Abstract
Manufacturing sectors are shifting their interest toward additive
manufacturing technologies, where components are fabricated directly
from CAD models layer by layer. Laser engineered net shaping most known
to produce a near net shape of functionally graded materials. In this
paper, process parameters that affect mechanical properties, surface
topology and physical properties are reviewed. Powder feed rate, hatch
distance and layer thickness more related to porosity of the parts that
are being produced. Mechanical properties are get affected by laser
power and scan speed. Hardness is sensitive to focal distance of the optimal
convergence of the maximal laser intensity and the localized spatial
concentration of the powder beam. To get homogeneous microstructure
shorter focal distance is preferable. However, working distance has no
such impact on density.
Keywords: Additive manufacturing, laser power, scanning
speed, focal distance.
Introduction
A three-dimensional object is primarily created utilizing the highly
developed fabrication technique known as additive manufacturing (AM),
which builds an object layer by layer. Charles Hull’s invention of
stereo lithography, later known as AM technology, received the first
acknowledged patent. In addition, he is credited with creating the STL
model format for standardized interface, which bears the same name as
this manufacturing method. Because AM has so many advantages over
traditional manufacturing processes like casting and machining, it is
becoming more and more popular. There can be significant savings in raw
material use and waste when designs are created additively rather than
subtractively. The use of additive manufacturing engineers increased
utilization of design freedom, manufacturing time and cost part
inspection reduced and counts radically reduced. Furthermore, components
produced on demand, reduce responsive time and storage needs.
Over the last four decades, scientific and industrial research has
enabled significant advances in additive manufacturing, allowing the
production of a variety of products made of polymers, metals, ceramics,
and composites with unviable or even impossible geometries by other
processes. The LENS machine is a ”real” direct-metal Rapid Prototyping
technique, producing items made of full strength metals. Based on the
Cooperative Research and Development Agreement, Sandia National
Laboratories and various other organizations produce it (CRADA). Direct
Energy Deposition (DED), Direct Light Fabrication, Direct Laser
Deposition, Direct Laser Fabrication, Laser Rapid Forming, and Laser
Solid Forming are some of its synonyms. The geometric data in a
Computer-Aided Design (CAD) solid model is used by LENS 3D printers to
autonomously control the LENS process as it builds a component layer by
layer. Powdered metals are fused together by the systems into completely
dense three-dimensional structures using high-power lasers. In order to
prevent impurities from picking up during deposition, the LENS process
is contained in a chamber that is purged with argon so that the oxygen
level stays below 10 parts per million. The Optomec patented powder-feed
mechanism, which can flow small volumes of powder very accurately, feeds
the process with the metal powder. Once finished, the component is
removed and can be machined, heat-treated, or polished in any other way.
LENS is a highly focused metal deposition technology that creates an
extremely small weld bead, exposing the component to far less heat than
traditional techniques. Stainless steel alloys, nickel-based alloys,
tool steel alloys, titanium alloys, and other speciality materials have
all been used to produce parts, in addition to composites and
functionally graded material deposition. The LENS components are fully
dense and exhibit no compositional degradation, according to microscopy
studies. Outstanding as-fabricated mechanical qualities are revealed
through mechanical testing.
Laser engineered net shaping has the following benefits:
Excellent material qualities: Fully dense metal components can be
created using the LENS technique. Produced metal parts may also include
embedded features and improved material characteristics. The
microstructure created is likewise generally of good quality.
Complex components: The LENS system excels in functional metal
components with intricate details.
Less post-processing is needed: Cycle time is shortened by
decreasing post-processing.
The limitation of LENS technique are:
Limited resources: Currently, the method is exclusively utilized
to create metal components.
Size of a large physical unit : To house the unit, a sizable space
is needed.
Heavy electricity usage : The watts needed by the laser system is
very high.
There are a number of applications for LENS technology.