SGC was a process developed by Cubital Inc. of Israel. The technology is no longer being produced, as Cubital Inc. no longer exists (though Objet Geometries Ltd. of Israel retains intellectual property of the process). I have included it here because it is an interesting and unique approach to printing.
SGC uses photosensitive liquid in a layer by layer process, however the main difference is that it exposes an entire layer at one time.
Before the process can begin, a series of plates must be printed. Software splits the CAD model up into thin layers, and each layer is printed (2-dimensionally) onto a plate. The plate acts as a mask; any model cross-section is transparent while the rest of the plate is opaque.
The machine first sprays a layer of photopolymer into the working area. The first printed plate is loaded right below a UV lamp; a shutter opens and the entire plate is exposed to the photopolymer at once. The cross-section that was exposed hardens the photopolymer, and afterwards the uncured photopolymer is sucked up by a vacuum.
Next a layer of wax is put down over the unexposed area (evening out the bed) and the entire layer is milled so that it is completely flat (all of the excess material from the milling stage is vacuumed up). Another layer of photopolymer is sprayed on, the next plate is loaded, and the process continues.
At the end the model is contained within a block of wax, which gets melted away. No other post processing is necessary.
efunda.com has a nice illustration of the process (it is fairly difficult to explain):
This method failed because of high acquisition and operating/maintenence costs.
Advantages (while it existed)?
• Very fast and decently accurate (though not as accurate as SLA).
• Produces a lot of waste.
• Expensive in comparison to other methods (for both material and operation).