1975 Pratt & Whitney laser turbine disk demonstration

Earliest known metal 3D printing — a 25 kW laser making a five-inch turbine disc, one month per disc. Proves the physics works but unaffordable.

Pratt Whitney developed the 25-kilowatt laser back in 1975, sort of a research-type thing. They said, why don't you make a turbine disc? They gave them a million dollars or something. It took them a month to make a six-inch turbine disc. They had a manual setup and it went around and around. But because the laser has such a high heat intensity, if you try to put in more heat you just evaporate more off the surface. So you can't get more heat in, and with the very thin layer they were laying down, it took a month to make a five-inch-diameter turbine disc. They did do 3D printing of metals back in 1975 — just unaffordable financially.

$75K ONR contract; 25 kW research laser; month to make a 6-inch disk on a $2M machine. Feasibility demo, not economic.

I think I told you that back in 1975 the Office of Naval Research gave a seventy-five thousand dollar contract for Pratt and Whitney to take their twenty-five-kilowatt laser, which was like a half-million-dollar research laser, to make a turbine disk by laser glazing, they called it. They took the powder and they poured the powder on, and then the laser came in and melted it to make a part about six inches in diameter, which they then spun and did a test to see if it had super strength — was it carbon nanotubes types of strength. Took them a month to make a six-inch diameter part on a machine that you could buy for about two million dollars back then. So how economical do you think? It wasn't economical at all, and no one even considered that. It was an attempt, a demonstration to show feasibility.