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DLP and LCD 3D Printers, How Different Are They?

Resin 3D Printing is a popular technology in the 3D Printing sphere, with every marketplace sporting a range of these 3D printers as part of their product fleet. It has massive applications in various industries and is its development is being prioritized to increase its print quality, financial viability, and access to a larger group of users.

DLP and LCD are two of the most standout technologies in resin 3D printing. Both of them work according to a similar principle and are comparable in many respects. However, there are some stark differences as well that users must be aware of before buying a resin 3D printer.

In this blog, we focus on DLP and LCD 3D Printers. We will discuss the base technology being used, their individual pros and cons, and how well do they line up with your specific 3D printing needs.

DLP and LCD 3D Printers, How Different Are They?

The Basics of Resin 3D Printing

Resin 3D Printing falls under the broad category of Vat Photo Polymerization, which is considered one of the core types of 3D Printing techniques. The concept revolves around the ability of liquid-phase photo-sensitive resins to solidify upon exposure to some form of light energy.

Resin 3D Printing utilizes this ability to create 3D objects from liquefied resins, which are selectively exposed to light to solidify desired regions of the resin. Only those portions of the resin become part of the 3D print that is solidified by the light source, the rest remains liquid.

A common resin 3D printing setup includes a tray, or a vat (in technical terms), which is filled with the liquid resin; a light source; and a mechanism to direct the light source to the specific point in resin that needs to be solidified.

Apart from this, there is also a build platform that can move up and down inside the vat with remarkable precision. For each new layer, the build platform dips down to the base of the vat, leaving just a tiny (0.5mm in most cases) gap in which the layer is built which sticks to the platform. For subsequent layers, the platform keeps moving upwards a little bit each time, with each new layer being built inside the newly created gap and sticking to the layer above. The resin 3D printing model is built upside down as the light is shone through from the bottom of the vat.

This is what Resin-Based 3D Printing is! Now, on to the two exciting technologies we want to discuss.

DLP 3D Printing

Digital Light Processing, aka DLP, makes use of a digital light projector as the light source to solidify resins. This light source is characteristic of this technology and is a major difference between it and LCD.
The projector shines its light onto a unique device known as a DMD, Digital Micromirror Device, which comprises a huge number of very small mirrors, each one capable of deflecting the project’s light in a different direction. For each layer, these mirrors are arranged in a specific orientation that reflects the digital light beam from the projector onto the vat, in the exact shape of the layer/slice being printed.

The mirrors are in no way capable of changing the light source’s nature, they just guide it. This means that the number of pixels created on the build platform is the same as the projector. So, if the layer is a bit smaller than that projector’s beam, the picture is actually a bit sharper and crisper than the projected one! There is a downside to this, though. The opposite happens if the slice being printed is larger than the projector screen. In that case, there is a decrease in resolution and there are risks of distortion around the edges as well, as light is refracted a bit too far (quite like the Elephant’s Foot in filament-printing).

Modern, more expensive DLP 3D Printers utilize advanced technologies to minimize this distortion issue and are quite good at maintaining layer quality despite magnification. This has been achieved to the extent that these DLP 3D printers easily qualify as products for professional use.

DLP has been around for a long time owing to the age of the light source – projectors are a century-old device extensively used in cinemas. Hence, the technology is tried and tested.

LCD 3D Printing

LCD 3D Printing, also known as MSLA 3D Printing, is a relatively newer technology compared to DLP. As mentioned above, it uses a different light source than DLP: Ultraviolet LEDs that shine through an LCD screen.
While LCD also creates full layers at the same time as DLP 3D printers, the layer quality depends upon the resolution of the screen. The higher the LCD’s pixel density, the better is the print quality. Also, there is no issue of distortion as the impression created by the LCD is transferred as it is to the resin without deflection. Since there is no change in the size of the original projection on the LCD, the print’s footprint is limited by the area of the screen, so a larger screen is necessary for bigger prints.

Cost is a complex issue with LCD 3D Printers. The hardware is cheap as the LCDs used in these devices is practically the same as the one used in smartphones. The catch, however, is that they need to be replaced frequently to maintain quality. The notion that LCD 3D Printers are cheap is true but one must know the operational costs involved.

DLP or LCD: Which One is Best for You?

DLP and LCD are quite similar in most regards: technology, print quality, speed, applications, etc. Are they the same, though? No.

There are a few things you need to decide before choosing which one to go for. Let’s discuss print quality first. As mentioned above, it is comparable for both 3D printers. The finish is smooth and layers are indistinguishable. However, DLP takes the edge in this regard. The cheaper options compare well with LCD printers but as soon as you consider medium-tier DLP 3D Printers (that cater for layer distortion and warping), the build quality is much more detailed and fine.

In terms of cost, LCD is the cheaper option. Even though the screen needs changing, the technology itself is so commonly available and cheap that DLP is still pricier. This comes at the expense of quality, though, which must be known.

Compatibility with resin material is another factor to consider. Most resins are usable with both DLP and LCD 3D printers but some are only suitable for either one. It depends on the energy intensity of the light source. LCD makes use of a low-energy light source so resins that cure quickly are suitable for it. If some other resin is used, it will not cure properly and the model’s structural integrity will be compromised. Understandably, DLP is compatible with resins that take some time to cure owing to their high energy-density source.

Overall, it all boils down to what your specific application is. People who require professional-level quality and have a higher budget should always go for DLP as it is better suited for detailed work. Consumers who are just starting or have low-precision applications with a tighter budget should consider LCD 3D Printers, which are quite good in many respects as well.

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