Additive Manufacturing

Additive manufacturing is a printing process that progressively builds up a 3-dimensional model by adding material layer upon material layer over time. Some people argue that the term is a misnomer since it is 2D printing, occurring repeatedly. Nevertheless, it is a technology that is evolving at a significant pace. 

Before 3D printing was developed, Manufacturers would purchase raw materials that were shaped via various mechanical processes to achieve the final desired outcome. This resulted in the removal of material, and thus waste since not all the material was required in the final product. This resulted in a waste of material and processing/time.  With 3-D printing, you only use the time and material required to build the desired product. Yes, there is some waste in building the support structures, but these processes are being improved and refined continuously. 

According to a 3D insider, there are now nine different types of additive manufacturing technologies

These are:

1.  Stereolithography (SLA) - The plastic or resin is first heated to turn it into a semi-liquid form, and then it hardens on contact with ultraviolet light. This technique is used for accuracy and precision. It's also common practice to post-cure the object in an ultraviolet oven. This process has become a favoured economical choice for a wide variety of industries. 

2.  Digital light processing (DLP) - This process is like SLA, given that it also works with resins. The one major difference, however, is that while SLA uses ultraviolet light, DLP uses a more traditional light source, usually arc lamps and is recognised as the oldest 3D printing technology.

3.  Fused deposition modelling (FDM) - This uses production-grade thermal plastic materials to print its 3D objects. It's popular for producing functional prototypes, concept models, and manufacturing aids. It's a technology that can create accurate details and boasts an exceptional strength to weight ratio.

4.  Selective laser sintering (SLS) - This technique uses high power CO2 lasers to fuse particles together. The laser sinters powdered metal materials (though it can utilize other materials too, like white nylon powder, ceramics and even glass). It's a process that repeats one layer at a time until it reaches the object's height. SLS produces durable, high precision parts, and can be used on a wide range of materials. It's an ideal technology for fully-functional, end-use parts and prototypes. SLS is quite like SLA technology in that the main difference lies with the materials, as SLS uses powdered substances, whereas SLA uses liquid resins.

5.  Selective laser melting (SLM) - This process also uses a high-powered laser beam to form 3D parts. During the printing process, the laser beam melts and fuses various metallic powders together. The main difference between SLM and SLS is that SLM completely melts the powder, whereas SLS only partly melts it (sinters). In general, SLM end products tend to be stronger as they have fewer or no voids.

6.  Electronic beam melting (EBM) - This is a 3D printing technology like SLM in that it uses a powder bed fusion technique. The difference between the two is the power source. The SLM approach above uses a high-powered laser in a chamber of noble, or inert gas whereas EBM uses a powerful electron beam in a vacuum. EBM's main use is to 3D print metal parts. Its main characteristics are its ability to achieve complex geometries with freedom of design. 

7.  Laminated object manufacturing (LOM) - this works by fusing or laminating layers of plastic or paper using both heat and pressure. A computer-controlled blade or laser cuts the object to the desired shape. Once each printed layer is complete, the platform moves down by about 1/16th of an inch, ready for the next layer. The printer then pulls a new sheet of material across the substrate where it's adhered by a heated roller. This basic process continues over and over until the 3D part is completed. Whilst not the most popular method of 3D printing today, it remains one of the fastest and arguably the most affordable method for creating 3D prototypes. This process is typically used by artists, architects and product developers. 

8.  Binder jetting (BJ) - a 3D printing process that uses two types of materials to build objects. A powder-based material (usually gypsum) and a bonding agent. As the name suggests, the bonding agent acts as a strong adhesive to attach (bond) the powder layers together. The printer nozzles extrude the binder in a liquid form similar to that of a regular 2D inkjet printer. After completing each layer, the build plate lowers slightly to allow for the next one. This process repeats until the object reaches its required height. The advantage of this process is that these printers allow one to print parts in full colour by simply adding colour pigments to the binder. 

9.  Material jetting (MJ) - this is also referred to as a wax casting. These printers produce high-resolution parts, mainly for the dental and Jewellery industries.

As these technologies are advancing all the time, so too are the costs reducing at an exponential rate. In 2010, a 3D printer could cost more than R 300 000. In 2013, this cost reduced to about R 15 000. One can now buy a good quality 3D printer for less than R 3 500.  

Whilst modelling and scanning (reverse engineering) still require a degree of skills and associated costs attached to them, there are now whole communities dedicated to delivering 3D printable designs.  www.thingiverse.com is one such site worth exploring. 

3D printing is leading to the democratisation of manufacturing. As this technology matures and spreads, it would not only supports developed and well- resourced communities but could help support marginalized and difficult-to-reach populations with essential products by providing disaster recovery aids, emergency medical products and even food supplies.