Suspensions of fine alumina powder in a paraffin wax have been successfully formulated with viscosity values sufficiently low to allow ink-jet printing using a commercial printer. A commercial-grade paraffin wax, with stearylamine and a polyester, were used as the dispersant system. Suspensions with powder loadings up to 40 vol% were passed through the ink-jet printer head. Unfired ceramic bodies with a feature size of <100 m have been successfully fabricated with waxes that had a powder loading of 30 vol%. The influence of suspension fluid properties on the ink-jet printing process has been studied, and the importance of the acoustic resonance within the ink-jet printing apparatus has been demonstrated.

Ink-jet printing is a versatile freeform fabrication technique with a high spatial resolution. By suspending ceramic particles in low melting point organic materials and printing above the melting point, rapid cooling on impact after printing results in rapid layer growth. Current results from a collaborative programme studying the hot wax ink-jet printing of structural ceramic components will be reported. The influence of key fluid properties on the ink-jet deposition process are discussed.

In order to successfully build three-dimensional shapes by hot-melt inkjet deposition it is essential to control the building block characteristics, i.e., the deposit geometry, dimensions and fine feature resolution. The deposit formation is mainly dependent on the material systems and their jetting behaviour. It is therefore crucial to understand how the jet formation is affected by the inks 'rheological properties and how to manipulate the jet-head driving parameters to achieve optimum deposition conditions. This paper reports our investigations with a model jet firing station, about the influence of driving parameters of hot-melt drop-on-demand print-heads (e.g., pulse shape and frequency) on the jet and deposit formation characteristics, for both unfilled and powder loaded vehicles.

A conventional rapid prototyping technology has been used to build prototypes using direct deposition through a drop-on-demand ink-jet printing system. Al2O3 - filled waxes have been developed with viscosity values close to those of the materials used in commercial printing systems. Commercial dispersants based on stearic acid and sterylamine have been studied and stable ceramic suspensions with ceramic volume fractions in the range 20–40 volume% produced with suitable viscosity. A suspension of 20% Al2O3 in an alkane wax has been successfully printed.