UNIVERSITI TEKNIKAL MALAYSIA MELAKA
DESIGN RULES ANALYSIS FOR SHEET METALWORKING
USING CAD TOOLS
This report submitted in accordance with requirement of the Universiti Teknikal Malaysia Melaka (UTeM) for the Bachelor Degree of Manufacturing Engineering
(Manufacturing Design) with Honours.
by
SHALIZAH AMAN SHAH
FACULTY OF MANUFACTURING ENGINEERING
DECLARATION
I hereby, declared this report entitled “Design Rules Analysis for Sheet
Metalworking Using CAD Tools” is the results of my own research except as cited in references.
Signature : ………..
Author’s Name : ………..
APPROVAL
This report is submitted to the Faculty of Manufacturing Engineering of UTeM as a partial fulfillment of the requirements for the degree of Bachelor of Manufacturing Engineering (Manufacturing Design) with Honours. The member of the supervisory committee is as follow:
(Signature of Supervisor)
………
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ABSTRACT
Sheet metal design is a critical part in the process of product design and development. The entire quality of design influences the product performance, product quality and cost of product. An optimal design can only be created based on experiences and knowledge. The problem of frequent redesign occurs due to have no well-documented rules in designing of sheet metalworking. The study of this project is to investigate the design parameters of sheet metalworking and analyze the design rules of sheet metal that influences the bending operation. Computer-Aided Design (CAD) and Finite Element Analysis (FEA) are applied in this study in order to design of safety factor and simulate the structural of bending parts. Bend allowance has strong relationship to determine the safe area in designing of sheet metalworking. As a result, a comprehensive set of design rules for sheet metal parts has been generated and assisted in reducing an infeasible design, cost and production cycle time.
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ABSTRAK
Rekabentuk kepingan logam merupakan komponen yang kritikal dalam proses rekabentuk dan pembangunan produk. Hal ini kerana kualiti sesuatu rekabentuk secara keseluruhannya akan mempengaruhi kebolehgunaan produk, kualiti produk dan kos produk. Oleh yang demikian, peraturan rekabentuk memainkan peranan penting pada peringkat ini. Masalah yang terjadi dalam industri ialah tiada peraturan yang didokumenkan secara formal. Rekabentuk yang optimum hanya boleh dihasilkan berdasarkan pada pengalaman dan pengetahuan semata-mata. Projek ini mengkaji tentang parameter-parameter rekabentuk kepingan logam dan menganalisis
peraturan rekabentuk kepingan logam yang mempengaruhi proses bending. Perisian
Computer-aided Design (CAD) dan Finite Element Analysis (FEA) diaplikasikan dalam projek ini untuk merekabentuk faktor keselamatan dan mengsimulasi struktural bahagian bending. Manakala bend allowance pula berkait rapat bagi menentukan bahagian yang selamat dalam merekebentuk kompenan atau produk kepingan logam. Pada penghujung projek ini, satu set peraturan rekabentuk kepingan logam yang komprehensif dibentuk dan ianya dapat membantu mengurangkan rekebentuk, kos dan kitaran masa pengeluaran yang tidak relevan.
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DEDICATION
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ACKNOWLEDGEMENT
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TABLE OF CONTENTS
ABSTRACT………...……i
ABSTRAK………...…….ii
DEDICATION………...…..iii
ACKNOWLEDGEMENT………..….iv
TABLE OF CONTENTS………...……...v
LIST OF TABLES………...……….x
LIST OF FIGURES………..……..xii
LIST OF ABBREVIATIONS AND SPECIALIZED NOMENCLATURE……...xvi
LIST OF APPENDICES……….……..xvii
CHAPTER 1 INTRODUCTION………..….………1
1.1 Background of Study………..………..…...….1
1.2 Problem Statement………..………..3
1.3 Objective of PSM………...…..….3
1.4 Scope of Work………...……….4
1.5 Schematic of Project………....….4
1.6 Gantt Chart………...………...…………..5
CHAPTER 2 LITERATURE REVIEW……...……….…...…8
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2.2 Sheet Metalworking………..………..…..8
2.2.1 Sheet Metal Forming Process………..….9
2.2.2 Determining material properties of sheet metal on a press brake………...…10
2.2.3 Type of Sheet Metalworking………...…11
2.2.3.1 Aluminum Alloys………...………..…11
2.2.3.2 Copper………...………..13
2.2.3.3 Steel………...………..13
2.2.3.4 Titanium ……...………..…....…14
2.3 Material Properties………..16
2.3.1 Tensile Strength………..16
2.3.2 Fatigue………..…………...………..……..16
2.4 Design for Sheet Metalworking………...…………...17
2.5 Bending………...……….……….18
2.5.1 Sheet Metal Bending………..…...….…….19
2.5.2 Bending Terminology………..……...…19
2.5.3 Bend Allowances………..…………..21
2.5.4 Bending Force……….25
2.5.5 Bending Models………...……...26
2.5.6 Computer aided process planning for sheet metal bending: A state of the art……….27
2.6 Press Brake………...…………...28
2.6.1 Press Brake Operations………..…...…..30
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2.7 Design Rules………..……….31
2.7.1 Inter-features Rules………...…………..…32
2.8 Mathematical Modeling………..……..…..34
2.9 Computer-aided Design (CAD)………..……36
2.10 Design for Manufacture (DFM)………..……37
2.11 Finite Element Analysis (FEA)………...….39
2.11.1 Introduction to Finite Element Analysis (FEA)………...……...…39
2.11.2 General Techniques and Terminology of FEA………...…...….41
2.11.3 A General Procedure for Finite Element Analysis………..…...……43
2.11.3.1Preprocessing………..………..……….43
2.11.3.2Solution………..………44
2.11.3.3Postprocessing………...……….……44
2.11.4 Example of Finite Element Analysis (FEA)……….…..45
2.11.5 Finite Element (FE) Modeling………..………….….46
2.11.6 Deformation Path………..……….….47
CHAPTER 3 METHODOLOGY AND MATERIALS……….…....48
3.1 Introduction………...………..……48
3.2 Methodology………..……….………48
3.3 Description of the Methodology………..………..…….50
3.4 Method to Conduct a CATIA simulation………55
3.4.1 Creation of the Part in Generative Sheet Metal Design………..55
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3.4.2.1 Step 1: Mesh Generation……….55
3.4.2.2 Step 2: Assigning Material Properties………....55
3.4.2.3 Step 3: Applying Restraint and Load………..56
3.4.2.4 Step 4: Launching the Solver………..57
3.4.2.5 Step 5: Postprocessing………...….57
CHAPTER 4 RESULTS………...58
4.1 Introduction……….58
4.2 Technical Drawing………..58
4.3 Data Calculation………..62
4.3.1 Bend Allowance………..62
4.3.2 Bending Force……….64
4.4 Report Generated by CATIA………..69
4.5 Simulation Results………..72
4.6 Safety Factor………...74
CHAPTER 5 DISCUSSION……….…76
5.1 Bend Allowance………..76
5.2 Bending forces………78
5.3 Simulation………...…84
5.3.1 The Simulation and Its Limitation………..84
5.3.2 Meshing………...84
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5.4 Safety Factor………...87
5.5 Generated Design Rules Table for Sheet Metal Bending………...87
CHAPTER 6 CONCLUSION………..…90
REFERENCES………...……….………..92
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LIST OF TABLES
2.1 Compositions and Mechanical Properties for Several Common
Aluminum Alloys 12
2.2 Room Temperature Mechanical Properties (in tension) for various
Materials 15
2.3 Material Database and Derived Parameter Ranking 15
2.4 Properties of Titanium Alloys 15
2.5 Explanation for Each Term of Bending Terminology and the
Description 20
4.1 Result of the Calculation for Bend Allowance 64
4.2 Bending force for Titanium 66
4.3 Bending force for Copper 66
4.4 Bending force for Steel 67
4.5 Bending force for Aluminum 67
4.6 Bending forces for 8mm of die opening 68
4.7 Bending forces for 12mm of die opening 68
4.8 Material Properties of Copper 69
4.9 Mesh’s Report 69
4.10 Element Type 70
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4.12 Direct Method Computation (Equilibrium) 70
4.13 Stiffness Computation 71
4.14 The Summary of Von Mises Stress (Maximum Stress) Results
After Simulation Using CATIA for Titanium and Aluminum 74
4.15 Summary of the Results for Safety Factor 75
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LIST OF FIGURES
1.1 Gantt Chart of PSM 1 6
1.2 Gantt Chart of PSM 2 7
2.1 Idealised Sheet Geometry (Left) Compared to Actual Geometry 10
2.2 Bending Terminology 20
2.3 Bend Allowance and Bend Deduction 22
2.4 Location of Neutral Line with Represents the K-factor 23
2.5 Bend Allowance 24
2.6 Volumetric Model (a), Foil Model (b), and Foil Model with Extended Flanges (c) 27
2.7 Foil Models with Flange Extension: (a) Model with Fully Extended Flanges and (b) Model with Limited Flange Extension 28
2.8 Press Brake Machine 29
2.9 Critical Dimension in the Design of Sheet Metal Part 32
2.10 Rules for Distance between Holes 33
2.11 Rules for Distance between Hole and Outer Edge 33
2.12 Rules between Bends and Holes 34
2.13 Angle Measurement by Mean of Shaft Encoders 34
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Laser Beam 35
2.15 Indirect Angle Measurement based on Four Contact Points 36
2.16 When Costs are Committed 49
2.17 (a) A General Two-Dimensional Domain of Field Variable Φ (X, Y), (b) A Three-Node Finite Element Defined in the Domain, and (c) Additional Elements Showing a Partial Finite Element Mesh of the Domain 42
2.18 A Mesh of Finite Elements over a Rectangular Region Having a Central Hole 45
2.19 The Forming FE Model and Schematics for Drawbead Settings 46
2.20 Deformation Path of an Element during Forming Operation 47
3.1 Methodology of Process Flow Chart 49
3.2 The Engineering Sketches for (a) Bending with One Hole, (b) Bending with Two Holes, and (c) Bending between Two Holes 54
3.3 CAD drawing of Sheet Metal using Computer Aided Three Dimensional Interactive Application (CATIA) 54
3.4 Restraint and Load Applied On the Part 56
4.1 Sheet Metal Bending with 90° of Bend Angle 59
4.2 Sheet Metal Bending with 60° of Bend Angle 60
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4.4 Graph of the Relationship between R/T Ratio and Tensile
Reduction of Area for Sheet Metals. Figure above Shows the
Selected Ratio of R/T 63
4.5 Die opening for press brake machine with size of 8mm and 12mm 65
4.6 Von Mises Stress (nodal values) for Aluminum with 0.5mm of
Thickness 71
4.7 (a) Geometry of Sheet Metal Bending for Aluminum with 90° of
Bend Angle; and (b) Deformed Mesh for Aluminum when 100N
of Load is applied on it 72
4.8 Von Mises Stress (Maximum Stress Value) Obtained after Simulation
using CATIA for Aluminum with 0.5mm of Thickness and 90° of
Bend Angle is 4.25x107N/m2 or 4.25N/mm2 73
5.1 Graph of Bend Allowance for Every Material 77
5.2 Graph of Bending Force for Titanium 78
5.3 Graph of Bending Force for Copper 79
5.4 Graph of Bending Force for Steel 80
5.5 Graph of Bending Force for Aluminum 81
5.6 Graph of Bend Force for 8mm of Die Opening For Titanium,
Copper, Steel and Aluminum 82
5.7 Graph of Bend Force for 12mm of Die Opening for Titanium,
Copper, Steel and Aluminum 82
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5.9 Von Mises Stress (maximum stress) predicted stress occurs in
the aluminum bending with a value of the Von Mises stress
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LIST OF ABBREVIATIONS AND SPECIALIZED
NOMENCLATURE
BA - Bend Allowance
CAD - Computer-aided Design
CAE - Computer-aided Engineering
CAM - Computer-aided Manufacturing
CATIA - Computer Aided Three Dimensional Interactive Application
Cr - Chromium
Cu - Copper
DFM - Design for Manufacture
FEA - Finite Element Analysis
FE - Finite Element
Mg - Magnesium
Mn - Manganese
Si - Silicon
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LIST OF APPENDICES
Figure 1: Boundary Conditions 96
Figure 2: Deformed Mesh 99
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CHAPTER 1
INTRODUCTION
1.1 Background of Study
Product design has been estimated that 70 to 80% of the overall costs of product and it become the most important stage in the product development. Besides that, it is also known as the critical stage where an innovative approach is required in order to design and manufacture high quality products at lower costs. A thorough understanding of the function and performance is highly desirable at this phase. The product design has to follow the rules to meet the specification to avoid encountering problems during manufacturing process which is only wasting the time and costs from redesigning the product. Therefore a specific rule is an essential in designing and manufacturing products.
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tensile strength from bending operation. However, it involves little changes on the material surface area.
Generally, the bending referred to the deformation is on only one axis. A various and different shape can be produced in implementing bending process by using standard die sets. The material needed to bend is placed on the die and positioned it in place with gages. It is held in place with hold-downs. In manufacturing, the bending process includes press brake, air bending and bottoming or coining.
Finite Element Analysis (FEA) software and Computer-Aided Design (CAD) are tool that can help to simultaneously analyze and simulates parts or products from a variety of functional perspectives and also increases product performance and product quality. At the same time, manufacturing cost is reduced. These tools also will also guide part designers to decide the appropriate factors of design. By implementing the software to this study, the bending part is produced with great consistency, accuracy and less time.
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1.2 Problem Statement
Design is a crucial stage in product development. It is because the product performance, product quality and final cost of product are more influence in this stage. Therefore, following the rules that meet the specification only can produce a high quality product. However, there is lack of communication between the designer and manufacturer. This typical manufacturing situation must be avoided. In order to perform an efficient manufacturing process, the knowledge of manufacturing in industry must be sharing together from design stage to manufacture the product. The expert design engineer only design the product based on experiences and knowledge but not well-documented. In contrast, the new designers who have no experience will encounter the problems in designing new parts or products and directly it will increase time and cost of manufacturing. Therefore, it is necessary to generate design rules for sheet metal.
1.3 Objectives of PSM
(a) To investigate the design parameters of sheet metalworking.
(b) To analyze the design rules of sheet metalworking that influence
bending operation.
