My Journal Paper Sha Version 3

Development of a Design Feature Database to support Design for Additive Manufacturing

Shajahan Bin Maidin and Dr R. I. CampbellDepartment of Design & Technology, Loughborough University,

Loughborough, United Kingdom

Abstract

This paper introduces a method to aid the conceptual design of additive manufactured product or part particularly for the Selective Laser Sintering (SLS) system to enable the achievement of improved design concepts by implementing the tool in the form of additive manufactured design feature database. A taxonomy has been developed as a guide for the development of the tool that comprises four taxons of reasons for additive manufacturing (AM) utilisations. These are user fit requirements, improved product functionality, parts consolidation and improvement of aesthetics (or form). Each of these requirements has been expanded into thirteen sub categories of application that contains various examples of design features that are only possible to manufacture using AM technology. The collected and grouped design features will be presented in a form of a database as a method to aid designing for AM by enabling industrial designers to visualise and gather design feature information that could be incorporated into their own design work. Finally, the results from the user trial and the validation of the tool are presented.

Keywords

Additive Manufacturing, Laser Sintering, Design Support Tool, Design Feature Taxonomy & Design Feature Database

Correspondence DetailsCorresponding Author: Shajahan Bin MaidinEmail address: [email protected] address: Department of Design & Technology

Loughborough UniversityLeicestershireLE11 3TUUnited Kingdom

1. Introduction

AM is a process and technology that currently has the potential and promise for

great flexibility in supporting customization of products via creative design, less

tooling cost and fast product development cycle time that enable companies to be

competitive in the market. One of the most important factors that enable this time

compression technique is the process of fast development of design ideas. At

present, industrial designers design additive manufactured part or product without a

proper design support tool, thus would sometimes reach wrong perceptions of the

value and advantage of designing for AM.

Use of current AM technology is developing a large amount of design information

such as the innovative design features and complex geometry that is generated

during designing a product or part for AM. This information often does not get

recorded, resulting in a potential loss of important design knowledge. This paper

introduces a method to aid the conceptual design of AM product or part particularly

for the Selective Laser Sintering (SLS) system to enable the achievement of

improved design concepts by implementing a tool in the form of additive

manufactured design feature database. This is expected to contribute new

knowledge to the development of the design support tool useful to industrial

designers.

1.1 Previous Work

The subject of design for AM is relatively new and thus not much information on how

to best exploit the advantages that it offers from the perspective of design. Most of

the AM support tools developed to date have been focusing on AM material and

system selection (Campbell and Bernie 1996) (Bibb, Taha et al. 1999) (Phillipson

1997)(Jones and Campbell 1997)(Masood and Soo 2002)(Byun and Lee 2005)(Rao

and Padmanabhan 2007)(Munguia 2008) (Cheng, Fuh et al. 1995)(Xu, Wong et al.

1997) (Lan, Chou et al. 1997) (Pandey, Thrimurtullu et al. 2004) (Pandey, Venkata

Reddy et al. 2007)

At present there are few established design support tools to aid industrial designers

to design products specifically for AM processes such as laser sintering. Previous

work, undertaken by Burton (2005) hypothesises that he can manipulate existing

Design for Manufacture (DFM) concept into his design for additive manufacturing

(DfAM) strategy. Providing a questionnaire feedback to five areas of concern to AM

such as production volume, part or product form, its function, its construction and

logistics issue confirms that a part or product is suitable for additive manufacture

and provide the concepts profile statements (Burton 2005). The statements serve as

guidelines and advice as to how to best exploit the design benefits of AM. However,

this method is time consuming because it was done manually. Moreover, there are

limited concepts profile statements and design features examples. Other authors

have made statements of what should constitute AM design methodology. Adding

aesthetic quality and consolidating parts are seen as techniques that AM design

methodology should adopt (Hague, Mansour et al. 2004).

Page at el. (2005), demonstrated the generation of 3D CAD data using coded

pattern projection and laser triangulation systems. The research demonstrated the

generation of 3D models using these two systems and claimed that imaging-based

scanners offer faster and more automated methods of generating CAD models

(Page, Koschan et al. 2005)

Kruf et al. (2006) published an ongoing research on design for AM of functional LS

parts that focus on materials properties and reproducibility, AM texturing software,

coatings for LS parts and design rules for LS. This research is about the use of

Computer Aided Optimization (CAO) software that has been used to remove non-

efficient material from an initial 3D CAD model to create a new design optimised for

laser sintering (Kruf, Van de Vorst et al. 2006)

Gerber (2008) proposed a design for manufacture guideline specifically for laser

sintering parts by selecting and analysing a range of available design for injection

moulding guidelines. However the accuracy of the design guideline for laser

sintering that have been proposed have to be verified by experimental work to

ensure it is reliable and relevant (Gerber and Barnard 2008)

Ariadi (2008) proposed a design template which a simple program containing a

database of product family architecture which allows consumers to customise the

features or aspects of a products design which is expected to be easy-to-operate for

instead of conventional Computer Aided Design. However, the interface between

design template, customisation features (uploading photo/image/logo, texting) and

pre-manufacturing process (creating STL file) still needs to be developed further

(Ariadi and Rennie 2008).

2. Development of the AM design feature taxonomy

A decision was made to apply a “software rapid prototyping” approach to develop

the design aid tool for AM. The starting point for this was the categorisation of 113

additive manufactured design features that have been gathered and grouped into a

taxonomy that would form the basis to assist the development of the design support

tool. Some examples of these design features are shown in Table 1. Taxonomy is

normally developed by analysing various sources of literatures and various domains

and grouping similar information until all the sub groups are included in a particular

group. However, there were not much published material existed to support and

form a comprehensive and organised AM design feature taxonomy. Therefore,

several iterations of the taxonomy were proposed before a satisfactory classification

was achieved.

A total of 113 design features have been collected progressively and a decision was

made to group and categorise them accordingly to form a taxonomy. Figure 1 to

Figure 4 shows four versions of the taxonomy. Finally, a decision was made to

select and developed further the taxonomy base on AM reasons of utilisations

because from an inital study conducted, it was noticed that one of the most

important issue related to designing for AM is it’s reasons of utilisation.

Figure 1 shows taxonomy of design features that have been divided into internal and

external design features. This taxonomy has been developed to group the design

features according to features that could be visualise externally and features that

was included internally in a part or product. As AM supports freedom of design, this

taxonomy was developed to group the design features by external and internal

geometries. Figure 2 shows another variation of the taxonomy. It is a taxonomy of

additive manufactured design features that has been grouped under functionality

and form. The justification behind the development of this features is, as AM

improve product functionality and also capable to manufacture complex design

features, the design features that has been collected has been grouped under these

two taxons.

Feature 1: Integrated ball and socket

Functionality Keywords:

i. Ball jointii. Encapsulationiii. Spherical movementiv. Self-levellingv. Ready assembled

Application: Consumer productMaterial: SLSOriginating Designer: Ian Campbell, Loughborough University, UK

Feature 2 : Snap fit hook


i. fasteningii. holding

Application: Avionic Enclosure Material: SLSOriginating Designer: Du Plessis, Saab Aviatronics, South Africa

Feature 3 : Internally Hinged Button


i. Integral buttonii. Internal accessiii. Hingeiv. Orthogonal operation

Application: AutomotiveMaterial: SLSOriginating Designer : Mike Burton, RMIT Australia

Table 1: Examples of Additive Manufactured Design Features

AM Design FeaturesExternal Design Features

Enclosed Volume

Thin Wall

Lofted Surface

Customised Thread / Helix

Embossed FeatureLogo

Serial Number

External Blade

Mounting Boss

Snap Fit Hook

Revolved Feature

Assembly Integration

Dual Functional Product

Circular Pocket

Sweeped Feature

Conformal Geometry

Rectangular Pocket

Spiral

Knot

Biomimics

Parts Consolidation

Internal Design Features Internal Channel

Internal Core Section

Internal Blade

Selective Reinforce Feature

Internal Hinge Button

Integrated Ball & Socket

Internal Chassis

Close Fit Enclosure

Integrated Cable Support

Internal Cooling Feature

Undercut

Variable Wall Thickness

HoleThreaded

Countersunk

Counter Bore

Blind

Drafted

Shelling

Internal Voids

Internal Flow Path

Dual Materials

Figure 1: Taxonomy of Internal and External AM Design Features

AM Design Features

Functionality

Enclosed Volume

Customised Thread

External Blade

Snap Fit Hook


Dual Functional Product

Dual Materials

Conformal Geometry

Form or Features

Drafted Feature

Shelling

Revolve Feature

Circular pocket

Sweeped Feature

Rectangular pocket

Spiral

Mounting boss

Knot (Fabrics)

Bio mimics (Asthethics)

Lofted Surface

Helix

Hole

Blind

Through

Embossing

Logo

Serial Number

Text

Thin Wall

Rib Feature

Figure 2: Taxonomy of Functionality and Form of AM design features

One of the methods to provide design aid for conceptual design of AM part or

product is having visual examples of design features by areas of application. Figure

3 shows a taxonomy of AM design features that has been grouped under areas of

applications. The areas of applications are medical, sport, consumer product,

automotive, military and marine, aerospace, motorsport and fabrics. These areas of

applications has been grouped under three taxons namely customised features,

consolidated features, complex geometrical features.

Figure 4 shows AM design feature taxonomy of functionality & complex geometrical

features which is similar to Figure 3. However, under the functionality taxon, the

design features that has been collected was grouped under eight different sub

categories namely fastening or holding features, weight reduction features,

embbosed features, size variations features, personalised parts or product,

consolidated parts, dual functionality product and dual material product. Under the

complex geometry taxon, the design features was grouped under instant assembly,

internal structuring, shape optimisation and profile features.

Following a pilot study with the MSc Industrial Design Postgraduate students from

the department during the first year of the research, it was noticed that one of the

most important issue related to designing for AM is its reasons of utilisation.

Designers have to understand the advantages and limitations of AM and its reasons

of utilisation prior to design and producing parts or product with AM systems. Figure

5 shows the design feature taxonomy base on AM reasons of utilisation. The second

level of taxons shows five groups of AM reason of applications that are user fit

requirement, improve functionality requirement, parts consolidation requirement,

aesthetics or form requirement and dual material requirement. There are fifteen sub

categories of applications that have been further expanded from the second level of

taxons. There are various design features that have been grouped under this

second level of taxons. Figure 6 shows a second version and Figure 7 shows the

simplified version of the final taxonomy that consist of four reasons of AM utilisation

and its thirteen sub categories of applications.

Figure 3: AM application design features

AM Design Features ApplicationsCustomised

Features Medical

Ear Implant

Dental Implant

Face / Body Reconstruction

Scaffold

Sport

Footwear

Body / Head Protective

Consumer Product

Furniture

Fashion

Electronics Appliances

Consolidated Features

Automotive

Dashboard

Military and Marine

Engine

UAV

Whale tracking device

Aerospace

Air Duct

Motorsport

Formula 1 Air Duct

Sport engine

Complex Geometrical Features

Consumer Product

Furniture

Arts

Electronic Products

Fabrics

Knots

Automotive

Dashboard

Body

Jigs & Fixtures

Why AM?

User fit requirement

Sport

Protective sport

garment

Golf Club Grip

Sport Safety Helmet

Rowing Helmet

Medical

Hearing Aid

Dental Joint

Skull Joint

Consumer Product

Joystick

Improve functionalityCombi

ne Functionality

Smoke

alarm & bulb holde

r

Weight

ReductionUndercut

Thin wall

Variable

wall thicknessInternal

selective reinforcin

gHollow

structure

Internal

Structuring

Internal

channel – cable route etc Internal

flow path

– liquid etcInternal

Blade

Geometr

yInternal

cooling

feature

Internal

shelving

Multiple

versionsSize

Variations

Customis

ed Thread

Surface

texture

Parts Consolidation

Remove Fasteners

Internal cable support

Snap fit hook

Mounting boss

Encapsulated spring

Snap fit cap

Instant Assembly

Integrated ball & socket

Internal hinge button

Enclosed volume –

single shell

Ready assembled

gear

Multiple links

Encapsulated bearing

Ball & Socket Joint

Self centring bracket

Aesthetics or Form

Profile

Freeform Geometry profile

External Blade

Geometry

Variable or lofted profile

Swept profile

Biomimics

feature

External ribbing

Surface texture

Embossed feature

Dual or Multi- materials

Over moulding

Tooth brush

Sat Nav

Razor Blade

Integrated damping

Wheel

AM Design Features

Functionality Features

Fastening or

Holding

FeaturesInternal

cable suppo

rt

Snap Fit

Hook

Mounting Boss

Weight saving Feature

s

Undercut

Thin Wall

Pocket

Rectangular

Circular

Embossed

Features

Logo

Serial Numb

er

Size Variati

ons

Tooth brush

Personalised Part /

Product

Customised Threa

d

Consolidated

Part/Product

Dual Functio

nal ProductSmok

e alarm and bulb holde

r

Dual Materia

l Product

s

Tooth brush

Multimeter

Complex Geometrical Features

Instant Assembly

Integrated Ball & Socket

Internal Hinge Button


Internal Structuring

Internal channel or flow path

Internal Core

Section

Internal Chassis

Internal Cooling Feature

Internal Selective

Reinforcing

Shape Optimisation

Freeform Geometry – Golf Club

Grip

Enclosed Volume –

Whale Detector

Variable Wall

Thickness

Profile

Lofted

Revolved

Sweeped

Drafted

Figure 4: AM design feature taxonomy of functionality & complex geometrical features

Figure 5: AM reason of utilisation design feature taxonomy version 1

Figure 6: AM reason of utilisation design feature taxonomy version 2

AM Utilisations ReasonsUser Fit Requirement

Customised Profile FeaturesSport Application

Medical Application

Consumer Product Application

Improve functionality RequirementWeight Reduction Features

Internal Structuring Features

Increase Surface Friction Features

Multiple Version Features

Consolidation RequirementFasteners Removal Features

Instant Assembly Features

Multiple Functions Features

Dual Material Features

Aesthetics RequirementVisual Features

Surface Features

Embossed Features

Customised Form features

Figure 7: AM design feature taxonomy version 3 (simplified layout)

The taxonomy in Figure 7 categorises various AM enabled features under four

groups of AM reason of utilisations namely user fit requirements, product

functionality improvement, consolidation, aesthetic and form requirements. These

four groups of AM reason of utilisations forms the top level taxons of the proposed

taxonomy and were further expanded to include thirteen sub categorise of

application on the second level of the taxons. User fit requirements can be defined

as parts or product that has been customised to accommodate user requirements

with the application of AM. From the perspective of AM, the user fit requirements

were applied into three groups of application namely sport, medical and consumer

product that forms the customised profile features.

Product functionality improvement can be defined as methods that can be used to

improve parts or product functionality from the perspective of AM. The product

functionality improvement comes from four approaches such as weight reduction

features, increase surface friction features, internal structuring features and multiple

versions features.

Consolidation requirement can be defined as to combine parts, its functions or its

material from the perspective of AM. The consolidation technique comes from four

approaches such as instant assembly features, fasteners removal features, multiple

functional parts and over moulding.

The aesthetic and form requirement can be defined as methods that could be

applied to improve product appearance from the perspective of AM. It includes

approaches such as embossed features, surface features, visual features and

customised form. The contents of the thirteen sub-categories that form the second

level taxons will be described in the next section.

2.1 User Fit Requirement

Based on the four reasons of AM utilisation and findings from published literature

and various websites, a total of 113 DfAM features (Table 2) have been identified

and clustered into thirteen sub-categories of applications. For instance, for the

weight reduction application there are seven design features have been collected.

Most of these design features were designed and manufactured with the laser

sintering process.

From the perspective of AM the user fit requirement were applied into three groups

of application namely sport, medical and consumer product. There are four types of

design features that have been found and grouped under the sport application.

There are nine types of design features under the medical application. There are

three types of design features under the consumer product application.

2.2 Improve Functionality Requirement

The improve functionality requirement were further expanded to include weight

reduction feature, increase surface friction features and multiple version features.

Table 6 shows the total number of design features grouped for each of this category.

2.3 Consolidation Requirement

The consolidation requirement were further expanded to include fasteners removal

features, instant assembly features, multiple functional parts and over moulding.

Table 6 shows the total number of design features grouped for each of this category.

2.4 Aesthetics and Form Requirement

The aesthetics and form requirement were further expanded to include embossed

feature, surface features, visual feature and customised form. In some cases there

are features that appear to be applicable to more than one category. In this case,

the author has to decide the appropriateness and relevancy of the application group

that the feature has to be included. Table 6 shows the total number of design

features grouped for each of this category.

Reasons for AM

Application Number of design features


Customised Profiles Features

Sport = 4 design features, Medical = 9 design features & Consumer Product = 7 design features

Improve functionality

Weight Reduction Features

7 design features

Increase surface friction features

3 design features

Internal structural features

8 design features

Multiple version features 2 design features

Parts consolidation

Instant assembly features

20 design features

Fasteners removal features

7 design features

Multiple functional parts 3 design features

Over moulding 1 design features

Aesthetics

Embossed features 3 design features

Surface features 13 design features

Visual features 3 design features

Customised form features

13 design features

Total 113 design features

2.5 Validation of the AM design taxonomy

Table 6: Number of design feature for a specific AM reasons and application

The final iteration of the taxonomy (Figure 7) that base on reason of AM utilisation

has to be validated before implementing and incorporating into a first “rough cut”

tool. To validate the final taxonomy, a questionnaire was send to a second group of

thirteen MSc postgraduate students on the Industrial Design Masters Programme at

Loughborough Design School. They were given a project to re-design a user-

interaction product so that it could be produced by any commercially available AM

system. They were given the paper version of the taxonomy and all the design

feature images to aid the designing task to search for applicable and innovative

features that could be included in their design work. In addition, a design diary kept

by each student also enabled further study and improvement of the DfAM system.

On completion, they were given a survey form to gain feedback on the effectiveness

and applicability of the AM taxonomy and the design feature list.

The validation of the taxonomy shows that differences between the top four levels of

taxons are reasonably clear and there is no overlap between them. Results from the

students’ questionnaires feedback can be summarised that the taxonomy is relevant

and usable. To improve the design feature list, one student suggested to include

more design feature examples. However, there are also suggestion to include the

explanation for all AM systems available and all other types of suitable materials

data into the list that is beyond the scope of this research at this stage. The

development of the AM taxonomy has been an aid in the identification and

organisation of AM design features for easy retrieval and assistance in conceptual

design. The design features taxonomy is by no means exhaustive and will be

expanded by adding more design features in the various sub-categories.

3.0 Implementation of the Design for Additive Manufacturing (DfAM) Feature Database

The DfAM feature database was developed based on four AM reasons of utilisation.

These are user fit requirements, improved product functionality, parts consolidation

and aesthetics or form requirement. These four top levels of the taxonomy were

further expanded into thirteen sub categories of application features namely

customised profile features, weight reduction features, increase surface friction

features, multiple version features, instant assembly features, fasteners removal

features, multiple functional parts, over moulding, embossed features, surface

features, visual features and customised form.

A “rapid prototyping” software approach has been utilised where a “quick and dirty”

version of the tool has been developed to enable rapid user testing and

improvement of the system. The tool have been implemented within a Ms Access

database known as the DfAM design feature database. A series of forms have been

created to enable designers to interact, guide, search or browse through the feature

categories. The database enables industrial designers to visualise and gather

design feature information from examples in the database that could be incorporated

into their own design work. Figure 8 shows the welcome screen and Figure 9 shows

the general information screen where the user is requested to provide the users

general information.

Figure 8: Screen shot of the welcome page of the DfAM feature database

Figure 9: General Information Screen

Before a user proceeds to the concept profile generation stage the feasibility for

additive manufacture of a certain part has to be evaluated. As shown in Figure 10

there are four AM feasibility evaluation criteria. The first question is regarding the

number of targeted production unit. If the given answer to this question is more than

100,000 units, then a message informing that AM is not suitable will appear (Figure

11). If the production unit is less than 10,000 units the user may proceed to provide

answer to the next three general questions which evaluate the overall surface finish,

overall mechanical property and the importance of the tolerance and accuracy of the

part or the product.

Figure 1: AM feasibility validation screen

Figure 21: Message showing AM is not suitable for production volume more than 100,000 units

For question about the overall surface finish, overall mechanical property and the

importance of the tolerance and accuracy of a part or product, a scoring technique is

used to evaluate the feasibility of AM. Figure 12 showing AM is not suitable if the

general mechanical property, surface finish and tolerance are very important for a

certain application.

Figure 3: Message showing that AM is not suitable if the general mechanical property, surface finish and tolerance is very important

Figure 13 shows the concept profile generation screen. There are 11 options that

can be selected individually. These questions have been grouped under the four AM

reasons of utilisation and its sub categories of application as shown in Table 7. For

example if a user select the first option (need custom fitting for individual user), then

by clicking the generate concept profile button, the customised profile feature button

and the customised form button will be enabled (Figure 14). This will assist the user

in selecting the appropriate features to be applied in their concept design.

Figure 13: AM Concept Profile Generation Screen

Figure 14: Buttons that has been enabled base on the concept profile selection

Table 7 shows which feature buttons will be enabled base on the concept profile

button that has been selected. Figure 15 shows a quick search function that enable

a user to find a specific features or information from the database.

Selected Options Enabled Button Reasons for AM

Does the product need custom fitting that conform to individual user?



Does the product need to be light lightweight?



Does the product subjected to hand held?

Increase surface friction features

Does the product have internal structures?

Internal structural features

Does the product benefit from being made available in a range of sizes or shapes to fit different users?

Multiple version features

Does the product benefit from number of parts reduction?

Instant assembly features

Parts consolidation

Does the product need to attach to other components?

Fasteners removal features

Does the product benefit from having several other functions?

Multiple functions parts

Does the product require over moulding?

Over moulding

Does the product need to be aesthetically pleasing?

Embossed features

Aesthetics

Surface features

Visual features

Does creative and innovative shape or geometry an important factor for the product?

Customised form features

Table 1: Result of concept profile selection

Figure 45: Quick search screen

The images currently used in the database have been sourced from various

websites, literatures and personal contact with the designers. Therefore, permission

would need to be sought from the owners of the images before the system be made

available online. The feature database contains macros and visual basic scripts that

could not be made available online at the time of writing.

4. DfAM Feature Database Appraisal and Validation

The implementation of the DfAM tool into the Ms Access as a prototype software

took place over a period of several months, during which time a number of revisions

and improvements were made. Prior to the user trial a series of pilot trials were

performed to establish a suitable format and test procedure before testing a finalized

system. The pilot trial was conducted with two groups of participants which are the

final year undergraduate student designers and the professional industrial

designers.

An exercise was devised for the trials in which both groups of participants were

asked to sketch a redesign of a familiar product of their choice for AM using the

DfAM tool. The students’ pilot trial was conducted in a room at the Design School.

Due to work commitment and travel distances the professional designers trials was

done by sending the database in a CD format accompanied with the design brief

and feedback questionnaire. Although the number of participant in this trial is small,

it provides an initial feedback of the usefulness of the tool prior to a more formal

validation.

4.1 Student Designer Pilot Trial

To ascertain user perceptions and verify its overall feasibility and to gather

suggestions for the improvement of the DfAM feature database, six final year

undergraduate students on the Industrial Design programme at Loughborough

University and two postgraduate students were recruited for the design trial. These

students were regarded as being competent industrial designers. In general, most of

these students have had some exposure to product design and had used AM

technology in their project due to the nature of the engineering and design courses

they were undertaking.

The basic idea behind the trial was that the students should develop sketches of

redesign concepts of a product of their choice with and without the use of the DfAM

tool and the results of doing so could be compared. Therefore, the trial was divided

into two concept sketching exercise sessions for each student, one using the

repository, one not. As shown in Table 8, students 1 to 4 were given access to the

DfAM feature database for their first sketching exercise, students 5 to 8 were given

access for their second sketching exercise. The students were given access to the

websites to get ideas and to help them in the conceptual sketch when they were not

using the repository. Table 8 shows the products that were sketched for the trial by

the students.

Student Designer

Product Sketched Using DfAM feature database

Product Sketched Without DfAM feature

database (Website Access)1 Table Lamp Toy

2 Toy Table Lamp

3 Chair Computer mouse

4 Computer mouse Chair

5 Salt Shaker Kettle

6 USB Stick Salt Shaker

7 Kettle Ice-cream scoop

8 Ice-cream scoop USB Stick

Table 8: Products that has been sketched by student designers

4.2 Student Designer Pilot Trial Discussion

Each student has produced six sketches in total, three concept sketches using the

website and three concept sketches using the feature database as an aid. In total

there are forty eight sketches that have been collected. A decision has been made

to evaluate the concept sketches and choose each best concept from each group

and compare them. There were eight criteria that have been evaluated: safety,

usability, manufacturability, functionality, ergonomics, durability and aesthetics.

Using pair wise comparison, the weight for each criteria has been assigned. Table 9

and Table 10 shows two examples of the selected concept sketches of products

with some text annotation developed by the student designers without using and

with using the DfAM features database.

Salt Shaker design without using DfAM feature database Salt Shaker design using DfAM feature database

Design Feature:1. Embossed Feature2. Snap fit feature

Design Feature:1. Weave Surface Feature2. Hock Clip Feature3. Spiral Element 4. Over moulding feature5. Hand grip contour

Table 9: Comparison of salt shaker sketched using and without using the DfAM feature database

Table 9 shows the comparison of the salt shaker sketched using and without using the DfAM feature database. Salt shaker sketched without using the DfAM feature database shows only two features such as embossed feature for its aesthetics and snap fit feature to open and close the lid. However, the salt shaker sketched using the DfAM feature database shows various features from the library such as weave surface feature, spiral element for enhanced aesthesis. The hand grip contour and over moulding feature for better ergonomics and the hook clip feature for improved functionality.

Ice-cream scoop design without using DfAM feature database Ice-cream scoop design using DfAM feature database

Design Feature:1. Press in mechanism load and unload the ice cream

Design Feature:1. Over moulding feature2. Transparent feature3. Hollow structure on the scoop4. Embossed pattern on the scoop

Table 20: Comparison of ice-cream scoop sketched using and without using the DfAM feature database

Table 10 shows the comparison of the ice-cream scoop sketched using and without using the DfAM feature database. Ice-cream scoop sketched without using the DfAM feature database shows just the press in mechanism load and unload the ice cream. However, the ice-cream scoop sketched using the DfAM feature database shows transparent feature that enhance its

aesthetics, over moulding feature for better ergonomic and hollow structure for reduced weight and embossed pattern for better functionality elements.

4.3 Student Designer Pilot Trial Results

The trial found that there are two factors that influence the results. Firstly, the skills

and creativity of the students designers and secondly, the number of features used

from the feature database. However, by analysing and comparing the sketches

produced by the student designers with using the DfAM feature database, it is found

that the tool provide ideas on how to incorporate various features to enhance and

improve aesthetics, ergonomics and functionality of a product or parts. The sketches

produced indicates that with using the DfAM tool, the student designer was able to

apply creative and innovative design features such as the variable wall thickness,

living hinge, over moulding, transparency and various surface features into the

concept sketches.

Table 11 shows the list of the features used from the repository extracted from all the

concept sketches using the DfAM feature database. An overall observation of the list

shows that the students had made used of the feature database and applied features

from twelve categories of applications with the exception of the multiple function

parts feature under the consolidation requirement. The weight reduction feature,

instant assembly features, embossed features, visual features, customised form

features has been applied in most of the conceptual sketches. The feature that was

mostly used from the feature database is the over moulding feature. As most of the

product is being hand held this is an important feature to be applied to the

conceptual sketches. However, only the hand grip contour feature has been applied

from the customised profile feature. As most of the design features in the user fit

requirement are collected from specific application areas such as medical, sport and

consumer product, this does not relevant to the student sketching exercise.

However, this is also depends to the students creativity to use the idea of the

features from the user fit requirements and apply it on other product. In summary,

Table 11 shows that the feature database is useful, relevant and helpful to support

conceptual design of parts and product for AM. The number of feature used from the

library would likely increase if the number of participants in the trial is increased.

Student Designers

AM Reason Application Design Features 1 2 3 4 5 6 7 8 Total

User Fit Requirement


Hand Grip Contour x x x x 4



Undercut Feature x x 2

Thin Wall Feature x x 2

Variable Wall Thickness Feature x x x x 4

Hollow Feature x x 2

External Ribbing Feature x 1

Increase Surface Friction Features

Textured Surface Feature x 1Circular Array Feature x 1Honey Comb Feature x 1

Internal Shelving x 1Internal

structuring feature Internal cable support x 1

Multiple Version Features

Customised Thread Feature x 1

Consolidation Requirement

Instant Assemblies

Features

Living Joint Feature x x 2Torus Feature x 1

Interconnected Feature x 1Encapsulated Track & Ball

Featurex 1

Living Hinge Feature x x 2Integrated ball and socket

featurex 1

Multiple link feature x 1Encapsulated bearing x x 2Ball and socket feature x 1

Hook clip feature x x 2Slide opening & closing x 1

Snap fit hook x 1

Fasteners Removal Features

Hook clip x x 2Slide opening & closing x 1Internal cable support x 1

Snap fit hook x 1

Over Moulding Over Moulding x x x x x x x 7

Aesthetics or Form

Requirement

Embossed Features

Embossed Alphabets x x x x x 5Logo x x 2

Surface Features

Weave Element x 1Alphabet Element x 1

Spiral Element x 1Overlapping Element x x 2

Visual FeaturesNet Shadow Effect x 1

Transparent Feature x x x x x 5

Customised Form Features

Curve Feature x 1Swept Feature x x 2

Alphabet Feature x 1Freeform geometry x x 2Floating Elements x 1

Replicated Element x 1Bio- mimic feature x 1

Table 3: Range of features used from the DfAM feature database

5. Professional Designer Pilot Trial

In addition to the student designer’s trial, a second trial was conducted with

professional designers. Seven professional industrial designers who had

experienced in designing products for AM and variety of market sectors were invited

to take part in the user trial to generate feedback on the proposed DfAM feature

database. Generally these designers had at least three years of working experience

and involve in product design and development activities.

5.1 Professional Designer Trial Discussion

The focus of the trial with the professional designers is to design three conceptual

designs for a product of their choice, possibly a product that they have previously

worked on or one that has already been identified for potential manufacture using

AM that they think has a potential to have its functionality, aesthetics, ergonomics or

parts consolidation improved through the use of AM. Comparison of using and not

using the DfAM feature database was not conducted with the professional designer.

The aim of the trial is to test the DfAM feature database to see if it is relevant,

effective and applicable to aid the conceptual design of part or product that are to be

produced using AM processes from the professional designer’s point of view.

Twenty one conceptual sketches were produced by the professional designer for the

trial. The best conceptual sketches have been selected to show the range of the

features that have been selected and applied in their sketches. Table 12 shows the

product sketched by the professional designers and the concepts that have been

selected for each product.

Professional Designer

Product Sketched

1 Computer mouse

2 Sensor

3 Thermometer

4 Watch Bracket

5 Electric Fan

6 Chair

7 Flashlight, Mini fan & USB

5.2 Professional Designer Trial Analysis of Results

Figure 16 and Figure 17 shows the concepts that have been selected for each

product sketched by the professional designers. These figures illustrate the features

that the designers have selected and applied in their concept sketches. Figure 16

shows the concept of a computer mouse sketched by professional designer number

1. The features that can be seen from the sketch are transparent feature that shows

the internal element of the computer mouse. The blue light from the transparent

feature will enhance the aesthetics aspect of the computer mouse. Other features

that have been used are circular array and honey comb surface features that will

improve the ergonomic aspect and the surface friction for better gripping of the

computer mouse.

Table 42: Concept Sketches by Professional Designer

Figure 56: Concept of computer mouse sketched by professional designer number 1

Figure 17 shows the concept sketch that has been selected for the thermometer. In

this sketch the designer used the integrated ball and socket feature from the instant

assembly category. From the user fit requirement category the designer applied the

hand grip contour feature. From the customised form category the designer applied

the bio mimic feature (concept of a “humming bird”). From the weight reduction

category the non uniform wall thickness feature has been applied.

Figure 17: Concept of thermometer sketched by professional designer number 3

Range of features that have been used by the professional designers for each sub

category of applications for all three conceptual designs of the product are

summarised in Table 13. An overall observation of the list shows that the designers

had applied features from all the thirteen categories of applications from the feature

database. The weight reduction feature, instant assembly features, visual features,

customised form features, increase surface friction features, aesthetic requirement

surface feature, customise form feature and the fasteners removal features has been

applied in most of the conceptual sketches. Three specific features that was mostly

used from the feature database is the Internal selective reinforce feature under the

weight reduction application, mounting boss feature under the fasteners removal

application and the transparent feature under the aesthetics or form requirement

visual feature application. In summary, Table 13 shows that the feature database is

useful, relevant and helpful to support conceptual design of parts and product for AM

from the professional designers’ perspective.

5.3 Summary

The user trial conducted to see the usability and relevancy as a means of improving

the DfAM feature database developed in this research. The user trial was conducted

twice which involve the first trial with a group of student designers and the second

trial with a group of professional designers. Both trial shows that the DfAM feature

database provides ideas on how to incorporate various features to enhance and

improve part or products aesthetics, ergonomics and functionality.

Professional DesignersAM Reason Application Design Features 1 2 3 4 5 6 7 Total

User Fit Requirement

Customise Profiles

FeaturesHand Grip Contour x x 2

Improve functionality requirement


Thin Wall Feature x 1Variable Wall Thickness

Featurex x 2

Internal selective reinforce feature

x x x 3

Hollow Feature x 1Increase Surface Friction

Features

Textured Surface Feature x 1Circular Array Feature x x 2

Honey Comb Feature x 1

Internal structuring

feature

Internal cable support x 1

Internal shelving x x 2

Multiple version feature

Size variations x 1

Consolidation Requirement

Instant Assemblies

Features

Living Hinge Feature x x 2Integrated ball and socket

featurex 1

Internal Hinge Button Feature

x x 2

Enclosed Volume Feature x 1Fasteners Removal Features

Internal cable support x x 2Mounting Boss Feature x x x 3

Snap fit cap x 1Multiple

Functional Part

Multiple Elements x 1

Over Moulding

Over Moulding x x 2

Aesthetics or Form

Requirement

Embossed Features

Embossed Alphabets x x 2

Surface feature

Double Mesh Feature x 1Fingerprint Feature x 1Perforated Feature x x 2

Visual Features

Transparent Feature x x x 3

Customise form feature

Replicated Element x 1Bio- mimic feature x 1

Table 53: Range of features used by the professional designers

6. Conclusions

The objective of the DfAM design feature database is to enable industrial designers

to access and reuse design knowledge accumulated over the years, specifically the

features designed for laser sintered additive manufactured parts or products. It

allows designers to visualize and retrieve AM design feature information and

knowledge at the conceptual design stage. By providing four reasons for utilization of

AM with various design feature examples that fall under thirteen sub-categories of

applications, the DfAM feature database provides an innovative way to approach AM

part or product conceptual design. The tool enables fast conceptual idea generation

and to demonstrate AM design freedom to novice designers.

The AM design features taxonomy is seen as a useful aid for industrial designers to

understand the design freedom associated with AM. The classification of four taxons

that were further expanded into sub-categories of various design features is

anticipated to help designers to visualize and extract design feature information to

assist the AM design process.

This research has shown that the DfAM method of providing designers with

examples of design features from the database is a suitable strategy to aiding the

conceptual design of additive manufactured part or product. The next stages of the

research are to improve and validate the repository with responses from professional

industrial designers and to create a web based system to gather, present and to

exploit the prominence of design for AM.

References

Ariadi, Y. and A. E. W. Rennie (2008). Template for consumer use in designing customised products. 9th Annual International Solid Freeform Fabrication Sympsosium, The University of Texas at Austin.

Bibb, R., Z. Taha, et al. (1999). "Development of a rapid prototyping design advice system." Journal of Intelligent Manufacturing 10(3): 331-339.

Burton, M. J. (2005). Phd Thesis: Design for rapid manufacture: Developing an appropriate knowledge transfer tool for industrial designers. Faculty of Social Sciences & Humanities, Department of Design & Technology. Loughborough, Loughborough University: 229.

Byun, H. S. and K. H. Lee (2005). "A decision support system for the selection of a rapid prototyping process using the modified TOPSIS method." The International Journal of Advanced Manufacturing Technology 26(11): 1338-1347.

Campbell, R. I. and M. R. N. Bernie (1996). "Creating a database of rapid prototyping system capabilities." 12th International Conference on Computer Aided Production Engineering 61(1-2): 163-167.

Cheng, W., J. Y. H. Fuh, et al. (1995). "Multi-objective optimization of part- building orientation in stereolithography." Rapid Prototyping Journal 1(4): 12-23.

Gerber, G. F. and L. J. Barnard (2008). "Designing for Laser Sintering." Journal for New Generation Sciences 6(2): 12.

Hague, R., S. Mansour, et al. (2004). "Material and design considerations for rapid manufacturing." International Journal of Production Research 42(22): 4691 - 4708.

Jones, K. G. and R. I. Campbell (1997). Rapid Prototyping Decision Support System. Proceedings Fast Freeform Fabrication Symposium, University of Texas at Austin.

Kruf, W., B. Van de Vorst, et al. (2006). Design for Rapid Manufacturing functional SLS parts. Intelligent Production Machines and Systems. Oxford, Elsevier Science Ltd: 389-394.

Lan, P. T., S. Y. Chou, et al. (1997). "Determining fabrication orientation for rapid prototyping with stereolithography apparatus." Computer Aided Design 29(1): 53-62.

Masood, S. H. and A. Soo (2002). "A rule based expert system for rapid prototyping system selection." Robotics and Computer-Integrated Manufacturing 18(3-4): 267-274.

Munguia, J. (2008). A soft computing based model for RM selection and cost estimation. 2nd International Conference on Additive Technologies, DAAAM Specialized Conference.

Page, D., A. Koschan, et al. (2005). "3D CAD model generation of mechanical parts using coded-pattern projection and laser triangulation systems." Assembly Automation 25(3): 230-238.

Pandey, P. M., K. Thrimurtullu, et al. (2004). "Optimal part deposition orientation in FDM using a multi-criterion genetic algorithm." Int. J. Prod. Res. 42(19): 4069-4089.

Pandey, P. M., N. Venkata Reddy, et al. (2007). "Part deposition orientation studies in layered manufacturing." ICAMT 2004 (Malaysia) & CCAMT 2004 (India) Special Issue 185(1-3): 125-131.

Phillipson, D. (1997). Rapid Prototyping Machine Selection Programme. Proceedings of the 6th European Conference on Rapid Prototyping and Tooling.

Rao, R. V. and K. K. Padmanabhan (2007). "Rapid prototyping process selection using graph theory and matrix approach." Journal of Materials Processing Technology 194(1-3): 81-88.

Xu, F., Y. S. Wong, et al. (1997). "Optimal orientation with variable slicing in stereolithography." Rapid Prototyping Journal 3(3): 76-88.

My Journal Paper Sha Version 3

Documents

Transcript of My Journal Paper Sha Version 3