When it comes to long-distance shipping, Andrew Tool & Machining of Plymouth probably holds the state record.
Its precision-machined gear boxes are currently en route to Mars, as the moveable joints in a robotic arm on the new Mars Rover, called Curiosity.
Scheduled to land on Mars Aug. 5, the nuclear-powered, MiniCooper-sized rover will use its robot arm to sample and analyze Martian soil and rocks for signs of life. The rover is expected to function for two Earth years, or one Martian year.
That will cap what may be Andrew Tool's most arduous and unusual precision machining project. Over 18 months, the firm built about 20 different rover parts to an accuracy of two ten-thousandths of an inch, under the watchful eyes of NASA's on-site technical people.
"The parts Andrew Tool was machining are some of the most complex parts on the rover," said Richard Rainen, manager of the rover's mechanical team at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "There are just a few machine shops in the country that have the ability to do that."
The parts underwent a detailed NASA review of 190 different features on a single 4-pound gear assembly called an "actuator." The rover has three of the actuators to move the different joints in its arm. (For a NASA video of Curiosity's robot arm, see tinyurl.com/7yghj82.) Andrew Tool also made six actuators that drive the rover's wheels and four that steer it.
"Being able to hold those tolerances was the real challenge," said Bruce Hanson, Andrew Tool's president.
The equipment that Andrew Tool used to make the parts seems like something out of a science-fiction movie. There's "electrical discharge machining," in which an underwater electrical charge bores out the inside of finger-length metal pipes, and "five-axis machining" in which a part can be moved up and down, sideways and back and forth while at the same time being spun and tilted. Hanson said it is a combination of machines, human care and elaborate testing that allowed the firm to make the finely detailed rover parts.