This document discusses various additive manufacturing techniques including 3D printing, droplet formation technologies, and laser engineered net shaping (LENS). It provides details on the LENS process which uses a laser to fuse metal powder layer by layer to build components. Key process parameters for LENS include laser power, powder feed rate, scan speed, and layer thickness. Materials that can be used include stainless steel, tool steel, titanium alloys, and copper. Benefits are repairing and fabricating parts with properties similar to native materials in less time. Applications include injection mold tooling and aerospace components.

1. Unit 5
CO5: Explain the process of printing and beam deposition
Droplet formation technologies-continuous mode-drop on demand mode-
Three Dimensional printing – Advantages- Bioplotter-Beam deposition process:
LENS –process description-Material delivery – Process parameters- Materials-
Benefits – Applications.

2. Droplet Formation Technologies
• The term “Direct Write” (DW) in its broadest sense
can create two- or three-dimensional functional
structures directly onto flat or conformal surfaces in
complex shapes, without any tooling or masks.
• build freeform structures or electronics with feature
resolution in one or more dimensions below 50 μm.
• Create meso-, micro-, and nanoscale structures using
a freeform deposition tool.
• Continuous dispensing, as in (a), has the merits of a
continuous crosssectional area and a wider range of
ink rheologies.
• Droplet dispensing, as in (b), can be done in a very
rapid fashion; however, the deposit cross sections are
discontinuous, as the building blocks are basically
overlapping hemispherical droplet splats, and the
rheological properties must be within a tighter range.

3. Print Head Technologies

4. Drop-on-Demand ink jetgenerator
Types of materials which have been deposited successfully using
nozzle-based processes.
• Electronic Materials—metal powders (silver, copper, gold, etc.)
or ceramic powders (alumina, silica, etc.) suspended in a liquid
precursor that after deposition and thermal post-processing form
resistors, conductors, antennas, dielectrics, etc.
• Thermoset Materials—adhesives, epoxies, etc. for
encapsulation, insulation, adhesion, etc.
• Solders—lead-free, leaded, etc. as electrical connections.
• Biological Materials—synthetic polymers and natural polymers,
including living cells.
• Nanomaterials—nanoparticles suspended in gels, slurries, etc

5. Metal droplet generator
Metal droplet generator design using wire feed system.
(a) Single droplet jet head. (b) Cluster jet head design.

6. Key benefits and drawbacks of ink-based approaches to DW
Aerosol Jet System. (1) Liquid
material is placed into an atomizer,
creating a dense
aerosol of tiny droplets 1–5 μm in
size. (2) The aerosol is carried by a
gas flow to the deposition head
(with optional in-flight laser
processing).
(3) Within the deposition head, the
aerosol is focused by a second gas
flow and the resulting high-velocity
stream is jetted onto the substrate
creating features as small as 10 μm
in size.

7. Advantages of 3D printing
• Cost reduction
• Less waste
• Reduce production time
• An enhanced competitive advantage
• Reduce errors
• Confidentiality
• Production on demand

10. LASER ENGINEERED NET SHAPING (LENS)
• The LENSTM process builds components in an additive
manner from powdered metals using a Nd:YAG (Neodymium:
Yttrium Aluminium Garnet) laser to fuse powder to a solid as shown
in Figure.
• It is a freeform metal fabrication process - fully dense metal
component is formed.
The LENSTM process comprises of the following steps:
• A deposition head supplies metal powder to the focus of a high powered
Nd:YAG laser beam to be melted.
• The laser is focused on a particular spot by a series of lenses, and a
motion system underneath the platform moves horizontally and laterally
as the laser beam traces the cross-section of the part being produced.
•
When a layer is completed, the deposition head moves up and continues
with the next layer. The process is repeated layer by layer until the part
is completed. The entire process is usually enclosed to isolate the
process from the atmosphere.
• Fabrication process takes place in a low-pressure argon chamber for
oxygen-free operation in the melting zone, ensuring that good adhesion
is accomplished

12. Process Parameters in LENS
• laser output power: 150-500W
• powder feed rate:a suitable feed rate as required for the specific metal
should be selected
• scan speed: If the scan speed is too low, the material is exposed to the laser
longer and more heat is generated and heat affected zone also increases. If the
scan speed is too high, the metal will not melt.
• laser beam diameter: high, the deposition accuracy reduces
• powder particle size:40–150μm is most appropriate
• laser pointer and the deposition point distance:
• raster angle: 30°, 60° or 90°
• layer thickness:The layer thickness depends on the particle size of the
powder too.

13. Build Materials on LENS
• Stainless Steel 316 alloy
• H13 Tool Steel
• Titanium with 6% Aluminum and 4% Vanadium
• Copper
• Inconel

14. Benefits of LENS
• Can be used to repair parts as well as fabricate new ones
• Has a very good granular structure
• Powder forming methods have few material limitations
• Doesn’t require secondary firing operations
• The properties of the material are similar or better than the properties of the
natural materials
• The manufacturing time is reduced with the scope of significant cost benefits
in the production of components.
• Additional savings can be achieved because of efficient material usage as
compared with any other method of material removal.
• LENS is environmental-friendly since hazardous material is contained during
processing in an inert atmosphere.

15. Applications of LENS
• Fabrication and repair of injection
molding tools
• Fabrication of large titanium &
other exotic metal parts for
aerospace applications
• Typical Repair Applications: Low-
wattage repair of titanium
components covers many potential
aerospace and Department of
Défense applications.