"Spatial forming"-a three dimensional printing process

A three-dimensional printing process which we call “spatial forming” has been conceived and demonstrated as a method of manufacturing parts for cardiac catheter systems.’ This work extends the range. of particulate forming techniques into the niicrostructure area; brings to bear on the manufacture of three-dimensional structures the high production capabilities of offset lithography; and allows us to visualize a complete process for the volume production of objects and assemblies of a geometric complexity hitherto found only in nature. This process combines several technologies to generate solid metallic microstructures from fine powder. Cross section data from computer solid niodcls are used for patterning of a chrome mask which images a lithographic printing plate like those used in the publishing industry. A custom built offset printin9 press prints “negative” material (the space around the parts) on a ceramic substrate in multiple registered layers of ceramic pigmented organic ink averaging 0.5 pm thick; each layer is cured with L5’ light. Periodically an ink heavily loaded with finely powdered metal is knifed onto the substrate, filling the non-image voids with “positive” part material. This material is also UV cured, the surface planarized, and the entire printing process repeated in proper register until the desired thickness (e.g. -SO0 pm) is reached. The semi-finished parts are then debinderized to remove organic ink components, and sintered in controlled atmosphere futnaces in processe.s similar to those used in the metal injection molding industr).. The negative material crumbles away and the finished paits separate from the substrate.