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What’s the Buzz About? Additive Manufacturing in a Nutshell

Posted: July 21, 2022

Guest Post by Vidya Srinivas
Senior Materials and Process Engineer

In recent years there’s been a lot of buzz about 3D printing to create products using Additive Manufacturing techniques. In this piece, we’ll explore what additive manufacturing is, what current additive manufacturing techniques are, and provide an overview of various industry use cases.

In conventional manufacturing, material is typically removed from a larger piece to make a component. In additive manufacturing, parts are made layer upon layer. Typically a computer aided model of a 3D object is used to deposit layers onto a substrate to generate the component.

There are 7 manufacturing methods recognized by the International Standards Organization (ISO):
 

  1. Binder jetting

Binder jetting constructs each layer of a component by depositing a liquid binder (an adhesive) on top of a powder bed made from various materials (e.g., chalk, plastics, ceramics, metal, glass, or sand)

Advantages:

  • Low waste: Any unused powder can be reused for future components
  • No thermal distortions occur since heat input is low.
  • Material Flexibility: Unlike some other techniques, binder jetting can create components made of a variety of different materials as opposed to just metal or glass.

Disadvantages:

  • Parts have poor mechanical properties
  • This is less accurate than material jetting process since uneven shrinkage can occur
  • High equipment costs: Binder jetting often requires machinery that can cost more than traditional manufacturing processes
     
  1. Directed Energy Deposition (DED)

DED involves of material being melted either by using lasers, electron beam or plasma arc to fuse each layer to the one below. The material that has been fused has to cool down before another layer can be added.

Advantages:

  • Parts can be repaired by layering material over damaged parts
  • Metallic material’s grain structure can be controlled 

Disadvantages:

  • High costs: Raw material  is expensive
  • Long production times: Parts have to cool down after each layer is deposited
  • Low material flexibility at this time as  only some materials can be processes using this method
     
  1. Material Extrusion

Material extrusion involves feeding a filament of material through a nozzle, heating it, and then releasing the material onto a platform in layers. This is the most popular method of additive manufacturing and is used by many hobbyist 3D printers

Advantages:

  • Low costs: Material extrusion equipment is readily available, even for non-commercial uses and filaments are usually cheaper materials like thermoplastics
  • “Small physical footprint: Equipment used is smaller than what is used for other methods
  • Relatively lower temperatures: Material Extrusion does not require as high temperatures as other methods

Disadvantages:

  • Surface quality of the part is poor
  • These parts are not fully dense hence strength may not be the same in all directions.
  • ow material flexibility: Few materials can be used as filaments and many filaments can be toxic
     
  1. Powder Bed Fusion (PBF)

 PBF involves using a laser or electron beam to heat up and fuse together layers of powder in a powder bed. 

Advantages:

  • Material flexibility: A variety of materials (ceramics, glass, plastic or metals) can be used 
  • Easily repeatable process: Can be used to produce multiple, near identical parts
  • Can be used to construct very complex shapes

Disadvantages:

  • Relatively slow compared to other methods
  • Power Intensive compared to other methods
  • Surface quality of the part depends on grain size of the powder

5.   Sheet Lamination

Sheet lamination involves using ultrasonic welding, brazing, or adhesive bonding to join sheets of material together and cutting away excess material to finalize the component.

Advantages:

  • In this process, material handling is easy
  • Faster processing times than other methods
  • Embedding Capabilities: Wires or sensors can be embedded in parts

Disadvantages:

  • Limited material flexibility: Material must be available in sheet form
  • Cutting excess material is a required 
  • Hollow parts are difficult to manufacture
     
  1. Vat polymerization

Vat polymerization involves curing a photosensitive resin layer-by-layer using ultraviolet light to construct a component. This is similar to powder bed fusion, but uses a photopolymer resin rather than a bed of powder.

Advantages:

  • Surface finish is good
  • Large parts can be made
  • Relatively fast production times

Disadvantages:

  • Only light sensitive material can used
  • Hollow parts may be difficult to produce
  • Parts can warp over time
     
  1. Material jetting

Material jetting involves spraying droplets of material onto a platform, much like an inkjet printer, and curing each layer using UV light or heat.

Advantages:

  • Parts can be made of different materials and different colors.
  • Parts can have very good surface finish
  • Efficiency: Material wastage is very low

Disadvantages:

  • Raw material has to be in liquid form and is costly
  • Parts made by this process have poor mechanical properties
  • Very slow process

 

A number of industries have taken advantage of the 7 additive manufacturing techniques described above for various use cases.

Some industries, such as the medical/dental industry and the automotive industry, have used additive manufacturing to create customized parts for their customers. For example, a patient might need specifically crafted implants or a driver may need a seat tailored to their body.

The aerospace and marine industries has used additive manufacturing to enhance the design process and reduce the number of parts made by hand. The Tubesat-POD satellite, for example, was fully 3D printed and 75% of the AMAZEA underwater scooter is made of 3D printed parts.

About the Author

Vidya Srinivas is a Materials and Process Engineer whose areas of knowledge include roduct Quality Auditing, Product Quality Planning, Root Cause Analysis, Product Quality Improvement, Non Destructive Testing, Failure Analysis, ISO 9000/ AS9100, Material Testing, Heat Treatment, Thermomechanical Analysis, Temper Etch & Hardness Testing, Taber Abrasion Testing, and Supplier Quality in both the aerospace and automotive sectors. Most recently she worked with Moog Inc. as a Senior Maters and Process Engineer. Prior to her role at Moog Inc., Srinivas spent nine years on the team at Northrup Grumman in multiple roles and has also served in roles at Alcoa Fastening Systems and Cal Poly Pomona. 

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