Laser Metal Deposition: Additive Manufacturing Technology

Running head: LASER METAL DEPOSITION 0
LASER METAL DEPOSITION
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INTRODUCTION,
Additive manufacturing, also known as rapid prototyping process is a great technology
that applies the principles of form fabrication. The additive manufacturing technology applied
utilizes the computer-aided design model in the net processing. This model is of great benefit
since it helps in repairing parts which are complex and that cannot be repaired by any other
conventional models of a manufacturing process. There are various technologies that are
involved in the process of additive manufacturing. These technologies include the direct metal
deposition or better known as the laser metal deposition technology, which is widely applied in
the various industries that apply the cladding techniques as well as the free form fabrication. The
main concept in the laser metal deposition is cladding of the laser metal for the purposes of
enhancing the process of deposition. (Bohandy et al, 2010)
Technologies related with additive manufacturing
The classification of the process involved in the additive manufacturing basically
depends on the stage of an application during the whole process of manufacturing. Besides, the
technology depends on the material used in coming up with the various parts including the metal
sheet, metal powder, solid polymer, metal wire and the liquid polymer. Based on the raw
materials that are used in the process, the technology is divided into metal additive
manufacturing and the plastic additive manufacturing. The picture below shows the discrete
description of the process (Lewis & Shlienger, 2010)

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Additive manufacturing process
There are various process that the metal laser deposition undergoes. These process includes,
Material extrusion
This technology involves the extrusion of material from a tiny hole and thereafter
repetitively creating a 2D layer which eventually generates a 3D layer. A fused filament
fabrication and fused deposition model is applied in this technique as shown in the figure below.
This technique has been widely
used in the manufacture of the thermoplastics that are basically polymers in nature (Dinda et al,
2012).

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Usually, at the heat nozzle, a thermoplastic material is supplied and the material is melted in
order to produce a two dimensional layer. The process is done recurrently and as this process
goes on, it begins to form with the thickest layer being on the lower part. At times, support
material spool is required for the purposes of object stationary in the manufacture of the complex
part of the entire process (Zhu et al, 2011).
Vat polymerization
The polymerization of vat can as well be referred to as the process of lithography and it
operates on two dissimilar configurations. The first configuration being the upright while the
second configuration is the reverse. Two key elements are needed in this process: resin exposure
for the purpose of allowing the regulation of spatial process on a single layer resin as well as the
photopolymerization resin. For the first configuration which is the upright conformation, the
whole plate gets formed and then it is put under the resin vat. This enables the product to form
inside the resin. For the second configuration which is the inverse pattern, the resins are
maintained within an array and the part that has formed is placed in an opposite position as the
layer that has been generated. The diagram below shows how the process of vat polymerization
is done. (Graf et al, 2011)

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Material jetting
The process of material jetting is the same as the ink jet printing technique, which is applied in
the printing of papers. In this process, the material droplets from the jetting head are deposited on
a surface as shown below.

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The material jetting technology is also applied in the support and model for the purposes of
generating a three-dimensional model. This is because of the high scalability in the model
growth, material flexibility and model dimension as compared to the selective laser sintering and
the extrusion of material. The material jet has a wide range of material flexibility and multiple
nozzles commercially. The equipment used for the material jetting has the ability to print a
variety of elastomer, plastic, waxes and rubber (Hong et al, 2011).
Sheet lamination
The process of laminating sheet is also referred to as the laminated object
manufacturing. The process comprises of two technologies which are combined for the purpose
of coming up with a three-dimensional model. The two technologies which are combined include
the substantive steps and the combined additive. The principle of operation of the instrument is
by an alternation of the bonding in the sheets through the use of pressure or heat, thereafter
cutting the sheet of material in a certain desired manner. This process is done simultaneously.
The diagram below describes the process of sheet lamination (Mohamood et al, 2015).

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The application of heat or pressure industrially helps in enabling the additive steps. Besides, the
adhesive steps can be accomplished mechanically by the use of an adhesive roller or chemically
by the application of a chemical substance. Additionally, an ultrasonically induced fabric can be
applied in the place of the adhesive materials due to strong metallurgical bonds that it offers
(Legget et al, 2012).
Powder Bed Fusion
There are various technologies associated with the powder bed fission depending on the
capability of the process, the characteristics of the as well as the condition. Despite this, all these
technologies operate on the same principle. The figure shown below shows how the fusion
operates. The raw material being the powder is spread on the build plate with the help of wiper
mechanism or a blade. The distance which exists between the built layer and the surface of the
build plate, as well as the spreading mechanism as it changes position in the area of the built
layer proves the thickness of the model.
The maximum allowable height of the metal layer is 100 microns and for the three-
dimensional printing id between 50 to 100 microns. Immediately that the layer gets formed, a
laser beam or an electron layer is put on the powder layer purposefully for the formation of the
three-dimensional layer. The developed product is mostly strengthened by this layer and in
particular its strength, quality and its microstructure. There exist two different types of variation
in the metal powder fusion including the selective laser melting and the selective laser sintering.
For the selective laser sintering, the metal powder is not completely melted but then it gets
heated to a certain temperature of solid state (Guo and Leu, 2013).

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Laser direct metal deposition
This technology forms part of the additive manufacturing that eventually forms the model
layer. Besides, this technique applies the laser beam for the purposes of generating the metal
pool which gets supplied above the surface of the base plate. The metallurgical bond is generated
by the melted powder and then the clad which is required either in the 2D or the 3D is obtained
by the use of a computer-aided software such as solid works or the PTC to parametric. The laser
technique incorporates the metal deposition technology. Below is the diagram showing the
operating principle of the metal disposition process (Yadroitsey & Smurou, 2011).