What is 3D Printing?
Three-Dimensional (3D) printing is a process of manufacturing three-dimensional objects from a digital model using an additive process (deposit, join or solidify). The process of creating objects by adding successive layers of material is known as additive manufacturing. Therefore, 3D printing is also known as additive manufacturing (AM), solid free-form technology (SFF), or rapid prototyping (RP). Many different materials are used in 3D manufacturing such as plastic, metals, ceramics, powders, liquids, or even living cells. 3D printing technology is fundamentally different from traditional subtractive or formative manufacturing. A simplistic block diagram of a traditional 3D printer is given below.
3D Printing Process
The overall printing process of a generic 3D printing is broadly classified into the following steps
- The first step is to create a three-dimensional digital file of an object that we want to print. Three different ways of doing this are listed as follows
- Design: Use 3D modelling software like AutoCAD, Blender, or others to create a 3D printable file.
- Scan: Use 3D scanning technology to analyze a real-world object and replicate its digital model suitable for printing.
- Download: Check for ready-made 3D models created by others that are available to download from popular websites.
- Next, the design model is stored in a proper file format to meet criteria like a maximum polygon count, water-tightness, minimum wall thickness, etc. The most common file formats are STL, OBJ, and 3MF. File formats for 3D printing in full color are X3D, WRL, and DAE.
- Slicing is the process of translating a 3D file format into a numerical code language format called G-code. In simple words, slicing is dividing the 3D model into a hundred or thousands of horizontal layers that are suitable for a step by step execution.
- The 3D printer starts printing as per the G-code instruction with proper calibration settings and continues printing unless there is no software error or the machine runs out of raw material.
- After the completion of printing, removing the finished parts from the 3D printer and post-processing vary for different printing technologies. Finally, the 3D printed object is ready to use.
Types of 3D Printers
There are different ways to 3D print. The choice of a particular type depends on the raw material to be used and how the layers are bonded. According to ISO/ASTM 52900 standard, 3D printer types can be broadly classified into the following categories.
- Material Extrusion: This material is selectively dispensed through a nozzle and the most commonly used technology in this process is Fused Deposition Modelling (FDM). In FDM, a plastic filament or metal wire is unwound from a coil and then fed to the extrusion head. The extrusion head equipped with a nozzle is heated to melt the material and a motor drives the filament through the nozzle. The melted material is poured at precise locations, which solidifies and forms layers. The process is repeated until the job is complete. ABS (Acrylonitrile Butadiene Styrene) and PLA (Polylactic acid) are the most widely used plastic filament material with this technology. Low-cost prototyping, fast turn-around are few advantages of material extrusion type 3D printers.
- Vat Polymerization: A Vat Polymerization type 3D printer has a container filled with liquid photopolymer resin which is hardened with an Ultra Violet (UV) light source. Stereolithography (SLA) and Digital Light Processing (DLP) are the two most commonly used methods in this process. SLA uses a single point laser light to expose the photopolymer resin and solidifies the pattern traced on the resin that joins the layer below. DLP is similar to SLP with a difference in the light source, where a digital light projector is used to flash a single image on each layer all at once. Smooth surface, high accuracy, and intricate details are a few advantages of this method.
- Material Jetting: Material is applied in droplets similar to inkjet printers that are selectively deposited in multiple layers and then hardened by UV light. Usually, water-soluble support structures are used in material jetting. These support structures are printed along with object material and can easily be melted during post-processing. Injection moulding-like finish with multi-material and full-color capabilities are few advantages of material jetting.
- Binder Jetting: Powder base material and a liquid binder are used in this method. Powder particles forming a thin layer are first deposited onto the build platform. Binder is then applied through a jet nozzle to selectively bind the powder particles together and build a part layer-by-layer. Low-cost batch production of metal parts and very large full-color printing capabilities in the sand are a few advantages of binder jetting.
- Powder Bed Fusion: Selective Laser Sintering (SLS) is the most commonly used technology in this method. In SLS, a high-energy source selectively fuses powder particles into a mass that has the desired three-dimensional shape.
- Sheet Lamination: Sheets of material are bonded and formed layer-by-layer with external force. Metal, paper, or polymer can be used as sheets.
- Direct Energy Deposition: It is mostly used in the high-tech metal industry where a high-energy source fuses the material as it is deposited.
Applications of 3D Printing
3D printing is being used in almost all industries ranging from medical, consumer products, automotive, robotics, construction, and aerospace. Few examples of 3D printed materials are listed below
- Eyewear, footwear, furniture, jewellery, and many more consumer products
- Manufacturing tools, prototypes, functional end-use parts, and other industrial products
- Prosthetics, dental products, bio-printing, and few others in the health care sector
- Architectural scale models, maquettes, replicating ancient artefacts, and reconstructing fossils in the design field
- Spare parts, tools, jigs, and fixtures in the automotive industry
- Structural fittings, fuel nozzles, and thousands of other parts in the aviation sector
- To materialize ideas in a fast and affordable way in the education field
- Extrusion, powder bonding, additive welding and even the fully completed residential building in the construction sector.