Introduction to Rapid Prototyping (SLS & DLP)

This is Part 2 of the series. You can read Part 1 here.

Thanks for staying tuned everyone, it means the world to us here at RPS. This week I’ll be discussing SLS & DLP (selective laser sintering and digital light processing). SLS is arguably the third most popular rapid prototyping, 3D printing technology, and for good reason. The laser sintering print technology opens up rapid prototyping to a whole new world of possibilities. In a later installment, I’ll get into DMLS which is a cousin to SLS technology and a big part of its diversity. DLP on the other hand is more so at the back of the pack, yet just as old of a technology as SLA printing essentially.

SLS (Selective Laser Sintering) 3d Printing

Onto SLS 3D printing, first patented by Carl Deckard who was a co-founder of DTM, Inc¹. The patent was issued to DTM, Inc. in 1989² which was later acquired by 3D Systems in 2001³. However, almost a decade prior to the acquisition, DTM, Inc. commercialized their SLS printing technology in 1992, under the name, Sinterstation 2000⁴. SLS prints are created by “sintering,” or fusing together powdered material with a high powered laser, such as a carbon dioxide laser. SLS prints are then built by fusing together a series of consecutive, super-thin layers of powdered material.

One major benefit to SLS 3D printing is not needing a support structure like SLA, FDM, and DLP prints require. This reduced post-processing of the support structure and the possibility of breaking your prints. However, the major downside of SLS 3D printing is the waste of loose powder material which acts as a support structure during the printing process. The preheating cycles required for sintering degrades the virgin powder material and should be discarded after printing, even if it was not contacted by the laser. Now, unlike SLA and FDM printing where the material selection is large, SLS materials are primarily Nylon (polyamide) based. However, SLS 3D printing expands the horizons for material strength with glass and mineral-filled versions. SLS 3D printing is definitely a formidable technology next to the rest of the rapid prototyping counter-parts and definitely can be useful when searching for extra strength out of your rapid prototyping components. Unfortunately, pricing and waste aspects of the SLS printing still hold back this rapid prototyping technology to date.

SLS Printer Build Platform with Component Patterns

DLP or DLS (Digital Light Synthesis)

Lastly, a brief overview of the DLP or DLS (digital light synthesis), which was conceived from a Kickstarter company B9Creations in 2012, under the name B9Creator⁵. DLP printing technology is most certainly in the infantile stages of life. There has recently been a break-through in the DLP technology arena, which was brought forth in 2015, by Carbon 3D, Inc. in their Carbon series 3D printers⁶. Their DLS printers implement a proprietary technology named, CLIP (continuous liquid interface production or originally known as continuous liquid interphase printing). This new technology reduces build times significantly, inherently in the fact of “continuous liquid interface”, versus traditional stop and start resin printers such as SLA.

DLP prints are created much like SLA prints by curing a photosensitive resin with a light source. Carbon 3D, Inc. has claims of improved accuracy, surface finish control, and a wider array of materials variations as compared to traditional SLA rapid prototyping. Carbon offers a plethora of materials and a significant portion in the dental industry, some even being FDA approved and biocompatible. In total, Carbon offers 21 different materials. Another major benefit to the selection of these materials is the fact that the Carbon platform printers can utilize high strength formulations unlike SLA printers, such as their CE 221 material which is as strong as a 15% glass filled Nylon type material which would typically be found in SLS printing. In my opinion, aside from the current pricing constraints ($40K/year) of Carbon platform printers, they seem poised for greatness and dominate control over the 3D printing sector very soon.

DLP Printer Critical Component Diagram

Continue to Part 3 of “Introduction to Rapid Prototyping” by clicking here.