Long ago I completed a PhD wherein I studied metal machining production processes. At that time, 3-D printing was unheard of but now I frequently see articles touting it as the future of manufacturing. I am not convinced, but I see merit in 3-D printing for special applications.
There are several 3-D printing technologies but they mostly boil down to building up a shape by successively melting small particles of material onto the part finished object, like building up a wall using bricks. The particles can be made from a wide range of materials, but are usually metal or plastic. A separate glue may be used to hold the particles together, or a LASER or other energy source can melt the particles together. All practical 3-D printing machines are completely automated and start with a CAD (Computer Aided Design) file that describes the finished shape. The machine then decomposes the finished shape into a series of parallel layers (like slicing an onion) and deposits particles sequentially to build up each layer one atop the other.
Current 3-D printers can only make products from one material at a time. You can easily 3-D print a bottle, but not a bottle full of juice, or even a bottle with a label on it. This mostly limits 3-D printing to single part products, or single parts of more complex products. Also, the materials used in 3-D printing must be specially, and expensively, formulated.
3-D printing is very flexible and can be used to make parts of any shape, even ones that are very difficult to create using conventional methods. We have all seen balls carved one inside the other, which is very difficult to do with conventional manufacturing machines, but is easy with 3-D printing, for example. However, the process is limited to smaller parts and it is also quite slow so it takes several hours make a coffee cup. Finally, because the objects are built from particles the finished surface is often rough and relatively inaccurate.
3-D printing is an example of an additive manufacturing process like molding and forging. However, these other additive manufacturing processes use a mold to shape the object – think of pouring molten metal into a casting mold. Using a mold gives you great speed and accuracy advantages, but to change the part you have to change the mold. Thus, using a mold is only effective if you want to make many copies of the same part. The mold also limits the range of objects that can be made – no balls within balls.
Finally, 3-D printers can be put anywhere, just like ordinary printers, so you do not need a factory or an expert operator. This means that individualized custom objects can be made on demand – think of emailing a design file to your local print shop and then picking up your own individually designed, and unique, lampshade the next day.
Taking all of the above into consideration, it is clear that 3-D printing is not particularly suited to large scale high-volume manufacturing, and will always be more expensive than conventional mass production in these situations. But it is very good for intricate custom or small volume production objects like prosthetic body parts, architectural models, prototype machine parts and “objets d’art”, as long as smooth surfaces are not needed, or the object can be hand finished.
3-D printing is very well suited to creative industries for making models and prototypes and customized products. I would very much like to see a 3-D printing shop set up in Macau so that local school kids and professional designers can make unique products for their own creative development and for sale.