内部人士和分析师预测，在我们最新的一系列文章中观看的3D打印趋势，重点是future of 3D printing。
艾德里安博士鲍耶,the founder of重复，已经制作了一篇博客文章，概述了一种新的多材料树脂3D打印方法。
Following a recentTweet that stated “SLA can’t do multiple materials in a single print”, Bowyer was met with a number of responses pointing out just how wrong he was. As is the case with any life-long learner, he saw it as an opportunity to broaden his horizons and share his own ideas on how to realize multi-material 3D printing using two or more resins.
鲍耶（Bowyer）将他的方法描述为简单但浪费的方法，因此那些确定材料的优先级的方法应该在继续之前就坐下。
树脂3D打印如何工作？
To appreciate Bowyer’s method, it’s essential to understand how conventional single-material resin 3D printing works. Vat photopolymerization, which encompasses the SLA, DLP, and LCD 3D printing technologies, involves curing photopolymer resins into solid parts.
UV-sensitive液体聚合物注入晒黑k that rests on top of a transparent film window. Underneath the window is a UV light engine filtered by an LCD mask, which exposes certain areas of the resin above to UV light. This cures the exposed areas of resin into a solid layer on the build plate. The build plate is raised by a fraction of a millimeter and the process repeats itself, curing layer after layer until the final 3D object has been fabricated.
这个过程有效，但是您的水箱中不能有一个以上的树脂，而不是没有交叉污染，因此不是一种多物质印刷品。
鲍耶的多物质方法
Bowyer’s multi-material proposal is a simple one. You could print the first layer in resin A and pour it away. Then add resin B and print the first layer again in resin B. Moving onto the second layer, you could print in resin B, pour it away, and print it again in resin A. By cycling through two resins like this, you could print every layer in a part with two different materials. To automate the resin removal process, you could angle the 3D printer towards one of its corners and drain the resins out using a solenoid valve.
Of course, this sounds too good to be true. It wouldn’t work because resin is sticky and simply pouring it out wouldn’t eliminate the problem of cross-contamination. Pouring and draining resin also results in bubbles, so those would have to be removed before any layers are cured.
To fix the cross-contamination issue, Bowyer proposes a brute force approach (this is what makes it wasteful). When replacing resin A with resin B, you could use resin B to flush away the remains of resin A, discarding the contaminated resin A-B mix. You could then pour pure resin B in, doing the same when it comes time to replace resin B with resin A.
This leaves the bubble problem. Resins have a very low vapor pressure, which is what makes them suitable for conventional vacuum resin casting. If the proposed 3D printing process were to take place in a vacuum chamber, the bubbles in the vat would be eliminated altogether.
如果这太浪费了，鲍耶还可以看到第三个溶剂被用来冲洗物质转换之间的树脂。异丙醇（首选的树脂清洁剂）无效，因为它在20°C下的蒸气压为33 hpa，这意味着它只会在真空中沸腾。但是，具有较低蒸气压的有机溶剂，例如苯胺（20°C时0.4 hpa），可能会起作用。
Bowyer concluded, “I can see no technical reasons why the process described here wouldn’t work. And it could obviously be extended to use any number of resins, not just two, allowing insulators and conductors, different filler materials, and different colours.”
As champions of open-source, Bowyer and the RepRap community have been the source of several novel 3D printing ideas over the years. The British engineer has previously detailed the design of asolenoid (a type of electromagnet) bed heater for use with FDM 3D printers。与传统的加热元件不同，电磁阀加热器还可以在关闭加热后卸下打印床。
More recently, RepRap created a novel Python script that enables users to3D print low-cost PLA beamsthat are as stiff as steel counterparts. The open-source FreeCAD program is designed to be as accessible as possible, as it only requires users to specify some very basic parameters. The script then automatically generates the entire beam in the form of a 3D printable model.
Interested in resin 3D printing? So are we! Take our树脂3D打印调查now.
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Featured image shows Dr. Adrian Bowyer. Photo via Phaidon.
