UNIVERSITI TEKNIKAL MALAYSIA MELAKA

DESIGN ANALYSIS OF A BABY STROLLER BY USING

DESIGN FOR MANUFACTURING AND ASSEMBLY METHOD

(BOOTHROYD DEWHURST)

This report submitted in accordance with requirement of the Universiti Teknikal

Malaysia Melaka (UTeM) for the Bachelor's Degree in Manufacturing Engineering

Technology (Product Design) (Hons.)

by

AZIE NOOR MARLIA BINTI RUSLAN

B071210430

931218-01-6116

FACULTY OF ENGINEERING TECHNOLOGY 2015

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

BORANG PENGESAHAN STATUS LAPORAN PROJEK SARJANA MUDA

TAJUK: Design Analysis of a Baby Stroller by Using Design for Manufacturing

and Assembly Method (Boothroyd Dewhurst)

SESI PENGAJIAN: 2014/15 Semester 2

Saya AZIE NOOR MARLIA BINTI RUSLAN

Mengaku membenarkan Laporan PSM ini disimpan di Perpustakaan Universiti

Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:

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pertukaran antara institusi pengajian tinggi.

4. **Sila tandakan ( )

(Mengandungi maklumat TERHAD yang telah ditentukan

oleh organisasi/badan di mana penyelidikan dijalankan) SULIT

(Mengandungi maklumat yang berdarjah keselamatan

atau kepentingan Malaysia sebagaimana yang termaktub

dalam AKTA RAHSIA RASMI 1972)

TIDAK TERHAD

TERHAD

Disahkan oleh:

______________________

AlamatTetap:

No.18, Jalan Makmur 50,

Taman Damai Jaya,

Johor Bharu.

Tarikh: ________________________

_________________________

Cop Rasmi:

Tarikh: _______________________

** Jika Laporan PSM ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi

berkenaan dengan menyatakan sekali sebab dan tempoh laporan PSM ini perlu dikelaskan sebagai

SULIT atau TERHAD.

DECLARATION

I hereby, declare that this report entitled “Design Analysis of A Baby Stroller by Using

Design for Manufacturing and Assembly Method (Boothroyd Dewhurst)” is the result of

my own research except as cited in the references.

Signature : ………………………………………….....

Name : AZIE NOOR MARLIA BINTI RUSLAN

Date : …………………………………………....

APPROVAL

This report is submitted to the Faculty of Engineering Technology of UTeM as a partial

fulfillment of the requirements for the degree of Bachelor of Engineering Technology

Product Design (Hons.). The member of the supervisory is as follow:

…………………………….

(Project Supervisor)

i

ABSTRAK

Projek ini menggunakan kaedah rekabentuk untuk proses dan pemasangan supaya

dapat mengkaji rekabentuk kereta sorong bayi (Sweet Cherry SCR 8 Series) dalam aspek

pembuatan, proses pemasangan dan juga kepayahan ketika memegang dan memasang

komponen. Masalah yang dikenal pasti dalam kajian ini adalah pada bentuk kereta sorong

bayi yang banyak menggunakan screw pengikat dan juga penggunaan kedua-dua belah

tangan untuk menggerakkan penyelak bagi melipat kereta sorong bayi tersebut. Objektif

projek ini adalah untuk mengurangkan komponen disamping mengekalkan fungsi kereta

sorong tersebut, untuk membuat perbezaan kadar kecekapan oleh rekabentuk asal

berbanding dengan rekabentuk baru, dan juga untuk mengurangkan jumlah waktu

pemasangan setelah analisis rekabentuk dan pemasangan dijalankan. Melalui kajian yang

telah dijalankan, terbukti dengan menggunakan kaedah ini , kos pemasangan dapat

dikurangkan sebanyak 452.29s, iaitu 23% lebih baik daripada yang sebelumnya. Kos

untuk satu bahgian juga dapat dikurangkan sebanyak RM 33.41. Bilangan bahagian juga

dapat dikurangkan daripada 179 bilangan kepada 149 bilangan sahaja. Indeks DFA juga

meningkat daripada 9.6 kepada 12.6. Kelebihan penggunaan kaedah ini telah dibuktikan

melaui rekabentuk baru untuk kereta sorong bayi

ii

ABSTRACT

This project implemented the design for manufacturing and assembly (DFMA)

methodology in order to study the design analysis of a baby stroller (Sweet Cherry SCR8

Series) in aspect of part for manufacturing, assembly process and also handling and

insertion difficulties. The problem identified in this study is on the features of the stroller

that shows a lot of fastener being used and also the usage of both hands in moving the fold

latch to fold the stroller. The objectives of this project are to reduce part while maintaining

the function of the baby stroller, to compare the efficiency of the original design and after

redesign, and also to reduce total assembly time with a new product design of a baby

stroller after DFMA analysis. The study has proven to save assembly time by 452.29s

which is 23% more efficient than the original design. Further ado, the total cost per product

for manufacturing has saved RM 33.41. The number of parts reduced from 179 parts to be

149 parts. The DFA index is also improved from 9.6 to 12.6. The advantages of using

DFMA method has been proved in the redesign of the baby stroller.

iii

DEDICATION

To my beloved parents and my brothers.

iv

ACKNOWLEDGEMENT

First and foremost I offer my sincerest gratitude to my adorable supervisor, Madam

Nurul Ain Binti Maidin, who has supported me throughout my project study with her

patience and knowledge sharing. I attribute the level of my degree to her encouragement

and effort and without this thesis, too, would not have been completed or written. One

simply could not wish for a friendlier supervisor.

In my daily life I have been blessed with my beloved parent, Mr Ruslan Bin Mohd

Dom and Mrs Kintan Binti Abdul Rahman. I owe them a deep sense of gratitude but not to

forget with my handsome big brothers, Mr Ahmad Mohammad Bin Ruslan and also Mr

Ahmad Muazzam Bin Ruslan that keep pushing me to success whenever I felt that I am not

the best.

I thank profusely both of my roommates, Ms Khalilah Binti Khalid and also Ms

Nurul Aima BintiMazlan for their kindness and co-operation throughout my study period.

v

TABLE OF CONTENTS

Abstrak i

Abstract ii

Dedication iii

Acknowledgement iv

Table of Content v

List of Tables ix

List of Figures x

List Abbreviations, Symbols and Nomenclatures xiii

CHAPTER 1: INTRODUCTION 1

1.1 Background 1

1.2 Problem Statement 2

1.3 Objectives 3

1.4 Scope of Project 3

CHAPTER 2: LITERATURE REVIEW 4

2.1 Design for Manufacturing and Assembly (DFMA) 4

2.2 Design for Assembly (DFA) 7

2.2.1 DFA Methods 7

vi

2.2.2 DFA Guidelines 10

2.2.3 DFA Product Simplication Software (BDI) 13

2.3 Design for Manufacturing 14

2.3.1 DFM Guidlines 14

2.3.2 DFM Concurrent Costing Software 15

2.4 DFMA Methodologies 15

2.4.1 Boothroyd-Dewhurst Method 16

2.5 History of A Baby Stroller 16

2.5.1 Types of Stroller 20

2.5.2 Sweet Cherry SCR8 Series 23

CHAPTER 3: METHODOLOGY 25

3.1 Introduction 25

3.2 Flowchart 26

3.2.1 Formulation of Project 27

3.2.2 Research for Literature Review 27

3.2.3 Part Identification of Baby Stroller 27

3.2.4 Run The Analysis by Using Boothroyd-Dewhurst DFMA Sotware 28

3.2.5 Redesign of The Baby Stroller 30

3.2.6 Generate Project Report 30

CHAPTER 4: RESULT & DISCUSSION 31

vii

4.1 Baby Stroller Information 31

4.2 Bill of Materials 32

4.3 Original Design for Sweet Cherry SCR8 Series 36

4.3.1 Exploded View of The Original Design 37

4.3.2 Structure Chart of The Assembly Sequences 37

4.3.3 Design for Analysis (DFA) of The Original Design 39

4.3.4 DFM Analysis of original Design 44

4.3.5 Suggestion for Redesign of Baby Stroller 47

4.4 Redesign 48

4.4.1 Exploded View of Redesign 49

4.4.2 Bill of materials 50

4.4.3 Structure Chart of Redesign 54

4.4.4 DFA Analysis of Redesign 55

4.4.5 DFM Analysis of Redesign 58

4.5 DFMA Analysis and Discussion 60

4.5.1 Design Comparison 62

4.5.2 Research Limitation 64

CHAPTER 5: CONCLUSION & RECOMMENDATION 65

5.1 Conclusion 65

5.2 Recommendation of Future Work 66

viii

REFERENCES 67

APPENDICES 69

ix

LIST OF TABLES

Table 2.1 Type of stroller nowadays

Table 4.1 Bill of materials (BOM) for original design

Table 4.2 DFA analysis of front bar part and handle part

Table 4.3 DFA analysis result for original design of Sweet Cherry SCR 8 Series

Stroller.

Table 4.4 DFM concurrent costing for front bar B of the original design

Table 4.5 Suggestion for redesign parts

Table 4.6 Bill of material for redesign

Table 4.7 DFA analysis for redesign (front bar and handle) of the baby stroller.

Table 4.8 DFA analysis result for redesign of Sweet Cherry SCR 8 stroller

Table 4.9 DFM concurrent costing for front bar of redesign for baby stroller

Table 5.1 Percent reduction for DFA analysis

x

LIST OF FIGURES

Figure 2.1 Time to deliver comparison between DFMA and CAE with Traditional

Methods

Figure 2.2 Typical steps taken in a DFMA study using DFMA software

Figure 2.3 Manual Handling and Manual Insertion –Estimated Times

Figure 2.4 Relative Cost Of Different Assembly Method By Type And Production

Volume

Figure 2.5 Production ranges for each type of assembly method

Figure 2.6 Standardize part

Figure 2.7 Geometry feature of tangle an untangled

Figure 2.8 Symmetrical part for ease of insertion

Figure 2.9 Provision of air- relief passages to improve insertion into blind holes Figure

2.10 Features affecting part handling

Figure 2.11 Provision of chamfer to allow easy of insertion

Figure 2.12 Horse-Drawn Baby Carriages (1700s)

Figure 2.13 Handles and Forward-Facing Carriages

Figure 2.14 The Pram

Figure 2.15 The Reversible Baby Carriage

Figure 2.16 The Umbrella Stroller

Figure 2.17 The Jogging Stroller

Figure 2.18 Modern stroller

Figure 2.19 Sweet Cherry SCR 8 Series Stroller

Figure 3.1 DFA Procedure.

xi

Figure 3.2 The Parameter in DFM.

Figure 4.1 The original design of Sweet Cherry SCR 8 Series Stroller

Figure 4.2 Exploded view of the original design for Sweet Cherry SCR 8 Series

Stroller.

Figure 4.3 The structure chart of the original design of the Sweet Cherry SCR 8

Series.

Figure 4.4 The evaluation properties interface in DFA analysis.

Figure 4.5 The breakdown of time per product for original design of the Sweet

Cherry SCR8 stroller (DFA)

Figure 4.6 Breakdown cost for front bar of the Sweet Cherry SCR8 stroller.

Figure 4.7 Distribution bar chart for the total cost

Figure 4.8 Redesign of Sweet Cherry SCR8 stroller

Figure 4.9 (a) Exploded view of front bar sub-assembly and bill of materials

Figure 4.9 (b) Exploded view of handle sub-assembly and bill of material.

Figure 4.10 Structure chart of redesign.

Figure 4.11 Breakdown of time per product for redesign

Figure 4.12 Breakdown of the cost for redesign of the baby stroller

Figure 4.13 Comparison of DFMA for original and redesign of the baby stroller

Figure 4.14 The comparison for breakdown of cost per product for original and

Redesign.

Figure 4.15 Design comparison of front bar

Figure 4.16 Design comparison of handle

xii

LIST OF ABBREVIATIONS, SYMBOLS AND

NOMENCLATURE

DFMA = Design for Manufacturing and Assembly

DFA = Design for Assembly

DFM = Design for Manufacturing

CAE = Computer Aided Engineering

1

CHAPTER 1

INTRODUCTION

Nowadays hundreds of stroller models are available with different branded and quality.

This made the features of the stroller to be different and unique depends on the designer

and company intention to be focused. However, the manufacturing process is the important

things to be considered as it will affect the price of the product itself. Hence, this project

focused on analyzing the design of a baby stroller in order to reduce cost then improve the

manufacturing and assembly process with a new design of a baby stroller after the analysis.

This chapter basically explain on how the project being made starting from the background

study, problem statement, objective, scope, organization of the project, and lastly result

expectations.

1.1 Background

Design for Manufacturer and Assembly in which being known as DFMA generally

is a combination of Design for Assembly (DFA) and Design for Manufacturing (DFM).

Through history of DFMA, it had been used before the Second World War by Ford and

Chrysler that using DFM philosophy in their design and manufacturing process of the

weapons, tanks and other military products. Early 1970’s the researching job of this new

technology had been done by Professors Peter Dewhurst and Geoffrey Boothroyd who

originated the Boothroyd Dewhurst, Inc. (BDI) in 1983. Initially on comprehensive work

studies, relating part characteristics to handling, fitting times and degrees of difficulties

etc., their work was genesis of the concept of “scoring” designs for DFA or DFM.

Currently Boothroyd Dewhurst methodology was the inspiration for many of its successors

around the world.

2

In essence, unstructured DFA and DFM guidelines and rules are transformed into a

structured form that can be applied using paper-based spreadsheet type analysis or

computer software. For DFA, a formalized step-by-step process being used to produce a

design metric that assesses the design efficiency related to its assemblability. The main

steps involved are based on general DFA concepts in which choose assembly method

(manual or automatic) analyze the design for ease of assembly and improve the design and

reanalyze.

Boothroyd Dewhurst’s, Inc. DFMA software is designed to be used at the concept

design stage. The aim is to optimize design for manufacture and assembly before

commitment to detail design and manufacture. The DFMA package contains a DFA

module and DFM module.

Normally the DFA module is used first, working from a concept drawing. The aim

is to improve design efficiency by eliminating of unnecessary parts, and choosing more

efficient assembly methods. This is followed by DFA, which provides estimates of time

and cost for assembly, as well as other operations. Through redesign, the design efficiency

figure is improved. This provides a relative measure between design alternative which

should influence the final design concept chosen. Meanwhile for DFM module is used to

evaluate design alternative from a manufacturing cost perspective.

This project fundamentally focused on the design analysis of Sweet Cherry SCR 8

Series Stroller by implementing DFMA method. Hence, Boothroyd Dewhurst

methodology had been used to complete this project.

1.2 Problem Statement

Nowadays, there are a lot of distinct process which all influence product cost,

quality and productivity of system that cause a huge losses to Business Company. This is

because a lot of product is made up of fasteners and redundant features (Othman, 2010).

Boothroyd Dewhurst DFA method could help to overcome the problem by suggested the

idle possible way to assemble a product with remove fastener. In a production of a baby

stroller, from the features show a lot of fastener such as screw, rivet and many more as the

structure need to be foldable. Hence, this project had analyzed the design for assembly to

3

reduce parts as well as the cost of production and come out with some improvement of the

design in an efficient way.

1.3 Objective

(a) To reduce part while maintaining the function of the baby stroller.

(b) To investigate the efficiency of the original design and after redesign (comparison)

(c) To reduce total assembly time with a new product design (redesign) of baby stroller

after DFMA analysis

1.4 Scope

In order to achieve the objective of the project, the scope had been list as shown below:

(a) Study of design for assembly of a baby stroller that focusing on mechanical parts

only by using Boothroyd Dewhurst method.

(b) Evaluate a baby stroller as a case study, analyze and redesign the product using

Boothroyd Dewhurst method.

(c) Solid Works software being used for drawing of each part and assemble of the

original and redesign of the baby stroller.

4

CHAPTER 2 LITERATURE REVIEW

As the time flies an organizations need to learn in order to improve their adaptability

and efficiency toward future. Through this idea with the help of new technologies

and philosophies of compete with other competitors literally could enhance the

development process with a good results to achieve target. Currently there are a lot of

tools that could be used to help production team to solve their problem at an early

stage. Hence, this chapter will review the past research from other sources with

citation.

2.1 Designs for Manufacturing and Assembly (DFMA)

Design for Manufacturer and Assembly (DFMA) is a tool that helps in

minimizing production cost by breaking the product down to be the simplest

components and parts. Concurrent Engineering (CE) is intended to cause developers

from the outset, to consider schedule, quality, cost, user demand and all elements of

product cycle from conception to disposal. Both of this Production Oriented Design

(DFMA and CE) could run activities simultaneously in a parallel form as being

showed in Figure 2.1 below. They were using simulation techniques that could give a

fully understanding among team member to find errors along the process and fix it

before the development ends.

5

(Sources: Junior, O.C. at. all, 2009. The White Goods Part Designed Based on DFM/DFA Concepts

in a Concurrent Engineering Environment)

Figure 2.1: Time to deliver comparison between DFMA and CAE with Traditional

Methods

There are two major concept in DFMA process in which design for assembly

(DFA) and also design for manufacturing (DFM). DFA is the design of the product

for ease of assembly (Boothroyd, 1994). It is an analysis method that brings together

multidisciplinary teams to evaluate and validate product design with respect to the

manufacture and assembly of its components parts. Meanwhile DFM is to design that

is based on reducing the cost of production and time to market for a product, while

maintaining appropriate level of quality the material and tooling side of the new

product. Hence, DFMA refers to working on both concepts together. Figure 2.2below

shows the typical steps taken in DFMA study using DFMA software.

6

(Sources: Boothroyd,G., Dewhurst,P., and Knight, W., 2002. Product Design for Manufacturing and

Assembly, 2nd

Edition, Marcel Dekker Inc)

Figure 2.2: Typical steps taken in a DFMA study using DFMA software

DFMA can be used effectively to reduce part count in the assembly that

brings to simplify the assembly process, lower manufacturing overhead cost,

minimize assembly time, and improve quality by reducing the possibilities for

introducing a defect. Also the amount of labor can be reduced once the component of

parts becomes fewer and simpler assembly processes. When the part count had been

reduced, automatically the development cycle become shortened as the philosophy

encourages simplifying the design and using standardize component whenever

possible.

7

2.2 Designs for Assembly (DFA)

Generally, there are two objective of DFA in which to minimize part count and to

have remaining parts of a nature that they are easily assembled together. The DFA

method accomplishes the objective by:

(a) Providing a tool for the designer and even design team which assures that

considerations of product complexity and assembly take place at the earliest

design stage. This eliminates the danger of focusing too much the whole

things during early design on product function with insufficient regard for

product cost and competitiveness.

(b) Guiding the designer to simplify the product so that the cost of assembly and

parts can be saving equally.

(c) Gathering information normally possessed by the experienced design

engineer and arranging it conveniently for use by less-experienced designers.

(d) Forming a database that comprises of assembly times and cost factors for

numerous design situations and production conditions.

2.2.1 DFA Methods

The analysis of a product design for ease of assembly depends to a large extent on

whether the product is to be assembled manually, fixed or hard automation, soft

automation (robotic), or a combination of these.

(a) Manual assembly

List of parts are assigned to workbenches where the component of product

being assemble manually by workers with the aids of hand tools. Even though

this is an idle method for assembly, there is usually an upper limit to the

production volume, and labor costs remain higher.

8

(Sources: Boothroyd,G., Dewhurst, P., and Knight, W.,2002. Product Design for Manufacturing and

Assembly, 2nd

Edition, Marcel Dekker Inc)

Figure 2.3: Manual Handling and Manual Insertion –Estimated Times