US Air Force turbine vane repair program (DAABER)

The "dabber" — arc welding machine to rebuild worn turbine vane tips. Five-hundred-dollar vane, couple hundred dollars repair, three thousand more hours of life. Ten-million-dollar automated machine in Oklahoma City repair facility making fifty million on the blades. Used to argue that we have been doing additive manufacturing for eighty years on high-value-added parts.

So the question posed to me by the Technology Review editor was, why don't we do 3D printing of metals? At the end of spending an hour with them, I said, but in fact we do, and we have been for eighty years. For example, the US Air Force about twenty-five years ago decided they needed to rebuild the tips of turbine vanes. These vanes go into a jet engine, they're spinning around, they get hot, they creep and get a little longer, and they wear out the top edge. They wanted to rebuild them — the thing's still good for another three thousand hours of use. They built a little arc welding machine, called it the dabber, and they would build up the edge and machine it back. You're talking about a vane that might be worth five hundred dollars — you can afford to spend a couple hundred dollars to repair it if you're getting a brand new vane. High-value-added part, high heat intensity, very limited geometry. They grew the thin vane an extra quarter of an inch, and then reamed it; it's not critical, it's not a lot of stress on it in service. The big stresses are down at the base where you have the biggest centrifugal forces. The tip doesn't.