additive manufacturing 2

[crazylazy]

looking to get a part prototyped using the above method.

having read about the amazing cost effective process that is additive manufacturing (in all its various forms) i decided to give it a go, the problem though is size.

all current systems seem to have a work envelope averaging 250 x 250 x 250 (mm)

my part is approx 20 x 20 x 508 (mm)

is their a machine currently able to produce this part?

 

[dgallup]

Can you split it in two and glue the parts together?

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[crazylazy]

i dont really want to redesign the part to do this.

im quite happy to stick with machining the part from a billet, but i wanted to explore this option first - in the interest of saving time and money.

 

[EdStainless]

You save money by saving time with AM. It is not uncommon to break parts down into smaller units. Either make them all by AM or only make the complex ones that way and machine the simple ones, then weld, braze, or diffusion bond the pieces together.

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Plymouth Tube

 

[crazylazy]

edstainless,

i don't know a lot about welding, brazing or diffusion bonding.

the part will be subjected to pressures around 40-60,000 psi and high temperatures, will it hold up against these without failing?

 

[cloa]

Brazing definitely not as the brazing metal has lower melting pointing than the base metal. Good welding with great quality control should as good or even better (due to higher alloy additions) than the base metal. Diffusion bonding is probably OK as it uses the metal to bond to itself. Welding or DB quality depend on many factors as always.

 

[crazylazy]

Thanks cloa and Edstainless I will look into those processes.

For people who may also be interested, I've also done a little more digging and found a company called ExOne who produce a machine called the M-7. This has a build envelope of 780 x 400 x 400 mm, but prints a binder onto the powdered metal, which then has to be sintered. Still for a complete part with complex geometry (using most of the build area), it would take approx 2-3 days which is still fast.

To me the whole point of Additive Manufacturing as Edstainless pointed out was to save money by saving time, chopping a part into several pieces or adding in another process, kind of negates the original advantage of saving time and money.

I'm sure there must be a reason for the limited build envelope, maybe an issue of maintaining quality of a larger build?

 

[btrueblood]

Realize that as the binder is baked out, and the powdered metal sintered, some shrinkage may/will occur. I don't know of any bit-wise additive manufacturing process for metals that doesn't have this issue. Further, the resulting sintered part will be fairly porous, which will reduce its mechanical properties, and it will likely leak if it is intended to be a vessel of some kind. Those issues can be solved by impregnating the part, either by sintering it with a filler (copper works for steel/stainless steel, you basically lay a slug of copper on the part, and it melts and fills the pores), or if the mechanicals are ok for you and you just need it sealed, a polymer sealant.

An alternative that works if you need a metal part without the above issues, is to make a plastic (or better, wax) copy of what you want, plus shrinkage, and then send the piece to an investment casting foundry. They will form a ceramic shell around your plastic/wax form, burn out the plastic leaving the shell, and pour the metal of your choice into the mold.

 

[crazylazy]

Machining from a forged billet (after stress relieving) will have better mechanicals over casting the part (to my knowledge).

I wanted to look for a viable option to reduce waste, tooling, and manufacturing time. Additive manufacturing sounded like the answer.

 

[rakuday]

Hi,

There are several methods of AM available and with different materials, ranging from plastics, resins and metals.

Please note that the parts made out of the above process are primarily used for form and fitment testing of components in the preliminary stages of design. These are also used for rapid tooling, where multiple prototypes are made within a short span of time.

Though you have not mentioned the exact nature of the part to be prototyped, you have mentioned that the part will be subjected to 40-60,000 psi.

As others have pointed out, the metal prototypes have their own limitations and I have my own doubts of how well the end objective will be achieved. Also note that, generally the strength of the components will be weak in the Z direction (vertical) and you have to consider this while prototyping and planning your tests.

With regard to the size of the component, I presume it to be a long and slender part, parts of this nature can be oriented in various ways to prototype within the average envelope.

Thanks

 

[crazylazy]

Thanks rakuday,

I wasn't aware of any weakness along the vertical axis. I have taken on board all the good advice posted and don't think AM is suitable for my part. Interestingly, having had a brief look at investment casting and hot isostatic pressing, this may be a route to explore.

Ultimately though, like all things, it will come down to cost and speed.

Thanks to everyone who posted!