Once completed, the part will be milled inside and out using a Thermwood five-access router that can operate on the x, y and z planes and rotate in two directions. The remaining parts will then be attached, including a 48-volt Renault powertrain, battery, motor and battery controllers, taillights with integrated turn signals, headlights, steering wheel apparatus, wheels and an electrical wire harness. Steel fasteners will be used to affix the motor and battery.
The additive manufacturing system, which Local Motors and ORNL developed from the model already on site at the lab, is being built by Cincinnati Inc. It is a gantry-style printer that can print objects as large as 12 feet long, 6.5 feet wide and 3 feet high.
Local Motors printed the prototype vehicle at ORNL in June. Because the test printer was smaller than the one that will used to build the Strati at IMTS, the prototype was printed in multiple parts that were fastened to an aluminum sub frame. It took 30 hours to print, while the company projects the Strati will require 60 to 80 hours. Rogers says the company will likely start printing the Strati a day or so before IMTS so that it will be finished halfway through the show.
Once completed, the Strati will operate within an 80 to 100-mile range at speeds of up to 40 mph. The first customer will be the Association for Manufacturing Technology, which signed a contract for the vehicle built at IMTS. Other potential customers may have to wait a little longer: Local Motors has no plans to offer the Strati to the public immediately following the show.
The Strati is a technological leap for additive manufacturing, advancing car production from multiple parts with a metal frame to a single 3-D printed composite main body. CFRP adds rigidity and strength to the ABS plastic and combats thermal contractions, says James Earle, an advanced materials engineer with Local Motors. He adds, “This simply couldn’t be done without composites.”