Industry Insider Michelle Du Toit, on top down, SLA DLP 3D Printing

Women in 3D Printing’s mission is to increase the visibility of women in the Additive Manufacturing industry and encourage more women to use 3D Printing technologies. We have been doing so by highlighting female leaders and innovators on our platform since 2014. To provide even more insights on female experts in the Additive Manufacturing Industry, we are inviting women to contribute to this series by sharing their business and tech expertise through guest blog posts to be published as Industry Insiders series.

Michelle is the co-founder of Gizmo 3D Printers Pty Ltd, located in Australia. The startup is recognized worldwide for manufacturing the world’s first super speed top down SLA DLP 3D printers. In her leisure time, she is also a mentor for The 3D Printing Revolution course by Coursera.org – an education platform that partners with top universities and organizations worldwide, to offer courses online for anyone to take.

Some of you may be wondering: What is SLA DLP 3D printing?

Let’s break it down…

“SLA” is short for Stereolithography – a term coined by Chuck Hull in 1986 which refers to making solid objects by individually printing thin layers of ultraviolet curable material one on top of the other.

“DLP” stands for Digital Light Processing – a 3D printing (also known as additive manufacturing) process whereby a design that is created in a 3D modeling software is printed in 3D using a digital light projector as the light source for curing photo reactive polymers or resin.

Thus, SLA DLP 3D printing describes the method of 3D printing whereby a projector casts individual layers of a 3D model (in digital format) as flat images onto a bath of liquid resin. The resin solidifies as the light from the projector shines onto it, each layer that is hardened forms the 3D object from the resin.

What is the meaning of Top Down SLA DLP 3D printing?
There are bottom up resin 3D printers and top down resin 3D printers. The fundamental  differences that will help you distinguish between the two types are:

With Bottom Up 3D printing, the resin is cured through a window in the bottom of the vat by a light source from below. The Form 2 SLA 3D printers by Formlabs are an example of the bottom up resin 3D printers.

In the case of Top Down 3D printing, the resin is cured by a light source above the vat. The Gizmo 3D printers are an example of top down resin 3D printers.

Common misconceptions about top down SLA DLP 3D printing

Chuck Hull originally invented the process in 1986, so it’s not a brand new technology. However, the technology hasn’t always been accessible to as many people as it is now as not many businesses and individuals could afford it. Due to lack of knowledge and misbelieves about the technology, many people that could benefit from it are mostly unaware of its incredible benefits.
These misunderstandings stem from assumptions that it is similar to other 3D printing processes or that it hasn’t changed much in the past few years. Exciting developments and facts about this 3D printing method include:

1. Resin prices have come down significantly. It used to be very expensive to fill a vat with resin. These days, resin prices have come down significantly, and buyers now have a large range of resins to choose from at lower prices than ever before. Resin manufacturer Fun To Do’s resin prices, for example, start at just US $65 per liter.

2. Top down SLA 3D printers have never been this affordable. This technology has never been priced as low as it is right now. Today you can buy a top down SLA DLP 3D printer for under US $4000.

3. 3D printed objects produced by top down SLA DLP 3D printers are strong. When a 3D printed object has just been freshly 3D printed, it is still soft. People that are unfamiliar with the technology might see it at this point and think the objects are too fragile but objects that are printed this way needs to undergo post processing. Post processing for these prints can involve different things (it varies on the project) including being cured entirely by placing it under the sun (or in a UV curing device) to become hard. We tested how much weight a 5cm x 5cm 3D printed hollow ball could withstand before breaking, and it took up to 30kgs of weight before cracks started showing!

4. Hardened resin bits in a resin tank that don’t form part of any 3D prints printed on the printer doesn’t interfere with new prints on a top down SLA DLP 3D printer. With some bottom up SLA 3D printers, hardened resin bits can create imperfections in new 3D prints. Unfortunately, this has caused some people to believe that it is the norm for resin 3D printers in general. It’s also wrongly assumed that when the build plate stirs the resin as it moves, it kicks up hardened resin bits in the resin to the surface which can cause varying degrees of print faults.
In fact, when you mix the resin, hardened resin bits sink to the bottom of the vat and doesn’t interfere with new prints at all.

5. It is quick and easy to remove a 3D printed object from a top down SLA DLP 3D printer. Some think that one needs to empty the vat/tank before and after printing objects. When printing on a Gizmo 3D printer, you don’t need to drain the tank or even remove the build plate as you do with some bottom up printers. You can start printing right away after you remove your finished 3D print. The ease and speed of removing a printed part is just one of the aspects that make the printing process fast.

6. Not only is the printing process fast, but the speed of printing on these machines has also increased significantly. Top down SLA DLP 3D printing has never been as fast as it is now. With the Gizmo 3D Printers, we’ve been able to print up to 7 inches in an hour! A comparative study that we’ve done showed that where popular FDM printers can take up to 7 hours to print a 5cm x 5cm hollow ball, the Gizmo 3D printers can print 2 of those balls only 19 minutes!

Machining manufacturer Prodways has also done a demo where they printed 20mm per minute on a top down printer.

7. It’s been discovered that the surface tension that occurs when printing on a top down resin 3D printer can be used to smooth the prints. Previously, some believed that surface tension causes defects, but a study named “Smooth Surface Fabrication in the Mask Projection based Stereolithography” by Yayue Pan, Xuejin Zhao, and Yong Chen has found that it can smooth the prints and be used as an advantage. We’ve seen it with our 3D printing tests too.

8. Unused resin can be stored and doesn’t need to be used up right away
When speaking to potential customers, I find many question whether the remaining resin can expire. With many resin types, it takes all but a quick stir to start printing again on a resin that has been stored away properly by covering it.

9. The magic happens underneath the surface of the resin. 

A top down, SLA DLP 3D printer printing

When you see a top down, SLA DLP 3D printer printing for the first time, you only see an outline projected by the light onto the surface of the resin, slowly changing shape. People that are used to seeing FDM (Fused Deposition Modeling)  3D printers while printing expect to see the object form in front of their eyes. When looking at a top down SLA DLP 3D printer while printing, they might think “But nothing is happening?” and walk away disinterested. With a top down 3D printer, however, the object forms under the resin as the build plate incrementally lowers further down into the resin as the light cures each layer of the object. It’s only at the end of the printing process that the finished print is revealed when the build plate lifts it out of the resin bath. The usual reaction at that point is “Wow!”.

How is it different to FDM 3D printing?

The SLA DLP 3D printing process is much faster than FDM 3D printing which is said to be the most common 3D printing method. One of the reasons for this is because FDM 3D printing only prints a section of each layer of a single 3D printed object at any given time whereas, with an SLA DLP 3D printer, entire layers of multiple objects can be printed at once.

Top down, SLA DLP 3D printing is also a highly sought after 3D printing technology due to the high resolution results it produces which is much higher than most FDM 3D printers.

Of course, it’s not to say that SLA DLP 3D printing is a better printing process than FDM 3D printing. I find the key is being aware of how the different 3D printers in the market can benefit your projects or business (reading informational blogs such as these is a great place to start) in regards to price, speed, build size, resolution, replacement parts and downtime. 

My hope is that by continuously educating people on the developments of this technology, industries that can benefit from it will recognize the value it can bring to their business. Finding the right fit can save businesses a lot of time and money printing their dream 3D prints.

Recommended reading and references:

1. Yayue P., Xuejin Z., and Yong C., Smooth Surface Fabrication in the Mask Projection based Stereolithography, posted 2012, accessed 1 August 2017, http://www-bcf.usc.edu/~yongchen/Research/NAMRC40-7715.pdf
2. Chuck Hull, Patention of his invention in 1986, Accessed 1 August 2017,  https://en.wikipedia.org/wiki/Chuck_Hull
3. WWW.LIVESCIENCE.COM
, Fused Deposition Modeling is said by some to be the most common 3D printing method. Posted 19 September 2013, Accessed 1 August 2017, https://www.livescience.com/39810-fused-deposition-modeling.html


More information about Gizmo 3D Printers is available here.

This is a guest post in our series Industry Insiders. if you’d like to participate in this series then contact us for more information.

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