During a successful SLS print, the laser sinters powder to build parts layer by layer. After the parts cool, separate the printed parts from the unsintered powder. Post-process the printed parts and reserve the unsintered powder for reuse or disposal.

Normally, an SLS 3D printed part has a slightly grainy surface. If the temperature inside the build chamber is too hot, or not hot enough, the resulting temperature difference causes defects on the part’s surface. Obstructions in the laser path can also cause print defects.

These cleaning and calibration steps are key to consistent and successful prints.

• Refresh rate: Each Formlabs SLS powder has a recommended refresh rate. Refresh rate defines how much powder can be reused from a previous build. A lower refresh rate, which uses less fresh powder, is considered more cost effective, but can lead to an increased print defect rate. The refresh rate advertised by Formlabs is decided by Formlabs as the best balance of cost, performance, and appearance.
• Bed temperature: Formlabs recommends tuning the bed temperature of your printer before printing with any nylon-based powder for the first time. Formlabs offers a tuning print for each powder type. An incorrect bed temperature can lead to print defects, such as poor surface finish, or complete print failures due to melting.
• Optical windows: The laser and camera on Fuse Series printers sit behind protective optical windows. If the laser window is contaminated by powder or lauralactam, powder may fail to fully sinter wherever the laser is blocked. If the camera window is contaminated, the printer may falsely flag the contamination as an issue with the print.
• IR sensor: The print process for Fuse Series printers requires that the material be sintered at a precise temperature, which is measured by the printer’s IR sensor. If the IR sensor is partially blocked or contaminated by powder or lauralactam, it may measure the bed temperature as lower than it actually is. This can cause the printer to overheat the powder, leading to melting.
• Print enclosure, build sheet, and troughs: The recoater and powder troughs are key parts of the powder distribution system in Fuse Series printers. Keep them clean to avoid powder contamination, partially-sintered powder being pulled into subsequent prints, and related print failures.
• Powder cake temperature: The build chamber (Fuse 1 generation) or build unit (Fuse X1) may be removed from the printer at 100 ºC, but unpacking the print at higher temperatures increases the risk of warping. For best results, wait for the powder cake to cool to below 30 ºC (86 °F) before unpacking parts.

If you experience print defects with a Formlabs SLS printer, consult the list below and visit the relevant support article to troubleshoot and resolve them.