2. METAL PRINTING
Department of Mechanical Engineering
RV Institute of Technology and Management (RVITM) Bengaluru
ABHAY SURYA M – 1RF19ME001
VIII Semester
Under the guidance of
Dr. SOLAIMUTHU C
(HOD / ME)
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4. ABSTRACT
• 3D metal printing also known as metal additive manufacturing is ‘a process of joining materials to make
objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing
methodologies.’
• This tool less manufacturing approach can give industry new design flexibility, reduce energy use and
shorten time to market.
• Main applications of additive manufacturing include rapid prototyping, rapid tooling, direct part
production and part repairing of plastic, metal, ceramic and composite materials.
• The two main parameters of any metal AM process are type of input raw material and energy source
used to form the part. Input raw material can be used in the form of metal powder or wire whereas
laser/electron beam or arc can be used as energy source (Fig. 1)
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5. INTRODUCTION
Metal Additive manufacturing processes broadly classified into two major groups, -
1.Powder Bed Fusion based technologies (PBF) and
2. Directed Energy Deposition (DED) based technologies.
1) Powder Based Fusion (PBF)
Selective Laser Melting(SLM)/ direct metal laser sintering(DMLS):In the laser beam melting
process, a powder layer is first applied on a building platform with a recoater (blade or roller)
and a laser beam selectively melts the layer of powder. Then the platform is lowered by 20 up
to 100 µm and a new powder layer is applied. The laser beam melting operation is repeated.
After a few thousand cycles (depending on height of the part), the built part is removed from
the powder bed.
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6. INTRODUCTION
2) Direct Energy Deposition (DED)
With the direct energy deposition process, a nozzle mounted on a multi axis arm deposits melted
material onto the specified surface, where it solidifies. This technology offers a higher
productivity than selective laser melting and also the ability to produce larger parts, but the
freedom in design is much more limited: for instance, lattice structures and internal channels
are not possible.
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7. WORKING PRINCIPLE OF DMLS
• The basic principle of the DMLS(Direct Metal Laser Sintering) Technology is to melt down thin layers (20 -
60 μm) of Metal Powder with an electronically driven Laser beam (200W).
• Metal powder is stored in dispenser unit and the recoater is used for coating of metal powder of uniform layer
thickness on steel base plates.
• It needs to be noted, that SLM, SLS and DMLS is describing basically the same process, main difference
being the nature of the powder. a powder layer is first applied on a building platform with a recoater (blade or
roller) and a laser beam selectively melts the layer of powder.
• Then the platform is lowered by 20 up to 100 µm and a new powder layer is applied. The laser beam melting
operation is repeated. After a few thousand cycles (depending on height of the part), the built part is removed
from the powder bed.
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8. WORKING PRINCIPLE OF DMLS
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During laser beam melting, the laser beam, with diameter such as 100 µm, will locally melt
the upper powder layer on the powder bed. The laser will be partially absorbed by metal
powder particles, creating a melt pool which solidifies rapidly. Laser power typically varies
from 200 W up to 1000 W.
9. PROCESS PARAMETERS TO IMPROVE
MATERIAL PROPERTIES
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• To achieve high mechanical strength and adequate fatigue behaviour, it is important to produce high density parts with optimal surface quality and to minimize
defects, through the optimization of process parameters. In this way, a working window is obtained with a define set of laser parameters where parts with high
densities and low roughness are guaranteed.
• The optimizeTo achieve high mechanical strength and adequate fatigue behaviour, it is important to produce high density parts with optimal surface quality and
to minimize defects, through the optimization of process parameters. In this way, a working window is obtained with a define set of laser parameters where
parts with high densities and low roughness are guaranteed.
• The optimization of parameters shall be done both for the interior of the part and for the borders, where a good balance of minimized defects in the sub-surface
and low roughness is pursued.
• To optimize parameters, it is a common practice to manufacture simple geometries like cubes maintaining constant the power and varying the scanning speed
in each cube, for a given layer thickness and hatch spacing. Thus, each cube is manufactured with different energy density. Afterwards, the cubes are
characterized where interior density, sub-surface density and roughness are determined, so as to identify the right energy density window and corresponding
parameterstion of parameters shall be done both for the interior of the part and for the borders, where a good balance of minimized defects in the sub-surface
and low roughness is pursued.
• To optimize parameters, it is a common practice to manufacture simple geometries like cubes maintaining constant the power and varying the scanning speed
in each cube, for a given layer thickness and hatch spacing. Thus, each cube is manufactured with different energy density. Afterwards, the cubes are
characterized where interior density, sub-surface density and roughness are determined, so as to identify the right energy density window and corresponding
parameters
Fig.4 Defects found in parts manufactured by SLM technology
10. KEY FEATURES OF MATERIALS PRODUCED BY AM
• The fine microstructure, due to the very rapid solidification process A slight anisotropy in Z
direction, which induces slightly lower mechanical properties due to the superposition of
layers.
• Anisotropy can be avoided in X and Y directions by using an adapted laser strategy. A few
small residual porosities, in particular below the surface.
• However, densities of 99.9% are commonly reached with additive manufacturing
processes. To achieve full density, post processing by HIP can be done, like for parts made
by investment casting.
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Fig.5Microstructure of material produced by laser beam melting
11. MECHANICAL PROPERTIES OF 3D PRINTED METALS
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Aluminium alloys Good mechanical &thermal
Properties Low density
Good electrical conductivity Low hardness
Stainless steel & tool
steel
High wear resistance
Great hardness
Good ductility and weldability
Titanium alloys Corrosion resistance
Excellent strength-to-weight ratio Low thermal expansion
Cobalt-Chrome
superalloys
Excellent wear & corrosion resistance, Great properties at elevated temperatures high hardness
Biocompatible
Nickel superalloys
(Inconel)
Excellent mechanical properties
High corrosion resistance Temperature resistant up to 1200o
C Used in extreme environments
• The microstructure of metal part is directly affects the mechanical properties of resulting parts made by 3d metal printing,
if there is proper heat treatment is carried out and reduced defects in the microstructure then the better properties can be
obtained.
• The additive manufacturing shows nearly same mechanical properties as casting process .the process like DMLS /SLM are
carried out in high temperature so part shows high heat resistance and better hardness.
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Freedom of design-AM can produce an object of virtually any shape even those not are producible today.
Complexity for free- Increasing object complexity will increase production cost only marginally
Potential elimination of tooling- Direct production possible without costly and time consuming tooling
Lightweight design- AM enables weight reduction via topological
optimization
Part consolidation – reducing assembly requirements by consolidation parts into a singal component
Elimination of production steps-even complex objects will be manufactured in one process step
Eco innovative process-due to less material loss, no tool process
Tool-free manufacturing- additive manufacturing is tool free manufacturing and less material
consumption
The fine microstructure-due to the very rapid solidification process resulting material shows fine
microstructure
Advantages Of 3D Metal Printing
13. Disadvantages of 3D metal printing
Slow build up rate-various inefficiencies in the process resulting from prototyping heritages
High production cost-high cost of metal powder
Discontinuous production process-use of non integrated system prevents economies of scale
Limited component size- as chamber or machine size is small so large components can not be
producible
Defects -In case of incorrect process parameters, build strategy, part orientation or
unsufficient powder quality, some typical defects can be observed.
Microstructure affects the mechanical properties of resulting part so post processing is required
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14. Applications of 3D metal printing
•Aerospace Industry
An important requirement for the aerospace industry is to consistently produce light complex geometries with good
mechanical properties in small quantities. These reasons make AM a very efficient manufacturing method for
aerospace applications. These techniques are used to fabricate low-volume complex aerospace parts, aircraft
wings, and replacement parts in the aerospace industry along with fabricating specialized parts, lightweight
structures, parts with minimal waste, on-demand parts, and replacement parts to support long term space
exploration Advanced materials such as aluminum alloys, titanium alloys, nickel super-alloys, and special steels
have been manufactured in the aerospace industry using AM technologies.
•Automotive Industry
Metal AM has significant implications on part design as well as supply chains and inventory systems, which is
particularly relevant for the automotive industry. An important feature of using metal AM processes in the
automotive sector is fabricating complex lightweight structures. The weight of the automotive parts can be
reduced significantly by leveraging the ability of AM processes to produce parts with complex geometries while
maintaining relative strengths. Examples of automotive parts produced by AM include structural composite
components, engine valves, and turbocharger turbines.
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15. Applications of 3D metal printing
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• Tooling Industry
For the tooling industry, AM can offer time saving through the reduction of the fabrication steps and cost
reduction through the elimination of material loss associated with traditional subtractive manufacturing.
In addition, the AM technology offers the ability to produce customized molds with optimized cooling
channels which can impart unique properties to parts and reduce production cycle time. AM molds made
with integrated conformal cooling also prolong their service life as it provides the designer with the
ability to reduce the thermal stress loading that the die experiences. The mechanical behavior of the tools
fabricated by AM affects the performance and service life of these tools.
• Military And Defense
In defense industry 3d metal printing reduce production cost for tools and components additional design
flexibility and localized manufacturing can considerably enhance the maintenance of military system
through the production of spare and obsolete parts and maintaining huge inventories to quick printing
replacement part on demand.
16. CONCLUSIONS
• In conclusion, 3D printing technology is a major on the original manufacturing technology, which is
slowly changes our production and life, but also plays an extremely important role in cultural creative
design, industry, biological and medical fields.
• With the recently increased production of 3D printers, and how quickly they have been updated to
appeal to the consumer, there is a lot of potential to reach out to other areas.
• From what was once just a printer that made small plastic objects, in a short amount of time, it has
evolved to become a lot more to the point that it can potentially take over a lot of manufacturing firms.
• Over the years, different institutions such as schools, hospitals, and within the workplace will be
introduced to this technology; that’s when people will be able to see what can be done for 3D printers to
be of actual use.
• Eventually developers and tech companies will work together to design and improve the 3D printers as
the years go by.
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