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.

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.

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

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.

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

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

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.

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.

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

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!

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

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