Selective Laser Sintering of Duraform Polyamide with Small-Scale Features

Selective Laser Sintering (SLS) has been used to make a fiber management module having very small feature size and ratios. Currently these modules are made out of Stereolithography using standard epoxy acrylate materials. SLS has been chosen to make these modules by the virtue of the material system it offers. The material system was chosen based on the flame retardant properties. The material used for this study is a Duraform Polyamide and Alumina-Ammonium Phosphate system. Ammonium Phosphate served as the binder in the Alumina-Ammonium Phosphate system. Experiments were done in order to find out the minimum feature size possible with the two material systems. Minimum hole diameters and maximum possible l/d ratios are determined by particle size, shape and processing conditions. Builds were made in different directions to understand the effect of the various processing parameters on the system. One particularly noteworthy observation was that part growth as a proportion of hole diameter became increasingly significant as hole size decreased. Optical microscopy was performed to measure the hole diameters and also to reveal the surface roughness. Results indicate material system determines the minimum diameter of micro-sized holes that can be effectively manufactured using Selective Laser Sintering. Introduction Selective Laser Sintering is a layer based manufacturing process. Successive layers of powder are deposited one above the other and the powder surface is raster scanned with a high power laser to achieve the desired geometry. The ability to manufacture any shape and geometry using Selective Laser Sintering has been well discussed in books and literature [1]. The current study focuses on manufacturing small sized features using three different material systems having flame retardant properties. Initially Stereolithography was used to manufacture the desired geometry. Layers of photocurable polymer are deposited from a vat and selective solidification is carried out by scanning with a laser beam. At a later stage the parts are flood exposed to UV light for 90 minutes to complete UV curing and is subjected to post thermal curing steps to achieve desirable properties of the material. The primary problem associated with Stereolithography Reviewed, accepted August 25, 2003