How long until we see 3D printed components in boat building?

Could the 3D printer produce wax models to be used for lost wax casting?

If so, it could be used to produce short runs of, for instance, bronze fittings.

 

This is already common using investment casting. Which is pretty much a high tech version of lost wax casting. The molds are faster to produce with a printer than with traditional methods, and allow for more form freedom.

The downside is that cast parts are unpredictably weaker than a machined part, so they are not sutable for structual members. While some will come out of the molds perfect, others have voids that can't reasonably be detected until the part breaks.

 

Yeah, I just put the quote there to illustrate that its probably much more attractive to use sintring with Ti than Al as Ti expensive to machine, waste material is pricey and its easier to sinter than Al.

Naturally printing (whatever you call it) allows structures previously impossible to be made. For example a mast could be done with internal webbing, varying thicknesses and internal ribs or whatever would be considered ideal.

 

I saw such sintered titanium components on C Class at Falmouth this summer. Stuff that would have been very difficult to fabricate in other ways. Was mightily impressed.

 

Well first off laser sintered titanium isn't exactly the same as a part milled from bar stock. One of the diffs is that the strain properties are not exactly the same and its possible to have voids from the sintering process. So QA ends up having to go up for the new processes.

As for complex parts being faster/cheaper with sintering - only a very very small handful of structures fit this diff. mostly things that have complex interior hollows

Yes for lost wax casting this can be done, but there ends up needing to be a manual stage, precisely because wax is so easy to melt, you end up having to hand fair it. A more effective method is to print partial molds for the wax that you then manually assemble - assuming its a complex part.

So the crossover between cost for most 3D printing outside of prototypes comes at fairly complex parts. That's because a dedicated milling robot can mill much much faster and cheaper than laser sintering can. Remember that sintering requires a specialized environment to prevent contamination of the material itself. Not a problem when you aren't building something that isn't heavily loaded but a real issue if your design relies on material properties

 

More and more parts for commercial airliners are created faster , cheaper stronger with sprayed TI.

Their Quality Control is one of the toughest in the world.

 

Some parts are ok that way. You also have to remember that airlines can afford the high cost tooling machines.

 

Fast Fred,

What process are you talking about?
I'm familiar with others besides "sprayed Ti"

 

> The downside is that cast parts are unpredictably weaker than a machined part, so they are not suitable for structural members

Are they truly not suitable or can they be tested and then used?

 

Jonr,

If it is critical to use casting for some reason, there are some parts that could be cast then tested (like a tension rod for instance), but they need to be individually tested which becomes very labor and time expensive very quickly. There are some other issues as well...

the cast part must be stronger. Let's say you need a part with a strength on 10,000 lbs. with a machined part you can assume that any part off the line will meet these requirements (if it was designed properly). But the cast part has to be tested to 10,000lbs to ensure it won't break at 9,000lbs. So really the part needs to be designed to be at least 10,001lbs. In practice the part is often designed more like 15% stronger when cast and tested than the same part that is machined. This is a lot of extra material, extra weight, and extra work.

 

As Stumble said, the cast part should always be expected to be heavier for the same saftey and load.
Actually in his example the cast part should be tested to 11,000#.
However, if you use appropriate factors, you really don't need to test each individual piece, unless you are only making one. With a one off you don't have history and a consistent process for you to trust.

Cast material is typically more brittle, breaking with less deformation before complete failure than a similar part machined from a wrought material form.

Of course, if you were making something from printed material, you probably would need an even greater saftey factor, unless you have done a complete material property study for that process.

 

And that's part of the problem with the sintering process. Essentially each pass of the laser is a unique "casting" step. And the heating/cooling stresses induced are different than those of casting and different yet than those of machining

 

Until you have significant material property data, the simplistic "everything is different" is not really very useful.
At work, a Ti welded wire process produces "cast" structure, but the material properties are within a few % of the forged/ machined properties.

You need hard defendable numbers to criticise or support. Everything you said is true, but the conclusion is not defendable.

 

I have had 3D printed waxes turned into AL castings. No problem at all, they were of excellent quality and the shrinkage factor is easily scaled in the 3D file.
Mainly in LM 25 material and heat treated to T5 or T6, so mechanical qualities were good. That was eons ago relatively, not had any Titanium done though we looked at it seriously for one project.

In the end the volumes 5,000 per year minimum 25,000 parts and handed so double that, warranted metal injection moulding in Stainless Steel. Now that, if you can afford the tooling is brilliant. Qualities of near forging but precision of injection moulding.

Had sintered nylons done and used for testing with UK mains water pressure ie a valving system min 80 psi + sometimes more than double that. It was pretty good, required a very small ammount of hand finishing on seal surfaces but minimal.

 

UpChurchMr

Its true I'm not actually designing these parts -and actually I've only been peripherally in the biz for the last few years. but I was very active in the industry when they were first coming out and while there are workarounds for many of the issues, they are not going to be the lowest cost or most effective design path in a ubiquitous manner.

Where they fit in the boat design process is exactly the way Bora Gulari used them on his moth: a fast path between a one-off model in CAD and actual implementation as a molded part.

But that's for expensive custom work.