Bending Metal With a Powerful Laser
New Laser Helps Form High-Endurance Metals Cheaply
When it comes to forming tough metal parts that can bear repetitive heavy stress and strain — say, a jumbo jet's landing gear or artificial knee implants for humans — the key is lots of heavy-handed pressure.
Peening, a process of hammering away at a piece of metal to strengthen it, has been used since the early days of the first blacksmiths. But forget about images of a sweaty smithy swinging an old-fashioned ball peen hammer. The metal industry is in the process of implementing a new peening tool for the 21st Century — one that generates a tremendous amount of pressure with literally, the lightest touch.
A new high-powered laser developed by scientists at the Lawrence Livermore National Laboratories in Livermore, Calif. holds promise to improve upon so-called laser peening.
Lloyd Hackel, program manager for laser science and technology at the lab, says the new LaserShot Peening System works much like other laser peening systems.
When high-intensity laser light strikes the metal, the beam creates a miniature shock wave that pushes the atoms of metal closer together. By reducing the microscopic spaces, the metal becomes more resistant to stress-induced cracks and fissures.
High-Pressure Light Beam
But the key to LaserShot system is a powerful new "neodymium-doped laser" first developed by the lab years ago under a DARPA contract that called for a a laser strong enough to illuminate space-based satellites for high-resolution pictures.
"The laser runs 25 times faster than any other laser in the world," says Hackel. "It has a peak power output of a billion watts for 20 nanoseconds. That's the [power] output of a huge electrical power plant for a city neighborhood."
Bringing such tremendous power onto a pinpoint piece of metal for just billionths of a second creates a huge microscopic shockwave — and pressures up to one million pounds per square inch, says Hackel.
And the new laser is fast, producing five high-pressure pulses every second. The best conventional lasers, meanwhile, can produce a pulse only once every four seconds or so, says Hackel.
