Stainless filament

[Ali]

Stumbled across this

https://www.123-3d.co.uk/pdf/DFB00013_UserGuidelines_EN.pdf

You apparently print it on conventional FDM / FFF (with shrinkage factor), and then send it for sintering (or, do it yourself if you have the equipment). Part in 316.

Wow.

Disclaimer: haven’t read much, sounds exciting though.

 

[Screwdriver]

Wow. That's a very interesting find.

TLDR: your parts are going to shrink by 20% (!) during sintering.

 

[Ali]

I might be able to justify getting some of this on work expenses for ‘R&D’ purposes, as it could be a game changer in the medical industry. The cheapest dedicated metal printer I’ve seen is around £65k, not including all the post-processing / heat-treatment gear. I’ll report back if I’m allowed to buy some.

 

[hotponyshoes]

I might be able to justify getting some of this on work expenses for ‘R&D’ purposes, as it could be a game changer in the medical industry. The cheapest dedicated metal printer I’ve seen is around £65k, not including all the post-processing / heat-treatment gear. I’ll report back if I’m allowed to buy some.

You'll just need a kiln that will hit 1200c.
Using fuel for about a day.
As the saying goes, ask the bill payer's permission first..

Its already well in use in the medical industry and filtering down to vetinary as well.

I'm not sure there are enough advantages for it to become a game changer?
I suppose if you have the space and inclination to run the kit required it's cheaper than getting a metal printer although check the costs on that if you only need small parts as there is probably not much in it now.

If you are not investing in all the kit needed I don't really see the point in it.
If you have to send it off for finishing you may as well just order it for print and delivery in the first place?

 

[hotponyshoes]

Wow. That's a very interesting find.

TLDR: your parts are going to shrink by 20% (!) during sintering.

TLTDL here. The guides I have seen say 20-25%,
That's too vague for me, if it was 20.5% fine, you just scale the print up by 20.5%

Having said that, I've got a few things I'd like to make out of stainless that would be far too time consuming to do manually and too costly/complicated to do via machining and wouldn't matter if they were +/- 5% of the drawn size...

 

[PhillipM]

It's been around a long time, problem is like most sintering operations your shrinkages aren't linear so it's either expensive trail and compensation per model or just as expensive CAD simulation software to get it right first time.

In the end it works out cheaper just to have stuff laser sintered out of stainless.

 

[Screwdriver]

I imagine it's use will be aimed ideally at complex organic shapes, manifolds which would be impossible to make with subtractive manufacturing. I think Elon Musk has taken this to the n'th degree with SpaceX extraordinary raptor engines. Also good for turbine rotors and the like.

But the shrinkage is a real issue and you'd probably want to allow for some post processing and finish machine critical dimensions.

Anyone know what the costs look like? cost of the filament, cost for sending it off to be sintered?

 

[hotponyshoes]

I imagine it's use will be aimed ideally at complex organic shapes, manifolds which would be impossible to make with subtractive manufacturing. I think Elon Musk has taken this to the n'th degree with SpaceX extraordinary raptor engines. Also good for turbine rotors and the like.

But the shrinkage is a real issue and you'd probably want to allow for some post processing and finish machine critical dimensions.

Anyone know what the costs look like? cost of the filament, cost for sending it off to be sintered?

£200-250 per kg for the filament in single rolls (low user)
So about 10x regular branded filament.
Although I suppose 12.5x more expensive allowing for the shrinkage.

Sintering services are a bit more complicated than just sending it off.
Each filament has fairly specific instructions so you can't just accept 20 items in the post from 20 people and chuck them all in the oven for a day or 2 on the same cycle.

Some of the bigger (industrial) manufacturers of the filaments offer a finishing service at about £50 per kg.
But only for there own filament.
No idea if they actually test your parts and refuse to take them if it's not there own material or if they just chuck them in and it's your problem if they don't come out right?

There are smaller places offering as well, generally higher prices about £250 a cycle but you get the whole capacity of the oven to yourself, or around £50 for one shelf worth but you wait until they have enough orders for the same cycle specs then they do the run.

It's taking off in the modeling/gaming crowd. Private individuals are already offering services informally for small parts for beer money.
Sooner or later they'll be selling those services to Joe public and prices will sink.

 

[Ali]

Sintering no problem, I work for an outfit who sell furnaces…

I suspect some places I know of already own the necessary post-production gear.

 

[RichardM]

oh good, you're the person to contact then.
Dan Gilbert did a YT video on it recently.

 

[hotponyshoes]

Sintering no problem, I work for an outfit who sell furnaces…

I suspect some places I know of already own the necessary post-production gear.

Well, just let us know what filament you are getting, we'll all get the same and send you the parts. Kilns must be like fridges and run more efficiently when they are fully loaded!

Or offer the full service, if I just email you the stl you can print it and post me the parts.
Might be an easy way to justify the cost of buying a roll of filament and running the kiln for your test pieces if you can gain some experience on 'non critical' parts and cover the costs at the same time?

 

[hotponyshoes]

Although,
I don't think it's a case of just putting the printed parts on a tray and sticking them in the kiln.

I think they need to be packed tightly in refractory compound. I guess that's to hold them together in the time between burning off the binder material and sticking the metal together.
No idea how you keep them tightly packed while they are shrinking 20% though?

This is part of the reason I haven't tried messing with it yet.
The same material is also available in powder/pellet form. If you were making something that was mouldable it would make sense just to use that. You could easily 3d print even complex moulds if you wanted and the mould might be enough to hold the powder in the kiln and save you the aggro of packing and tamping?

 

[RichardM]

oh good, you're the person to contact then.
Dan Gelbart did a YT video on it recently.

Fixed that for me!

 

[Ali]

Fixed that for me!

Got a link? I had a look but wasn’t sure which you were referring to

 

[RichardM]

 

[Erie Fred]

Interesting.
Looks like an offshoot of the metal injection molding method.

 

[knighty]

I'd be very interested in doing this

if I can find a step by step for the sintering process I'll order a resin printer and a furnace

 

[Ali]

It looks like this is relating to a resin (SLA) process, whereas the one that caught my attention is FDM (extruded filament). Equally interesting though, and much greater accuracy. I do also use resin printers, but the process looks a bit more involved. Working my way through the video, thanks.

 

[Erie Fred]

I just skimmed the pdf, does the furnace need an inert gas ?

 

[hotponyshoes]

I just skimmed the pdf, does the furnace need an inert gas ?

I think the high end ones use a vacuum furnace.
I don't see why you couldn't use the same methods as heat treating high tolerance parts, ie, inert gas purge or encasement methods?