Additive Manufacturing Fundamentals

Welcome to our training page on Additive Manufacturing! If you’re just starting your journey in this exciting field, it’s important to have a solid understanding of the fundamentals. In this section, we’ll be diving into the fundamental background of additive manufacturing and introducing you to the different types of terms and technologies that fall under this umbrella. Whether you’re new to the industry or looking to brush up on your knowledge, our free training is designed to provide you with the information and resources you need to succeed. From the basics of 3D printing to the latest advancements in the field, we’ve got you covered. So, let’s get started and learn about the exciting world of Additive Manufacturing!

What is Additive Manufacturing (3D Printing)?

Additive manufacturing, also commonly referred to as 3D printing, is a process defined by the ISO/ASTM 52900 terminology standard as the process of joining materials to make parts from 3D model data. This technology involves building up layers of material, as opposed to subtractive and formative manufacturing methods. Other terms for additive manufacturing include 3D printing, additive fabrication, direct digital manufacturing, freeform fabrication, solid freeform fabrication, rapid manufacturing, and rapid prototyping.

Additive manufacturing uses data computer-aided-design (CAD) software or 3D object scanners to direct hardware to deposit material, layer upon layer, in precise geometric shapes. As its name implies, additive manufacturing adds material to create an object. By contrast, when you create an object by traditional means, it is often necessary to remove material through milling, machining, carving, shaping or other means.

Additive manufacturing has a wide range of applications, including the production of models, prototypes, patterns, tooling, and even final parts for use in industries such as consumer, industrial, medical, and military. It can be used to improve product development by reducing time to market, improving product quality, and reducing costs. It can also be used as a visualization tool to gain early feedback and reduce the likelihood of delivering a flawed product. In addition, companies can benefit from the ability to produce parts on-demand and reduce inventory.

As additive manufacturing continues to evolve with the introduction of new machines, materials, and applications, it has the potential to have a significant impact on a growing number of industries and geographic regions. It is an exciting technology with endless possibilities for improving efficiency and driving innovation.

The video below from GE Additive shows what Additive Manufacturing is from a metal powder bed fusion point of view.

What are the Different Types of Additive Manufacturing (3D Printing)?

So this is where Additive Manufacturing can get really confusing, because there are many different types of Additive Manufacturing processes and technologies. 

Although the media frequently refers to all additive manufacturing technologies as “3D printing,” there are many distinct processes that differ in how objects are created layer-by-layer. Depending on the material and machine technology employed, specific processes will vary. In order to define the variety of additive manufacturing processes into 7 categories, the American Society for Testing and Materials (ASTM) group “ASTM F42 – Additive Manufacturing” developed a set of standards in 2010. These 7 categories (as per the image) are material extrusion, vat polymerization, material jetting, laminated object manufacturing, powder bed fusion, directed energy deposition, and binder jetting. Most AM systems fit into one of the seven categories. Future AM processes could develop that do not fit into one of the categories, which could require an update to the ISO/ASTM 52900 standard. The following sections provide more detail about the 7 types of AM processes:

Material Extrusion

Courtesy of Wohlers Associates

Material Extrusion is a 3D printing process in which material is selectively dispensed through a nozzle or orifice to create a three-dimensional object. This is done by depositing layers of material, through the heated extruder nozzle and either lowering the build platform or raising the extruder head. The part’s shape is determined by movements of the extruder and platform using G-code which is a pre-loaded file created by a software called a “slicer.”

There are various materials that can be used in Material Extrusion, including thermoplastics in filament form (e.g. ABS, nylon, PEEK, PLA, etc.), composite and filled materials such as carbon-filled and glass-filled filaments, and even paste-like materials such as concrete, ceramics, or food items like chocolate or dough. The process may require the use of sacrificial support material for overhanging features. Fused Deposition Modeling (FDM) an example of Material extrusion is better explained in the video from Solid Concepts below:

VAT Polymerization

Vat Photopolymerization (VPP) is a 3D printing process in which liquid photopolymer is selectively cured by light-activated polymerization. The photopolymer is held in a vat, and the printing process starts with the resin in this vat. There are two main types of VPP: laser-based and LED-based. In laser-based VPP, a laser is used as the energy source to cure the resin, while in LED-based VPP, light-emitting diodes and digital light processing are used. In the laser-based process, one layer is cured before the build volume is lowered and a new layer of liquid photopolymer is added. In DLP systems, light is projected from below the vat and the resin is cured through an optical window.

VPP is attractive for creating high-resolution parts at a reasonable cost, but it requires a secondary curing and washing step for post-processing, and also sacrificial support material for overhanging features. Stereolithography, an example of a VPP technology is discussed in the video below from Solid Concepts.

Courtesy of Wohlers Associates

Material Jetting

Courtesy of Wohlers Associates

Material jetting (MJT) is a 3D printing process where droplets of feedstock material are selectively deposited using inkjet print heads. This material is typically photopolymers or wax-like substances and is solidified with UV light. The process starts by depositing the material on the build platform, layer by layer. Once a layer is cured, the print head’s nozzles deposit new material on top of it. MJT parts require support structures, which are usually made of a dissolvable material that can be removed during post-processing. The process also allows for creating graded material combinations, resulting in different properties or colors throughout the part. The Material Jetting process called PolyJetting is explained in the following video. 

Laminated Object Manufacturing

Laminated Object Manufacturing (LOM) or Sheet lamination (SHL) is a 3D printing process that creates parts by bonding sheets of material together. The process can use various materials such as metal, paper, polymers, or composites. It involves adhering one layer of material onto another using an adhesive or welding process. The shape of each layer is typically created by a cutting or machining process, either before or after it’s deposited. parts created using LOM may have limitation in design as internal cavities can be hard or impossible to remove material from, but it allows to embedded electronics or low melting point materials due to the limited heat required in this process. Sheet lamination printing is not as common as the other AM technologies but it’s still a great technology to learn about and can be done at home with some paper, scissors, and some glue. The video below highlights the technology. 

Courtesy of Wohlers Associates

Powder Bed Fusion

Courtesy of Wohlers Associates

Powder Bed Fusion (PBF) is a 3D printing process that selectively melts regions of a powder bed using thermal energy from a laser or electron beam. The areas that the beam contacts become solid as the material cools and adheres to the previous layer. Once a layer has been fused, a new layer of powder is added.

PBF can use a wide range of polymers or metals, and typically, the polymers used are semi-crystalline thermoplastics. For polymers, the unfused powder surrounding the part serves as a support material, but for metal PBF, support structures are required to anchor parts and features to the build plate. PBF can lead to thermal stress and heat treatment is typically required for metal parts. Selective Laser Sintering (SLS) and Selective Laser Melting (SLM) are 2 different types of Laser Powder Bed Fusion technologies. One is commonly used for plastics and the other for metals. The two videos below explain the differences of each. 

Directed Energy Deposition

Directed Energy Deposition (DED) is a metal additive manufacturing process that uses focused thermal energy to fuse materials by melting them as they are being deposited. DED uses feedstock in the form of a metal powder or wire, which is delivered through a nozzle mounted on a multi-axis arm. It is sometimes combined with computer numerical control (CNC) milling to make hybrid parts. The process produces parts that are close to their final shape, but usually require additional machining to achieve the required tolerances.

DED has unique capabilities, such as the ability to deposit multiple materials simultaneously. It can also be used to repair damaged parts by depositing material directly onto them. Meltio uses a DED process called wire-laser metal deposition (W-LMD). The video by them below explains more about this DED process. 

Courtesy of Wohlers Associates

Binder Jetting

Courtesy of Wohlers Associates

Binder Jetting (BJT) is a 3D printing process that joins powder materials by selectively depositing a liquid bonding agent. The process begins with a layer of powder, which can be made of a polymer, metal, ceramic, or sand. The print head releases droplets of the binding agent on the powder material in a pre-determined pattern. After one layer is complete, the build platform moves downward and a new layer of powder is added.

The parts created using BJT typically requires post-processing to improve their mechanical properties, this can include applying an additional adhesive or heating the part in an oven or furnace to sinter the particles. The Colour Jetting binder jetting technology from 3D Systems is explained in greater detail in the following video. 

Advantages of Additive Manufacturing (3D Printing)

When used properly, Additive Manufacturing offers a number of advantages. Given the lack of advanced and accessible manufacturing technologies, some of those benefits are even more advantageous for Africa than for other continents. This offers a unique opportunity for additive manufacturing in Africa because the solutions offered by additive manufacturing are uncontested by other manufacturing technologies that have been adopted by developed countries. Additive Manufacturing is a rapidly developing technology with the potential to transform manufacturing and production in Africa. There are several benefits to using additive manufacturing, including:

1. Customization: One of the main advantages of additive manufacturing is the ability to produce customized products on demand, which is particularly useful for small batch production or creating one-of-a-kind designs.

2. Speed: Traditional manufacturing methods often require the creation of molds or tooling, which can be time-consuming and costly. Additive manufacturing allows for the production of parts and products almost instantly, significantly reducing lead times.

3. Material options: Additive manufacturing enables the use of a wide range of materials, including metals, plastics, and even ceramics and glass. This provides designers and manufacturers with greater flexibility in the materials they can use for their products.

4. Reduced waste: Traditional manufacturing often generates a significant amount of waste as material is machined or cut away to create the final product. Additive manufacturing produces minimal waste as it builds up the product layer by layer.

5. Cost-effectiveness: Additive manufacturing can often be more cost-effective than traditional manufacturing methods, particularly for small batch production or customized products. It also reduces the need for expensive tooling and molds.

6. Sustainability: Additive manufacturing has the potential to significantly reduce the environmental impact of manufacturing. It produces less waste and uses less energy than traditional methods, and it allows for the production of products closer to the point of use, reducing the need for transportation.

Overall, additive manufacturing has the potential to greatly impact the way we produce and consume products in Africa. It offers increased customisation, speed, material options, reduced waste, cost-effectiveness, and sustainability, making it a valuable manufacturing technique for a wide range of industries.

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