现在，利用3D打印制作汽车部件原型的想法，已经真正变成了一种省时省成本的成熟技术。一家立志于用3D打印技术打造整车的初创企业Local Motors，不仅在北美国际汽车展上展示了他们的先进技术，还将一辆汽车驶入了展区内。该公司的生产系统名为BAAM（大面积增材制造），可以实现大型部件的3D打印制造。

3D打印机制造商Cincinnati Inc与美国能源部下属的橡树岭国家实验室曾达成一项协议，共同开发BAAM设备与生产流程。Local Motors的项目是该领域中的一项尝试，也是第一个通过“打印”技术制造汽车的项目。

雷诺电动车的“City Car”部件

当然，整辆车是无法直接打印出来的，但3D技术却可以打印出完整的车身和底盘。Local的展车搭载了雷诺电动汽车的部件，该部件来自“City Car”的Twizy，据称是一辆最高转速为25mph（40kph）的社区用电动汽车。在Local公司对其进行了碰撞测试和其他测试，完成了铣削等加工工序，使其成为一辆可以出售的成品车之前，它还仅属于概念车的范畴。Local公司表示，雷诺并非其机电部件的指定供应商，选择雷诺参与原因很简单，是因为他们不仅适合该项目并且有实力。

车身与底盘，甚至小到茶杯架这样的细节，都是分成多个层面制造的，每一层都有独自的刀位轨迹。使用的原料是粒状的碳纤维复合材料ABS，比3D打印通常使用的塑料线便宜得多。Local公司正在进行试验，希望可以使用浓度范围为13%-20%的碳纤维。他们的材料供应商SABIC是一家业务涉及面广泛的化学品与塑料生产商，可提供聚烯烃、聚乙烯、聚丙烯等塑料原料。

凡是车中不涉及到机械或电子功能的部件，都可以整合成一个整体，而座椅和座垫则在Local Motors的一家工厂单独制作。

Local公司所展示的这辆车离成品还非常遥远，从图上就能看出这点。它的层次还相当粗糙，而且尽管机械铣削和多色制造并非高不可攀的尖端技术，但它们仍需得到验证。

在现阶段，观众看到的只是一个多部件的结合体，而且车辆的主要结构部分无论在3D打印还是铣削工艺方面，都需要大大提升精度。而要从一辆酷似高中生手工作业的项目作品提升至可以出售的商业产品，其中所面临的挑战巨大，远不只是将3D打印领域多年来只专注的小型部件变得“更大、更多”那么简单。因此，从证明工艺可行性到生产出可售的汽车，这一过程可能会比较漫长，而Local公司所预估的两年时间，也许是比较乐观的判断。

打印时间44小时

Local的首席执行官Jay Rogers称，这辆名为Strati（意大利语中的意思是“层次”）的展车的生产时间为44小时，但他相信一辆完整的汽车可以在一天以内生产出来。公司将汽车的目标售价范围定在1.8万-3万美元，并将客制化作为其卖点，他希望这一点可以通过软件的改变来实现。

这辆车是Local能够在全球召集到的10万名工程师共同参与的研究成果，由公司内部团队负责最终验证，该团队位于亚利桑那州的钱德勒。Rogers表示，做出贡献的工程师们将根据其贡献的重要性转换成的一个专利税点数，并获得相应报酬。Local打算在全美范围内开设小型工厂，每个厂房的造价约为800-1000万美元，生产力约为3000辆/年，每家工厂将配置5台或更多的3D打印机与铣削机，实现流水作业模式。

Rogers表示会在田纳西州靠近橡树岭国家实验室的地方开设第一家工厂，而第二家工厂计划开在马里兰州的国际港，那是一个靠近华盛顿特区的商业开发区。如果成功，他还打算将小型工厂的计划扩展至其他国家。

从电动汽车到越野车，再到摩托车，3D生产理念已经渗入到各种机动车辆的生产中。在一个基于计算机技术的，生产工艺快速发展的时代，Local Motors可能有足够的远见，已经能够看到未来的完成品的模样。如果它能将车展上那辆尚在基础阶段的展车提升为接近组装车的产品，那么未来的市场就在前方。值得嘉许的是，除了安装了机械和电子部件外，Local Motors并未使用任何手工精加工技术来伪装它的作品。这家公司坦诚地表明了自己的态度：这就是我们现在的实力，而我们的未来，请大家拭目以待。

The idea of using 3-D “printing” to perform rapid prototyping of many automotive parts has become a well-established technology to save time and money. But Local Motors, an ambitious startup that intends to build complete cars, demonstrated its technology at NAIAS, and showed a vehicle that it drove into its display area. The production system is called “BAAM,” for Big Area Additive Manufacturing, which is a description for 3-D manufacturing of big parts.

Cincinnati Inc., a maker of 3-D printers and the Department of Energy's Oak Ridge National Laboratory have an agreement to develop the equipment and processes for BAAM. Local Motors project is just one of the efforts in this area, and the first seeking to "print" a car.

Renault EV "city car" components

All right, the entire car can’t be printed of course, but a complete body and chassis can, and the Local show vehicle is equipped with Renault electric vehicle components (from the Twizy, a “city car,”) and described as a neighborhood EV with a top speed of 25 mph (40 kph). Until Local has gone through crash and other testing, and milling and other work, to produce a finished car that can be sold, it is in the proof-of-concept category. Renault is not a designated supplier for the electrical and mechanical componentry, and was used simply because of suitability and availability for the project, the company said.

The body-chassis, down to the cup holders, is made in layered sections, with specific toolpaths for each layer. The material is a carbon-fiber composite ABS that is most readily available in pellet form and much less expensive than the more common filament plastic that normally is used in 3-D printing. Local is experimenting with carbon-fiber concentrations ranging from 13% to 20%. SABIC, which is supplying the material, is a diversified producer of chemicals and such plastic materials as polyolefins, polyethylene, and polypropylene.

Every part of the car that is not mechanically or electrically involved is fused into a single piece. Seats and cushioning will be made in a Local Motors facility.

The demonstration vehicle that Local drove into the show display is far from a finished vehicle, as a look at the illustrations indicates. The layering look is crude, and although robotic milling and multi-color manufacturing may not be insurmountable challenges, they still have to become proved processes.

At this stage the viewer sees an assemblage of parts, with one major structure that needs much more precision in both the 3-D process and the finish milling. And taking what presently resembles a high school hand-built project car to a level that will command the necessary price for a business case may be a greater challenge than just "bigger and more" of the smaller parts for which 3-D production has been used for many years. So the road from proving the process to making salable vehicles may take longer to travel than the two years in the company's optimistic projections.

"Print" time is 44 hours

Local CEO Jay Rogers said that production time for the show vehicle, called the Strati (layer in Italian) is 44 hours, but his belief is that a complete vehicle can be built in a day. The company has a target price range of $18,000 to $30,000 for vehicles, with the appeal in the idea of customization, which he hopes would become primarily a matter of a software change.

The car was the achievement of an engineering community of 100,000 worldwide that the Local startup was able to assemble, with central validation by an in-house team in Chandler, AZ. Engineering contributors will be paid on a royalty basis according to the importance of their work, Rogers said. Local intends to set up micro-factories throughout the U.S., each with an estimated cost of $8-10 million for a production capacity of about 3000 units per year, from five or more 3-D printers and milling machines, which operate in series.

Initially, Rogers said, there will be one factory in Tennessee, close to the Oak Ridge National Laboratory. A second is planned for National Harbor in Maryland, a commercial development close to Washington, D.C. If the approach is successful, he said, he envisioned micro-factories in other countries as well.

The 3-D production concept lends itself to a wide variety of motor vehicles, from EVs to off-road to motorcycles. In an era of rapid improvements in computer-directed processes, Local Motors may merely be visionary, able to see its finished projects of the future. If it can go from the rudimentary look of its NAIAS show vehicle to something more akin to kit cars, it could find a waiting market. To its credit, Local Motors did not try to disguise its vehicle with hand-finishing, beyond the installation of the electrical and mechanical parts. It delivered an apparently honest "here is where we are now, but watch us" presentation.