Introduction to Additive Manufacturing (AM)
Additive Manufacturing (AM) is a production process of building 3-Dimensional Products by adding layers of materials like metal, plastic, or Concrete, etc. People also refer to the process commonly as 3-D Printing – A process that makes 3D physical objects using Computer-aided design (CAD).
The Additive Manufacturing (AM) began almost 40 years ago in 1981, when Hideo Kodama of the Nagoya Municipal Industrial Research Institute, published information regarding the manufacturing of a solid printed model.
How AM Works?
AM creates an object by creating layers. Each layer lies over another layer that differs in shape. Then, it sticks to the layer below it. The below layer has either melted or partially melted material.
A CAD software identifies the shape of the Object. It creates a file with (extension. stl). This file contains a 3-D drawing of the object. Then, using this file, the software can slice the object into very thin layers.
A nozzle is present on the machine which releases material to make the layer. Using information of layer from CAD software, it decides a path and follows it. Therefore, in this way, the nozzle makes the perfect shape of the layer.
Alternative to the nozzle, AM uses a laser or electron beam. It melts or partially melts in a bed of powdered material based on selection.
Then materials are allowed to cool with cure. As a result, the materials of each layer stick together to form a 3-D object.
Additive Manufacturing Process Types
1. Material Extrusion (ME)
ME process uses nozzles and beds. The nozzle moves horizontally and the bed moves vertically. Here, the nozzle takes a fixed path based on the shape of the layer to move horizontally. Whereas the bed keeps track of the nozzle to complete its path. If completed then the bed moves down for a new layer.
This allows materials to be built layer by layer. Also, proper stacking of layers is ensured either by controlling the temperature perfectly or by using some chemicals. In the nozzle, the material is first heated and then is applied to the layer.
2. Direct Energy Deposition (DED)
DED is a complex process and is used for fixing or adding material to existing components. A DED Machine has a nozzle fixed on an arm having multiple axes. It releases melted material on the given surface where the material becomes solid.
DED’s process is almost similar to ME with a slight difference. In DED, the nozzle can move in any direction, and in ME, the nozzle can move only horizontally. Materials given to DED are either in wire or in powdered form.
3. Material Jetting (MJ)
It uses the concept of a 2-D inkjet printer for the process. So the material is dropped on the base surface where it becomes solid. Then, MJ builds the object layer by layer on the base surface, and the nozzle moves in a horizontal manner on the surface.
Different machines for MJ are available. They differ in ways of controlling the material released on the build surface. UV light is used for curing and hardening the material. Since MJ releases materials as drops, so such materials are less. Waxes and Polymers are suitable as they are able to form drops.
4. Binder Jetting (BJ)
BJ allows printing objects with colors and the process is faster than others. It uses two materials i.e. binder and powdered-based material. Binder is in liquid form which acts as a glue to make sure that each layer sticks with the one below it. Then, Powdered material is used for building a layer.
BJ has a print head that moves horizontally and vertically along the axis of the machine. Then, it releases build material along with binder material in alternate layers. After completing each layer, the object is lowered on the base surface.
5. Sheet Lamination (SL)
SL process includes two methods of achieving it. These are Ultrasonic Additive Manufacturing (UAM) and Laminated Object Manufacturing (LOM).
UAM uses either metal ribbons or sheets. Ultrasonic welding binds these materials. Also, it needs additional CNC machining and removal of metal which are not bound in the welding process.
LOM uses the same approach of layer-by-layer printing. It uses paper as material and adhesive other than welding. Also, it uses a method for printing that makes it easy to remove materials after printing is completed.
6.Powder Bed Fusion
Powder Bed Fusion systems use lasers, electron beams, or thermal print heads to melt or partially melt ultra-fine layers of material in a three-dimensional space. As the process Completes, the excess powder is blasted away from the object.
This Technology is used in a variety of Additive manufacturing (AM) like selective laser sintering (SLS), direct metal laser melting (DMLM), direct metal laser sintering (DMLS), selective heat sintering (SHS), and electron beam melting (EBM)
In Vat Polymerization Process the Object is created in a vat of a liquid resin photopolymer. photopolymerization is a Process that cures each microfine resin layer using ultraviolet (UV) light precisely directed by mirrors.
Benefits of Additive Manufacturing (AM)
1.Low cost of Entry & Equipment
In the beginning, companies had suffered from the high costs of equipment. Previously, AM machine was too costly for small manufacturers to keep it. But because of improvements in technology, the machine became affordable.
Also, AM has the capability to reduce the amount of capital needed to expand production. Without making big changes, manufacturers may be able to increase the production speed.
2. Easy to Change or Improve the Product
AM not only can create a product but can be used to innovate designs. It gives freedom to create new structures with the least cost and time. AM solves the problem of the old manufacturing method by allowing engineers to make various designs with speed in a cost-effective manner.
Engineers using AM can easily make objects again and again without any human effort.
3.Ease of Operator Training
AM needs to operate and control the machine only. So training process becomes easy as compared to training on making the entire physical object which asks a lot of hard work.
A load of designing complex parts, deciding the number of parts for an assembly, the number of sub-assemblies in the main assembly, etc. is removed.
4.Less material Waste
In the old way of manufacturing lot of materials are wasted. Because the processes involve i.e. cutting, carving, shaving the materials. Due to which the waste created cannot be reused.
But in AM, since it works on layers, so only required materials are used. Rest other materials are saved. The nozzle uses the material in a perfect manner and does not need to cut, carve or shave it.
AM enables you to make Complex Geometry Products that are not possible with other methods in the industry. The parts that previously required assembly or welding can be grown as a single part with AM.
The designers are not limited to Traditional machines offering greater design freedom to designers for designing Parts.
Materials for additive manufacturing
Variety of Materials are used for Additive manufacturing like
Thermoplastic Polymer is the most popular material for Additive manufacturing. Most of the Popular Thermoplastic polymers like Water-soluble polyvinyl alcohol (PVA), Acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and polycarbonate (PC)
From Strategic metals like Stainless Steel and Titanium to Precious Gold and Silver medals and alloys are used in Additive manufacturing.
A variety of ceramics including Zirconia, Alumina, and Tricalcium Phosphate used for additive manufacturing.
Hardened material from silicon, calcium phosphate and zinc used biochemical Healthcare applications to support bone structures as new bone growth occurs.
Additive manufacturing has changed the way objects are designed and manufactured in the industry. Am is used to create a wide range of products across exponentially growing industries like medical, Aerospace, Construction, and Automotive.
Am has major applications in Aerospace due to its weight-saving capability and to produce complex geometric parts. Digitalization in the medical sector has seen the increasing application of AM to manufacture critical instruments and devices.
In recent times the Construction industry has started using 3D printed homes and buildings to increase productivity and reduce the time duration of Construction