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  3. 【F1】GE, a large American conglomerate, is now proposing to make ultrasound transducers by "additive"manufacturing—or three-dimen

【F1】GE, a large American conglomerate, is now proposing to make ultrasound transducers by "additive"manufacturing—or three-dimen

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问题 【F1】GE, a large American conglomerate, is now proposing to make ultrasound transducers by "additive"manufacturing—or three-dimensional printing, as it is also known. A new laboratory at the firm’ s research centre in Niskayuna, New York, is taking a hard-headed look at the technique, which some see as a fad and others as the future, and working out which products might be made more efficiently by addition rather than subtraction.
【F2】The GE process for making a transducer begins by spreading onto the print table a thin layer of ceramic slurry containing a light-sensitive polymer. This layer is exposed to ultraviolet light through a mask that represents the required pattern. Wherever the light falls on the polymer it causes it to solidify, binding the particles in the slurry together. The print table is then lowered by a fraction of a millimetre and the process repeated, with a different mask if required. And so on. Once finished, the solidified shape is cleaned of residual slurry and heated in a furnace to sinter the ceramic particles together. More work will be needed to turn the process into a production-ready system. But Prabhjot Singh, who leads the project, hopes that it will be possible to use it to make not just cheaper ultrasound probes, but also more sensitive ones that can show greater detail.【F3】Although researchers have had new transducer designs in mind for years, it has been impractical to construct them subtractively. Additive manufacturing could change that.
The new laboratory will look at other forms of additive manufacturing, too.【F4】Some 3D printers spread metal powders on the print table and sinter the pattern with lasers or electron beams, rather than using masks. Others deposit thin filaments of polymer in order to build structures up. GE is interested in how the technology could be used right across the firm’s businesses, from aerospace to power generation and consumer products, according to Luana Iorio, head of manufacturing technologies at GE Global Research.
The gains include less waste and the ability to make bespoke parts more easily. But one of the most compelling advantages is freeing designers from the constraints of traditional production. Those constraints include having to design things not in their optimal shape but to be machined, often as a series of pieces. Additive manufacturing can combine parts into a single item, so less assembly is needed. That can also save weight—a particular advantage in aerospace.【F5】These new production opportunities mean manufacturers, big and small, are about to become a lot more inventive.
【F3】
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答案多年以来，压电式换能器的研究者们一直都有新型设计的想法，但应用“对比相减式”的加工流程实际上很难能把这样的构想变为现实。
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