A novel 3D printing technique suspends light-curing resin in a gelatinous medium rather than using conventional structural support material during the build process. The gel acts as an omnidirectional support material and is reusable.

The technique is the brainchild of Brian Harms， who is still pursuing a Masters in Design Research at the Southern Calif. Institute of Architecture （SCI-Arc）。 The suspended deposition method he devised has yet to be commercialized， though that could happen in the future.

The suspended deposition prototype uses a Scara robot arm with a pump and extruding nozzle on its end effector. Once the material gets deposited in the gel， it is exposed to UV for curing. One interesting facet of this method is that the build material can be ‘erased’ any time before it cures simply by sucking it back into the nozzle. Another point to note is that material can deposit in 3D vector-based toolpaths. This contrasts with virtually all other 3D printing processes where successive layers must harden before the machine can move on to the next.

The fact that the resin sits in space without support material also makes it possible to fabricate directly on and around other objects sitting in the Gel. And the build material can sit in the gel waiting while the robot arm makes a tool change， injects a different material， or implements other changes that require a pause in the action.

Harms says he‘s just applied for a provisional patent covering the basic functions of the system in the context of rapid prototyping. “There may very well be patents on file that cover some of the aspects of the system，” he says， “but in case there aren’t， I decided it would be prudent to at least get a filing date.”

Harms also calls the suspended deposition technique “purely an experimental endeavor” at the moment. He adds that he‘d like to continue researching the idea but has no specific time frame in mind for commercialization. “There’s a lot of work that would need to be done to make this process robust enough to become part of the 3D-printing market， and much of that would rely on funding，” he says. “But we do have several ideas for improving the process both in terms of it‘s interface and physical set up. One of the most pressing issues would be the design of needle-tip attachments or articulated needle tips. This would help mitigate one of the major problems we face， which is the tendency for the resin to travel up alongside the needle as it passes through the gel， leaving a temporary void.”

Accuracy and resolution is another issue. “Our needle is rather large and has an interior diameter a little larger than 1/16 inch. We haven’t experimented much with any other sizes， but we think there is a lot of potential there，” Harms says. “We are dealing with a liquid as opposed to a filament （which has a very consistent diameter） so we could actually actuate the needle opening， potentially allowing us to vary the resolution throughout the print.”

Harms says the impetus for the project arose out of pondering how a robot would handle 3D printing. “The answer for us was articulation. A six-axis robot gives us possibilities for motion that the three-axis machines can‘t，” he says.Harms’ first pump was a dual-nozzle， dual-centrifugal design created with the idea of handling multi-material injections simultaneously -- perhaps dispensing two-part resins that would only cure in the gel once the two parts had come in contact with one another. The idea didn‘t work well because the pumps put out too much material， even at their slowest settings. He ended up building his own peristaltic pump that is integrated into the tool.

Harms says the first items fabricated on the machine were a series of wireframe cubes chosen because they gave developers an idea of how changes in process parameters affected build quality. “For example， if we kept the flow rate constant but changed the speed of the robot， we would see the resin thin out as the robot sped up. So we used those objects as a way to calibrate the system，” Harms says.

“We also created a series of spheres to show that while each was identical geometrically， it could be generated using very different toolpaths （which this system affords）。 One was built using vertical as opposed to horizontal contours， one was made using vertical radial arcs， and one was done in a continuous spiral，” Harms says.

“We also printed a ring of resin that interlocked with a plastic ring that we had previously submerged in the gel. This was our sort of proof of concept for multi-material/multi-object operations，” he relates.

Harms says the suspended deposition method will probably be limited to resins for the foreseeable future. “I think metals would be really tricky just given the temperature ranges you would have to deal with，” he says. “I suppose if you were working with metals with really low melting points and you had a substrate that was incredibly insulative， you might be able to work that out. But that’s just speculation at this point.”

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3D打印新方式：懸浮物體凝固

一種新穎的3D印刷技術(shù)暫停光固化樹(shù)脂膠狀介質(zhì)，而不是在構(gòu)建過(guò)程中使用傳統(tǒng)的結(jié)構(gòu)支撐材料。凝膠充當(dāng)一個(gè)全向載體材料并且是可重復(fù)使用的。

該技術(shù)是布賴恩·哈姆斯，誰(shuí)仍然在奉行一個(gè)大師設(shè)計(jì)研究在建筑的南加州學(xué)院（SCI?。┑男难Y(jié)晶。他設(shè)計(jì)的懸浮沉積方法尚未實(shí)現(xiàn)商業(yè)化，通過(guò)這可能在未來(lái)發(fā)生。

懸浮沉積原型采用SCARA機(jī)器人手臂用泵和擠壓嘴的末端。一旦物質(zhì)被沉積在凝膠，它是暴露于UV固化。這種方法的一個(gè)有趣的方面是，建立材料可以“刪除”前的任何時(shí)間，治療僅僅通過(guò)吸回噴嘴。另一點(diǎn)需要注意的是，材料可以在基于路徑的三維矢量存款。這與幾乎所有其他3D打印過(guò)程中逐層必須硬化前的機(jī)器可以移動(dòng)到下一個(gè)。

該樹(shù)脂在沒(méi)有支撐材料的空間坐的事實(shí)還使得能夠制造上直接與周圍的其他對(duì)象坐在凝膠。和制作材料所用的凝膠等待坐而機(jī)器人臂使換刀，噴射不同的材料，或?qū)崿F(xiàn)該要求在動(dòng)作暫停其他變化。

哈姆斯說(shuō)，他只是申請(qǐng)了臨時(shí)專利涵蓋快速成型的背景下，系統(tǒng)的基本功能。 “有很可能覆蓋一些系統(tǒng)的各方面的專利文件，”他說(shuō)，“但萬(wàn)一有沒(méi)有，我決定這將是審慎的做法至少可以得到一個(gè)申請(qǐng)日?！?/p>

危害也要求此刻的懸浮沉積技術(shù)“純粹的實(shí)驗(yàn)努力”。他補(bǔ)充說(shuō)，他想繼續(xù)研究這個(gè)主意，但具有商業(yè)頭腦中沒(méi)有具體的時(shí)間框架。 “還有很多需要做才能使這個(gè)過(guò)程足夠強(qiáng)大，成為3D打印市場(chǎng)的一部分，而且大部分將依賴于資金的工作，”他說(shuō)。 “但我們確實(shí)有一些想法改善的過(guò)程無(wú)論在它方面的接口和物理的設(shè)置。其中最緊迫的問(wèn)題是針尖附件或鉸接針尖的設(shè)計(jì)。這將有助于減輕主要原因之一我們所面臨的問(wèn)題，這是因?yàn)樵摌?shù)脂在旅游向上沿著針，因?yàn)樗ㄟ^(guò)凝膠，留下一個(gè)臨時(shí)空隙的傾向“。

精度和分辨率是另一個(gè)問(wèn)題。 “我們的針是相當(dāng)大，有一個(gè)內(nèi)部直徑小于1/16英寸的大了一點(diǎn)。我們沒(méi)有太多嘗試與其他任何尺寸，但我們認(rèn)為還有很大的潛力在那里，”哈姆斯說(shuō)。 “我們正在處理的，而不是一個(gè)燈絲（其中有一個(gè)非常一致的直徑）的液體，所以我們實(shí)際上可以促動(dòng)針口，有可能使我們能夠改變整個(gè)打印分辨率?！?/p>

哈姆斯說(shuō)，推動(dòng)項(xiàng)目產(chǎn)生于思考如何機(jī)器人將處理3D打印的。 “對(duì)我們來(lái)說(shuō)，答案是銜接。六軸機(jī)器人為我們提供了可能性運(yùn)動(dòng)的三軸機(jī)器不能，”他說(shuō)。危害“第一泵是具有同時(shí)處理多材料注射的想法創(chuàng)建一個(gè)雙噴嘴，雙離心設(shè)計(jì) - 也許分配兩部分組成的樹(shù)脂，將只治愈在凝膠一旦兩個(gè)部分已經(jīng)到來(lái)在接觸與一種另一回事。這個(gè)想法并沒(méi)有很好地工作，因?yàn)楸媚贸鎏嗟牟牧希词乖谧盥脑O(shè)置。他結(jié)束了自己造的蠕動(dòng)泵集成到工具。

哈姆斯說(shuō)，制造機(jī)器上的第一個(gè)項(xiàng)目是一系列的選擇，因?yàn)樗麄兘o了開(kāi)發(fā)人員的變化，工藝參數(shù)如何影響建設(shè)質(zhì)量的想法線框立方體。 “舉個(gè)例子，如果我們保持流速不變，但改變機(jī)器人的速度，我們將看到樹(shù)脂薄膜作為出機(jī)器人加快。因此，我們使用的對(duì)象，以此來(lái)校準(zhǔn)系統(tǒng)，”哈姆斯說(shuō)。

“我們還創(chuàng)建了一系列的球體顯示利用非常不同的刀具路徑（該系統(tǒng)能提供哪些）。使用垂直而非水平輪廓的一建，雖然每個(gè)是相同的幾何，它可以產(chǎn)生，一個(gè)被利用垂直徑向弧線取得，一個(gè)是在連續(xù)的螺旋形做，“哈姆斯說(shuō)。

“我們也印刷的樹(shù)脂的環(huán)，與我們?cè)谀z以前淹沒(méi)塑料環(huán)互鎖。這是我們這類概念的多材料/多對(duì)象操作的證據(jù)，”他涉及。

危害說(shuō)懸浮沉積方法可能會(huì)被限制為樹(shù)脂，在可預(yù)見(jiàn)的未來(lái)。 “我認(rèn)為剛才的溫度范圍內(nèi)，你將不得不處理的金屬將是非常棘手的，”他說(shuō)。 “我想，如果你正與金屬與真正的低熔點(diǎn)和你有一個(gè)底，這是令人難以置信的絕緣，你也許可以工作了這一點(diǎn)。但是，這僅僅是猜測(cè)在這一點(diǎn)上?！?/p>