustrated makes some sense I suppose if you are happy to out source in order to make something so simple, but remember that most automotive castings have under cuts and cavities which cannot be created by just pressing a pattern into some sand and need core boxes, loose parts and odd sides etc.
To make a crankcase pattern (as I have done) a CNC machined pattern is the best way. To have all the pattern equipment for such a part 3d printed would cost an absolute fortune and personally I don't mind a bit of dust and noise- machines generally do that. Another problem with printed parts is that they are not as geometrically stable over a period of time as urethane parts.
In regard to 3d printed sand, by the very nature of bonding the sand in layers creates a stata effect which can only be reduced by building up in very thin layers, which massively increases the work time and ultimate cost, to make what can only be a sacrificial one chance casting.
If you need to 3d print a crankcase pattern please let us know how much you were quoted- it would give me a warm feeling of self satisfaction if nothing else.


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 Post subject: Re: Sand cast pattern
PostPosted: Wed Nov 19, 2014 7:48 pm 
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Joined: Wed May 12, 2004 4:26 pm
Posts: 2620
Location: Reeuwijk, The Netherlands
My experience with 3D printing ABS or PLA is speed: These machines usually are very slow.

Increasing size of these printers is less of a problem than extending the size of a router: forces on the printing head are very low, so dimensional stability of the printer itself is less of an issue, so less material, less cost than with CNC, where forces can be considerable.

I know of a guy 3D printing a model boat, 1,27 meter long. He prints in smaller pieces, and progress is slow.

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 Post subject: Re: Sand cast pattern
PostPosted: Thu Nov 20, 2014 12:53 am 
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Joined: Sun Aug 16, 2009 3:17 am
Posts: 1041
Location: Baden-Baden Germany
I have a CNC machine for making patterns , 3600 x 1600 x 500mm . The machine was designed to make patterns for aircraft parts with glass fibre reinforced plastic . All I have to do is take the router off and use a printhead . If you go to big dimensions you use 2 printheads . What is difficult , you need a well calibrated aluminum plate to glue the first layer . You have to paint the aluminum plate with some special glue for the first layer , and the plate need a little heat like 50 celsius . Printing is slow , but compare to CNC milling , I can not see a big difference . And who cares if the machine runs over night . I am building crankcase patterns for aircraft engines up to 1,3 meter long for the last 25 years . And I can say , I am able to print parts so easy where I have problems to do it with a CNC machine . I can print core boxes ready as a negative . 1 kg of the material cost 25€ . So printing is very cheap . My small printer runs almost 24 hours , and we all are fascinated . No tool change , no tools ! No big blocks of material to clamp down . Just a roll of 3 mm plastic and press the button , hours later you have it . In the Netherlands is a designer , he prints chairs with a self made printer .
Sand printing , one core for a T57 is about 50€ . All together for a T57 is about 2000€ .
In Italy is a company , they make a scan from a 6 cylinder cylinder head and you get the casting unmachined for 2500€ .
Scanning and printing is a big future business . Go next time to the Euromold exhibition in Frankfurt . And it looks like a science fiction movie if you see all the possibilities we have today .


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 Post subject: Re: Sand cast pattern
PostPosted: Thu Nov 20, 2014 1:52 pm 
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Joined: Wed Aug 13, 2008 12:10 am
Posts: 334
Goodness me Udo- it only seems like yesterday when you were sending PM's to me, asking me how and with what do I CNC machine foundry patterns and now you claim to have your own machine that is big enough to remake the hull of the Graf Spee.

I'm bored of comparing hard ons with people I don't know on the Internet. I've got real work to do.


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 Post subject: Re: Sand cast pattern
PostPosted: Thu Nov 20, 2014 3:37 pm 
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Joined: Sun Aug 16, 2009 3:17 am
Posts: 1041
Location: Baden-Baden Germany
Is it strange to ask other people how they do it ? If you like to improve , you ask questions about everything to anybody .


The wise learn from everything and from everyone, the normal from experience and the fool knows everything. Sokrates (470 - 399 v. Chr.)


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 Post subject: Re: Sand cast pattern
PostPosted: Mon Nov 24, 2014 9:13 am 
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Joined: Sun Aug 16, 2009 3:17 am
Posts: 1041
Location: Baden-Baden Germany
by the way , the biggest CNC machine we used some time ago to make patterns was 6000 x 2000 x 500 mm . To make aircraft patterns like a complete wing or half a fuselage .


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