So great is the attention devoted to 3D printing that one might forget that industry is loving 3D printing, too. 3D printing of metal parts, not so long ago thought to be an expensive specialty of a few hardware vendors, is so hot that 3D metal printer vendors cannot keep up with demand.
"We try to get one of our 3D metal printers in our showroom but it's bought before it's finished and goes right to the customer," says Rachael Dalton-Taggart of 3D Systems, which bought metal 3D printer company Phenix in June, 2013.
A Revolution Starting?
BMW is planning to make all of its engine cores by 3D printing within the next 10 years, according to ExOne CEO David Burns, whose 3D printer company raised $90M after its IPO.
If you were used to 3D printing trinkets and just starting to believe that metal may be usable in one-off parts, may be small batches, statement of intention by a major manufacturer using 3D printing for its mass production ought to have made you sit bolt upright.
The appeal of going directly from image onscreen to real life as promised by 3D printing is unmistakable and understandable. Being able to do that in metal... not so much. Metal is ground down to a powder and re-solidified in a 3D printer machine. The concept may be simple, lay down the powder, apply heat and there's your part. But there must be more to it. These metal 3D printers are the size of toolsheds. I'm hearing prices from $700k to over a million.
We Love Metal
With mankind, it was love at first sight. Engineers love and trust metal. It has built our bridges, sent people to the moon, we won't have a car without it. Our eras are marked with names of metals, the Iron Age, Bronze Age. Sure, plastic are super, they can be engineered to have some great properties, they're lighter, they get better every day. But they're still not metal. For the strongest, most reliable, most trustworthy part...we'll keep using use metal.
So, now I can get metal parts directly from my computer? No machinist, no CNC machines, no waiting. Where do I sign?
What's the Catch?
- Density. Getting powdered metal back to its solid state, or even close, can't be that easy. Powder particles will have space between them, no matter how tightly they are packed. "We get 99.5% density in our Inconel process," says David Burns, speaking of his latest metal alloy Inconel 665. "They said it couldn't be done."
- Strength. Metals have been made strong by alloying, heat treatments and forging. Most 3D printing methods cannot include these methods. king stronger metals. So is forging. Toughness and strength , probably no better exemplified than by the beaten blade of Damascene steel or a Japanese sword -- is still a long way away with 3D printing.
- Voids. Does the process of sintering, melting powder produce voids? In all fairness, probably the pouring of molten metals into molds may have that risk, too.
- Cost. The powdered metal that must be somehow solidified is costly on both ends. It takes energy -- a lot of it -- to grind solid metal into a powder that is used as the raw material for a 3D metal printer. Then it takes a lot of energy to melt that powder so it solidifies. Then there's the cost of the machine...
The biggest allure of metal parts by any 3D printing process is pure and simple: you can create a design, push a button to get a part made. There's not even a machinist in the picture. And other than the wait for the part to emerge from the machine, there is no other waiting, no scheduling or coordination with other departments. If you own the machine, the process could not be any more straightforward. True, the machine may cost in the neighborhood of a million dollars. That's worth it to big companies like Boeing and BMW.
I hear of a Boeing aircraft part that gets made in a day on an ExOne machine -- as opposed to 10 months.
A Ford engineer makes a part and opens the hood of a Mustang, bolts it into place, and drives of to the test track.
In both cases, they have short circuited processes put into place over years that drag out design cycles and involve many people. Suddenly, a million dollar machine looks like a bargain.
Production, Not Prototypes
Again, these are metal parts that works in real life environments, not a plastic replica that could be used just for show and tell. The gains being made with 3D printing are pushing parts into production.
Material research is the key to the revolution. "We are concentrating our R&D efforts on materials," says David. "In fact, our machine design improvements are close to a standstill.
I imagine factories of the future being banks of 3D print machines.
What Stopping the Revolution?
It all sounds ideal, parts from your computer, in metal, in large volumes. No set up, no wait, no "middlemen."
According to Dave, the reason he's not sellig way more metal 3D printers is the massive inertia inherent in the system. Metal cutting does work and has worked for a long time. How something is done in the past is being used as justification of how it should be done in the future. Change is risk. A factory manager won't get fired for getting another Mori Seiki 5 axis CNC machine, but will he go out on a limb and have all his CNC machines replaced by some new fangled technology? And what to do with all the machinists?