The enchanting world of 3D printing

CAPE TOWN – The Fourth Industrial Revolution (4IR) is really proving to be one of the most significant opportunities of our time. Jobs, policies, industries and entire economies are changing as the digital and physical worlds merge. The changes are fundamental and are reshaping our society and environment like each technological revolution has done before. Distinct changes to the way people, businesses and governments operate are becoming visible.

The 4IR are driven by innovative technologies such as Artificial Intelligence (AI), nanotechnology, agile robotics, the Internet of Things (IoT), quantum computing and 3D printing. One important area disrupted by these technologies is the manufacturing industry where they are unlocking new ideas and potential that were previously inconceivable. 

Specifically, 3D printing is at the vanguard of digital manufacturing.  It has the potential to disrupt and reinvent almost every aspect of the manufacturing industry. It is reshaping the manufacturing sector and realising the era of smart production from design to manufacturing across the complete supply chain.

With the advent of 3D printing (also known as additive or digital manufacturing), parts and products can be designed, prototyped, and manufactured in a fraction of the time that it takes using established manufacturing technologies and processes. Additionally, 3D printing entails just-in-time manufacturing that brings about new efficiencies and limits unnecessary redundancy and large volumes of unused inventory.

But what is 3D printing? 3D printing is a manufacturing process through which three-dimensional (3D) physical objects are created from a 3D digital model. The solid object is typically created by fusing plastic, metal or ceramic to lay down a series of thin layers of the material. The series of additive layers or layered development framework, where layers are laid down in succession on a sub millimetre scale, are continued until a complete 3D object has been created.

The 3D printing process is completed in several stages. In order to initiate the process, a 3D model of the object or products must be created on the computer through the use of a 3D Computer-Aided Manufacturing (CAM) software tool. The software will then slice the graphical data of the CAD file into separate object layers or components to convert the design into a file readable by the 3D printer. The segmented or layered graphical data is sent to the 3D printer, which applies the defined combination of raw material for that particular layer. The printer then “builds” the product layer by layer until it is fully designed and completed according to the design criteria. 

3D printers regularly use a variety of materials such as polymers, metals, ceramics and sand for prototyping and production. Newer applications of 3D printing also involves bio materials and different types of food. At entry level 3D printing, polymers and nylon are the most used, although an increasing number of printers can also use food such as sugar, chocolate, pasta and even meat.

However, the printing or manufacturing process is not uniform. The different types of 3D printers each employ a different technology that processes materials in a different way. 

The Stereolithography (SL) process is the first commercialised 3D printing process and consists of controlled solidification of liquid photopolymer resins in ultra-thin layers through the use of a laser to produce very accurate objects. It is limited by the manual curing process by intense light to fully harden the resin. Over time the materials can also become brittle.

A similar process to SL is Digital Light Processing (DLP) that also uses photopolymers, but with the difference of using a more conventional light source such as an arc lamp. The operating costs of DLP is much lower.

Some 3D printers, for instance, employ a process called Selective Laser Sintering (SLS), which fuses (sinter) powdered material (nylon, plastic, ceramic, and certain metals) through the energy from a high power laser to build an object. This process enables plastic or nylon to be mixed with carbon or glass fibres to give greater rigidity. It also allows the manufacturing of very complex shapes, but due to the extremely high laser temperatures the cooling periods are rather long. Porosity is also a problem that requires further treatment.

Selective Deposition Laminating (DSL) is a further printing process that involves the laser cutting of successive layers of standard copier paper that are fixed to each other with adhesive. This process is one of the few processes that can produce full colour 3D products.

Other 3D printers use a process called Binder Jetting, which entails the spraying of fine droplets of binder into a powder bed of material. This basically entails the same process as 2D inkjet printing that are common in many households. Durability may be a problem without further processing. A related technique is Material Jetting, whereby the actual build material in molten form are jetted through multiple jet heads to form the product. Each layer of the liquid polymers is cured with an ultraviolet light. It is a very precise method allowing the use of multiple materials to produce a very accurate product.

The most common 3D printing process currently used, is Fuse Deposition Modelling (FDM), which uses thermoplastic polymers, mostly Polylactic Acid (PLA) or Acrylonitrite Butadiene Styrene (ABS), in filament form through a heated extruder to form the layers and create the object. PLA is much easier to use and is deemed safer since it is bio-degradable, while ABS is stronger, more flexible, and allows the printing of more durable objects. FDM printing is the preferred printing technique used by the general public, since most of the entry-level 3D printers use the FDM process, often called Freeform Fabrication (FFF). The process are rather slow for some product geometries and layer-to-layer adhesion can be a problem resulting in products that are not watertight without post-processing with Acetone.

Whatever 3D printing technique will dominate over time, additive manufacturing will change the way we are creating things – metal, plastic, concrete, food and even human tissue. The main reason for this is that among many other benefits, additive manufacturing drastically reduce the design-to-product time, is more cost effective, allows small batch manufacturing and greater flexibility, makes the production of overly complicated designs possible, and reduces waste throughout the production process.

3D printing provides an alternative to the conventional product manufacturing process, where objects were designed by machining and shaping of raw material through removing some material (subtractive manufacturing) or constructing an object through the ancient technique of casting and forging.

The digital manufacturing revolution is upon us and the possibilities are almost endless. But are the manufacturing industry in South Africa ready? Have we started with the retraining of many workers that may lose their job? It is time to reinvent manufacturing if South Africa wants to remain competitive.

Professor Louis Fourie is the deputy vice-chancellor: knowledge & information technology – Cape Peninsula University of Technology.

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