Quality Study Of Parts Produced By 3D Printer.
UTeM Library (Pind.l/2005)
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS TESIS*
I
JUDUL: QUALITY STUDY OF PARTS PRODUCED BY 3D PRINTER
SESI PENGAJIAN : 2/2006-2007
Saya
KEVIN JOK SAGENG
mengaku membenarkan tesis (PSM/Sarjana/Doktor Falsafah) ini disimpan di
Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat
kegunaan seperti berikut:
1. Tesis adalah hak milik Universiti Teknikal Malaysia Melaka.
2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja.
3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran
antara institusi pengajian tinggi.
4. **Sila tandakan Ｈ ｾ Ｉ＠
D
SULIT
D
TERHAD
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TIDAK TERHAD
(Mengandungi maklumat yang berdarjah keselamatan
atau kepentingan Malaysia yang termaktub di dalam
AKTA RAHSIA RASMI1972)
(Mengandungi maklumat TERHAD yang telah ditentukan
oleh organisasi / badan di mana penyelidikan dijalankan)
Disahkan oleh:
(TANDATANGAN PENULIS)
(TANDATAN
N PENYELIA)
RUlY HARYATJ BINTI HAMBAU
Alamat Tetap:
N0. 1452, LORONG E7,TAMAN SATRIA
JAYA, BDC,
93350 STAMPIN , KUCHING , SARAWAK
Cop Rasmi:
Tarikh: 14 MEl 2007
Tarikh: _ _I....;..
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Pensyarah
Fakulti K!!JUruteraan Pembuatan
Unrv&rsiti Tekmkal Maliys1a Melau
Karung BerkUI'ICI 1200. Aytr Keroh
75450 Melakd
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* Tesis di maksudkan sebagai tesis bagi ljazah Doktor Falsafah dan Sarjana secara penyelidikan, atau
disertasi bagi pengajian secara kerja kursus dan penyelidi kan, atau Laporan Projek Sarjana Muda (PSM).
** Jika tesi s i ni SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan
dengan menvat akan sekali sebab dan t empoh tesi s i ni perlu dikelaskan sebagai SULIT at au TERHAD.
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
Quality Study Of Parts Produced By 3D Printer
Thesis submitted in accordance with the requirements of the Universiti
Teknika1 Malaysia Melaka for the Degree of Bachelor of Engineering
(Honours) Manufacturing (Design)
By
Kevin Jok Sageng
Faculty of Manufacturing Engineering
Apri12007
DECLARATION
I hereby, declare this thesis entitled "Quality Study OfParts Produced by 3D Printer"
is the results of my own research except as cited in the reference.
Signature
Author's Name
Kevin Jok Sageng
Date
13th April 2007
APPROVAL ..
,
.
This thesis submitted to the Faculty of Manufacturing Engineering ofUTeM and has
been accepted as partial fulfillment of the requirement for the degree of Bachelor of
Manufacturing Engineering (Honours) (Manufacturing Design).
ﾷ ﾷﾷ
ﾷ ﾷｾＭ＠
Main supervisor
Faculty ofManufacturing Engineering
RUZV HARYATI BINTI HAMBALI
Pensyarah
Fiiikulti Kejuruteraan Pembuatan
Univers1ti Teknikal Malaysia Meliilka
Karur!! lierltunci 121)(', Aver Keroh
75450 Meta....
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The "Quality Study of Parts Produced by 3D Printer" is based on Rapid Prototyping (RP)
concept where RP model named Master Pattern is designed by Computer Aided Engineering
(CAD) modeling software. The Master Pattern consists of shape and features of triangular
and circular protrusion as well as triangular and circular hollow cavity and also part features
consists of sections with draft angle were designed by using Solidwork CAD software.
ZCorp ZPrinter 310 Plus 3D Printer Apparatus is used to produce three Master Pattern's
physical prototype. This study investigates the surface finish, dimensional accuracy, flatness
and straightness of the three Master Pattern samples produced using 3D Printer apparatus by
using appropriate measuring equipment for quality testing namely the Digital Caliper,
Coordinate Measuring Machine (CMM) and Portable Surface Roughness SJ-301 Measuring
Instruments. The result of the study shows that the 3D Printer has a process capability to
produce parts with a dimensional tolerance of ± 0.1000 to ± 0.2000mm and the surface
roughness, Ra is correlated to the flatness and straightness. The findings shows that shape,
surface and dimensional irregularities as the main defects and problem to parts produced by
3D Printer and the problem can be reduced by ensuring the process parameter such as part
orientation, part hardening period, post processing method and curing time is properly
adhered to produce parts with the highest quality.
Ill
ACKNOWLEDGEMENT
First and foremost, I would love to extend my prayer and thanksgiving to God for the
wonderful blessings and spiritual guidance that matures and strengthens me as each
days passes along the implementation of this study.
I would also like to express my deepest gratitude to my thesis supervisor, Pn. Ruzy
Haryati Binti Hambali for the guidance and advice through out the process of this
thesis writing. God bless you for your sincere thought and assistance.
Special thanks also to Mr. Shajahan Bin Maidin acting as my Second Panel for the
time and commitment in assessing my thesis writing and also for being a caring and
understanding person in regards to difficulties in concluding this thesis work.
My greatest gratitude also goes to Universiti Teknikal Melaka Malaysia (UTEM) for
the privileges to complete my thesis proposal implementation and providing the
platform and eager assistance in providing the technical apparatus and advice
especially the technician, Mr Fairuz at Rapid Prototyping Lab.
Most of all, my heartfelt thank to my family for their continuous love and support
through good and bad times. Last but not least, my fellow peers Petrus Ak. Japong,
Nur Wadiah bt. Mohd Andai, Nor Fairuz Hayati and Mobd. Hafiq Ikhwan; I would
like to say thank you for your friendship, encouragement and motivation.
IV
TABLE OF CONTENTS
J
ｾ＠
Abstract
'
II
(
Acknowledgement
Ill
Table of Contents
IV
List ofFigures
IX
List ofTables
X
1. INTRODUCTION
1
2
1.1 Objectives ofthe Study
3
1.2 Scope of the Study
3
1.3 Problem Statements
4
LITERATURE REVIEW
5
2.1 Rapid Prototyping Background
5
2.2 Rapid Prototyping Process Advantages and Disadvantages
6
2.3 Classification ofRapid Prototyping
7
2.4 Basic Processes ofRapid Prototyping
9
2.4.1 CAD Model Creation
9
2.4.2 Conversion to STL Format
10
2.4.3 Slicing ofthe STL file into thin cross sectional layers
10
2.4.4 Construction ofthe model one layer atop another
11
2.4.5 Finishing and clean editing the model
11
2.5 STLFile
11
2.6 3D Printer Apparatus
12
2.7 3D Printer Components
12
2.8 Basic Process of 3D Printing
13
2.9 3D Printing Process Capabilities
16
2.10 Quality of Parts Produced by 3D Printing
18
2.11 Protective Coatings
19
2 .12 Advantages of3D Printing Machine
19
v
2. 13 Disadvantages of 3D Printing Machine
22
2.14 3D Printer Materials Systems
23
23
2. 14. 1 Powder Materials
.
2. 14 .1. 1 High Performance Composite Material
.
2.14.2 Casting Materials
23
24
(
2.14.2.1 Investment Casting Material
24
2.14.2.2 Direct Casting Material
24
2.14.3 Specialty Material
24
2.14.3.1 Snap Fit Material
25
2.14.3.2 Elastomeric Material
25
2.15 Epoxy
25
2.15.1 Resin
26
2.15.2 General Characteristic and Advantages ofResin
27
2.15.3 Adhesive Properties ofResin
28
2.15.4 Mechanical Properties of Resin
28
2.15.5 Micro Cracking ofResin
29
2.15.6 Fatigue Resistance ofResin
30
2.15.7 Degradation from Water Absorption
31
2.15.8 Typical Applications ofResin
32
32
2. 16 Hardening (Infiltration) Material
2.16.1 Physical and Chemical Properties
33
2.16.2 Stability and Reactivity
34
3. METHODOLOGY
3.1 Sample Manufacturing
35
3.2 ZCorp ZPrinter 310 Plus 3D Printer Operating Mechanism
35
3.3 ZCorp ZPrinter 310 Plus 3D Printer Technical Specifications
36
3. 4 Experimental Methodology
36
3.5 Methodological Procedure
38
3.6 Virtual Prototyping Introduction
38
3.6.1 Virtual Part Design ofMaster Pattern
38
3.6.2 Solidwork CAD Model Creation
39
VI
3.6.2.1 Numerical Information for Master Pattern
3.6.3 Conversion to STL Format
40
41
3.7 3D Printer Preparation
4I
3.8 Virtual Prototyping with ZPrint Software
42
3.8. I Orientation ofMaster Pattern
(
3.8.2 Checking the Build Settings
42
42
3.9 Physical Prototyping
43
3. 10 Post Processing
45
3.10.1 De-powdering of the Master Pattern
45
3.10.2 Removal of Master Pattern from Build Box
46
3.10.3 De-powdering Process in the Powder Recycling Unit
47
3.10.4 Drying the Master Pattern
48
3.10.5 Application of Resin Glue to Master Pattern
48
3.11 Sample Preparation for Testing
49
3 .11 .1 Product Quality
49
3. 12 Dimensional Accuracy Measurement
3.12. I Dimensional Accuracy Measuring Information
3.13 Surface Roughness Measurement
3.13.1 Surface Roughness Measuring Information
3. 14 Flatness and Straightness Measurement
3 .14.1 Flatness and Straightness Measurement Information
50
51
56
56
57
58
59
3.15 Validation
60
4. RESULTS AND ANALYSIS
4.1 Introduction to Dimensional Accuracy Result and Analysis
60
4.1.1 Dimensional Accuracy Measurement Result
61
4.1.2 Dimensional Accuracy Graph and Analysis
62
4 .2 Introduction to Flatness and Straightness Result and Analysis
73
4.2.1 Flatness and Straightness Measurement Result
73
4.2.2 Flatness and Straightness Graph and Analysis
75
4.3 Introduction to Surface Roughness Result and Analysis
4.3. 1 Surface Roughness Measurement Result
VII
78
78
4.3.2 Surface Roughness Graph and Analysis
80
5. DISCUSSIONS
84
5. 1 Introduction
84
5.2 Detailed Analysis for Dimensional Accuracy Measurement
84
5.3 Detailed Analysis for Flatness and Straightness Measurement
88
5.4 Detailed Analysis for Surface Roughness Measurement
89
6. CONCLUSIONS
91
6.1 Conclusions
91
6.2 Suggestions and Recommendations
92
REFERENCES
93
APPENDICES
A
Detail Projection Sketching for Master Pattern
B
Dimensional Accuracy Measurement Data Table
C
Theoretical Equation for Calculation for X Control Chart Tolerance Limit
D
Data Table for X Chart Tolerance Limits
E
Calculation For X Control Chart Tolerance Limit
F
Compatibility Data for Tolerance
G
Straightness and Flatness Measurement Data Table
H
Straightness and Flatness Printed Measurement Data Sheet
I
Surface Roughness, Ra Measurement Data Table
J
Surface Roughness, Ra Printed Measurement Data Sheet
K
Measuring Instruments for Dimensional Accuracy, Surface Roughness and
Flatness and Straightness
L
Table for Measurement Standard for Ra according to TIS B0601-1994
Standard
M
Gantt Chart for Thesis Report Writing
Vlll
LIST OF FIGURES
2.1
.
3D Printer Main Unit
,.I
14
(
2.2
Powder Recycling Unit
2.3
Build Box
15
2.4
Resin Binder
15
2.5
The 3D Printing Layering Principle
16
2.6
The 3D Printing Operating Principle
16
2.7
Strength of Part in Regards to Part Orientation
18
2.8
Comparative Tensile Strength and Stiffness ofResins
30
2.9
Typical Fibre Reinforced Plastic Stress/Strain Graph
31
2.10
Typical Resin Stress/Strain Curves (Post Cure 5hrs @80°C)
31
2.11
Effect of Periods of Water Soak at 100°C on
14
Resin Inter-Laminar Shear Strength
32
3.1
Experimental Design of the Experiment
39
3.2
Master Pattern Isometric View
43
3.3
Master Pattern Isometric View with Dimension
44
3.4
Master Pattern Sample 1, 2 & 3 (Top View)
48
3.5
Master Pattern Sample 1, 2 & 3 (Bottom View)
48
3.6
Soft Horsehair Brush and the Polypropylene Scraper
50
3.7
Plaster Ceramic Powder
50
3.8
Powder Recycling Unit
52
3.9
AirBrush
52
3.10
Cyanoacrylate Resin Glue
53
3.11
Dimensional Element of the Master Pattern
56
3.12
Surface Roughness Measurement Information for Top Surface
60
3.13
Surface Roughness Measurement Information for Bottom Surface
60
3.14
Surface Roughness Measurement Information for Top Surface
62
3.15
Surface Roughness Measurement Information for Bottom Surface
62
........
lX
4.1
Tolerance Limit Line Indicator
66
4.2
Graph for Master Pattern Length, Dl versus Number of Samples
68
4.3
Graph for Master Pattern Width, D2 versus Number of Samples
69
4.4
Graph for Master Pattern Height, D3 versus Number of Samples
70
4.5
Graph for Protrusion Length, D4 and the Triangular Protrusion Width, D5
versus Number of Samples
71
4.6
Graph for Triangular Protrusion Height, D6 versus Number of Samples
72
4 .7
Graph for Triangular Hole Length, D7 and Triangular Hole Width, D8
versus Number of Samples
73
4.8
Graph for Circular Protrusion Diameter, D9 versus Number of Samples
74
4.9
Graph for Circular Hole Diameter, D 10 versus Number of Samples
75
4.10
Graph for Protrusion Circular Protrusion Height, D 11
versus Number of Samples
4.11
76
Graph for Master Pattern's Overall Average Major Diameter
versus Number of Samples
4.12
77
Graph for Flatness & Straightness for Left and Right X-axis andY-axis
versus Number of Samples
4.13
80
Graph for Flatness of Top and Bottom Surface
versus Number of Samples
4. 14
82
Graph of Surface Finish, Ra (!lm) for Top Side (A) X andY-axis
versus Number of Samples
4.15
86
Graph of Surface Finish, Ra (!lm) for Bottom Side (B) X andY-axis
versus Number of Samples
4.16
87
Graph of Surface Finish, Ra (!lm) for Top and Bottom Side
88
versus Number of Samples
X
LIST OF TABLES
2.1
Physical and Chemical Properties for Cyanoacrylate
34
2. 2
Stability and Reactivity Properties for Cyanoacrylate
35
3.1
Technical Data Specifications for ZCorp ZPrinter 310 Plus
37
3.2
Drying Time for Parts
52
3.3
Data for Surface Roughness, Ra Measurement Parameter
59
4.1
Data for Flatness of Top and Bottom Surface Testing
79
4 .2
Data for Average Surface Roughness, Ra value for A and B Side
85
Xl
CHAPTER 1!
INTRODUCTION
3D Printing process is a techruque which used the resin binder as the main medium to
cure the powder ceramic material compound. In this study, a mixture of powder
material will be cured using the resin bonding curing technique in 3D Printing
method. The method of construction is of layer by layer construction of which a layer
or powder will be resurfaced by a layer of binder or bonding agent on top and the two
layer will bond together to form a solid surface and the process is repeated by the
application of a new layer of powder and binder from bottom until the top of the
design. Recently, there is a high demand in faster development time for parts and
product before manufacturing substituting conventional methods thus scientists and
engineers is turning their attention to Rapid Prototyping (RP) method to initiate the
Rapid Tooling (RT) application to produce the physical prototype of a part which is
then to be examined and analyzed for further improvement to the part design with the
aim of high quality finish.
The selection of Quality Study of Parts Produced by 3D Printing Application for
study is because of the necessity to understand its importance in terms of product
development especially in tooling where the accuracy, surface finishing and the
reliability of parts that can be produced in multiple production process especially in
terms of the ability in holding close tolerance can affect the production in a whole.
3D Printer is the most effective means of tooling production which integrates RP and
RT application for faster product development. The process offers lots of advantages
compared to the conventional technique in production tooling such as by
Stereolithogrpahy (SLA). It seems that 3D Printer application is fast gaining
recognition and popularity as a modern technology and starts to stirs up the interest
1
of product manufacturer, developer, scientists and engineers to develop a study on
the effectiveness of the method in RP and RT field in aid to manufacturing. Thus, it
is the right time to study and understand this technique and hopefully it can
contribute to the improvement and promote better understanding to the 3D printing
.
process.
(
The extensive use ofRP and RT technique can help to reduce a products production
time using the 3D Printer prototyping process. Besides that, the print bonding curing
is a process which utilizes the epoxy resin to increase the viscosity of the powder
ceramic material thus produced a strong bond among the molecules of the material to
hold each interlinked layer of surface together achieving a hard molded compound.
Generally, the liquid resin material is coated onto the surface inducing a chemical
process that causes the liquid to undergo a phase transition to a solid state once it is
bonded with the powder ceramic material. Traditionally, this process has been
accomplished by conventional heating in oven which involves extra cost and time.
The resin material to be deposited is printed and applied to atop the surface of
powder layer and cured layer by layer to finally construct a full physical prototyping
model of the part.
This study emphasizes on the quality study of the parts produced using 3D Printer in
RP and RT application. The quality study is based on criterion such as the
dimensional accuracy, surface finish, flatness and straightness. Further study is
conducted to investigate and to analyze the effect of the design in relation to the
process capability of the 3D Printer machine in order to maximize the overall surface
finish of the part.
2
1.1
Objectives of the Study
The purpose of this investigative study is to achieve the following:
(1)
To identify the quality study includjng the dimensional accuracy, surface
finish, flatness and straightness ofthe resulting parts by metrological means
(2)
To study the effect and causes of the 3D Printing process in relation to
constructed part' s quality in order to maximize dimensional accuracy, surface
finish, flatness and straightness of each resulting part
1.2
Scope of the Study
( 1)
Design the virtual part which ts the Master Pattern using the Soljdwork
software
(2)
Convert the CAD drawing file into STL data file format recognized by the 3D
Printer
(3)
Produce the part using the 3D Printer Machjne
(4)
Produce three Master Pattern samples using the 3D Printer Machine
(5)
Study the dimensjonal accuracy of the three Master Pattern samples
(6)
Study the surface finish of the three Master Pattern samples
(7)
Study the flatness and straightness of the three Master Pattern samples
(8)
Analyzed the results and make future work recommendations
3
1.3
Problem Statements
Manufacturing and production has evolved into a competitive and challenging
proposition to produce the best tooling product with the best design and cost effective
with high function ability. The needs for fast and productive manufacturing
production must be synchronized with the utilization of rapid prototyping
development in manufacturing to enhance design function and workability to the
maximum.
Rapid Prototyping (RP) is one of the tools that utilize the CAD concept to create the
mechanical structure of the part in visual prototyping. The 3D Printer Machine
manages the manufacture process of the physical prototype as an application of
Rapid Tooling (RT) concept under the Direct Tooling classifications. 3D Printer
production operation uses the STL format to program instructions that controls the
layer by layer construction of the 3D Printer machine and subsequently produced the
complete designed part.
Tooling now days
IS
very important m product development. The accuracy,
durability, finishing and the amount of parts that a tool can produce affect the
production. Tool manufactured by conventional methods usually offers good quality
of the product but the cost of these tolls could be up to hundreds pound and the time
required for their manufacture up to months.
This study investigates the surface finish, dimensional accuracy, flatness and
straightness of the parts produced using 3D Printer in rapid tooling application.
4
CHAPTER2
LITERATURE REVIEW
2.1
Rapid Prototyping Background
Rapid Prototyping (RP) is a fast tracked and advanced manufacturing tool which
relies on the Computer Aided Design (CAD) and Computer Manufacturing
Application (CAM) to produce prototypes by using various advanced manufacturing
apparatus and method. Prototype part is usually in the form of solid and cost effective
physical model which can be produced in a fast production steps. Parts produced are
highly precise and detailed with good dimensional stability and tolerances that
resembles the actual concept of the designed product.
Rapid Prototyping in general is referred to as "Fabrication of a physical, threedimensional part of arbitrary shape directly from a numerical description typically a
CAD model by a quick, highly automated and totally flexible process." (Rapid
Prototyping Report, October 1992)
RP is an excellent tool for communicating and interacting ideas among the personnel
involved in the design of the part and also the research and development personnel
right up to the management. RP presents as visual aids to enable the relaying and
conveying of vital information between the product development phase and the full
production run of which data are obtained through design testing and production test
run of the prototype model of the part.
In addition to prototypes, RP techniques can also be used to make tooling which can
be referred to as rapid tooling. For small production runs and complicated objects,
5
(5)
A production tool used to examine manufacturing methods offabricated parts
and assembly processes and procedures to obtain the best and most effective
manufacturing methods.
(6)
A communications tool for internal design reviews and also for design
reviews with the customer
(7)
RP is a design verification and optimization tool to qualify the form, fit and
function of individual parts and assemblies where its physical visualization
concept enables verification of design details as a mean to gain internal
design acceptance and justification.
However, RP also have several disadvantages where part may have s1ze and
geometry limitation for example a part volume is generally limited to 0.125 cubic
meters or less, depending on the RP machine. Metal prototypes are difficult to make
and for metal parts with large production runs, the conventional manufacturing
techniques are usually more economical. RP generated tools may not easily be
modified or corrected using typical tool making or conventional techniques.
2.3
Classification of Rapid Prototyping
Generally, there are five main RP processes most commonly used in the industry.
These processes are described and listed as the following:
( 1)
3D Printer
3D design built using 3D CAD is converted into cross section or slices and
the printer then prints the cross sections one atop another from bottom to top
of the design. The printer spreads a layer of powder based material and the
print head applies a mixture of resin solution to the powder causing powder
particles to bind to one another to the printed cross section one layer below.
The process is continuous with new layer of powder and resin binder applied
to complete the shape design.
7
(2)
Stereolithography Apparatus (SLA)
Selective curing of a photopolymer resin by an ultraviolet laser, built on a
descending platform, in a vat.
.
(
(3)
Selective Laser Sintering (SLS)
A laser traces the shape of the part to be modeled in a thin layer of powder.
The laser softens and bonds the powder particles together. This process is
repeated over layers of powder.
(4)
Laminated Object Manufacturing (LOM)
A laser cuts the outline of a cross section ofthe CAD file into an ultra thin
layer of modeling material. A new layer of material is then indexed, bonded
to the previous layers, and cut. This process is repeated using very thin layers
of material.
(5)
Fused Deposition Modeling (FDM)
Fused Deposition Modeling Process (FDM) Thermoplastic modeling material
such as ABS plastic, polycarbonate is fed into the temperature-controlled
FDM extrusion head and heated to a liquid state. The head extrudes and
deposits the material in ultra thin layers onto a fixtureless base.
(6)
Solid Ground Curing (SGC)
CAD model of the part is created and it is sliced into layers using Cubital's
Data Front End® Ｈｄｆｅｾ＠
software and the flat work surface is sprayed with
photosensitive resin in the beginning of each layer. For each layer, a
photomask is produced using Cubital's proprietary ionographic printing
technique. The photomask is positioned over the work surface and a powerful
8
UV lamp hardens the exposed photosensitive resin. After the layer is cured,
all uncured resin is vacuumed for recycling, leaving the hardened areas intact.
The cured layer is passed beneath a strong linear UV lamp to fully cure it and
to solidify any remaining particles. Then, wax replaces the cavities left by
vacuuming the liquid resin. The wax is hardened by cooling to provide
continuous, solid support for the model as it is fabricated. In the final step
before the next layer, the wax/resin surface is milled flat to an accurate,
reliable finish.
2.4
Basic Processes of Rapid Prototyping
There are numerous rapid prototyping techniques commonly used. Each of these
techniques can be simplified by five basic step processes that define the rapid
prototyping concept in a whole. These steps are listed as the following:
( 1)
Creation of a CAD model of the intended design and features of the part
(2)
Conversion of the CAD model to STL format
(3)
Slicing ofthe STL file into thin cross sectional layers
( 4)
Construction of the model one layer atop another
(5)
Finishing and clean editing the model
The above step processes can be briefly described in this following section:
2.4.1 CAD Model Creation
The part is modeled using a Computer Aided Design (CAD) software package such
as Solidworks or Catia. The Solidwork software is specifically used in the design of
the part because Solidwork is solid modelers that represent the part in 3D features
with more precise details and characteristic of the assemblies and sub assemblies of
the part. Solid modeling concept is important because of its high accuracy in defining
the surfaces of the part to be produced in rapid prototyping. Wire frame modeler such
as AutoCAD is deemed not suitable for the CAD model creation simply because
Solidwork is a better option in generating a solid model of the part with all the design
9
parameters such as surface curves or geometry specification of the part 1s fully
represented as 3D Solid modeling.
2.4.2 Conversion to STL Format
.
I
Various CAD software package uses different algorithms to represent solid object
modeling. The STL format has been adopted as the benchmarking format in rapid
prototyping. It is the standard format used universally in the rapid prototyping
industry. The next process involves the conversion of the CAD file into STL format
which can where the 3D printer machine will read and process the data file
specifically as STL format. STL format defines a 3D dimensional surface is made of
an assembly of planar triangles. The file contains the coordinates of the vertices and
the direction of the outward normal of each triangle. However, the STL files cannot
represent curved surfaces to the exact detail because it uses planar elements. While
increasing the number of triangles improves the approximation, the size of the file
also increases requiring more time to process and build the part design. Therefore, it
is important to balance the accuracy with manageability to produce a useful STL file
in terms of development time effectiveness.
2.4.3 Slicing of the STL file into thin cross sectional layers
In the third step, a pre processing program prepares the STL file to be built. The size,
location and the orientation of the model is adjusted by the user according to the
types of programs used. Build orientation of the model is very important considering
the fact that properties of rapid prototypes vary from one coordinate direction to
another. The part orientation partially determines the time required to build the model
because it will define the number of layers needed to construct the model. An
example of this is when placing the shortest dimension in the z (vertical) direction
reduces the number of layers thus shortening the model build times. The preprocessing software slices the STL model into a number of layers from 0.01 mm to
0.7 rnm thick depending on the build technique. The program may also generate an
10
auxiliary structure to support the model during the build. Supports are useful for
complex features such as overhangs, internal cavities, and thin-walled sections.
2.4.4 Construction of the model one layer atop another
The actual construction of the part occurs during this stage. The RP machines will
build the model one layer at a time from constructing materials such as polymers,
plastic or powdered metal. The process is an auto run by the RP machine needing
minimum human supervision. The most common and advanced RP machine used in
building the actual model is the 3D Printing and Stereolithography (SLA) machine
which will be described in the next section. There are also other types of RPO
machine such as the Selective Laser Sintering (SLS) or the Fused Deposition
Modeling (FDM) machine.
2.4.5 Finishing and clean editing the model
The final step involves the post processing of the model where the model is taken out
of the RP machine and removed the model from its supporting base and support
structure. Minor cleaning is done and some heat treatment process may be applied to
the model for extra strength and durability. Sanding, sealing or painting the model
will improve its overall appearance to be presented as high quality surface finishing.
Some photosensitive materials need to be fully cured before use.
2.5
STL File
The .STL file format has bec.ome the Rapid Prototyping industry's standard data
transmission furmat and is the format required to interact with 3D Primed parts. This
format approximates the surfaces of a solid model with triangles. The more complex
the surface. the more tiiangles produced in the STL file format. AJI modern CAD
software system such as So1idworks, CA.TIA and Pro Engineers can generate STL
file to be applied to any Rapid Prototy-ping (RP) machine.
11
2.6
3D Printer Apparatus
3D Printing is a rapid prototyping process which produces a physical parts which
embodies the three dimensional conception of an object or product in design. It is an
advanced manufacturing technology method that can produces high quality product
with good surface finish and high dimensional accuracy.
3D Printing in general is a process where a visual conception of a product is
produced from a 3D computer modeling which is then generated into a physical
geometry from the data derived in the 3D modeling. 3D Printer allows the creation of
solid, plastic and 3D objects in CAD drawings in a short time. 3D Printing method
involves building plastic parts layer by layer at a time using a resin binding agent to
cure plaster ceramic powder to finally create the solid physical as conceptualized in
the 3D drawing.
2.7
3D Printer Components
3D Printer apparatus consists of two main important components. These are:
(1)
3D Printer Main Unit
3D Printer Main Unit as shown in Figure 2.1 consists of main components
such as the Binder Cartridge which supply and print the bonding agent on top
the layer of powder, the Feed Piston that moves up to supply powder for
printing, the Build Piston that moves down once a layer of powder resin
material is bonded to initiate a new layer, a roller attached to the Gantry
which spreads the powder and lastly the Build Box which is filled with
powder ceramic material as the main material for construction of model.
12
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
BORANG PENGESAHAN STATUS TESIS*
I
JUDUL: QUALITY STUDY OF PARTS PRODUCED BY 3D PRINTER
SESI PENGAJIAN : 2/2006-2007
Saya
KEVIN JOK SAGENG
mengaku membenarkan tesis (PSM/Sarjana/Doktor Falsafah) ini disimpan di
Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat
kegunaan seperti berikut:
1. Tesis adalah hak milik Universiti Teknikal Malaysia Melaka.
2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan
untuk tujuan pengajian sahaja.
3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran
antara institusi pengajian tinggi.
4. **Sila tandakan Ｈ ｾ Ｉ＠
D
SULIT
D
TERHAD
Q]
TIDAK TERHAD
(Mengandungi maklumat yang berdarjah keselamatan
atau kepentingan Malaysia yang termaktub di dalam
AKTA RAHSIA RASMI1972)
(Mengandungi maklumat TERHAD yang telah ditentukan
oleh organisasi / badan di mana penyelidikan dijalankan)
Disahkan oleh:
(TANDATANGAN PENULIS)
(TANDATAN
N PENYELIA)
RUlY HARYATJ BINTI HAMBAU
Alamat Tetap:
N0. 1452, LORONG E7,TAMAN SATRIA
JAYA, BDC,
93350 STAMPIN , KUCHING , SARAWAK
Cop Rasmi:
Tarikh: 14 MEl 2007
Tarikh: _ _I....;..
Cf-_ m_
€ _1｟ ｾ ｟ ｯ ｟ ｄｦＫＭ
Pensyarah
Fakulti K!!JUruteraan Pembuatan
Unrv&rsiti Tekmkal Maliys1a Melau
Karung BerkUI'ICI 1200. Aytr Keroh
75450 Melakd
ﾷＭ
* Tesis di maksudkan sebagai tesis bagi ljazah Doktor Falsafah dan Sarjana secara penyelidikan, atau
disertasi bagi pengajian secara kerja kursus dan penyelidi kan, atau Laporan Projek Sarjana Muda (PSM).
** Jika tesi s i ni SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan
dengan menvat akan sekali sebab dan t empoh tesi s i ni perlu dikelaskan sebagai SULIT at au TERHAD.
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
Quality Study Of Parts Produced By 3D Printer
Thesis submitted in accordance with the requirements of the Universiti
Teknika1 Malaysia Melaka for the Degree of Bachelor of Engineering
(Honours) Manufacturing (Design)
By
Kevin Jok Sageng
Faculty of Manufacturing Engineering
Apri12007
DECLARATION
I hereby, declare this thesis entitled "Quality Study OfParts Produced by 3D Printer"
is the results of my own research except as cited in the reference.
Signature
Author's Name
Kevin Jok Sageng
Date
13th April 2007
APPROVAL ..
,
.
This thesis submitted to the Faculty of Manufacturing Engineering ofUTeM and has
been accepted as partial fulfillment of the requirement for the degree of Bachelor of
Manufacturing Engineering (Honours) (Manufacturing Design).
ﾷ ﾷﾷ
ﾷ ﾷｾＭ＠
Main supervisor
Faculty ofManufacturing Engineering
RUZV HARYATI BINTI HAMBALI
Pensyarah
Fiiikulti Kejuruteraan Pembuatan
Univers1ti Teknikal Malaysia Meliilka
Karur!! lierltunci 121)(', Aver Keroh
75450 Meta....
II
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The "Quality Study of Parts Produced by 3D Printer" is based on Rapid Prototyping (RP)
concept where RP model named Master Pattern is designed by Computer Aided Engineering
(CAD) modeling software. The Master Pattern consists of shape and features of triangular
and circular protrusion as well as triangular and circular hollow cavity and also part features
consists of sections with draft angle were designed by using Solidwork CAD software.
ZCorp ZPrinter 310 Plus 3D Printer Apparatus is used to produce three Master Pattern's
physical prototype. This study investigates the surface finish, dimensional accuracy, flatness
and straightness of the three Master Pattern samples produced using 3D Printer apparatus by
using appropriate measuring equipment for quality testing namely the Digital Caliper,
Coordinate Measuring Machine (CMM) and Portable Surface Roughness SJ-301 Measuring
Instruments. The result of the study shows that the 3D Printer has a process capability to
produce parts with a dimensional tolerance of ± 0.1000 to ± 0.2000mm and the surface
roughness, Ra is correlated to the flatness and straightness. The findings shows that shape,
surface and dimensional irregularities as the main defects and problem to parts produced by
3D Printer and the problem can be reduced by ensuring the process parameter such as part
orientation, part hardening period, post processing method and curing time is properly
adhered to produce parts with the highest quality.
Ill
ACKNOWLEDGEMENT
First and foremost, I would love to extend my prayer and thanksgiving to God for the
wonderful blessings and spiritual guidance that matures and strengthens me as each
days passes along the implementation of this study.
I would also like to express my deepest gratitude to my thesis supervisor, Pn. Ruzy
Haryati Binti Hambali for the guidance and advice through out the process of this
thesis writing. God bless you for your sincere thought and assistance.
Special thanks also to Mr. Shajahan Bin Maidin acting as my Second Panel for the
time and commitment in assessing my thesis writing and also for being a caring and
understanding person in regards to difficulties in concluding this thesis work.
My greatest gratitude also goes to Universiti Teknikal Melaka Malaysia (UTEM) for
the privileges to complete my thesis proposal implementation and providing the
platform and eager assistance in providing the technical apparatus and advice
especially the technician, Mr Fairuz at Rapid Prototyping Lab.
Most of all, my heartfelt thank to my family for their continuous love and support
through good and bad times. Last but not least, my fellow peers Petrus Ak. Japong,
Nur Wadiah bt. Mohd Andai, Nor Fairuz Hayati and Mobd. Hafiq Ikhwan; I would
like to say thank you for your friendship, encouragement and motivation.
IV
TABLE OF CONTENTS
J
ｾ＠
Abstract
'
II
(
Acknowledgement
Ill
Table of Contents
IV
List ofFigures
IX
List ofTables
X
1. INTRODUCTION
1
2
1.1 Objectives ofthe Study
3
1.2 Scope of the Study
3
1.3 Problem Statements
4
LITERATURE REVIEW
5
2.1 Rapid Prototyping Background
5
2.2 Rapid Prototyping Process Advantages and Disadvantages
6
2.3 Classification ofRapid Prototyping
7
2.4 Basic Processes ofRapid Prototyping
9
2.4.1 CAD Model Creation
9
2.4.2 Conversion to STL Format
10
2.4.3 Slicing ofthe STL file into thin cross sectional layers
10
2.4.4 Construction ofthe model one layer atop another
11
2.4.5 Finishing and clean editing the model
11
2.5 STLFile
11
2.6 3D Printer Apparatus
12
2.7 3D Printer Components
12
2.8 Basic Process of 3D Printing
13
2.9 3D Printing Process Capabilities
16
2.10 Quality of Parts Produced by 3D Printing
18
2.11 Protective Coatings
19
2 .12 Advantages of3D Printing Machine
19
v
2. 13 Disadvantages of 3D Printing Machine
22
2.14 3D Printer Materials Systems
23
23
2. 14. 1 Powder Materials
.
2. 14 .1. 1 High Performance Composite Material
.
2.14.2 Casting Materials
23
24
(
2.14.2.1 Investment Casting Material
24
2.14.2.2 Direct Casting Material
24
2.14.3 Specialty Material
24
2.14.3.1 Snap Fit Material
25
2.14.3.2 Elastomeric Material
25
2.15 Epoxy
25
2.15.1 Resin
26
2.15.2 General Characteristic and Advantages ofResin
27
2.15.3 Adhesive Properties ofResin
28
2.15.4 Mechanical Properties of Resin
28
2.15.5 Micro Cracking ofResin
29
2.15.6 Fatigue Resistance ofResin
30
2.15.7 Degradation from Water Absorption
31
2.15.8 Typical Applications ofResin
32
32
2. 16 Hardening (Infiltration) Material
2.16.1 Physical and Chemical Properties
33
2.16.2 Stability and Reactivity
34
3. METHODOLOGY
3.1 Sample Manufacturing
35
3.2 ZCorp ZPrinter 310 Plus 3D Printer Operating Mechanism
35
3.3 ZCorp ZPrinter 310 Plus 3D Printer Technical Specifications
36
3. 4 Experimental Methodology
36
3.5 Methodological Procedure
38
3.6 Virtual Prototyping Introduction
38
3.6.1 Virtual Part Design ofMaster Pattern
38
3.6.2 Solidwork CAD Model Creation
39
VI
3.6.2.1 Numerical Information for Master Pattern
3.6.3 Conversion to STL Format
40
41
3.7 3D Printer Preparation
4I
3.8 Virtual Prototyping with ZPrint Software
42
3.8. I Orientation ofMaster Pattern
(
3.8.2 Checking the Build Settings
42
42
3.9 Physical Prototyping
43
3. 10 Post Processing
45
3.10.1 De-powdering of the Master Pattern
45
3.10.2 Removal of Master Pattern from Build Box
46
3.10.3 De-powdering Process in the Powder Recycling Unit
47
3.10.4 Drying the Master Pattern
48
3.10.5 Application of Resin Glue to Master Pattern
48
3.11 Sample Preparation for Testing
49
3 .11 .1 Product Quality
49
3. 12 Dimensional Accuracy Measurement
3.12. I Dimensional Accuracy Measuring Information
3.13 Surface Roughness Measurement
3.13.1 Surface Roughness Measuring Information
3. 14 Flatness and Straightness Measurement
3 .14.1 Flatness and Straightness Measurement Information
50
51
56
56
57
58
59
3.15 Validation
60
4. RESULTS AND ANALYSIS
4.1 Introduction to Dimensional Accuracy Result and Analysis
60
4.1.1 Dimensional Accuracy Measurement Result
61
4.1.2 Dimensional Accuracy Graph and Analysis
62
4 .2 Introduction to Flatness and Straightness Result and Analysis
73
4.2.1 Flatness and Straightness Measurement Result
73
4.2.2 Flatness and Straightness Graph and Analysis
75
4.3 Introduction to Surface Roughness Result and Analysis
4.3. 1 Surface Roughness Measurement Result
VII
78
78
4.3.2 Surface Roughness Graph and Analysis
80
5. DISCUSSIONS
84
5. 1 Introduction
84
5.2 Detailed Analysis for Dimensional Accuracy Measurement
84
5.3 Detailed Analysis for Flatness and Straightness Measurement
88
5.4 Detailed Analysis for Surface Roughness Measurement
89
6. CONCLUSIONS
91
6.1 Conclusions
91
6.2 Suggestions and Recommendations
92
REFERENCES
93
APPENDICES
A
Detail Projection Sketching for Master Pattern
B
Dimensional Accuracy Measurement Data Table
C
Theoretical Equation for Calculation for X Control Chart Tolerance Limit
D
Data Table for X Chart Tolerance Limits
E
Calculation For X Control Chart Tolerance Limit
F
Compatibility Data for Tolerance
G
Straightness and Flatness Measurement Data Table
H
Straightness and Flatness Printed Measurement Data Sheet
I
Surface Roughness, Ra Measurement Data Table
J
Surface Roughness, Ra Printed Measurement Data Sheet
K
Measuring Instruments for Dimensional Accuracy, Surface Roughness and
Flatness and Straightness
L
Table for Measurement Standard for Ra according to TIS B0601-1994
Standard
M
Gantt Chart for Thesis Report Writing
Vlll
LIST OF FIGURES
2.1
.
3D Printer Main Unit
,.I
14
(
2.2
Powder Recycling Unit
2.3
Build Box
15
2.4
Resin Binder
15
2.5
The 3D Printing Layering Principle
16
2.6
The 3D Printing Operating Principle
16
2.7
Strength of Part in Regards to Part Orientation
18
2.8
Comparative Tensile Strength and Stiffness ofResins
30
2.9
Typical Fibre Reinforced Plastic Stress/Strain Graph
31
2.10
Typical Resin Stress/Strain Curves (Post Cure 5hrs @80°C)
31
2.11
Effect of Periods of Water Soak at 100°C on
14
Resin Inter-Laminar Shear Strength
32
3.1
Experimental Design of the Experiment
39
3.2
Master Pattern Isometric View
43
3.3
Master Pattern Isometric View with Dimension
44
3.4
Master Pattern Sample 1, 2 & 3 (Top View)
48
3.5
Master Pattern Sample 1, 2 & 3 (Bottom View)
48
3.6
Soft Horsehair Brush and the Polypropylene Scraper
50
3.7
Plaster Ceramic Powder
50
3.8
Powder Recycling Unit
52
3.9
AirBrush
52
3.10
Cyanoacrylate Resin Glue
53
3.11
Dimensional Element of the Master Pattern
56
3.12
Surface Roughness Measurement Information for Top Surface
60
3.13
Surface Roughness Measurement Information for Bottom Surface
60
3.14
Surface Roughness Measurement Information for Top Surface
62
3.15
Surface Roughness Measurement Information for Bottom Surface
62
........
lX
4.1
Tolerance Limit Line Indicator
66
4.2
Graph for Master Pattern Length, Dl versus Number of Samples
68
4.3
Graph for Master Pattern Width, D2 versus Number of Samples
69
4.4
Graph for Master Pattern Height, D3 versus Number of Samples
70
4.5
Graph for Protrusion Length, D4 and the Triangular Protrusion Width, D5
versus Number of Samples
71
4.6
Graph for Triangular Protrusion Height, D6 versus Number of Samples
72
4 .7
Graph for Triangular Hole Length, D7 and Triangular Hole Width, D8
versus Number of Samples
73
4.8
Graph for Circular Protrusion Diameter, D9 versus Number of Samples
74
4.9
Graph for Circular Hole Diameter, D 10 versus Number of Samples
75
4.10
Graph for Protrusion Circular Protrusion Height, D 11
versus Number of Samples
4.11
76
Graph for Master Pattern's Overall Average Major Diameter
versus Number of Samples
4.12
77
Graph for Flatness & Straightness for Left and Right X-axis andY-axis
versus Number of Samples
4.13
80
Graph for Flatness of Top and Bottom Surface
versus Number of Samples
4. 14
82
Graph of Surface Finish, Ra (!lm) for Top Side (A) X andY-axis
versus Number of Samples
4.15
86
Graph of Surface Finish, Ra (!lm) for Bottom Side (B) X andY-axis
versus Number of Samples
4.16
87
Graph of Surface Finish, Ra (!lm) for Top and Bottom Side
88
versus Number of Samples
X
LIST OF TABLES
2.1
Physical and Chemical Properties for Cyanoacrylate
34
2. 2
Stability and Reactivity Properties for Cyanoacrylate
35
3.1
Technical Data Specifications for ZCorp ZPrinter 310 Plus
37
3.2
Drying Time for Parts
52
3.3
Data for Surface Roughness, Ra Measurement Parameter
59
4.1
Data for Flatness of Top and Bottom Surface Testing
79
4 .2
Data for Average Surface Roughness, Ra value for A and B Side
85
Xl
CHAPTER 1!
INTRODUCTION
3D Printing process is a techruque which used the resin binder as the main medium to
cure the powder ceramic material compound. In this study, a mixture of powder
material will be cured using the resin bonding curing technique in 3D Printing
method. The method of construction is of layer by layer construction of which a layer
or powder will be resurfaced by a layer of binder or bonding agent on top and the two
layer will bond together to form a solid surface and the process is repeated by the
application of a new layer of powder and binder from bottom until the top of the
design. Recently, there is a high demand in faster development time for parts and
product before manufacturing substituting conventional methods thus scientists and
engineers is turning their attention to Rapid Prototyping (RP) method to initiate the
Rapid Tooling (RT) application to produce the physical prototype of a part which is
then to be examined and analyzed for further improvement to the part design with the
aim of high quality finish.
The selection of Quality Study of Parts Produced by 3D Printing Application for
study is because of the necessity to understand its importance in terms of product
development especially in tooling where the accuracy, surface finishing and the
reliability of parts that can be produced in multiple production process especially in
terms of the ability in holding close tolerance can affect the production in a whole.
3D Printer is the most effective means of tooling production which integrates RP and
RT application for faster product development. The process offers lots of advantages
compared to the conventional technique in production tooling such as by
Stereolithogrpahy (SLA). It seems that 3D Printer application is fast gaining
recognition and popularity as a modern technology and starts to stirs up the interest
1
of product manufacturer, developer, scientists and engineers to develop a study on
the effectiveness of the method in RP and RT field in aid to manufacturing. Thus, it
is the right time to study and understand this technique and hopefully it can
contribute to the improvement and promote better understanding to the 3D printing
.
process.
(
The extensive use ofRP and RT technique can help to reduce a products production
time using the 3D Printer prototyping process. Besides that, the print bonding curing
is a process which utilizes the epoxy resin to increase the viscosity of the powder
ceramic material thus produced a strong bond among the molecules of the material to
hold each interlinked layer of surface together achieving a hard molded compound.
Generally, the liquid resin material is coated onto the surface inducing a chemical
process that causes the liquid to undergo a phase transition to a solid state once it is
bonded with the powder ceramic material. Traditionally, this process has been
accomplished by conventional heating in oven which involves extra cost and time.
The resin material to be deposited is printed and applied to atop the surface of
powder layer and cured layer by layer to finally construct a full physical prototyping
model of the part.
This study emphasizes on the quality study of the parts produced using 3D Printer in
RP and RT application. The quality study is based on criterion such as the
dimensional accuracy, surface finish, flatness and straightness. Further study is
conducted to investigate and to analyze the effect of the design in relation to the
process capability of the 3D Printer machine in order to maximize the overall surface
finish of the part.
2
1.1
Objectives of the Study
The purpose of this investigative study is to achieve the following:
(1)
To identify the quality study includjng the dimensional accuracy, surface
finish, flatness and straightness ofthe resulting parts by metrological means
(2)
To study the effect and causes of the 3D Printing process in relation to
constructed part' s quality in order to maximize dimensional accuracy, surface
finish, flatness and straightness of each resulting part
1.2
Scope of the Study
( 1)
Design the virtual part which ts the Master Pattern using the Soljdwork
software
(2)
Convert the CAD drawing file into STL data file format recognized by the 3D
Printer
(3)
Produce the part using the 3D Printer Machjne
(4)
Produce three Master Pattern samples using the 3D Printer Machine
(5)
Study the dimensjonal accuracy of the three Master Pattern samples
(6)
Study the surface finish of the three Master Pattern samples
(7)
Study the flatness and straightness of the three Master Pattern samples
(8)
Analyzed the results and make future work recommendations
3
1.3
Problem Statements
Manufacturing and production has evolved into a competitive and challenging
proposition to produce the best tooling product with the best design and cost effective
with high function ability. The needs for fast and productive manufacturing
production must be synchronized with the utilization of rapid prototyping
development in manufacturing to enhance design function and workability to the
maximum.
Rapid Prototyping (RP) is one of the tools that utilize the CAD concept to create the
mechanical structure of the part in visual prototyping. The 3D Printer Machine
manages the manufacture process of the physical prototype as an application of
Rapid Tooling (RT) concept under the Direct Tooling classifications. 3D Printer
production operation uses the STL format to program instructions that controls the
layer by layer construction of the 3D Printer machine and subsequently produced the
complete designed part.
Tooling now days
IS
very important m product development. The accuracy,
durability, finishing and the amount of parts that a tool can produce affect the
production. Tool manufactured by conventional methods usually offers good quality
of the product but the cost of these tolls could be up to hundreds pound and the time
required for their manufacture up to months.
This study investigates the surface finish, dimensional accuracy, flatness and
straightness of the parts produced using 3D Printer in rapid tooling application.
4
CHAPTER2
LITERATURE REVIEW
2.1
Rapid Prototyping Background
Rapid Prototyping (RP) is a fast tracked and advanced manufacturing tool which
relies on the Computer Aided Design (CAD) and Computer Manufacturing
Application (CAM) to produce prototypes by using various advanced manufacturing
apparatus and method. Prototype part is usually in the form of solid and cost effective
physical model which can be produced in a fast production steps. Parts produced are
highly precise and detailed with good dimensional stability and tolerances that
resembles the actual concept of the designed product.
Rapid Prototyping in general is referred to as "Fabrication of a physical, threedimensional part of arbitrary shape directly from a numerical description typically a
CAD model by a quick, highly automated and totally flexible process." (Rapid
Prototyping Report, October 1992)
RP is an excellent tool for communicating and interacting ideas among the personnel
involved in the design of the part and also the research and development personnel
right up to the management. RP presents as visual aids to enable the relaying and
conveying of vital information between the product development phase and the full
production run of which data are obtained through design testing and production test
run of the prototype model of the part.
In addition to prototypes, RP techniques can also be used to make tooling which can
be referred to as rapid tooling. For small production runs and complicated objects,
5
(5)
A production tool used to examine manufacturing methods offabricated parts
and assembly processes and procedures to obtain the best and most effective
manufacturing methods.
(6)
A communications tool for internal design reviews and also for design
reviews with the customer
(7)
RP is a design verification and optimization tool to qualify the form, fit and
function of individual parts and assemblies where its physical visualization
concept enables verification of design details as a mean to gain internal
design acceptance and justification.
However, RP also have several disadvantages where part may have s1ze and
geometry limitation for example a part volume is generally limited to 0.125 cubic
meters or less, depending on the RP machine. Metal prototypes are difficult to make
and for metal parts with large production runs, the conventional manufacturing
techniques are usually more economical. RP generated tools may not easily be
modified or corrected using typical tool making or conventional techniques.
2.3
Classification of Rapid Prototyping
Generally, there are five main RP processes most commonly used in the industry.
These processes are described and listed as the following:
( 1)
3D Printer
3D design built using 3D CAD is converted into cross section or slices and
the printer then prints the cross sections one atop another from bottom to top
of the design. The printer spreads a layer of powder based material and the
print head applies a mixture of resin solution to the powder causing powder
particles to bind to one another to the printed cross section one layer below.
The process is continuous with new layer of powder and resin binder applied
to complete the shape design.
7
(2)
Stereolithography Apparatus (SLA)
Selective curing of a photopolymer resin by an ultraviolet laser, built on a
descending platform, in a vat.
.
(
(3)
Selective Laser Sintering (SLS)
A laser traces the shape of the part to be modeled in a thin layer of powder.
The laser softens and bonds the powder particles together. This process is
repeated over layers of powder.
(4)
Laminated Object Manufacturing (LOM)
A laser cuts the outline of a cross section ofthe CAD file into an ultra thin
layer of modeling material. A new layer of material is then indexed, bonded
to the previous layers, and cut. This process is repeated using very thin layers
of material.
(5)
Fused Deposition Modeling (FDM)
Fused Deposition Modeling Process (FDM) Thermoplastic modeling material
such as ABS plastic, polycarbonate is fed into the temperature-controlled
FDM extrusion head and heated to a liquid state. The head extrudes and
deposits the material in ultra thin layers onto a fixtureless base.
(6)
Solid Ground Curing (SGC)
CAD model of the part is created and it is sliced into layers using Cubital's
Data Front End® Ｈｄｆｅｾ＠
software and the flat work surface is sprayed with
photosensitive resin in the beginning of each layer. For each layer, a
photomask is produced using Cubital's proprietary ionographic printing
technique. The photomask is positioned over the work surface and a powerful
8
UV lamp hardens the exposed photosensitive resin. After the layer is cured,
all uncured resin is vacuumed for recycling, leaving the hardened areas intact.
The cured layer is passed beneath a strong linear UV lamp to fully cure it and
to solidify any remaining particles. Then, wax replaces the cavities left by
vacuuming the liquid resin. The wax is hardened by cooling to provide
continuous, solid support for the model as it is fabricated. In the final step
before the next layer, the wax/resin surface is milled flat to an accurate,
reliable finish.
2.4
Basic Processes of Rapid Prototyping
There are numerous rapid prototyping techniques commonly used. Each of these
techniques can be simplified by five basic step processes that define the rapid
prototyping concept in a whole. These steps are listed as the following:
( 1)
Creation of a CAD model of the intended design and features of the part
(2)
Conversion of the CAD model to STL format
(3)
Slicing ofthe STL file into thin cross sectional layers
( 4)
Construction of the model one layer atop another
(5)
Finishing and clean editing the model
The above step processes can be briefly described in this following section:
2.4.1 CAD Model Creation
The part is modeled using a Computer Aided Design (CAD) software package such
as Solidworks or Catia. The Solidwork software is specifically used in the design of
the part because Solidwork is solid modelers that represent the part in 3D features
with more precise details and characteristic of the assemblies and sub assemblies of
the part. Solid modeling concept is important because of its high accuracy in defining
the surfaces of the part to be produced in rapid prototyping. Wire frame modeler such
as AutoCAD is deemed not suitable for the CAD model creation simply because
Solidwork is a better option in generating a solid model of the part with all the design
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parameters such as surface curves or geometry specification of the part 1s fully
represented as 3D Solid modeling.
2.4.2 Conversion to STL Format
.
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Various CAD software package uses different algorithms to represent solid object
modeling. The STL format has been adopted as the benchmarking format in rapid
prototyping. It is the standard format used universally in the rapid prototyping
industry. The next process involves the conversion of the CAD file into STL format
which can where the 3D printer machine will read and process the data file
specifically as STL format. STL format defines a 3D dimensional surface is made of
an assembly of planar triangles. The file contains the coordinates of the vertices and
the direction of the outward normal of each triangle. However, the STL files cannot
represent curved surfaces to the exact detail because it uses planar elements. While
increasing the number of triangles improves the approximation, the size of the file
also increases requiring more time to process and build the part design. Therefore, it
is important to balance the accuracy with manageability to produce a useful STL file
in terms of development time effectiveness.
2.4.3 Slicing of the STL file into thin cross sectional layers
In the third step, a pre processing program prepares the STL file to be built. The size,
location and the orientation of the model is adjusted by the user according to the
types of programs used. Build orientation of the model is very important considering
the fact that properties of rapid prototypes vary from one coordinate direction to
another. The part orientation partially determines the time required to build the model
because it will define the number of layers needed to construct the model. An
example of this is when placing the shortest dimension in the z (vertical) direction
reduces the number of layers thus shortening the model build times. The preprocessing software slices the STL model into a number of layers from 0.01 mm to
0.7 rnm thick depending on the build technique. The program may also generate an
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auxiliary structure to support the model during the build. Supports are useful for
complex features such as overhangs, internal cavities, and thin-walled sections.
2.4.4 Construction of the model one layer atop another
The actual construction of the part occurs during this stage. The RP machines will
build the model one layer at a time from constructing materials such as polymers,
plastic or powdered metal. The process is an auto run by the RP machine needing
minimum human supervision. The most common and advanced RP machine used in
building the actual model is the 3D Printing and Stereolithography (SLA) machine
which will be described in the next section. There are also other types of RPO
machine such as the Selective Laser Sintering (SLS) or the Fused Deposition
Modeling (FDM) machine.
2.4.5 Finishing and clean editing the model
The final step involves the post processing of the model where the model is taken out
of the RP machine and removed the model from its supporting base and support
structure. Minor cleaning is done and some heat treatment process may be applied to
the model for extra strength and durability. Sanding, sealing or painting the model
will improve its overall appearance to be presented as high quality surface finishing.
Some photosensitive materials need to be fully cured before use.
2.5
STL File
The .STL file format has bec.ome the Rapid Prototyping industry's standard data
transmission furmat and is the format required to interact with 3D Primed parts. This
format approximates the surfaces of a solid model with triangles. The more complex
the surface. the more tiiangles produced in the STL file format. AJI modern CAD
software system such as So1idworks, CA.TIA and Pro Engineers can generate STL
file to be applied to any Rapid Prototy-ping (RP) machine.
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2.6
3D Printer Apparatus
3D Printing is a rapid prototyping process which produces a physical parts which
embodies the three dimensional conception of an object or product in design. It is an
advanced manufacturing technology method that can produces high quality product
with good surface finish and high dimensional accuracy.
3D Printing in general is a process where a visual conception of a product is
produced from a 3D computer modeling which is then generated into a physical
geometry from the data derived in the 3D modeling. 3D Printer allows the creation of
solid, plastic and 3D objects in CAD drawings in a short time. 3D Printing method
involves building plastic parts layer by layer at a time using a resin binding agent to
cure plaster ceramic powder to finally create the solid physical as conceptualized in
the 3D drawing.
2.7
3D Printer Components
3D Printer apparatus consists of two main important components. These are:
(1)
3D Printer Main Unit
3D Printer Main Unit as shown in Figure 2.1 consists of main components
such as the Binder Cartridge which supply and print the bonding agent on top
the layer of powder, the Feed Piston that moves up to supply powder for
printing, the Build Piston that moves down once a layer of powder resin
material is bonded to initiate a new layer, a roller attached to the Gantry
which spreads the powder and lastly the Build Box which is filled with
powder ceramic material as the main material for construction of model.
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