Additive Manufacturing (AM) is a general word for all technologies that have a parts-by-layer accumulation of material at the micron level, to perform the needed shape, except for the metal removal process which is a standard subtractive process. How to define Additive Manufacturing (AM)? It is a creative process in which an object produce layer by layer in an option design. A 3D model made using a computer-aided design (CAD), i.e. 3D scanning, exists cut into individual layers that provide the tool path code for a 3D printing machine at that point. Based on the specific software, the machine performs a parallel process that replicates the model from the base to the top until the object finishes.
Here is the article to explain, What are the Additive Manufacturing (AM) Technologies?
AM technologies can exist broadly divided into three types. The first of which is sintering whereby the material heat without standing liquified to create complex high-resolution objects. Direct metal laser sintering uses metal powder whereas selective laser sintering uses a laser on thermoplastic powders so that the particles stick together.
The second AM technology fully melts the materials, this includes direct laser metal sintering which uses a laser to melt layers of metal powder, and electron beam melting, which uses electron beams to melt the powders. The third broad type of technology is stereolithography, which uses a process called photopolymerization; whereby an ultraviolet laser stands fired into a vat of photopolymer resin to create torque-resistant ceramic parts able to endure extreme temperatures.
Additive manufacturing technology, commonly referred to as 3D printing, has captured our overall creativity, producing wild visions of 3D-printed aircraft and bio-printed organs. Even though innovation guarantees the eventual destiny of assembly; it already has a great impact on our immediate environment, but these visions are still far from existing fully realized. Whether the effects will occur in the immediate future or the long term, 3D printing will change how things stand done.
Types of 3D printing;
There are seven different types of 3D printing procedures dealing with:
- Binder jetting: A procedure that occurs when a liquid bonding agent place on a powder bed.
- Direct Energy Deposition: where the metal is liquified onto a substrate layer by layer.
- Physical extrusion: content deposited from an extruder on a substratum usually liquified by a heating mechanism by a thermoplastic filament.
- Material jetting: Materials that hardened by ultraviolet light, for example, photopolymer.
- Powder bed fusion: the process whereby an energy source such as a laser or an electron beam steer to a powder bed to heat the individual particles until they melted together.
- Sheet lamination: a process where sheets of material combined, with the coveted shape carved into each shape.
- VAT photopolymerization: the resin of the photopolymer exposed to an energy source such as a laser beam that solidifies the material bit by bit.
3D Printing Innovations;
Fused Deposition Modelling (FDM);
In the late 1980s and mid-1990s, a few organizations introduced new non-SL technologies the develop 3D commercial center. FDM is an extrusion-based process in which thermoplastic heat to its melting point as filament spools and deposits in a substratum. Thermoplastics are different from thermosets and may exist melted and cooled several times.
FDM requires a thermal extrusion process which is why the process is notable for producing strong parts which serve a more functional purpose of the processes made with a printing technology called stereolithography (SL) which is a form of VAT photopolymerization. These FDM parts formed in industries with performance-critical applications such as in Spacecraft Industries.
Selective Laser Sintering (SLS);
A powder bed modified software that selectively combines plastic powder with a laser into complete 3D objects. The process is exceptional in that the printing framework acts as integrated support for unlike FDM sintered parts that require 3D printing of support structures. This allows the printing of very complex geometries, including interlocking and moving parts.
Although material jetting may not have existed entirely conquered by the 3D framework; it has existed dominated by another colorful 3D printing method. This process uses piezoelectric inkjet print heads: however, instead of keeping the photosensitive ink, it stores a fluid-restricting agent that results in sandstone-like prints in full color.
Metal 3D Printing;
Although 3D printing plastics can become invaluable to many industries, manufacturers of aerospace and defense exist keenly interested in development.
Direct Energy Deposition (DED);
Also known as laser cladding, which requires the addition of metal powder to a source of heat that melts particles when deposited. Due to the ability of the technology to inject metal powder directly into the heat source often attached to a 4 or 5-pivot arm, DED systems exist not limited to 3D printing with a level substratum. It can exist conceived instead on bent surfaces with existing metal structures. For this reason, laser cladding in the aerospace industry exists often used to repair damaged parts. Likewise, DED machines as a print volume may not exist limited
Powder Bed Fusion;
Unlike DED systems, powder bed machines stand housed in a high-powered energy source inert gas chamber, usually, a laser that melts metal particles layer by layer, similar to the plastic SLS process. Electron beam melting is a special category of SLM technology that relies on an electron beam instead of a laser which makes construction time much faster. This technology can exist better suited to the production of finely detailed parts in small lots when the machine is large enough.
Applications of Additive Manufacturing (AM);
Although many of the newest technologies are now on the market, many of the processes mentioned stand widely used for rapid prototyping, auxiliary production, and the manufacture of finished parts.
Visual and Functional Prototypes;
Manifesting physical 3D printing pre-production plans was a quick prototyping technique. 3D printing can be a quicker and more precise technique than craftsmanship as a design.
The different designs mentioned above are suitable for different prototyping applications such as SL and DLP for fine features; although they may be fragile, they reflect the details that stand included in the end product and FDM for mechanical testing. PolyJet can reflect the real properties of the material, including rubber flexibility of glass transparency.
These technologies can exist used to produce secondary products. For example, many processes exist used to print 3D objects that help to create metal parts such as tooling and investment casting models.
Tooling defines as any type of part that stands specialized in the production of a particular component. Examples of tooling include a shape that can exist used to frame the end part from the raw material; a hop designed to hold a part while other processes, such as assembly drilling; cutting tools.
Pros or Benefits of additive manufacturing:
Similar to standard 3D printing, AM allows for the creation of bespoke parts with complex geometries and little wastage. Ideal for rapid prototyping, the digital process means that design alterations can exist done quickly and efficiently during the manufacturing process. Unlike with more traditional subtractive manufacturing techniques, the lack of material wastage provides cost reduction for high-value parts; while AM has also existed shown to reduce lead times.
In addition, parts that previously required assembly from multiple pieces can stand fabricated as a single object; which can provide improved strength and durability. AM can also exist used to fabricate unique objects or replacement pieces where the original parts exist no longer produced. The following advantages below are;
Material waste reduction;
In conventional manufacturing processes, the material exists typically removed from a larger piece of work; think timber milling or cutting shapes from sheets of steel. In contrast, AM starts from scratch, adding material to create a component or part. By using only the substance necessary to create that part, AM ensures minimal waste. AM also reduces the need for tooling, therefore limiting the amount of material needed to produce components.
Manufacturing and assembly;
A significant benefit of additive manufacturing is the ability to combine existing multi-part assemblies into a single part. Instead of creating individual parts and assembling them at a later point, additive manufacturing can combine manufacturing and assembly into a single process. Effectively consolidating manufacture and assembly into one.
Additive manufacturing is appealing to companies that need to create unusual or complex components that are difficult to manufacture using traditional processes. AM enables the design and creation of nearly any geometric form, ones that reduce the weight of an object while still maintaining stability. Part flexibility is another major waste reduction aspect of AM. The ability to develop products on-demand inherently reduces inventory and other waste.
AM has gifted companies the ability to recreate impossible-to-find, no longer manufactured, legacy parts. For example, the restoration of classic cars has greatly benefited from additive manufacturing technology. Where legacy parts were once difficult and expensive to find; they can now exist produced through the scanning and X-ray analysis of original material and parts. In combination with the use of CAD software, this process facilitates fast and easy reverse engineering to create legacy parts.
Inventory stock reduction;
AM can reduce inventory, eliminating the need to hold surplus inventory stock and associated carrying costs. With additive manufacturing, components exist printed on-demand, meaning there is no over-production, no unsold finished goods, and a reduction in inventory stock.
In conventional manufacturing, machinery and equipment often require auxiliary tools that have greater energy needs. AM uses fewer resources, has less need for ancillary equipment, and thereby reduces manufacturing waste material. AM reduces the number of raw materials needed to manufacture a product. As such, there is lower energy consumption associated with raw material extraction, and AM has fewer energy needs overall.
AM manufacturing offers design innovation and creative freedom without the cost and time constraints of traditional manufacturing. The ability to easily alter original specifications means that AM offers greater opportunities for businesses to provide customized designs to their clients. With the ease of digitally adjusting the design, product customization becomes a simple proposition. Short production runs exist then easily tailored to specific needs.
Cons or Drawbacks of additive manufacturing:
The following disadvantages below are;
Production costs are high. Materials for AM exist frequently required in the form of exceptionally fine or small particles; that can considerably increase the raw material cost of a project. Additionally, the inferior surface quality often associated with AM means there is an added cost to undertake any surface finishes and the post-processing required to meet quality specifications and standards.
Cost of entry;
With additive manufacturing, the cost of entry is still prohibitive to many organizations and, in particular, smaller businesses. The capital costs to purchase necessary equipment can be substantial and many manufacturers have already invested significant capital into the plant and equipment for their traditional operations. Making the switch is not necessarily an easy proposition and certainly not an inexpensive one.
Currently, there is a limit to the types of materials that can stand processed within AM specifications and these are typically pre-alloy materials in a base powder. The mechanical properties of a finished product exist entirely dependent upon the characteristics of the powder used in the process. All the materials and traits required in an AM component have to exist included early in the mix. It is, therefore, impossible to successfully introduce additional materials and properties later in the process.
A certain level of post-processing exists required in additive manufacturing; because surface finishes and dimensional accuracy can be of a lower quality compared to other manufacturing methods. The layering and multiple interfaces of additive manufacturing can cause defects in the product; whereby post-processing exists needed to rectify any quality issues.
As mentioned, additive manufacturing technology has been around since the eighties, yet even in 2021; AM stands still considered a niche process. That is large because AM still has slow build rates and doesn’t provide an efficient way to scale operations to produce a high volume of parts. Depending on the final product sought, additive manufacturing may take up to 3 hours to produce a shape that a traditional process could create in seconds. It is virtually impossible to realize economies of scale.
Principles of Additive Manufacturing;
AM technologies fabricate models by fusing, sintering, or polymerization of materials in predetermined layers with no need for tools. AM makes possible the manufacture of complex geometries including internal part detail that is approximately not possible to manufacture using machining and molding processes, because the process does not require predetermined tool paths, draft angles, and undercuts.
In there, the layers of a model are formed by slicing CAD data with professional software. All AM system work on the same principle; however, layer thickness depend upon parameters and machine being used, and the thickness of the layer range from 10µm up to 200µm. Layers are visible on the part surface in AM operation, which controls the quality of the final product. The relation between the thickness of the layer and surface orientation is known as the staircase effect. However, the thinner the layer is the longer the processing time and the higher the part resolution.
Layers in AM are built up at the top of the previous one in the z-axis. After the layer gets processed the work platform is dropped down by the single-layer thickness on the z-axis and the fresh material layer is recoated differently for several other methods. In a resin-based system traversing edge flatten the resin, in a powder-based system deposited powder is spread using a roller or wiper, in some systems the material is deposited through a nozzle that deposits the required material. Because recoating time is even longer than the layer processing time. For that sake, multiple parts are built together in the time of single material recoating build. Different software is available to position and orient parts so that a maximum number of parts can be built together. Available software is VISCOM RP and Smart Space used in MAGICS.
Some delicate parts produced through AM technologies need a support structure to hold the part in the work platform during the build process. All AM machine uses different support structure that is designed from specific material for effective use of build parts. Commonly used support structures are thin small pointed teeth to minimize the part contact so that they can be removed easily with the hand tools.