Selective Laser Sintering (SLS)
What is Selective Laser Sintering?
Selective Laser Sintering (SLS) is the 3d printing process of creating 3d objects with an expensive laser and plastic powders. SLS was invented by Dr. Carl Deckard at University of Texas at Austin in the mid-1980’s. He then established the startup company DTM to design and build the SLS machines. In 2001, DTM was acquired by 3D Systems. EOS and 3D Systems provide the most commonly used SLS machines. SLS is also referred to as Laser Sintering (LS).
SLS is very similar to the SLA process in that it uses a laser to make a 3D object except that it uses powder material instead of a liquid material. 3D printed parts in SLS primarily use nylon materials as well as glass filled nylon materials. This makes the process perfect for printing tough prototype parts, living hinges (with annealing process), fit function and testing parts as well as end use production components. Assemblies can easily be printed in one piece because of the self-supporting powder bed. Because of the expensive lasers and the powdered material, SLS printers are primarily found in industrial companies and service bureaus. Of all the 3D printing processes, SLS has been the most commonly used one for production printed components. Most parts for prototype and production can be delivered within a couple days.
How does SLS work?
SLS creates a 3D model of a component from a 3D CAD file using a high powered laser to sinter or cure tiny particles of powder (typically nylon) together layer by layer. After each layer is sintered, the bed of material is lowered and the next layer is started. Unlike other 3d processes, After the print is finished, parts are left in the machine to cool. SLS is self-supporting during the print process due to the powder material bed, so parts do not require much post-processing.
- Tough & Durable Prototype Parts
- Nylon & Glass Filled Nylon Materials
- End Use Production Parts
- Economy of Scale Prints
- Print Working Assemblies
- No size limitation – Section and Bond Large Parts Together
3D Systems & EOS SLS Machines
There are many different SLS machines available, but most are supplied from equipment manufacturers 3D Systems and EOS. SLS printers have large build platforms of up to 26” x 15” x 22” (660mm x 380mm x 560mm) and build parts at 0.004” (100 micron) layers. These are great printers for building large parts or loading up lots of smaller parts.
Although more SLS material are available upon request, here are the two most common SLS materials.
- Nylon PA (Polyamide)
- BEST for STANDARD PROTOTYPING or PRODUCTION PARTS
- White Nylon Material (similar to Nylon 12)
- Tough, Durable and Flexible
- Applications: Form, Fit and Function Prototyping, Snap Fits, Testing, Production Parts
- Nylon GF (Glass Filled)
- BEST for FUNCTIONAL PROTOTYPES or PRODUCTION PARTS
- Grey Glass Filled Nylon Material (similar to 30% Nylon GF)
- Tough & Rigid
- Applications: Form, Fit and Function, Production Parts
SLS Finishes Available (*Standard*):
- *Level 2 – Bead Blast Finish = Support Removal & Bead Blast*
- Level 4 – Primer Finish = Sand/Remove/Fill All Build Lines & Primer
- Level 5 – Painted Finish = Sand/Remove/Fill All Build Lines, Primer and Paint/Mask/Texture as Needed (Show Quality Finish)
- Dyed Finish = Level 2 then Dye Material Custom Color Match
- Minimum Wall Thickness = 0.040”
- Minimum Features Size = 0.030”
- Tolerances = +/- 0.010” for first inch then +/- 0.002” per inch thereafter
- Inserts = Install in Post-Processing with Adhesives
- Holes = Drill, Ream and Tap