Using 3D prints for casting

[Chris Pattison 1Participant @chrispattison1]

Here in NZ, if I were to order castings from the UK, not only will these be very costly, but I suspect that their shipping weight will add substantial cost to their purchase. So, with the advent of 3D printing, I wonder if anybody has explored making patterns for either sand casting or lost-wax casting of parts? In the long run, these 3D programs could be exchanged across the world at minimal cost.

[Chris Pattison 1Participant @chrispattison1]

[David JuppParticipant @davidjupp51506]

3D printing of patterns, and direct 3D printing of wax is becoming commonplace in commercial casting.

Compared to hiring a pattern maker, 3D printing is quick and relatively cheap. The 3D file can very easily be derived from CAD design files – a scaling operation and add draft where required.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by David Jupp on 18/02/2015 07:32:44:

… direct 3D printing of wax is becoming commonplace in commercial casting.

.

David,

That's very good to know … especially as [in 2013] we were discussing 'direct 3D printing of wax' as a possibility.

'Hope' to 'Commodity' in less than two years.

MichaelG.

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Edit: added link to the earlier thread.

 

Edited By Michael Gilligan on 18/02/2015 08:41:55

[JasonBModerator @jasonb]

David, what sort of cost would one be looking at to print out say a set of castings like these, thats a 6" flywheel for size. I know what they cost me to get shipped from the US, cost of casting would be comprable in either case.

I know of a few Builders in Australia that have made their own patterns or fabricated the simpler parts but still found it more cost effective to have the complicated castings like cylinders shipped fropm the UK. Also know of a crake containing about a tonne of castings that has recently arrived over there.

[Peter BondParticipant @peterbond14804]

The Solidscape range of printers has been around for quite a long time; they're effectively glorified inkjet printers that use wax rather than ink. They give some fantastic results, but I've heard a few owners say they can be a bit twitchy, particularly if only used intermittently.

Wax milling through CNC remains popular – the claim is that the surface finish exceeds anything you'll get from a printer.

SLA resins exist that can be burned out as part of the lost wax process; they don't handle exactly like wax though, so need fairly specific handling.

Lost PLA casting has been done; last I read about it there tended to be a moderate amount of ash.

Sand casting using the printed model is possible – on a small scale it can be done with Delft clay.

My interest is focussed on the small-scale stuff, so sub-mm features and build volumes in the order of 40x70x100mm max.

[Neil WyattModerator @neilwyatt]

An interesting topic as some foundries won't touch this idea with a bargepole, while a few others are happily doing it.

I have someone who is in conversation with a foundry specifically with the aim of producing an article that not only describes HOW you can do this, but also will give readers an idea of WHERE they can get the castings done.

Neil

[David JuppParticipant @davidjupp51506]

Sorry – can't help with pricing of 3D prints. Depends on system used, how you factor the capital cost of the printer, size, any support materials needed in the print process.

One way to get a feel for price would be to upload part files to one of the bureau services that now abound. That would obviously include delivery and a profit margin.

For fine scale stuff – optical or inkjet based systems are probably the way to go, for larger stuff fused filament printers might be OK.  There are a few 'castable resins' or waxes available.

Edited By David Jupp on 18/02/2015 09:18:17

[Paul LousickParticipant @paullousick59116]

Hi Chris,

I live in Sydney and had a similar problem to you with shipping. Originally, I ordered most of the castings for my engine from a supplier in the UK. They weighed about 250 kg and cost me about $700 for shipping which I considered reasonable. Unfortunately I did not include a casting which is required for my engine. This casting weighs approx 30 kg and sells for about $150, BUT the cost of shipping by sea was quoted at more that $200. I asked if it could be sent by air freight and was told that it would be more expensive.

Apparently heavy items like the casting has to be packaged in a large wooden box and fumigated before it is shipped. The box that I originally received was about 900 x 900 x 900 and was only 1/4 full. (probably so it could be handled by a forklift). It is the cost of the and handling fees which add to the cost. OK for large quantities but not for small numbers. I am now fabricating the part instead of using a casting.

3D printed patterns and having then cast is a good option, especially for 1-off castings made from wax.

Paul.

[HomeUseParticipant @homeuse]

I have been experimenting with direct extrusion of wax but the problems i have encountered have been trying to cool (solidify) the wax quick enough after the hothead so as to retain its shape and not “sag” – At the moment the extruder is hand worked as the full printer is not completed. – A fellow experimenter is developing the idea of producing 3d printed (plastic) moulds into which wax can be injected for lost wax casting – this can become complicated if there are a lot of undercuts.

[JasonBModerator @jasonb]

One problem I see with using printed parts as the master or to burn/melt out is that nowhere is there a button on a CAD package that gives you the experience of a good pattern maker.

If you print out the item as you want it to look with scale, draft and machining allowance added then have it printed in say wax and then cast what happens if there is excessive shrinkage in a bulky part that a good pattern maker would have forseen and added extra material or larger gates to fill this part as it cools.

Now with a wooden pattern at least you get a second chance as you can add a bit to it or just cast it again in sand with suitable feeders. If burning or melting it you would have to print the part again.

J

[David JuppParticipant @davidjupp51506]

Agreed Jason – you can use a 3D printed pattern like a wooden pattern if surface finish is good enough (either straight from printer or with some 'post processing' ) , you are not forced to go down the burn out route.

Edited By David Jupp on 18/02/2015 10:48:13

[JasonBModerator @jasonb]

Well did a quick look at costings from a couple of googled sources. Based on just one 6" flywheel

Sent a STL file to one with instant online quote, choice of colours, done on Ultimakers, from photos on their site looks quite basic quality but came in at £101.

Using a basic guide for the volume on another site in white nylon with a good quality surface finish cost would be £112.50.

Given that I got that whole set of castings posted from the states for $105 it may just work out a bit cheaper if I want a poor finish on the parts.

EDITED a sI sent an imperial file not metric so the 6.99 flywheel wil actually be 101.00

Edited By JasonB on 18/02/2015 12:24:38

[EnnechParticipant @ennech]

If you are concerned about the shipping weight I would suggest that for such size parts you would be even more concerned about the cost of 3D printing whether direct wax printing or or 3D printing a pattern. 3D printing is affordable for small items but for larger patterns CNC machining is more cost effective. I would also suggest that there is more to making foundry patterns than just converting a 3D CAD file to stl form and making the pattern directly from it. There is a degree of know how involved.

Eric

[David JuppParticipant @davidjupp51506]

Cost can be potentially be reduced by making inside of pattern a structural mesh rather than solid – uses less material, so can be cheaper with some printing processes. Unfortunately that's a bit 'fancy' to attempt on many CAD systems. Design tools need to evolve a bit to take best advantage of 3D printing.

[Ketan SwaliParticipant @ketanswali79440]

Jason,

Costs for shipping into USA and out of the USA into UK are reasonably cheap.

Sending goods to Australia and New Zealand is expensive, be it by sea or by courier/air, and then it gets worse if the person lives in an 'out of zone' area = more rural Australian or New Zaland region.

For sea freight into Australia, there is fumigation process to be costed in if using solid wood. Plywood or any other material packaging does not need it in case of engineering goods/casting.

Sea freight is calculated per 1CBM or 1 Metric ton, which ever is the greater, and then the other handling shipping and clearance charges are applicable.

For New Zealand, almost every courier parcel gets stopped by their customs nowadays!….adding to the delay.

Ketan at ARC.

Edited By Ketan Swali on 18/02/2015 12:21:46

[Ketan SwaliParticipant @ketanswali79440]

Jason,

Sorry I forgot to add:

In other words, keeping above transport costs in mind, I can see why they would want to consider 3D printed parts. Do not know if it would still be cost effective though.

Ketan at ARC.

[Neil WyattModerator @neilwyatt]

I've seen acetone-fumed 3D prints and the surface finish is almost like glass, alternatively I've seen the surface finish left by a quick going over with wet and dry paper, and it looks plenty good enough for sand casting to me.

Neil

[David JuppParticipant @davidjupp51506]

In industry, some foundries miss out the pattern all together and 3D print the sand mould shell directly.

[JasonBModerator @jasonb]

Parcel Force website quotes £199 to send 20kg down under which is more than that whole set of castings weighs but the same money would only buy me two flywheel prints so does not seem economical if out sourcing the printing.

Printing your own would become more cost effective with the more parts you print as that will even out the cost of a printer.

J

[EnnechParticipant @ennech]

Yes but if you are talking about sand printing for making castings you will have A BIG surprise at the cost. It is only cost effective for small cores that would be difficult to make by conventional means

Eric

On the subject of shipping costs…..I wonder how ever the Chinese can be so rich shipping their stuff all over the world!

[Ketan SwaliParticipant @ketanswali79440]

Posted by JasonB on 18/02/2015 12:34:52:

Parcel Force website quotes £199 to send 20kg down under which is more than that whole set of castings weighs but the same money would only buy me two flywheel prints so does not seem economical if out sourcing the printing.

Printing your own would become more cost effective with the more parts you print as that will even out the cost of a printer.

J

You make a good point.

Ketan

[EnnechParticipant @ennech]

There are a lot cheaper and reliable outfits to send parcels Jason. I have just checked the cost of sending 20kg from UK to Australia using the people I normally use….£77

Eric

[JasonBModerator @jasonb]

Thanks Eric, I'm sure I could have looked about a bit more but that does actually make the cost not a lot different to what those castings cost to get from the states to here. But then the guy I got them from just went with US postal service and could probably have got it cheaper too.

One other thing to think about when sand casting if you are not burning out is that it may also need core boxes or loose pieces printing so the part can actually be cast and the pattern pulled from the sand which will all add to the costs

[Ketan SwaliParticipant @ketanswali79440]

Posted by Ennech on 18/02/2015 12:37:13:

On the subject of shipping costs…..I wonder how ever the Chinese can be so rich shipping their stuff all over the world!

Eric,

There is no simple answer to this. All I will say is 'there is no level playing field'.

examples:

a. China and India are still regarded by the developed nations of this world as 'third world countries' in terms of import duties. Imports from China into E.U. attract very low duty rates. the same is not the case if you export a British made product to China. For example, into U.K. we pay maximum 2% import duty on Chinese origin goods, where as exporting to China – China import duties are 50~60% +

b. Regulatory and compliance requirements in developed countries are far more strict in comparison to China = more cost for a British manufacturer.

c. Chinese work legally as well as illegally through platforms such as eBay and Alibaba, and the average model engineer who 'imports' from there is very happy and satisfied with the 'facilities' these guys provide to beat the systems in their countries.

I could carry on. Perhaps our politicians will get their heads out of their anuses one day to see the light. Heres to hoping..

Ketan at ARC

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