Bespoke Binder Jetting System and Powder Bed Temperature Assessment

Abstract

Binder jetting is an additive manufacturing process in which powdered material is bound together via a printhead that jets binder, similar to an inkjet printer. Parts are created from powder and binder, built up layer-by-layer. The parts produced are called green parts. These green parts are often post-processed by sintering in a furnace to fully solidify and densify them to achieve desired mechanical properties and final geometric characteristics.

New and continuing developments in additive manufacturing as well as research requirements motivates the development of an open-architecture binder jetting system that can be updated modularly, is capable of producing complex parts at reasonable scale, and which provides full control of the software and hardware to researchers and users. The development of such a system is described herein.

To demonstrate the research ability of the system and provide information on binder jetting parameters, the thesis also details the use of thermocouples and a thermal camera to gather data on the effects of infrared heating on powder bed temperature, used for in-situ curing to improve green part properties. The heating rate at the surface of the powder bed can exceed 8°C/s, even for relatively modest heater powers (400 W), and heater parameters can be directly related to the peak temperatures achieved in the bed, consistently producing peak temperatures of over 100°C for linear energy densities of 70 J/mm, providing data for evaporation in aqueous binders. The presence of binder caused substantial differences compared to dry powder, producing consistently lower heating rates until solvent evaporation, but having minimal effect on long-term peak temperatures. The thermal camera was able to produce qualitative data on the surface of the build bed, indicating that the temperature differences across the surface can be significant, on the scale of 10°C to 20°C.