OpenSLS: An Open Source Laser Sintering Experimentation Platform

Release status: Experimental

Description	This is a prototype SLS system designed to interface with a laser cutter to create a platform for experimentation with the SLS process.
License	GPL
Author	User:Andreas
Contributors
Based-on	SLS wax printer
Categories	SLS, Laser, Powder
CAD Models
External Link

Introduction

Under active development-- stay tuned here!

OpenSLS is a platform for exploring the selective laser sintering process and a functioning prototype SLS 3D printer capable of fabricating objects in a variety of materials. It was developed at the Advanced Manufacturing Research Institute (AMRI) and is being used for research in regenerative medicine and tissue engineering at Jordan Miller's lab for microphysiological systems and advanced materials. This project is unique in that it appropriates existing, affordable laser hardware, namely laser cutters, for use as in the SLS process. This changed the nature of the challenge from one of procurement (ie, where to find a sufficiently powerful laser and optics) to one of integration, modular hardware design, and material development. The openSLS hardware is designed to be a drop-in powder management module whose sole purpose is to synchronously lay out layers of powder for the laser motion system (the laser cutter's gantry and laser) to sinter or melt. By adapting commercial and widely available laser cutters for this process, the barrier to entry for this technology can be lowered.

SAFETY

Because SLS is an inherently high-energy process involving a high-powered, invisible laser, CNC equipment, and hazardous materials, it should not be treated like the more familiar extrusion-based machines. This is a very dangerous process. Much can go wrong. If you decide to explore this technology, please exercise extreme caution: the potential for lasting bodily harm is real and ever-present and should taken very seriously.

Laser

The lasers used in laser cutters are incredibly powerful-- literally tens of thousands of times more powerful than the pocket laser pointers that already bear a eye-safety warning label. This is a whole other class of laser safety. Your eyes are no longer the only thing at risk. In addition to the danger of the laser radiation, the gas tube that emits the laser is driven by a high voltage power supply with voltages upwards of 30kV. Extreme care should be taken when working on the laser cutter electronics as the high voltage supply holds charge for some time after the laser cutter is powered down. Sam Goldwasser has prepared an excellent page on laser safety, including an extensive section on DIY lasers and the safety challenges there-in. Please read through it before attempting any of the work described here.

Materials

Finely powdered materials are often VERY FLAMMABLE or EXPLOSIVE in addition to being a serious respiratory hazard. Extreme care should be taken when handling powdered materials. Static shocks are in some cases enough energy to ignite clouds of dust, causing an explosion. Additionally, this first prototype does not incorporate inert-gas shielding of the powder-laser interface, which, for some materials, could be very dangerous, especially if any powder becomes airborne.

Process Overview

Terminology

Mechanics

Hardware

Print Materials

Methods of Fabrication

Isomalt and Sucrose Powders

Wax-based Powder

Sucrose

Detail of laser-melted crystalline sucrose.	Melted region at higher magnification.

Isomalt

Beading of laser traces in fine crystalline isomalt.	Melted bridges and cavities in laser trace in isomalt glass.

Candelilla Wax

The wax and carbon mixture at low magnification.	At higher magnification, the individual carbon and wax particles can be clearly seen.

Nylon

Laser trace of Nylon powder illustrating melting.	(placeholder).

Iron

Four passes of the laser show promising sintering.	This gear was sintered with no optimization of the parameters, but serves as a proof-of-concept.

Steel

Electronics

RAMBo Board

Native Laser Cutter Electronics

Integration

Software

Videos

Source Files

Source files will be hosted on github and Thingiverse (solid models only) by mid-October.

Future Work

The next prototype is under active development and features heated Aluminum pistons and basic positive pressure inert-gas shielding. Progress can be tracked on Andreas Bastian's dev blog.

OpenSLS

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