Binder Jetting: Development workflow
At Added Scientific, we have a standard approach to developing binder materials for binder jetting, based on our material development methodology for inkjet printing.
We use our considerable expertise of metallic, polymeric and ceramic powders to characterise these and understand the powder-fluid interaction for applications such as binder jetting of printed pharmaceuticals.
The development workflow for binders and powders is typically conducted in parallel. Binder development is very similar to ink development for material jetting, with the first stage based around establishing the “jettability” of the fluid. This is done by assessing temperature dependent viscosity (Anton Paar Rheometer) and analysing droplet characteristics (Krüss DSA100). The formulation can be modified at this stage, if necessary. Compatibility with the intended printhead must be considered.
Next, a dropwatcher (ImageXpert) is used to develop a material-specific waveform. A waveform is a continuous signal of voltage applied to the printhead to eject droplets of material. The voltage and timing can be adapted to deliver a target droplet morphology with adequate penetration and limited powder displacement due to impact.
Powders can be characterised to understand their particle size distribution, shape and morphology (Malvern Mastersizer 3000), surface chemical composition (Toshiba TM3000 SEM-EDX), flowability (Freeman Technology FT4 powder rheometer, Hall flowmeter) as well as apparent and tap density.
Next, testing is carried out to understand the quality of the powder layer spread by the powder dispenser and recoat mechanism. Powder packing density and uniformity of the surface can be assessed.
A research-scale binder system (modified LP50) or industrial binder system (Integrity) is then used to conduct printing trials. Both are fully-open systems with the ability to use various printheads and select a range of printing parameters. Systems can be set up to use UV or IR curing or drying between layers and the exposure time can also be controlled.
Parts are then post-processed where necessary and materials characterised. Surface metrology such as white light interferometry (Alicona Infinite Focus) can be useful to understand the resulting surface condition.
If you’re looking to explore commercial or small-scale binder jetting - get in touch!