【英语生活】3-D印制技术的工作原理

People have traditionally made things─from doorknobs to scalpels to engine cylinders─in one of two ways. They start with a solid block or sheet of metal, wood or other material and cut, stamp, drill or shave it to create a desired shape. Or they use a mold made of metal or sand, pour liquefied plastic or metal into it and let it cool to create a metal casting or molded plastic part.

Now for something completely different.

Three-dimensional printing and other forms of what is known as additive manufacturing use neither machining nor molds. They build an object from the bottom up by piling razor-thin layers of material on top of each other until a three-dimensional shape emerges. The computer-guided technologies enables individuals to create objects, particularly prototypes, without a shop full of metal presses, cutting lathes or plastic injection molds.

There are a variety of processes for 3-D printing. Some of the most widely used rely on a printer that makes objects from powdered material. A 3-D printer bears little resemblance to a document printer in an office. It has two major parts: a 'build box' that contains a smooth, thin bed of finely ground material such as pulverized stainless steel or powdered plastic; and a printing head. Depending on the type of printer, the head contains either a heat source, such as a laser or an electron beam, that melts the powdered material or jets that spray binder over the powder in a precise pattern. The binder functions as a glue for the material as an object is built.

The world-wide market for 3-D printing, which includes materials, machines and service, totaled $2.2 billion last year, up 29% from 2011, according to industry estimates. But the process has some limitations. For high-volume jobs, 3-D printing can't yet match the speed and efficiency of traditional fabrication methods and machinery. Not all materials are suitable for powder-based additive manufacturing, and not all objects, particularly those made of metal, are able to stand up to high-stress use. For manufacturers of 3-D equipment, the future of their nascent industry depends on broadening the appeal of their equipment by expanding its uses and versatility.

The accompanying graphic shows how some common forms of 3-D printing work.

Bob Tita

不论是门把手、手术刀还是发动机气缸，人类一般仅通过两种方法制造物件。其中一种是，首先选取一块（或一片）金属、木头或者其它原材料；然后通过裁剪、烙印、钻孔或者切削等工艺制成他们想要的形状。另外一种则是把液化金属或者塑料倒进合金或砂砾制成的模具中，冷却后制成金属铸件或塑料成品。

如今，颠覆性的事情发生了。



3-D印制(Three-dimensional Printing)和其他被统称为“添加剂制造”(Additive Manufacturing)的生产形式既不属于机械制造又不属于模具制造。这项技术通过堆砌刀锋般纤薄的多层材料形成三维立体形状，并逐层打造物件。此项电脑技术让人们能够不用再去那些装备着金属印压机，切割车床或注塑模具的店铺，就能自己打造物件，尤其是模板类物件了。

据业内人士估计：3-D印制行业（包括原材料，设备和服务等方面）在2012年全球范围内的市场总额达到了2.2亿美元，较2011年同比增长29％。但这一发展也有些局限性。对于规模化生产，3-D印制尚未能在速度和效率方面与传统的制造方法以及机械化相提并论。而且，并非所有的材料都能适用粉末添加剂的制造方法；也不是所有的物体，特别是那些由金属材质制成的物体，能够在高强度下经久耐用。对于3-D设备的制造商，这项新生行业的未来取决于他们如何通过扩大3-D印刷机的用途和多样性来增加其吸引力。

附图阐述了一些常见的3-D印刷机的工作原理

Bob Tita

（本文版权归道琼斯公司所有，未经许可不得翻译或转载。）