3D Printing

3D Printing

In spite of the fact that 3D printers have been around for nearly 30 years, their current popularity wouldn’t indicate that. The availability of low-cost 3D printers has now made the product development process much more efficient, as well as enabling distributed manufacturing.

The term 3D printing refers to the process of building an object from scratch rather than machining it away, such as when you make something from wood or squirt plastic into a mould. Its flexibility and the magic of creating something from nothing have captured the imagination of people for years, and future applications are sure to be unexpected.

It involves starting with nothing and successively adding material until you get a completed object. Natural examples abound, and lower-tech variations, such as brick walls, have been practised for millennia.

Despite the fact that 3D printing seems like an advanced technology, organisms have been doing the equivalent for millions of years. Molluscs, which produce seashells, are a few of nature’s many 3D printers. Molluscs add calcium carbonate to their outer shells as they grow, giving them more room to grow. You can see growth lines in seashells if you observe carefully. Likewise, many rock formations in the southwest of the United States were laid down when ancient oceans built up layers of silt. Wind and rain have carved away these layers of sandstone. (Horvath, 2014)

History

In 1984, Charles W. (Chuck) Hull developed the first working robot 3D printer, which was commercialized by 3D Systems in 1989. The machines were SLA systems, and this technology is still used today in large commercial machines. A flurry of patents followed for a variety of power-based systems in the early 1990s at the Massachusetts Institute of Technology and the University of Texas. These systems squirt a binder very precisely on the surface of a vat of powder to create layers. In addition to using lasers to bind powders, another early printer company, Z Corp, also created industrial printers based on SLS patents. Z Corp is now owned by 3D Systems.

Additionally, S. Scott and Lisa Crump co-founded Stratasys, Ltd. in 1989 and patented fused deposition modelling (FDM). With this technology, plastic filaments are fed into heated extruders and then precisely laid down. It was based on this technology when key patents expired in 2005, resulting in RepRap development.

A 3D printing technique known as two-photon polymerization uses femtosecond pulsed lasers to fuse powders at the molecular level to print at the molecular level. These are mainly documented in the scientific literature at the moment. At the other extreme, large concrete structures can be printed. Researchers are printing food and even human organs. The pace of development in the field is fast; commercial companies as well as academics are inventing new methodologies, making it difficult to keep up with it all and distinguish between the new and the dubious. (Horvath, 2014)

Additive Manufacturing

Additive manufacturing has existed for a very long time. An example is the humble brick wall. Building a brick wall is one brick at a time, with mortar added. It is usually built on a formal plan drawn by an engineer or architect, or perhaps from the head of a contractor, depending on how routine the job is. You will see all the steps in 3D printing that you would in building a brick wall: designing the end product, planning how to arrange the layers so that the structure will not collapse while it is being built, and then building it one layer at a time. This process of building up an object by layer is enhanced by 3D printers because they add the element of robotic control to it.

There are three general types of additive manufacturing: selective binding, selective solidification, and selective deposition. They are typically referred to by the acronyms SLS, SLA, and DLP.

The selective binding technique involves applying binding agents or heat to a powder (metal and gypsum are common materials) to fuse its particles together into a 3D-printed object.

In selective solidification, energy is selectively applied to a vat of liquid to solidify it one layer at a time to form a solid object. Once again, a first layer is typically created on a build platform, which then moves down into the liquid (or, in some cases, pulls up from the liquid).

The selective deposition method places only the material where you want it. It involves melting the filament and then adding it to the object precisely. There are also 3D printers that inkjet-print liquid resin, and then cure it with UV light. (Horvath, 2014)

3D printing technique – Paolo Cignoni, 2017

Making a 3D Model

In order to use a 3D printer, you need to create a 3D computer model. You can do this by scanning an existing object, downloading a model from the web, or creating one from scratch. Design is more than picking a software package, though, and you can simplify the printing process by making certain design decisions.

Models must be in a format that can be used by programs that “slice” them for 3D printing, regardless of the source of the model. People can become confused when they want to print something using a 3D printer since the term 3D computer model is used in many different contexts. An object can be printed using a 3D computer model because it contains enough information about its surface to make the object printable.

The STL file is the most common file format for consumer 3D printers. It is sometimes referred to as STereoLithography or Surface Tesselation Language in the open-source 3D printing world. The STL file format is the lowest common denominator, consisting of a long list of triangles covering the entire surface of the object. The STL format is not the most efficient, but it is relatively easy to generate and deal with, making it the de facto standard. The OBJ format is similar to STL, but it also preserves colour and other information. (Horvath, 2014)

References

Horvath, J. (2014) Mastering 3D Printing. 1st ed. 2014. Berkeley, CA: Apress.

First try

I wanted to try out 3D printing before semester two, so I picked one of the models I had made earlier to be the guinea pig. The Groke was a perfect choice, as her design and silhouette are very simple. I discussed the idea with the staff first, and there was some concern about the hands, especially the fingers. I decided to go ahead anyway, as the 3D printing support person felt like it should be okay. And out she came! In one piece.

The print quality wasn’t the best, it seems that the model wasn’t high quality enough which resulted in some “pixelated” seams in the print. Also, the automated supports were a little tricky to remove, which resulted in a finger accident as she lost her pinky finger on her left hand. Other than that the model was very neat and tidy and I was super excited. So excited in fact, that I had to show it to Sean for no reason right after I collected the model.

Back at home, I tried to sand the model down with 120-grit sandpaper, but to my horror realised that the green colour of the paper actually transferred onto the model! In a panic, I switched to a pet nail grinder I had for my dog and that worked like a charm. It was way faster too. Unfortunately, the damage on the left side was already done and the green colour stuck for the rest of the time, so in the end, I decided to paint the green half with acrylics.

In the end, I painted four layers of paint in total as the slippery plastic surface of the model didn’t hold the paint too well. In the future, the model should be sanded more thoroughly in order for the shiny surface to be erased in case I wanted to use paint again. The end result was quite neat, it was pretty amazing seeing the model I made in 3D actually be held in my hands. I ended up liking the painterly texture on top of the model, which is something I could possibly think about implementing in the future in a bigger volume. Applying the paint in impasto for example could result in some very interesting outcomes!