Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-12, 2016 ISSN: 2454-1362, http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 440

Strength Improvement of Fused Deposition Modeling Parts.

Satish Kumar Singh1 & Prof. R.K.Agrawal2 1 PG student, Machine Design,YTIET, Chandhai, Karjat

2 Associate Professor, YTCEM, Chandhai, Karjat

Abstract: The Fused Deposition Modelling (FDM) process is a highly efficient Rapid Prototyping approach that makes it possible to rapidly generate even much complicated parts. FDM that produce prototypes from plastic materials such as acrylonitrile butadiene styrene (ABS) by laying tracks of semi-molten plastic filament onto a platform in a layer wise manner from bottom to top. Unfortunately, the Fused Deposition Modelling is affected by several major parameters like layer thickness, number of contours and orientation, whose setting may have an impact on the different areas of the components like main material, support material, built up time, total cost per part and most important the components strength. This work is devoted to the study the effects of major parameters of the FDM process on the compression and flexural strength of the fabricated components. Compression and flexural specimens were prepared as per the ASTM standard with different built-up orientation, layer thickness and number of contours. It can be concluded from the experimental analysis that the compression strength mainly depends on layer and flexural strength of the FDM parts. These conclusions will help the design engineers to decide on proper build orientation, layer thickness and number of contours so that FDM parts can be fabricated with good mechanical properties..

1. Introduction The Fused Deposition Modeling process is a highly efficient Rapid Prototyping approach that makes it possible to rapidly generate even much complicated parts in a short time and at low costs, when their requested mechanical proprieties are not too high. The Rapid Prototyping (RP) process experienced great advances in the last few years. The main advantages consist in the easy generation of a 3D prototype from a concept and in the possibility of making the manufacturing and the assembly tasks less complicated. For this purpose, it is often possible to consolidate subassemblies into single units, thus reducing the number of parts, the handling time, and the number of mating surfaces, which helps simplifying the mounting task. Moreover, the RP process is highly flexible since it is easy and

economical to rearrange the process, when design changes must be taken into account. Unfortunately the strength and the stiffness of components built by this technology are not particularly high and, furthermore, they are difficult to be defined due to their strong anisotropy (Dario Croccolo, 2013).

The Fused Deposition Modelling (FDM) from Stratasys is a typical example of a RP process. The FDM is able to produce prototypes from plastic materials, such as Acrylonitrile Butadiene Styrene (ABS) or Polyetherimide (ULTEM), and the process consists in the deposition of filaments of the material at the semi-molten state (Sung-Hoon Ahn, 2002). The filament is fed through a nozzle, located at the output of a heating device, and is deposited onto the partially constructed part. Since the material is extruded and laid in tracks at a semi-molten state, the newly deposited material fuses with adjacent material that has already been deposited. Afterwards, other material tracks are deposited, upon the completion of the current layer, and then the deposition of a new layer is started, as shown in Figure 1.

.

Figure 1 Fused Deposition Modeling Process The final mechanical properties of parts obtained by means of the FDM process are often uncertain, since they are influenced by a large amount of production parameters, which are, really, difficult to combine, in order to increase the strength and the stiffness of the built parts. As a consequence, the practical application of components processed by the FDM is

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-12, 2016 ISSN: 2454-1362, http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 441

limited to low-loaded products and to those whose failures do not lead to severe effects. Possible applications are in the manufacturing of electro-mechanical actuators or in that of children’s toys, for instance bows and arrows or small catapults.

2. Problem Definition Generally the parts build by Fused Deposition

Modeling (FDM) do not have enough strength. So that it is unable to be used in the manufacturing of various parts, which can sustain the compressive and the bending stress. As a consequences, the practical application of components processed by the Fused Deposition Modeling (FDM) is limited to low loaded products and to those whose failures do not lead to severe effect It is found that From above building parameters part build direction is always perpendicular to the build plate-form, bead width is depends on layer thickness and usually double of layer thickness, raster angle and air gap generally fixed are +45°⁄−45° and zero respectively. So, these above parameters are almost fixed means that these parameters are not affect that much strength of components.

Layer thickness, build-up orientation and number of contours are these parameters whose affect are more on the components strength as well as surface finish of components. So, considering these are main parameters for present experimental study.

3. Methodology to improve the FDM parts Based on the background study following

methodology has been developed. This methodology defines how the parameters are to be selected and how the test should be carried out in series. It also tells the procedure which is needed to be followed to optimize our time required to get the good results.

• Study of parameters which improve the strength in various study and literature.

• Analyzing parameters and their effect on strength improvement

• Design the specimen according to ASTM standard.

• Design of experiment done by Taguchi Method

• Prepare CAD model in .stl format • Selecting machine according to

requirements • Manufacturing of specimen with specified

parameters • Designing the test setup • Selecting loading boundary condition • Testing of specimen • Results & discussion

4. Design of Experiment The strength of components which is manufacture

by FDM process will mainly depends on number of parameters like orientation, layer thickness and number of Contours. To get the strength of components for certain application on certain direction, will depends majorly on particular parameters. To find that parameters, it is always better to follow to do experiment by designing it with suitable method. In this master thesis Taguchi method has been followed to minimize number of experiment and to get or decide the particular parameters which affect the strength of components.

The effect of many different parameters on the

performance characteristic in a condensed set of experiments can be examined by using the orthogonal array experimental design proposed by Taguchi. Once the parameters affecting a process that can be controlled have been determined, the levels at which these parameters should be varied must be determined. Knowing the number of parameters and the number of levels, the proper orthogonal array can be selected. Using the array selector table or Minitab software. In this project of master thesis for compression test experimentation 3-important parameters orientation, layer thickness and number of contours with each have 3-level. So, from array selector the size of orthogonal array is L9 as shown in Table 1.

Table 1. L9 Orthogonal Array for Compression Test Specimen

Serial No.

Orientation

Layer thickness (µm)

No of contours

1 x-axis 100 2

2 x-axis 200 3

3 x-axis 300 5

4 y-axis 100 3

5 y-axis 200 5

6 y-axis 300 2

7 z-axis 100 5

8 z-axis 200 2

9 z-axis 300 3

Similarly, for flexural test experimentation 3-important parameters orientation, layer thickness and

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-12, 2016 ISSN: 2454-1362, http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 442

number of contours with each are having 4-level except layer thickness has 3-level. So, from array selector the size of orthogonal array is L16 as shown in Table 2. Table 2. L16 Orthogonal Array for Flexural Test

Specimen (Rectangular component

Serial No.

Orientation Layer thickness (µm)

No of contours

1 x-axis-0° 100 2 2 x-axis-0° 200 3 3 x-axis-0° 300 4 4 x-axis-0° 100 5 5 x-axis-90° 100 3 6 x-axis-90° 200 2 7 x-axis-90° 300 5 8 x-axis-90° 200 4 9 y-axis-0° 100 4 10 y-axis-0° 200 5 11 y-axis-0° 300 2 12 y-axis-0° 300 3 13 y-axis-90° 100 5 14 y-axis-90° 200 4 15 y-axis-90° 300 3 16 y-axis-90° 100 2

5. Fabrication

Manufacturing of specimens made of ABS (Acrylonitrile Butadiene Styrene) plastic, a widely used material for FDM processed parts. Manufacturing of compression test specimens according to ASTM D695 has been done and similarly for flexural test ASTM D790 standard has been followed. The CAD model of Specimen for compression test is a cylinder with dia. 12.7 mm and length 25.4 mm. the stl file format of CAD model as shown in Figure.2 Coming to the rectangular test specimen has a dimension of 127mm×13mm×3.5mm (length×width×thickness), which is shown in Figure. 3

Figure.2 (a) CAD Model Compression Specimen (b) CAD Model Specimen in Stl File Format

Figure.3 (a) CAD Model of Flexural Test

Specimen, (b) .stl File Format of Specimen .stl file format sent to the FDM machine for

manufacturing of test specimen. Every FDM has supportive software that corrects the error of .stl file as well as slicing of components, find the number of support material layer and main material layer and amount of consume main and support material, time required for manufacturing of test specimen etc. After slicing compression test specimen and flexural test are shown in axially and vertically direction in Figure.4 and Figure.5 respectively.

Figure.4 Compression Test Specimens after

Slicing (a) In Axially Y-axis Direction (b) In Vertically Y-axis Direction

Figure.5 Flexural Test Specimen after Slicing (a) In axially Y-axis direction (b) In Vertically Y-axis Direction.

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-12, 2016 ISSN: 2454-1362, http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 443

6. Experimental Setup And Tests After manufacturing of all compression and

flexural specimen. The compression test and flexural test are conducted on HELCO Electro Mechanical tensile testing machine, Capacity-20KN

Figure.6 HELCO Electro Mechanical Tensile Testing Machine, Capacity-20KN

The block diagram of test setup is shown Figure.7 (a) Show compression setup and Figure.7 (b) Show for flexural test. In compression test the cylindrical block which has prepared in FDM is kept between two compression plates and force of 10 KN has been applied. During the test the parameters like Peak load, Displacement at Peak Load, compression Strength, Load at Proportionality limit and Displacement at proportionality limit are observed. The details of results will be discussed in subsequent chapter.

The Flexural test setup which conducted is completely different from compression test and the parameters like peak Load, displacement at peak Load, Flexural stress, Flexural strain, Modulus of rupture and modulus of elasticity are need to be studied. In Flexural test the test the test specimen is like a thick rectangular strip. The boundary are defined as simple support with point load at center. The Loading which is done on the test specimen is a time dependent and load cell capacity is 2.5KN. Figure.7 (a) Block Diagram for Compression Test Setup, (b) Block Diagram for Flexural Test Setup.

Figure.7 Real Time Test Setup for (a) Compression Test (b) Flexural Test on HELCO

Electro Mechanical Tensile Testing Machine

After complication of compression tests and 3-point bending tests. Some of deformed/failure specimen are shown in Figure.8 and Figure.9 for compression and flexural test respectively

Figure.8 Deformed Specimens after Compression Test.

Figure.9 Deformed Specimens after 3-Point

Bending Test 7. RESULTS AND DISCUSSION After putting all test results of compression in Minitab software, it showing the S/N ratio and mean for strength are shown in Figure.10 and Figure.11 respectively.

Figure.10 Main Effect Plot for Signal to Noise Ratios for Strength.

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-12, 2016 ISSN: 2454-1362, http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 444

Figure.11 Main Effect Plot for Signal to Noise

Ratios for Strength.

Figure.12 Main Effect Plot for Means for strength.

The above graph gives the idea about the parameters and its effect on compressive strength improvement of components. First section of graph, gives the orientation effect on its compressive strength. It has been shown the 3-points, from point 1-2, where change the orientation from X-axis to Y-axis and point 2-3, where the orientation from Y-axis to Z-axis. The slope of line from X-axis to Y-axis direction is much lower than from Y-axis to Z-axis direction. It signified that, when it changes the orientation in Z-axis direction, it gives better strength improvement than X-axis and Y-axis direction.

As level of experiment is 3. So, the number of points will be same as that in previous section. The point-1 defines 0.1mm layer thickness, point-2, 0.2mm layer thickness and point-3, 0.3mm layer thickness. If there is an increase in layer thickness from 0.1mm to 0.2mm the slope of line is negative. Similarly from point 2 to 3. The slope of line from 1-

2 is higher than slope of line from 2-3. It indicates that the reduction in strength is more when the layer thickness is increased from 0.1mm to 0.2mm than that in case of increasing the layer thickness from 0.2mm to 0.3mm

In case of number of contours the output graph is the replica of orientation graph. In similar way effect of orientation will be followed for number of contours. That is if increase the number of contours from 2-contours to 3-contours, the strength improvement will be lower than 3 to 5 contours. From above 3-parameters and 3-levels, got following table.3

Table.3 Response Table for signal noise ratios,

Larger is better.

Level Orientation Layer No.of Contours

1 27.02 30.13 26.79 2 27.44 27.70 27.35 3 29.95 26.58 30.27 Delta 2.93 3.5 3.48 Rank 3 1 2

The above table gives the idea about which parameters strongly affect the compressive strength of specimen and ranking of those parameters.

The analysis of result data can be done by best way by plotting its behavior between various parameters. Figure.13 showing graph between Load vs Time for compressive test. Here graph show the characteristic of load bearing capacity of specimen vs time. Graph shows the specimen-7 has maximum load bearing capacity and its value is 6.3 KN and minimum for specimen-6 and its value is 2.1 KN, means increase in strength is 200 %.

Figure.13 Graph between Loads vs. Time for all Compressive Specimen

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-12, 2016 ISSN: 2454-1362, http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 445

Similarly in Figure.14 shows stress vs. strain for compressive test. In Figure 7.4 shows, at initial Stage where it follows some relation between stress and strain after that the curve is horizontal or slightly decreasing. The point need to study is that find the maximum stress point. I.e. the Component which can bear the maximum stress.

Figure.14 Stress vs. Strain for Compression

Test.

Figure 7.5, shows the maximum stress bearing capacity in bar chart form. In Figure 7.4 it is difficult to find the maximum stress of specimen to understand this bar chart has been selected. It is clear from Figure.15, specimen-7 can bear maximum stress/load and its value is 49.732 Mpa and least for specimen-6 and its value is 16.577 MPa

Strength of specimen-7 is maximum because all 3-parameters, orientation is z-axis, layer thickness minimum (0.1mm) and number of contours is 5 and all these parameters are supporting for improving the strength of components

Figure.15 Maximum Stress Value for Compression Test.

Similarly for compression test, after putting all the results value in Minitab software, it gives the following graph. Figure.16 showing graph between Load vs. Time for flexural test. Here graph show the characteristic of load bearing capacity behavior of specimen with time. In Figure.16 Graph shows the specimen-4 has maximum load bearing capacity and its value is 145N and minimum for specimen-11 and its value is 68N, means increase in strength is 113.23%, as shown in Figure.17. Due to anisotropic behavior material, there is no any load at proportionality and also no any displacement at proportionality but at starting load bearing capacity is increasing with time increase and after some time it goes parallel and then decrease.

Figure.16 Loads vs. Time Behavior Graph

for Flexural Specimens Figure.17 and Figure.18 shows the maximum load bearing capacity and maximum stress bearing capacity respectively.

Figure.17 Maximum Load Bearing

Capacities for Flexural Specimen

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-12, 2016 ISSN: 2454-1362, http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 446

Figure.18 Maximum Stress Bearing Capacities for

Flexural Specimen

Here specimen-4 has higher strength because of minimum layer thickness (0.1mm) and maximum no of contours (5-contours) conversely for specimen-11 has lower strength because of y-axis-0°, higher layer thickness 0.3mm and minimum number of contours. 8. Conclusion In the present work, the effect of built orientation, layer thickness and number of contours on the mechanical strength was investigated. The responses considered in this study are mechanical property of FDM produced parts such as compression and bending strength. Test specimens were fabricated on Flash forge Dreamer Dual Extruder FDM machine. FDM rapid prototyping machine coupled with Flash Print software and ABS is used as main material. Design of Specimen for compression and Flexural test are done by the help of ASTM D695 and ASTM D790 respectively and Design of Experiment was done by Taguchi Method, L9 for compression and L16 for flexural. After manufacturing of all specimens, test is done on HELCO Electro Mechanical Tensile Testing Machine. After testing, it comes in to conclusion that decrease in layer thickness increase the strength, increase in number of contours, increase the strength all and in z-axis has highest the strength and minimum in y-axis direction. Also all results of are analyzed by the Taguchi design by the help of Minitab software. Results are plot for S/N ratio and mean for strength by the Minitab software. Plotted graphs are showing effect of parameters on strength. It also giving ranking of parameters which affect more. For compression test ranking of parameters layer thickness, number of contour and orientation in decreasing order but for flexure test it shows the ranking of parameters are layer thickness, orientation and number of contours. For compression test, specimen-7 has highest strength of 49.732 MPa because of its minimum layer thickness, maximum number of contours is 5 and minimum for specimen-6 of 16.577 MPa due to maximum layer thickness and minimum number of contours is 2. Means that increase in strength of

specimen-7 is 200% when compare with weakest specimen-6.

Similarly for flexural test, strength of components depends on orientation, layer thickness and number of contours in decreasing order of ranking. Here specimen-4 has highest flexural strength of 115.363 MPa because of x-axis orientation, minimum layer thickness of .1mm and higher no of contours (5-contours) and conversely for specimen-11 has least strength of 54.229 MPa because of y-axis-0° orientation, higher layer thickness of .3mm and minimum number of contours is 2. That is percentage increase in strength is 112.733.

After analyzing the test result, it is easy to conclude that for increase the strength layer thickness should minimum, number contours is maximum and orientation should be z-axis or x-axis. By choosing appropriate parameters, strength of components increases drastically and can be used components for real application. 9. Acknowledgements

I take this opportunity to express my sincere thanks and deep sense of gratitude to my guide, Prof. R. K. Agrawal (Associate Professor in Mechanical Engg.) for his constant support, motivation, valuable guidance and immense help during the entire course of this work. Without his constant encouragement, timely advice and valuable discussions, it would have been too difficult to complete this work.

I am highly indebted and express my heartfelt gratitude to our beloved Head Of Department Prof. S. R. Wankhede, YTIET for his all-time support cooperation and inspiration to enable me to complete this work without whom it would had been difficult task all together his support and immense poll of knowledge, which he so graciously place to me and made all the facilities available for the completion of this project.

I also wish to express my sincere thanks to Dr. Rajendra Prasad (Principal YTIET), for their valuable and motivating support throughout the course of project.

I am wish to express my sincere thanks and gratitude to my father, mother entire family, colleagues and my friends for their constant help and support during entire project work.

10. References [1] Sandeep Rauta, Vijay Kumar S. Jattib,*, Nitin K. Khedkarc, T.P.Singhd, Investigation of the effect of built orientation on mechanical properties and total cost of FDM parts.

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-12, 2016 ISSN: 2454-1362, http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 447

[2] Dario Croccolo*, Massimiliano De Agostinis, Giorgio Olmi, Experimental characterization and analytical modeling of the mechanical behavior of fused deposition processed parts made of ABS-M30

[3] Anoop Kumar Sood a, R.K. Ohdar b, S.S. Mahapatra c,* Parametric appraisal of mechanical property of fused deposition modeling processed parts.

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[5] Anoop K. Sood a, Raj K. Ohdar b, Siba S. Mahapatra c,* Experimental investigation and empirical modeling of FDM process for compressive strength improvement.

[6] C.S. Lee a, S.G. Kimb, H.J. Kimb, S.H. Ahnb,∗,Measurement of anisotropic compressive strength of rapid prototyping parts.

[7] M.R. KaramoozRavari n, M. Kadkhodaei, M. Badrossamay, R. Rezaei, Numerical investigation on mechanical properties of cellular lattice structures fabricated by fused deposition modeling

[8] W Lee, C Wei, SC Chung , Development of a hybrid rapid prototyping system using low-cost fused deposition modeling and five axis machining.

[9] L.M. Galantucci (1)*, F. Lavecchia, G. Percoco, Study of compression properties of topologically optimized FDM made structured parts.