A Designer's Guide for Dimensioning and Tolerancing SLS Parts

Because additive manufacturing (AM) is a relatively novel industry, with the first commercial machines introduced in the late 1980s, many designers are unaware of the capabilities of AM technologies. Many engineers also find it difficult to utilize AM because of a lack of “Design for AM” knowledge in the public domain. Reliable information on material properties, dimensions and tolerances, and other process-related specifications is often scattered throughout the literature, if it is publicly available at all. The objective of the research reported in this paper is to begin to create a designer's guide for dimensioning and tolerancing parts that are additively manufacturing using selective laser sintering (SLS) technology. The guide is based on a series of experiments designed to determine the limiting feature sizes for various types of features fabricated in commercially available SLS machines. The features include slits, holes, letters, mating gears, and shafts built in a preassembled state. The impact of part thickness, orientation, clearance, and dimensions on the resolvability of features is examined. Results are reported in a series of matrices that relate realizable feature sizes to other important variables such as part thickness.