Inkjet printing is almost identical to FDM, however the plastic is held in a liquid state inside of the machine before being dispensed. As soon as the print head dispenses the liquid plastic, it cools and solidifies on the model. This process makes for very smooth finishes, however the print time is slow.

The print head on most inkjet printing machines consists of two dispensers; one for the thermoplastic, and the other for wax that acts as a support material. Another feature typically included in this technology is a plane milling stage. Between each layer a plane is rolled over the model, cutting extraneous material off of the top layer. This ensures that the layer is precisely flat. This has something to do with the slow print speed.

This method sees some of the smallest layer thicknesses of any of the technologies: as small as 0.0005 inches per layer. MultiJet is indentical to inkjet, but with many print heads simultaneously dispensing plastic. 3D Systems manufactures MultiJet machines (though they call them Pro-Jet) which have several hundred nozzles.

Advantages

• Very accurate.
• Smooth surface finish.
• Supports are wax and can therefore be melted away.
• Quick print time for MultiJet.
• Milling stage means better accuracy.

Disadvantages

• Slow print time for Inkjet.
• Supports must be melted– a separate process in itself.