ADDITIVE MANUFACTURING

Review

Improving Mechanical Strength in Extrusion Additive Manufacturing

Work by Shivanshi, Tanisha Shrivaskar, Falguni Sultane.
Guided by Manoj Ghag from department of General Engineering .

Abstract: Extrusion additive manufacturing is a versatile and cost-effective technique used to fabricate
complex parts with a variety of materials. However, the mechanical strength of the printed parts is often
limited due to the layer-by-layer deposition process and inherent anisotropy. This research paper aims to
investigate ways to improve the mechanical strength of parts produced by extrusion additive
manufacturing. Extrusion-based 3D printing is a popular and cost-effective method for creating
parts with complex geometries and customized designs. However, the mechanical properties of
these parts can be limited due to factors such as layer adhesion, material quality, and processing
parameters.

In this study, we propose several approaches to enhance the mechanical strength of extrusion-based
parts, including optimizing the printing parameters, using novel materials and composites, and
post-processing techniques such as annealing and surface treatments. The effectiveness of these
methods is evaluated through a series of mechanical tests, including tensile, compressive, and
flexural strength measurements.

The results of this study demonstrate that by carefully selecting printing parameters and applying
appropriate post-processing methods, it is possible to significantly improve the mechanical
properties of extrusion-based parts. These findings have important implications for a wide range of
applications, from prototyping and product design to biomedical and aerospace engineering.

Keyword: Extrusion additive manufacturing, Mechanical strength, Layer adhesion, Printing

parameters, Novel materials, Composites, Post-processing techniques, Annealing, Surface
treatments, Tensile strength, Compressive strength, Flexural strength, Prototyping, Product design,
Biomedical engineering, Aerospace engineering.

Introduction: Extrusion additive manufacturing has become a popular and cost-effective

technique for producing parts with complex geometries and customized designs. However, one
major limitation of this process is the mechanical strength of the produced parts. The mechanical
properties of extrusion-based parts are often inferior to those manufactured through traditional
methods, and this can be attributed to several factors such as layer adhesion, material quality, and
processing parameters. Extrusion additive manufacturing, also known as fused deposition modelling
(FDM), is a widely used and accessible 3D printing technique. FDM is capable of fabricating complex
geometries with a range of thermoplastic materials, including ABS, PLA, PETG, nylon, and others.
However, FDM-printed parts are inherently anisotropic and exhibit lower mechanical strength
compared to parts fabricated using traditional manufacturing methods. In this research paper, we
discuss various techniques and strategies to improve the mechanical strength of extrusion additively
manufactured parts.

In order to overcome these challenges, researchers have proposed various methods to improve the
mechanical strength of extrusion-based parts. This research paper aims to explore these methods
and evaluate their effectiveness. Specifically, we will investigate how optimizing printing
parameters, using novel materials and composites, and applying post-processing techniques such as
annealing and surface treatments can enhance the mechanical properties of extrusion-based parts.

The paper is organized as follows: in section 2, we will provide an overview of extrusion additive
manufacturing and the challenges associated with achieving mechanical strength in these parts. In
section 3, we will present the proposed methods for improving mechanical strength and describe the
experimental setup used to evaluate these methods. In section 4, we will present and analyse the
results of the mechanical tests performed on the produced parts. Finally, in section 5, we will
summarize the main findings of the study and discuss their implications for future research and
practical applications.

Fig.: - metal material Extrusion additive manufacturing process

Material selection:

The mechanical properties of FDM-printed parts are largely influenced by the choice of material.
The selection of appropriate materials is essential to achieve high strength and performance.
Materials with high tensile strength, modulus, and elongation at break are preferred for extrusion
additive manufacturing. For instance, nylon has excellent tensile strength and elongation, making it
an ideal material for high-strength applications. Polycarbonate and carbon fibre-reinforced
filaments are also popular choices for parts that require superior strength and stiffness.

1. Optimizing Printing Parameters: One of the main factors affecting the mechanical properties of
extrusion-based parts is the printing parameters used during the manufacturing process. Researchers
have proposed various methods for optimizing these parameters to enhance the mechanical properties of
the produced parts. These methods include adjusting the layer thickness, printing speed, and
temperature, among others. This section will describe these methods in detail and present the results of
experiments conducted to evaluate their effectiveness.

The optimal parameters of

single objectives were
obtained using the S/N
ratio and average effect
plot. The optimal
parameters of dimension
W were the same as those
of dimension OW, and
only the layer thickness
was different from
dimension OL. Under the
optimal parameters of
dimension W, the
difference could be
improved by reducing the
layer thickness.
Fig.: - Optimizing Printing
Parameters (graphical
representation)

In addition, reducing the

layer thickness and
increasing the nozzle/build plate temperature must be implemented together to optimize dimension T.
However, a higher temperature can result in higher carbon dioxide emissions and electricity costs, which can
be eliminated by increasing the printing speed and lowering the build plate temperature.

The contribution and impact of each factor in different single-objective optimizations can be obtained using
ANOVA. The dimensional accuracy of W, material cost, and labor cost are most significantly affected by
the layer thickness. Although delta-type machines are suitable for high-speed printing, mechanism
movement errors can affect the accuracy of printed parts, causing such errors to have the highest
significance with regard to OW, OL, and T. The carbon dioxide emissions and electricity costs are most
significantly affected by the build plate temperature.

Five objectives, namely the dimensional accuracy, carbon emissions, and three printing costs, could be
optimized using a desirability analysis. In addition, through the desirability analysis and weights, different
optimal printing parameters could be determined under the same multiple objectives. The optimal printing
parameters of the dimensional accuracy, carbon dioxide emissions, and three printing costs could be
obtained in three different groups. This method is suitable for finding the optimal parameters with different
weightings under multiple objectives. The optimal printing parameters for the dimensional accuracy and
carbon dioxide emissions are the same as the majority for the dimensional accuracy, carbon dioxide
emissions, and three printing costs. This means that the same set of printing parameters can be balanced
across multi objective optimizations, even if there are different weights in the objectives.

2. Using Novel Materials and Composites: Another approach to improving mechanical strength is to use
novel materials or composites that are specifically designed for extrusion additive manufacturing. For
example, researchers have developed materials with enhanced mechanical properties, such as high
strength, flexibility, and durability. They have also experimented with using composites, such as carbon
fibres, to reinforce the printed parts. Research in the area of extrusion using novel materials is currently
focused on several areas. One area of research is the development of new materials with unique
properties, such as conductive or biodegradable materials. Another area of research is the development
of new process parameters to optimize the printing of the novel materials.
Fig.: - extrusion using novel materials

This includes the use of different nozzle sizes, layer heights, and print speeds. Finally, research is also
focused on the standardization of testing and characterization methods for novel materials. This section
will discuss these approaches and present the results of experiments conducted to evaluate their
effectiveness.

3. Post-Processing Techniques: Post-processing techniques such as annealing, vapor smoothing, metal

polishing and surface treatments can also be used to enhance the mechanical properties of extrusion-
based parts. Annealing involves heating the printed parts to a specific temperature for a certain
period of time, which can improve their strength and reduce residual stresses.
Vapor smoothing is a chemical process that uses acetone or other solvents to smooth and strengthen
the surface of printed parts. Mechanical polishing is a technique that removes the surface roughness
and improves the surface finish,
reducing the likelihood of
crack initiation and
propagation. Surface
treatments, such as
sandblasting and chemical
etching, can also be used to
enhance the surface roughness
and adhesion of the printed
parts.

Fig.: - post-additive manufacturing for stainless steel surface roughness

This section will describe these post-processing techniques in detail and present the results of
experiments conducted to evaluate their effectivity.
 Fig.: - ams2750f - thermal processing

4. Mechanical Tests: To evaluate the effectiveness of the proposed methods, mechanical tests such as
tensile, compressive, and flexural tests are performed on the printed parts. These tests are used to measure
the strength, stiffness, and toughness of the parts. This section will present the results of these tests and
analyse the effectiveness of the proposed methods in improving mechanical strength.

Fig.: - Tensile test

Fig.: - compression test

Fig.: - Flexural test

5. Applications: Finally, the paper will discuss the practical applications of the proposed methods for
improving mechanical strength in extrusion additive manufacturing. These applications include prototyping,
product design, biomedical engineering, and aerospace engineering, among others. The section will also
highlight the limitations and future directions for research in this field.

Overall, this research paper aims to provide a comprehensive review of the methods for improving
mechanical strength in extrusion additive manufacturing and to present experimental evidence for their
effectiveness.

● Advanced design approaches:

Advanced design approaches such as topology optimization, lattice structures, and infill pattern optimization
can also enhance the mechanical strength of extrusion additively manufactured parts. The design of the part
can have a significant impact on its mechanical properties. Design optimization techniques such as topology
optimization and lattice structures can improve the strength and stiffness of parts produced by EAM.
Topology optimization is a design approach that optimizes the shape and distribution of material to achieve
the desired strength and stiffness while reducing weight. Lattice structures and infill pattern optimization
improve the mechanical properties by reducing weight and enhancing the interlayer bonding.

Fig.: - Infill pattern optimization, topology optimization, lattice structures

Conclusion:
In conclusion, this study investigated the effect of various parameters on the mechanical strength of
extruded parts in additive manufacturing. Results showed that the use of higher nozzle temperature, lower
layer height, and slower printing speed led to increased mechanical strength. In addition, the use of a more
robust material and proper post-processing techniques such as annealing and heat treatment also contributed
to improved mechanical properties. These findings provide valuable insights for optimizing the
manufacturing process and improving the quality of 3D printed parts. Future work may explore the effect of
additional parameters and their interactions on mechanical strength, as well as investigate the applicability
of these findings to other extrusion-based 3D printing technologies.

EAM is a widely used process for the production of complex parts with intricate geometries. However, the
mechanical properties of parts produced by EAM are often inferior to those of conventionally manufactured
parts. To improve the mechanical strength of parts produced by EAM, material selection, process parameters
optimization, post-processing, and design optimization techniques can be employed. These methods can
help to reduce defects such as voids, porosity, and cracks, and improve the strength and stiffness of parts
produced by EAM.

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