Print Methods for 3D Inkjet Printing & Additive Manufacturing

Industrial inkjet printheads offer a wide range of possibilities when implemented in 3D and Additive Manufacturing (AM) print systems. While traditional manufacturing methods often involve taking material away from an object in order to shape or produce the object, Additive Manufacturing builds the object in slices (or layers).

The 3D and Additive Manufacturing space is constantly evolving, but this article briefly describes commonly applied print methods. In the 3D and Additive Manufacturing print methods described below, a digital version of the object must be sliced into printable layers. The most common file type is STL coming from a 3D design application. Since inkjet is a raster type device (pixel-by-pixel), the layers must be in a raster format appropriate for the printhead. Modern industrial printheads will produce the best results for inkjet based Additive Manufacturing using grayscale mode. This allows for variable size inkjet droplets. Variable size droplets have a variety of advantages, one of which is the ability to construct a harder shell on the exterior surface alongside lattice infill, which can make the object stronger and lighter.

Binderjet (Sand Material)
Sand binderjet is most often used to produce sand casting molds and cores. The digitally designed and printed molds are then used by conventional foundries for making metal castings. Molton metal, frequently aluminum, is poured into a mold made in the binderjet printer. Inkjet's role is accurately controlled printing (or jetting) of the binder fluid. The basic steps in sand based binderjet are: (1) Spread a sand layer the thickness of one slice, (2) Print binder fluid in the areas which will form the object, (3) Repeat steps 1 and 2 until all layers are printed, and (4) Remove the un-bound sand. The sand held together with all the slices of binderjet fluid produces the 3D object.

Binderjet (Metal Material)
Metal binderjet print systems are very similar to a sand binderjet system. The main difference is that instead of sand being held together with binder fluid, finely ground powdered metal material is used. A variety of metals are available such as aluminum, stainless steel, copper, and titanium. The basic steps in metal based binderjet are: (1) Spread a layer of powdered metal the thickness of one slice, (2) Print binder fluid in the areas which will form the object, (3) Repeat steps 1 and 2 until all layers are printed, and (4) Remove the un-bound powdered metal. The remaining material produces a "green" 3D object ready for the final process called sintering. It’s called “green” because it has not been fully processed. The final sintering step involves placing the green object in an oven or furnace, which will essentially fuse the powdered metal into a single solid metal 3D object.

Photopolymer Jetting
Photopolymer jetting uses an ultraviolet (UV) curable polymer resin to print each layer of the 3D object. Jettable polymers offer a wide range of material choices including color, texture, and density. Objects produced using this method are frequently used for prototype and design models. They can also be used for tooling and fixtures as part of other manufacturing processes.

Composite-Based Additive Manufacturing (CBAM)
With the Composite-Based Additive Manufacturing process, the object area within each slice is printed on a sheet of a fiber material; this material absorbs the jetted fluid and serves as an adhesive. A powdered polymer is then applied to the sheet, and the polymer gets removed from areas without adhesive. This process is repeated until all layers have been printed. Once produced, the stack of sheets gets heated and pressed together. The final step is to remove the fiber material areas which did not have any jetted adhesive fluid.

Wax 3D Printing
Wax 3D Printing is probably the simplest type of inkjet based Additive Manufacturing; this is because the object requires no curing, and the object is normally ready for use immediately after printing. The system begins with wax in solid form which is then heated to a temperature high enough for the wax to melt and achieve a viscosity in the jettable range of the printhead. Special printheads with built in heating elements are used to ensure consistent viscosity in the piezo chamber. This process is sometimes referred to as phase-change inkjet since the wax material changes from solid, to liquid, and back to solid after printing. The wax based 3D objects are often used for making investment casting patterns and cores, but they can also used for making models. In model making it is useful to print with colored wax to provide more a more realistic appearance of the object.

Other types of inkjet based Additive Manufacturing
There are many other uses for inkjet in manufacturing and industry including Layered Object Manufacturing (LOM), applying functional coatings to materials, printed electronics using conductive inks, printing biological fluids for medical and research purposes, and many other uses.

Meteor Software and Hardware Packages give industrial inkjet system builders access to support a wide range of printheads including Epson, FujiFilm, Konica Minolta, Kyocera, Ricoh, Seiko, Toshiba Tec, Xaar, and Xerox.



3D Printing and Additive Manufacturing Workflow and Development Packages

When you develop your 3D inkjet printer using Meteor, you can offer your customers a wide range of choices for their design and file preparation software packages; plus, Meteor print systems have the added benefit of working with a variety of input formats.