What Is Additive Manufacturing?- Types And Working

What Is Additive Manufacturing?

Additive manufacturing (AM), also known as 3D printing, is a transformative approach to industrial production that enables the creation of lighter, stronger parts and systems. As its name implies, additive manufacturing adds material to create an object.

Additive manufacturing (AM) or additive layer manufacturing (ALM) is the industrial production name for 3D printing, a computer-controlled process that creates three-dimensional objects by depositing materials, usually in layers.

According to GE Additive, This is another technological advance made possible by the transition from analog to digital processes. In the past few communication, imaging, decades, architecture, and engineering have gone through their own digital revolutions. Now AM can bring digital flexibility and efficiency to manufacturing.

Additive manufacturing uses CAD (Computer-Aided Design) software or 3D object scanners to control the hardware so that material is deposited layer by layer in precise geometric shapes. As the name suggests, additive manufacturing adds material to create an object. In contrast, when creating an object by conventional means, it is often necessary to remove material by machining, carving, milling, molding, or otherwise.

Although the terms “3D printing” and “rapid prototyping” are used casually to discuss additive manufacturing, each process is actually a subset of additive manufacturing.

While additive manufacturing may seem new to many, it has actually been around for several decades. In the right applications, additive manufacturing delivers a perfect trifecta of improved performance, complex geometries, and simplified manufacturing. As a result, there are many opportunities for those who are actively committed to additive manufacturing.

• Related Article: What is 3D Printing?
• Related Article: What is Rapid Prototyping?

Who Invented AM?

The earliest production equipment for 3D printing was developed by Hideo Kodama of the Nagoya Municipal Industrial Research Institute when he invented two additive methods of making 3D models.

How Does Additive Manufacturing Work?

With the help of CAD (Computer-Aided Design) or 3D object scanners, additive manufacturing enables the creation of objects with precise geometric shapes. These are built up layer by layer, in contrast to traditional manufacturing which often requires machining or other techniques to remove excess material.

3D printing, rapid prototyping and additive manufacturing are terms used to describe the same processes in general. Complex structures and components are created by layering materials that are built up step by step.

This technology, which has been around for more than three decades, It has only recently grown in popularity and is no longer just a means of making a 3D printed prototype, but offers fully functional components. The possibilities are almost limitless as the 3D printing industry serves sectors from heavy industry to medicine that want to take advantage of the precision technologies on offer.

While additive manufacturing offers the potential for new opportunities in science, the concept and how it works is surprisingly simple.

Additive manufacturing technologies

1. Sintering

During sintering, heat is used to create a solid mass without liquefying it. Sintering is similar to traditional 2D photocopying, in which toner is selectively melted to create an image on paper.

2. Direct Metal Laser Sintering (DMLS)

Within DMLS, a laser sinters each layer of metal powder so that the metal particles adhere to one another. DMLS machines produce high-resolution objects with desirable surface features and required mechanical properties. With SLS, a laser sinters thermoplastic powders to cause particles to adhere to one another.

3. Direct Metal Laser Melting (DMLM) and Electron Beam Melting (EBM)

In contrast, materials in the DMLM and EBM processes are completely melted. With DMLM, a laser completely melts each layer of metal powder, while EBM uses high-power electron beams to melt the metal powder. Both technologies are ideal for creating dense, non-porous objects.

4. Stereolithography (SLA)

Stereolithography (SLA) uses photopolymerization to print ceramic objects. The process uses a UV laser that is selectively burned into a container made of photopolymer resin. The UV curable resins produce torque-resistant parts that can withstand extreme temperatures.

How Long Does the Process Take?

The printing time takes in a few factors, including the size of the part and the settings used for printing. The quality of the finished part is also important when determining print time, as higher quality items take longer to produce.

AM can last from a few minutes to several hours or days – speed, resolution, and volume of the material are important factors here.

Additive manufacturing materials

It is possible to use many different materials to create 3D-printed objects. AM technology makes jet engine parts from advanced metal alloys and also makes chocolate treats and other foods.

• Thermoplastics: Thermoplastic polymers remain the most popular class of materials for additive manufacturing. Acrylonitrile-butadiene-styrene (ABS), polylactic acid (PLA), and polycarbonate (PC) each offer different advantages in different applications. Water-soluble polyvinyl alcohol (PVA) is typically used to create temporary support structures that are later dissolved away.
• Metals: Many different metals and metal alloys are used in additive manufacturing, from precious metals like gold and silver to strategic metals like stainless steel and titanium.
• Ceramics: A variety of ceramics have also been used in additive manufacturing, including zirconia, alumina, and tricalcium phosphate. In addition, glass powder and adhesive are alternately baked together to create entirely new classes of glass products.
• Biochemicals: Health care biochemical applications include the use of hardened materials made from silicon, calcium phosphate, and zinc to support bone structures when new bone growth occurs. Researchers are also investigating the use of bio-inks made from stem cells to form everything from blood vessels to blisters and beyond.

Types of Additive Manufacturing Processes

There is a number of distinct AM processes with their own standards, which include:

• Binder Jetting
• Directed Energy Deposition
• Material Extrusion
• Powder Bed Fusion
• Sheet Lamination
• Vat Polymerisation
• Material Jetting

1. Binder Jetting

The binder jetting process uses two materials; a powder-based material and a binder. The binder acts as an adhesive between layers of powder. The binder is usually in liquid form and the building material is in powder form.

A print head moves horizontally along the machine’s x and y axes and alternately deposits layers of the building material and the binding material. After each level, the object to be printed is lowered onto its build platform.

Due to the binding method, the material properties are not always suitable for components, and despite the relative printing speed, additional post-processing can significantly extend the overall process.

As with other powder-based manufacturing processes, the object to be printed is self-supporting in the powder bed and is removed from the unbound powder after completion.

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Binder Jetting  – Step by Step

• The powder material is spread over the build platform using a roller.
• The print head deposits the binder adhesive on top of the powder where required.
• The build platform is lowered by the model’s layer thickness.
• Another layer of powder is spread over the previous layer. The object is formed where the powder is bound to the liquid.
• The unbound powder remains in position surrounding the object.
• The process is repeated until the entire object has been made.

2. Directed Energy Deposition/ Electron Beam Melting (EBM)

Directed Energy Deposition (DED) covers a number of terms: ” Laser engineered net shaping, directed light fabrication, direct metal deposition, 3D laser coating”. It’s a more complex printing process, commonly used to repair or add extra material to existing components.

A typical DED machine consists of a nozzle mounted on a multi-axis arm that deposits molten material on the specified surface where it solidifies. The process is similar in principle to material extrusion, but the nozzle can move in multiple directions and is not attached to a specific axis.

The material, which can be deposited from any angle thanks to 4 and 5-axis machines, is melted during deposition with a laser or electron beam. The method can be used with polymers and ceramics but is typically used with metals in the form of powder or wire. Typical applications include repairing and maintaining structural parts.

Direct Energy Deposition  – Step by Step

• A4 or 5 axis arm with nozzle moves around a fixed object.
• Material is deposited from the nozzle onto the existing surfaces of the object.
• Material is either provided in wire or powder form.
• Material is melted using a laser, electron beam, or plasma arc upon deposition.
• Further material is added layer by layer and solidifies, creating or repairing new material features on the existing object.

3. Material Extrusion

Fuse Deposition Modeling (FDM) is a common material extrusion process and is trademarked by Stratasys. The material is drawn through a nozzle where it is heated and then deposited layer by layer. The nozzle can move horizontally and a platform moves vertically up and down after each new layer has been deposited. It’s a commonly used technique found on many low-cost home and hobby 3D printers.

The process has many factors that affect the final model quality, but it has great potential and feasibility when these factors are successfully controlled. While FDM is similar to all other 3D printing processes in that it is built up layer by layer, it varies in that material is added through a nozzle under constant pressure and in a continuous stream.

This pressure must be kept constant and at a constant speed to enable accurate results. Layers of material can be bonded by temperature control or by using chemical means. The material is often added to the machine in coil form as shown in the diagram.

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Material Extrusion  – Step by Step

• First layer is built as nozzle deposits material where required onto the cross sectional area of first object slice.
• The following layers are added on top of previous layers.
• Layers are fused together upon deposition as the material is in a melted state.

4. Powder Bed Fusion

The powder bed fusion process includes the following commonly used printing techniques: Direct Metal Laser Sintering (DMLS), Electron Beam Melting (EBM), Selective Heat Sintering (SHS), Selective Laser Melting (SLM), and Selective Laser Sintering (SLS).

Powder Bed Fusion (PBF) processes use either a laser or an electron beam to melt powdered materials and fuse them together. Electron beam melting (EBM) processes require a vacuum but can be used with metals and alloys to make functional parts. In all PBF processes, the powder material is distributed over the previous layers.

There are several mechanisms to make this happen, including a roller or a blade. A funnel or a reservoir under the bed ensures the supply of fresh material. Direct metal laser sintering (DMLS) is the same as SLS, but uses metals, not plastics.

The process sinters the powder layer by layer. Selective heat sintering differs from other methods in that it uses a heated thermal printhead to melt the powder material together. As before, layers are added with a roller between fusing layers. A platform lowers the model accordingly.

Powder Bed Fusion  – Step by Step

• A layer, typically 0.1mm thick of material is spread over the build platform.
• A laser fuses the first layer or first cross section of the model.
• A new layer of powder is spread across the previous layer using a roller.
• Further layers or cross sections are fused and added.
• The process repeats until the entire model is created. Loose, unfused powder is remains in position but is removed during post processing.

5. Sheet Lamination

Sheet lamination processes include the manufacture of Ultrasonic Additives (UAM) and the manufacture of Laminated Objects (LOM). In the manufacture of ultrasonic additives, metal sheets or strips are used, which are connected to one another by ultrasonic welding.

The process requires additional CNC machining and removal of the unbound metal, often during the welding process. Laminated Object Manufacturing (LOM) uses a similar layer-by-layer approach but uses paper as the material and adhesive instead of welding. The LOM process uses a hatching method during printing for easy removal after creation.

Laminated objects are often used for aesthetic and visual models and are not suitable for structural purposes. UAM uses metals and includes aluminum, copper, stainless steel, and titanium. The process has a low temperature and enables the creation of internal geometries. The process can combine different materials and requires relatively little energy as the metal is not melted.

Sheet Lamination  – Step by Step

• The material is positioned in place on the cutting bed.
• The material is bonded in place, over the previous layer, using the adhesive.
• The required shape is then cut from the layer, by laser or knife.
• The next layer is added.
• Steps two and three can be reversed and alternatively, the material can be cut before being positioned and bonded.

6. Vat Polymerisation

In vat polymerization, a vat made of liquid photopolymer resin is used, from which the model is built up layer by layer. Ultraviolet (UV) light is used to cure or harden the resin as needed, while a platform moves the manufactured object downward as each new layer cures.

Because the process uses liquid to form objects, there is no structural support from the material during the construction phase. In contrast to powder-based processes, in which the support is provided by the unbound material. In this case, it is often necessary to add support structures.

Resins are cured using a photopolymerization process or UV light, in which light is directed across the surface of the resin using motorized mirrors. When the resin comes into contact with the light, it hardens or hardens.

Photopolymerisation – Step by Step

• The build platform is lowered from the top of the resin vat downwards by the layer thickness.
• A UV light cures the resin layer by layer. The platform continues to move downwards and additional layers are built on top of the previous.
• Some machines use a blade which moves between layers in order to provide a smooth resin base to build the next layer on.
• After completion, the vat is drained of resin and the object removed.

7. Material jetting

Material jetting create objects in a similar way to a two-dimensional inkjet printer. The material is injected onto a build platform using either a continuous or a drop-on-demand (DOD) approach.

The material is sprayed onto the surface or platform, where it solidifies and the model is built up layer by layer. The material is deposited from a nozzle that moves horizontally across the build platform. Machines differ in their complexity and in their methods of controlling material deposition. The layers of material are then cured or hardened using ultraviolet (UV) light.

Because the material must be deposited in drops, the number of materials available for use is limited. Polymers and waxes are suitable and widely used materials because of their viscous nature and ability to form droplets.

Material Jetting  – Step by Step

• The print head is positioned above build platform.
• Droplets of material are deposited from the print head onto surface where required, using either thermal or piezoelectric method.
• Droplets of material solidify and make up the first layer.
• Further layers are built up as before on top of the previous.
• Layers are allowed to cool and harden or are cured by UV light. Post processing includes removal of support material.

Advantages of Additive Manufacturing

• The Cost Of Entry Continues to Fall
• You’ll Save on Material Waste and Energy.
• Prototyping Costs Much Less.
• Small Production Runs Often Prove Faster and Less Expensive.
• You Don’t Need as Much On-Hand Inventory.
• It’s Easier to Recreate and Optimize Legacy Parts.
• You can improve parts reliability.
• You can consolidate an assembaly in single parts.
• It uniquely support New Ai-Driven design methods
• It uniquely supports Lattice structure.

• Related Article: What is 3D Printing?
• Related Article: What is Rapid Prototyping?

Application of Additive Manufacturing

Aerospace

AM excels at manufacturing parts with weight-saving, complex geometric designs. Hence, it is often the perfect solution for making lightweight, strong aerospace parts.

In August 2013, NASA successfully tested an SLM imprinted rocket injector during a hot fire test that generated 20,000 pounds of thrust. In 2015, the FAA approved the first 3D printed part for use in a commercial engine. CFM’s LEAP engine has 19 3D printed fuel nozzles. According to Aviation Week, FAA-certified Boeing 787 structural parts made of titanium wire were exhibited at the Paris Air Show 2017.

Automotive

CNN reported that the McLaren racing team is using 3D-printed parts in its Formula 1 race cars. A rear wing replacement took about 10 days to produce instead of five weeks. The team has already produced more than 50 different parts using additive manufacturing.

In the auto industry, AM’s rapid prototyping potential garners serious interest as production parts are appearing. For example, aluminum alloys are used to produce exhaust pipes and pump parts, and polymers are used to produce bumpers.

Healthcare

At New York University School of Medicine, a clinical study with 300 patients is evaluating the effectiveness of patient-specific, multicolored kidney cancer models using additive manufacturing. The study investigates whether such models effectively support surgeons with preoperative assessments and guidance during surgery.

Global medical device manufacturer Stryker is funding a research project in Australia to use additive manufacturing technology to create bespoke, on-demand, 3D-printed surgical implants for patients with bone cancer.

In general, healthcare applications for additive manufacturing are growing, especially when the safety and effectiveness of AM-built medical devices are demonstrated. The production of unique synthetic organs is also promising.

Product Development

As the potential for AM’s design flexibility is realized, once impossible design concepts are now being successfully re-imagined. Additive manufacturing unleashes the creative potential of designers who can now operate free of the constraints under which they once labored.

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