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甘比英文拓展写作-3-D printer-Jo
Day 18 2017-02-05 Sunday
hours, words
1 hour, 213 words
Essentially, a 3-D printer uses molten plastic to produce a prototype, one (2D) layer at a time.
The plastic it uses is easy to melt and quick to set. Therefore, ABS is usually and ideally the material of choice, for this unique plastic melts at a little over 100 degrees centigrade (220 F) and quickly cools down to form a solid at room temperature. Besides, ABS’s whitish color makes it possible to paint the finish with pigment, rendering the prototype more accurate in intended color and thus appearance. Other than plastic, however, the raw material for 3-D printing can theoretically be anything from sugar, chocolate, to (valuable) stones that can be melted for the nozzle to squeeze out to form a solid later on.
To ensure precise printing, the plastic is fed in filament and extruded through a nozzle under the control of computer following a digitally designed pattern. The nozzle extrudes the molten plastic on a base that is moving horizontally back and forth in a fixed area. A 2D layer is formed in one such movement and, after this one hardens and sets, another is formed on top. Then, the two layers are fused in between with adhesive or ultraviolet light. Such mechanics goes on upward until a prototype is finished.
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