Intelligent Information Management, 2010, 2, 1-13
doi:10.4236/iim.2010.21001 Published Online January 2010 (http://www.scirp.org/journal/iim)
Using Rapid Prototyping Data to Enhance a
Knowledge-Based Framework for Product Redesign
Stefano FILIPPI1, Ilaria CRISTOFOLINI2
1DIEGM Department, University of Udine, Viale delle Scienze Udine, Italy
2DIMS Department, University of Trento, Via Mesiano Trento, Italy
Abstract
The particular characteristics of Rapid Prototyping technologies, both in terms of constrains and opportuni-
ties, often require the reconfiguration of the product model to obtain the best compliance with the product
functionalities and performances. Within this field of research, a knowledge-based tool named Design
GuideLines Collaborative Framework (DGLs-CF) was developed to support both the designers defining the
product consistently with the manufacturing technologies and the manufacturers defining the building setup
consistently with the product requirements. Present work is focused on enhancing the DGLs-CF knowledge
base and on updating the DGLs-CF knowledge management by using the information gathered on some RP
technologies. The added-value of this research is represented by an improvement in the Redesign/Reconfig-
uration Package, the final result of the DGLs-CF adoption. This is a list of actions to be performed on the
product model and on the process parameters to avoid the limitations of the technology and to exploit at best
its opportunities.
Keywords: rapid prototyping, knowledge-based engineering, product redesign, collaborative engineering
1. Introduction
The increasing complexity of design tasks and continu-
ous developments in technology require the improve-
ment of designers’ problem-solving capabilities, through
the development of Design for X (DfX) methods and
tools accordingly. Moreover, they must be flexible enou-
gh to allow an easy customization according to the evo-
lution of the technologies that they address. Up to now,
several examples of DfX appeared in the research land-
scape, as described in [1–11] The next research step was
to investigate the possibility of merging several DfXs
together in an integrated framework able to generate de-
sign guidelines related to more than one phase of the
product lifecycle. In this context, the Design GuideLines
Collaborative Framework (DGLs-CF) was developed as
a knowledge-based tool to help designers defining the
product consistently with manufacturing and verification
technologies. The aim of the DGLs-CF is to evaluate the
feasibility of the product (model) with available manu-
facturing technologies, to exploit the particular charac-
teristics of them and to measure the conformity of the
product to the requirements with specific verification
technologies [12].
Purpose of this work is enhancing the DGLs-CF
knowledge base and updating the DGLs-CF knowledge
management by exploiting the information related to
several Rapid Prototyping (RP) technologies. The goal is
to generate richer and more effective guidelines informa-
tion for the designers. RP technologies build physical
models starting directly from their CAD representations,
as this way costs and times are drastically reduced. They
are a very powerful tool in product development. New
products normally develop in Concurrent Engineering
environments where many actors play different roles; in
these scenarios it is of great help having a physical pro-
totype of the product, something tangible, which may
help communicating different skills and developing new
ideas [2,13–20]. The specific characteristics of the RP
technologies, however, are not so widely known in depth
and thus it is worthwhile customizing the DGLs-CF for
them. This may be a good way of helping non-expert
designers in exploiting the opportunities of RP technolo-
gies.
The paper opens with a short description of the DGLs-
CF and then goes on to describe the four RP technologies
selected for this research. The core section of the paper
concerns the data collection and their elaboration to get

S. FILIPPI ET AL.
2
compatibility with the knowledge base format inside the
DGLs-CF. Some considerations about the use of these
new pieces of information relating with specific classes
of products close the paper.
2. The DGLs-CF
The DGLs-CF is a decision support methodology aimed
at effectively helping and leading the activities of de-
signers, manufacturers and inspectors for product redes-
ign and process reconfiguration. The initial consideration
is that designers are not necessarily experts in manufac-
turing and verification processes; likewise, manufactur-
ers and inspectors are not experts in design. A detailed
description of the DGLs-CF appears in [12,21–23]The
DGLs-CF structure is shortly described in the next para-
graph using IDEF0 formalism [24]. IDEF0 is preferred to
more sophisticated description methods (UML, for ex-
ample) because its simplicity makes it a good tool for
sharing information in a concurrent engineering envi-
ronment, especially for non-expert users.
2.1. The DGLs-CF Roadmap
Shortly speaking, the DGLs-CF considers the set of
available technologies and the product to be redesigned
and suggests a list of actions – the Redesign/Reconfigu-
ration Package – to get the best compatibility.
The easiest way to describe this methodology is by
using the so-called DGLs-CF roadmap. It puts in the
correct logical order all the activities required by the
DGLs-CF adoption as well as the related algorithms and
modules. Figure 1 shows the main level of the IDEF0
diagram.
In the first setup phase (A1), the DGLs-CF is custom-
ized considering the characteristics of the class of the
available manufacturing and verification technologies as
well as the features characterising the product under
study. Technological characteristics and product features
are then related to each other using rules, which relate
the limitations (but sometimes also the opportunities) of
the technologies to each product feature. Rules are cou-
pled with expressions, which are needed to evaluate
Figure 1. Main level of the IDEF0 diagram of the DGLs-CF roadmap

S. FILIPPI ET AL. 3
quantitatively the compatibility of the existing version of
the product (model) with the available technologies.
When the compatibility is not present, the rules suggest
actions to be executed to overcome the limitations of the
technologies and to exploit their opportunities. It must be
noted that some actions may also affect different features
when they are performed on a single feature to gain its
compatibility. A “dynamic coefficient” is thus associated
to the actions, with its value determined by the amount of
features the action may affect. This value is decisive in
defining the sequence of actions during the generation of
the Redesign/Reconfiguration Package.
The Technological Configuration phase (A2) allows to
set the parameter values of the manufacturing and veri-
fication characteristics, given the specific brands/models
of the available equipments.
Finally, the Redesign/Reconfiguration Package Gen-
eration phase (A3) generates the list of actions (the Re-
design/Reconfiguration Package) to be applied to the
product (model) and to the technological process pa-
rameters by means of a recursive algorithm that evalu-
ates time by time different product (model) configura-
tions.
In this work the DGLs-CF knowledge base is en-
hanced with information related to some RP technologies;
for this reason the main characteristics of the RP tech-
nologies considered here are described in the following.
3. RP Technologies
The RP technologies considered here are Fused Deposi-
tion Modelling (FDM), Stereolithography (SLA), Selec-
tive Laser Sintering (SLS), and Laminated Object Manu-
facturing (LOM). All of these systems build parts in mul-
tiple thin layers and their main characteristics, which are
used in the DGLs-CF customisation, are summarised
hereafter [25–27].
3.1. Fused Deposition Modelling (FDM)
This technology extrudes a molten thermoplastic fila-
ment (ABS, polyolefin, polyamide...) through a nozzle in
the form of a thin ribbon and delivers it in computer-
controlled locations appropriate for the object geometry,
thus building the sections of the part. No high powered
lasers are used. Typically, the delivery head moves in the
horizontal plane while the support plane, where the part
is built, moves vertically, so that each section is built
over the previous one. The application temperature is
such that the applied material bonds firmly with the pre-
vious layer. Some support material may be necessary to
build the model, depending on the geometrical complex-
ity of the part and on its orientation inside the workspace.
The quantity and the shape of the support, which has to
be removed from the final part, are calculated automati-
cally. The first section is always built on a support plane,
which section is slightly larger than the model to allow
an easy removal of the part from the building platform.
Precision and surface finishing of the parts are affected
by the so-called”slicing” (the layering), which depends
on the kind of equipment used, and can vary typically
from 0.17 mm to 0.33 mm. The final parts do not need
post-processing, except for support removal and some
grinding for a better surface finishing.
3.2. Stereolithography (SLA)
A platform that can be lowered and elevated is usually
located the thickness of a layer below the surface of a
liquid photosensitive polymer contained in a tank. Each
slice is etched onto the surface of the photosensitive pol-
ymer that solidifies when exposed to the laser beam.
Once the laser has covered the whole surface of the layer,
the platform lowers to a depth of another layer thickness,
allowing the liquid resin to flow over the previously cur-
ed layer. A re-coating blade passes over the surface to
ensure that a consistent layer thickness is present before
the beginning of the next layer. Different building styles
for the prototypes can be used with a SLA system. Nor-
mal style involves building full resin prototypes while
other styles leaves some resin in the liquid state for dif-
ferent purposes (stresses minimization, generation of
models for investment casting, etc.). Supports are re-
quired when islands (portion of a layer that is discon-
nected from any other portion of the same layer), over-
hangs, or cantilevered sections exist in the part being built.
SLA parts have good surface texture and dimensional
accuracy, however the orientation of the model in the
workspace (due to the staircase effect) and the presence
of support can influence the surface finishing. At the end
of the building phase the model is carefully removed
from the platform and a post-curing phase is performed,
in a UV-beam oven, to completely solidify the part.
3.3. Selective Laser Sintering (SLS)
Here the object is built over a platform, where a layer of
plastic, metal or ceramic powder (particle size approxi-
mately 50μm) is spread and kept heated. A laser beam
melts the powder particles selectively. As the layer is
finished, the platform moves down by the thickness of
one layer (approximately 0.10–0.15 mm), and a new
layer of powder is spread on the previous one. When the
laser exposes the new layer, it melts and bonds to the
previous one. The process repeats until the part is com-
plete. Surrounding powder particles act as supporting

S. FILIPPI ET AL.
4
material for the objects but in any case additional struc-
tures are needed during the building of overhangs. SLS
parts have average surface texture and dimensional ac-
curacy, the quality being mainly influenced by the pow-
der particle size. On completion, the built volume has to
cool down to room temperature after which the proc-
essed objects can be removed from the powder bed by
brushing away excess powder. Sandblasting or other fin-
ishing manufacturing techniques are used to remove all
un-sintered particles and to improve the final accuracy of
the sintered objects. Of course in this case the support
removal is not straightforward and requires special ma-
chining and tools.
3.4. Laminated Object Manufacturing (LOM)
In this technology, a sheet of thick paper (coming from a
feed roll) with a polyethylene coating on the reverse side
is placed on a platform. The coating is melted by a
heated roller making the paper adhere to the building
platform that, just like the technologies described before,
can lower and lift along the Z axis. A laser then cuts the
paper following the boundaries of the section of the ob-
ject. The laser also creates hatch marks, which generate a
collection of cubes in the final building volume of glued
paper. These cubes behave as a support structure for the
overhangs of the model. When the laser has finished the
layer, a new paper sheet is applied. At the end of the job,
the model is captured within a block of paper. When all
of the surrounding cubes have been removed, the unfin-
ished part is sanded down. In the case of cavities prob-
lems could be faced in the removal of the paper cubes.
The natural sensitivity of the paper to humidity and
temperature can be reduced by coating the model. The
surface finishing and the accuracy of the model are not to
the same standard as the other methods, however objects
have the look and feel of wood and thus can be worked
and finished like wood.
4. DGLs-CF Knowledge Base Enhancement
4.1. Collection of Data
The aim of this work is the enhancement of the DGLs-
CF knowledge base with pieces of information coming
from the RP field. The attention is focused on the manu-
facturing characteristics, in order to determine the com-
patibility between the RP technologies and the products.
Interviews with expert users and to equipment manufac-
turers, the previous experience of the authors, papers,
user manuals and brochures, etc., have been the sources
used for data collection. The goal of this task is to collect
the characteristics of the four RP technologies described
previously and to identify the related parameters that will
be used afterwards by the DGLs-CF users to describe the
available equipments [28–38].
4.2. Insertion of Data in the DGLs-CF
The DGLs-CF data structure is organized in tables.
Those concerned with in this research have a left side
where the characteristics of the class of technology and
the related parameters are listed and a right side where
the values of the parameters are set, given the specific
available equipment. In this research, only the left side is
considered, given that the goal is to characterize classes
of RP technologies and not specific equipments. The
information concerning the four RP technologies consid-
ered in this paper are inserted in the DGLs-CF data
structure, the result is reported in Table 1 (FDM), Table 2
(SLA), Table 3 (SLS), and Table 4 (LOM).
Some characteristics are common to all the RP tech-
nologies considered, as they are intrinsic to the “nature”
of the technologies themselves, these being the volume
of the manufacturing workspace, the slicing (all the tech-
nologies build the models by layers) and the kind of ma-
terial. Another important issue to consider in determining
the compatibility between the RP technology and the
product is the need for support for all of them, except for
the LOM. SLA and SLS also allow the definition of the
building style, as hatching and contouring style, and this
characteristic also affects the product features.
5. Discussion
The outcomes of the activities described previously are
presented here as an overview of the added-value of this
result of this research inside the DGLs-CF. As seen be-
fore, in the DGLs-CF all the technological characteristics
and the product features are expressed in terms of the
related parameters. These features are described in the
DGLs-CF data structure in another important table where
again the left side contains the parameters allowing to
describe a class of products, while the right side is filled
by the parameter values of the specific product under
study. The analysis of the RP parameters of Tables 1,2,3,
and 4 suggests to identify some classes of products,
which can be specifically considered here to highlight
the enhancement in the DGLs-CF knowledge base. Table
5 shows the collected product features describing plastic
front covers, Table 6 for headlights, Table 7 for moulds
for headlights and Table 8 for dashboards. The right side
of these tables is different from the technology-related
ones as there is more than one column to highlight that
the information processing in the DGLs-CF comes in an

S. FILIPPI ET AL.
5
Table 1. Parametric manufacturing characteristics for the FDM technology
Characteristic
Label Name Description Parameters
Parameter values of the
specific available
equipment
M1 Workspace
Volume of the manu-
facturing workspace
Workspace_x, Workspace_y, Workspace_z: dimensions
of the manufacturing workspace
Workspace_x=…
Workspace_y=…
Workspace_z=…
Material_wire: diameter of the wire Material_wire=…
Material_: mechanical properties of the material
(minimum strength) Material_=…
M2 Material Kind of material used
Material_tx, Material_ty, Material_tz: dimensional
tolerances related to the material
Material_tx=…
Material_ty=…
Material_tz=…
Slicing_zmin: minimum thickness of the slice Slicing_zmin=…
Slicing_x, Slicing _y, Slicing _z: mechanical properties
(minimum strength in the three dimensions)
Slicing_x=…
Slicing _y=…
Slicing _z=…
M3 Slicing
Material deposed slice
by slice
Slicing_Ra_z: minimum obtainable roughness in z direction Slicing_Ra_z=…
Support_x, Support_y, Support_z: support dimensions
Support_x=…
Support_y=…
Support_z=…
Support_: critical angle for supports removal (angle between the
vertical wall and the overhang) Support_=…
M4 Support
Support needed when
building overhangs/
sloped surfaces or
cavities
Support_Ra_xy: minimum obtainable roughness in xy plane Support_Ra_xy=…
Table 2. Parametric manufacturing characteristics for the SLA technology
Characteristic
Label Name Description Parameters
Parameter values of the
specific available equip-
ment
M1 Workspace
Volume of the
manufacturing
workspace
Workspace_x, Workspace_y, Workspace_z: dimensions
of the manufacturing workspace
Workspace_x=…
Workspace_y=…
Workspace_z=…
Material_: mechanical properties of the material (minimum strength) Material_=…
Material_Ra_xy: minimum obtainable roughness in xy plane
related to the material Material_Ra_xy=…
M2 Material
Kind of material
used Material_tx, Material_ty, Material_tz: dimensional tolerances
related to the material
Material_tx=…
Material_ty=…
Material_tz=…
Slicing_zmin: minimum thickness of the slice related to slicing Slicing_zmin=…
Slicing_x, Slicing_y, Slicing_z: mechanical properties
(minimum strength in the three dimensions) related to slicing
Slicing_x=…
Slicing_y=…
Slicing_z=…
M3 Slicing
Material deposed
slice by slice
Slicing_Ra_z: minimum obtainable roughness in z direction
related to slicing Slicing_Ra_z=…
Support_x, Support_y, Support_z: support dimensions
Support_x=…
Support_y=…
Support_z=…
Support_: critical angle for supports removal (angle between the
vertical wall and the overhang) Support_=…
M4 Support
Support needed
when building
overhangs/sloped
surfaces or cavi-
ties
Support_Ra_xy: minimum obtainable roughness in xy plane Support_Ra_xy=…
Building_style_x, Building_style_y, Building_style_z: mechani-
cal properties (minimum strength in the three dimensions) related to
hatching and contouring style
Building_style_x=…
Building_style_y=…
Building_style_z=…
Building_style_Ra_xy: minimum obtainable roughness in xy plane
related to hatching and contouring style Building_style_Ra_xy=…
M5 Building
style
Different building
styles
Building_style_Ra_z: minimum obtainable roughness in z
direction related to hatching and contouring style Building_style_Ra_z=…

S. FILIPPI ET AL.
6
Table 3. Parametric manufacturing characteristics for the SLS technology
Characteristic
Label Name Description Parameters
Parameter values of the
specific available
equipment
M1 Workspace
Volume of the
manufacturing
workspace
Workspace_x, Workspace_y, Workspace_z: dimensions of the
manufacturing workspace
Workspace_x=…
Workspace_y=…
Workspace_z=…
Material_zmin: minimum thickness of the slice related to the particle size Material_zmin=…
Material_: mechanical properties of the material (minimum strength) Material_=…
M2 Material
Kind of material
used
Material_Ra_xy: minimum obtainable roughness in xy plane related to the
particle size Material_Ra_xy=…
Slicing_zmin: minimum thickness of the slice related to slicing Slicing_zmin=…
Slicing_x, Slicing_y, Slicing_z: mechanical properties
(minimum strength in the three dimensions) related to slicing
Slicing_x=…
Slicing_y=…
Slicing_z=…
M3 Slicing
Material deposed
slice by slice
Slicing_Ra_z: minimum obtainable roughness in z direction related to slicing Slicing_Ra_z=…
Support_x, Support_y, Support_z: support dimensions
Support_x=…
Support_y=…
Support_z=…
Support_: critical angle for supports removal
(angle between the vertical wall and the overhang) Support_=…
M4 Support
Support needed
when building
overhangs/sloped
surfaces or cavities
Support_Ra_xy: minimum obtainable roughness in xy plane Support_Ra_xy=…
Building_style_x, Building_style_y, Building_style_z: mechanical
properties (minimum strength in the three dimensions) related related to
hatching and contouring style
Building_style_x=…
Building_style_y=…
Building_style_z=…
Building_style_Ra_xy: minimum obtainable roughness in xy plane
related to related to hatching and contouring style Build- ing_style_Ra_xy=…
M5 Building
style
Different building
styles
Building_style_Ra_z: minimum obtainable roughness in z direction
related to related to hatching and contouring style Build- ing_style_Ra_z=…
Table 4. Parametric manufacturing characteristics for the LOM technology
Characteristic
Label Name Description Parameters
Parameter values of
the specific available
equipment
M1 Workspace
Volume of the
manufacturing
workspace
Workspace_x, Workspace_y, Workspace_z: dimensions
of the manufacturing workspace
Workspace_x=…
Workspace_y=…
Workspace_z=…
Material_zmin: minimum thickness of the slice related to
the paper thickness Material_zmin=…
Material_ mechanical properties of the material (minimum
strength in the three dimensions) Material_=…
Material_Ra_xy: minimum obtainable roughness in xy plane
related to the material Material_Ra_xy=…
M2 Material Kind of material
used
Material_tx, Material_ty, Material_tz: dimensional
tolerances related to the material
Material_tx=…
Material_ty=…
Material_tz=…
Slicing_x, Slicing_y, Slicing_z: mechanical properties
(minimum strength in the three dimensions) related to slicing
Slicing_x=…
Slicing_y=…
Slicing_z=…
M3 Slicing Material deposed
slice by slice Slicing_Ra_z: minimum obtainable roughness in z direction
related to slicing Slicing_Ra_z=…

S. FILIPPI ET AL.
7
Table 5. Parametric product features for plastic front covers
Product feature Parameter
values of the
product (model)
(iterations)
Label Name Description Parameters
Labels
I II
Bounding_box_X =…=…
Bounding_box_Y =…=…
F1 Bounding
box
Overall dimensions
of the product
Bounding_box_X, Bounding_box_Y,
Bounding_box_Z: maximum dimensions
Bounding_box_Z =…=…
Minimum_dimensions_x =…=…
Minimum_dimensions_x,
Minimum_dimensions_y: minimum
dimensions in horizontal plane
Minimum_dimensions_y =…=… F2 Minimum
dimensions
Minimum
dimensions in
the product
Minimum_dimensions_z: minimum thickness Minimum_dimensions_z =…=…
F3
Overhangs/
Sloped
surfaces
Overhangs and
protrusions
Overhangs/Sloped_surfaces_: over-
hangs/sloped surfaces angle (angle between
the vertical wall and the overhang)
Overhangs/Sloped_surfaces_ =… =…
Cavities_x =…=…
Cavities_x, Cavities_y: minimum dimensions
Cavities_y =…=…
Cavities_d: maximum depth Cavities_d =…=…
F4 Cavities
Through and blind
holes, undercuts
and other cavities
Cavities_: angle between the vertical wall
and the axis of the cavity Cavities_ =… =…
Surface_finishing_Ra_xy_max: maximum
allowable roughness in the horizontal plane Surface_finishing_Ra_xy_max =…=…
F5 Surface
finishing Surface texture
Surface_finishing_Ra_z_max: maximum
allowable roughness in the vertical plane Surface_finishing_Ra_z_max =…=…
Mechanical_properties_x =… =…
Mechanical_properties_y =… =…
F6 Mechanical
properties
Main mechanical
properties
Mechanical_properties_x,
Mechanical_properties_y,
Mechanical_properties_z: minimum
mechanical strength in the three directions
Mechanical_properties_z =… =…
F7 Cylindrical
shapes
Minimum curvature
radius of cylindrical
shapes
Cylindrical_shapes_rmin: minimum
curvature radius Cylindrical_shapes_rmin: mini- mum curvature radius =… =…
Shrinkage_tx =…=…
Shrinkage_ty =…=…
F8 Shrinkage
Shrinkage effect of
the material
Shrinkage_tx, Shrinkage_ty, Shrinkage_tz:
Dimensional tolerances
Shrinkage_tz =…=…
iterative way. The product (model) is analyzed for com-
patibility with the available technologies, some actions
are performed and the resulting product (model) is proc-
essed from the beginning (new iteration).
Finally, Table 9, Table 10, Table 11, and Table 12 show
the relations between the technological characteristics
and the product features, expressed in a qualitative way,
for each meaningful couple technology/product.
This result is important because, as stated in the sec-
tion of the DGLs-CF overview, the following step of the
DGLs-CF roadmap consists in generating the rules that
will be the source of the actions to be performed on the
product (model) to get the best compatibility. The values
“Strong” and “Weak” drive the rule and action definition

S. FILIPPI ET AL.
8
Table 6. Parametric product features for headlights
Product feature Parameter values
of the product
(model)
(iterations)
Label Name Description Parameters
Labels
I II
Bounding_box_X =… =…
Bounding_box_Y =… =…
F1 Bounding
box
Overall dimensions
of the product
Bounding_box_X, Bounding_box_Y, Bounding_box_Z:
maximum dimensions
Bounding_box_Z =… =…
Minimum_dimensions_x =… =…
Minimum_dimensions_x, Minimum_dimensions_y:
minimum dimensions in horizontal plane Minimum_dimensions_y =… =…
F2 Minimum
dimensions
Minimum
dimensions in the
product Minimum_dimensions_z: minimum thickness Minimum_dimensions_z =… =…
F3
Overhangs/
Sloped
surfaces
Overhangs and
protrusions
Overhangs /Sloped _surfaces_ : overhangs/sloped
surfaces angle (angle between the vertical wall
and the overhang)
Overhangs/
Sloped_s urfaces_  =… =…
Cavities_x =… =…
Cavities_x, Cavities_y: minimum dimensions
Cavities_y =… =…
Cavities_d: maximum depth Cavities_d =… =…
F4 Cavities
Through and blind
holes, undercuts and
other cavities
Cavities_: angle between the vertical wall and the axis
of the cavity Cavities_ =… =…
Surface_finishing_Ra_xy_max: maximum allowable
roughness in the horizontal plane
Surface_finishing_
Ra_xy_max =… =…
F5 Surface
finishing Surface texture
Surface_finishing_Ra_z_max: maximum allowable
roughness in the vertical plane
Surface_finishing_
Ra_z_max =… =…
Mechanical_properties_x =… =…
Mechanical_ prop erties_y =… =…
F6 Mechanical
properties
Main mechanical
properties
Mechanical_ prop erties_x, Mechanical_properties_y,
Mechanical_ prop erties_z: minimum mechanical
strength in the three directions
Mechanical_ prop erties_z =… =…
F7 Cylindrical
shapes
Minimum
curvature radius
of cylindrical shapes
Cylindrical_shapes_rmin: minimum curvature radiusCylindrical_shapes_rmin:
minimum curvature radius =… =…
Shrinkage_tx =… =…
Shrinkage_ty =… =…
F8 Shrinkage
Shrinkage effect of
the material
Shrinkage_tx, Shrinkage_ty, Shrinkage_tz: Dimensional
tolerances
Shrinkage_tz =… =…
Influence_of_environment_x =… =…
Influence_of_environment_y =… =…
Influence_of_environment_x, Influ-
ence_of_environment_y, Influ-
ence_of_environment_z: minimum mechanical
strength in the three directions Influence_of_environment_z =… =…
Influence_of_environment_x =… =…
Influence_of_environment_y =… =…
Influence_of_environment_x, Influ-
ence_of_environment_y, Influ-
ence_of_environment_z: maximum deflection in the
three directions Influence_of_environment_z =… =…
F9 Influence of
environment
Environment influ-
ence on materials
(humidity, tempera-
ture, …)
Influence_of_environment_KIc: fracture toughness indexInfluence_of_environment_KIc =… =…
F10 Free-form
surfaces
Complex shape
surfaces Free-form_surfaces_c: curvature Free-form_surfaces_c =… =…
Ribs/webs_zmin:_minimum rib thickness Ribs/webs_zmin =… =…
F11 Ribs/webs Supports or net of
supports Rib s/webs_ : angle between the
vertical wall and the rib inclination Ribs/web s_ =… =…
Pins__eqmin: minimum equivalent
diameter of a section Pins__eqmin =… =…
F12 Pins
Small structures
with circular or
prismatic section Pins_h/ _eq: height/ equivalent
diameter of a section ratio Pins_h/ _eq =… =…

S. FILIPPI ET AL. 9
Table 7. Parametric product features for moulds for headlights
Product feature Parameter values
of the product
(model)
(iterations)
Label Name Description Parameters
Labels
I II
Bounding_box_X =… =…
Bounding_box_Y =… =… F1 Bounding box
Overall dimensions
of the product
Bounding_box_X, Bounding_box_Y,
Bounding_box_Z: maximum
dimensions
Bounding_box_Z =… =…
Minimum_dimensions_x =… =… Minimum_dimensions_x,
Minimum_dimensions_y: minimum
dimensions in horizontal plane
Minimum_dimensions_y: =… =… F2 Minimum
dimensions
Minimum dimen-
sions in the product
Minimum_dimensions_z: minimum
thickness Minimum_dimensions_z =… =…
F3
Overhangs/
Sloped sur-
faces
Overhangs and
protrusions
Overhangs/Sloped_surfaces_:
overhangs/sloped surfaces angle
(angle between the vertical wall and
the overhang)
Overhangs/Sloped_surfaces_ =… =…
Cavities_x =… =…
Cavities_x, Cavities_y: minimum
dimensions
Cavities_y =… =…
Cavities_d: maximum depth Cavities_d =… =…
F4 Cavities
Through and blind
holes, undercuts and
other cavities
Cavities_: angle between the verti-
cal wall and the axis of the cavity Cavities_ =… =…
Surface_finishing_Ra_xymax:
maximum allowable roughness in the
horizontal plane
Surface_finishing_Ra_xymax =… =…
F5 Surface
finishing Surface texture Surface_finishing_Ra_zmax:
maximum allowable roughness
in the vertical plane
Surface_finishing
_Ra_zmax =… =…
Mechanical_properties_x =… =…
Mechanical_properties_y =… =…
F6 Mechanical
properties
Main mechanical
properties
Mechanical_properties_x,
Mechanical_properties_y,
Mechanical_properties_z:
minimum mechanical strength
in the three directions
Mechanical_properties_z =… =…
F7 Cylindrical
shapes
Minimum curvature
radius of cylindrical
shapes
Cylindrical_shapes_rmin: minimum
curvature radius Cylindrical_shapes_rmin =… =…
Shrinkage_tx =… =…
Shrinkage_ty =… =… F8 Shrinkage
Shrinkage effect of
the material
Shrinkage_tx, Shrinkage_ty,
Shrinkage_tz: Dimensional
tolerances
Shrinkage_tz =… =…
Influence_of_environment_x =… =…
Influence_of_environment_y =… =…
Influence_of_environment_x,
Influence_of_environment_y,
Influence_of_environment_z:
minimum mechanical strength
in the three directions
Influence_of_environment_z =… =…
Influence_of_environment_x =… =…
Influence_of_environment_y =… =…
Influence_of_environment_

x,
Influence_of_environment_y,
Influence_of_environment_z:
maximum deflection in the
three directions Influence_of_environment_z =… =…
F9 Influence of
environment
Environment influ-
ence on materials
(humidity, tempera-
ture, …)
Influence_of_environment_KIc:
fracture toughness index Influence_of_environment_KIc =… =…
F10 Free-form
surfaces
Complex shape
surfaces Free-form_surfaces_c: curvature Free-form_surfaces_c =… =…
Pins _
_
eqmin: minimum equivalent
diameter of a section Pins __eqmin =… =…
F11 Pins
Small structures
with circular or
prismatic section Pins_h/_eq: height/ equivalent
diameter of a section ratio Pins_h/_eq =… =…

S. FILIPPI ET AL.
10
Table 8. Parametric product features for dashboards
Product feature Parameter values
of the product
(model)
(iterations)
Label Name Description Parameters Labels
I II
Bounding_box_X =… =…
Bounding_box_Y =… =…
F1 Bounding box Overall dimensions of
the product
Bounding_box_X, Bounding_box_Y,
Bounding_box_Z: maximum dimensionsBounding_box_Z =… =…
Minimum_dimensions_x =… =…Minimum_dimensions_x,
Minimum_dimensions_y: minimum
dimensions in horizontal plane Minimum_dimensions_y: =… =… F2 Minimum
dimensions
Minimum dimensions in
the product Minimum_dimensions_z: minimum
thickness Minimum_dimensions_z =… =…
F3 Overhangs/
Sloped surfaces
Overhangs and
protrusions
Overhangs/Sloped_surfaces_:
overhangs/sloped surfaces angle (angle
between the vertical wall and the overhang)
Overhangs/Sloped_surfaces_ =… =…
Cavities_x =… =…Cavities_x, Cavities_y: minimum
dimensions Cavities_y =… =…
Cavities_d: maximum depth Cavities_d =… =…
F4 Cavities
Through and blind holes,
undercuts and other cavi-
ties Cavities_: angle between the vertical wall
and the axis of the cavity Cavities_ =… =…
Surface_finishing_Ra_xymax: maximum
allowable roughness in the horizontal planeSurface_finishing_Ra_xymax =… =…
F5 Surface
finishing Surface texture Surface_finishing_Ra_zmax: maximum
allowable roughness in the vertical planeSurface_finishing_Ra_zmax =… =…
Mechanical_properties_x =… =…
Mechanical_properties_y =… =…
F6 Mechanical
properties
Main mechanical proper-
ties
Mechanical_properties_x,
Mechanical_properties_y,
Mechanical_properties_z: minimum
mechanical strength in the three directionsMechanical_properties_z =… =…
F7 Cylindrical
shapes
Minimum curvature radius
of cylindrical shapes
Cylindrical_shapes_rmin: minimum
curvature radius Cylindrical_shapes_rmin =… =…
Pins __eqmin: minimum equivalent
diameter of a section Pins __eqmin =… =…
F8 Pins
Small structures
with circular or
prismatic section Pins_h/_eq: height/ equivalent diameter
of a section ratio Pins_h/_eq =… =…
Influence_of_environment_x =… =…
Influence_of_environment_y =… =…
Influence_of_environment_x,
Influence_of_environment_y,
Influence_of_environment_z: minimum
mechanical strength in the three directionsInfluence_of_environment_z =… =…
Influence_of_environment_x =… =…
Influence_of_environment_y =… =…
Influence_of_environment_x,
Influence_of_environment_y,
Influence_of_environment_z: maximum
deflection in the three directions Influence_of_environment_z =… =…
F9 Influence of
environment
Environment influence on
materials (humidity,
temperature, …)
Influence_of_environment_KIc: fracture
toughness index Influence_of_environment_KIc =… =…
F10 Free-form
surfaces
Complex shape
surfaces Free-form_surfaces_c: curvature Free-form_surfaces_c =… =…
Table 9. Relations between FDM manufacturing characteristics and the product features for plastic front covers
F1 F2 F3 F4 F5 F6 F7 F8
Bounding
box
Minimum
dimensions
Overhangs/
Sloped
surfaces
Cavities Surface
finishing
Mechanical
properties
Cylindrical
shapes Shrinkage
M1 Workspace Strong
M2 Material Weak Weak Weak Strong Strong
M3 Slicing Strong Strong Strong Strong Strong Strong
M4 Support Strong Strong Strong Weak Weak Weak

S. FILIPPI ET AL. 11
Table 10. Relations between SLA manufacturing characteristics and the product features for headlights
F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12
Bounding
box
Minimum
dimensions
Overhangs/
Sloped
surfaces
Cavities Surface
finishing
Mechanical
properties
Cylindrical
shapes Shrinkage Influence of environment
Free-form
surfaces
Ribs/
webs Pins
M1 Workspace Strong
M2 Material StrongStrong Weak Strong
M3 Slicing Strong Weak StrongStrong Strong Weak Strong StrongStrong
M4 Support Strong Strong StrongStrong Weak Strong StrongStrong
M5 Building
style Weak Weak WeakWeak Weak Weak Strong Weak
Table 11. Relations between SLS manufacturing characteristics and the product features for moulds for headlights
F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11
Bounding
box
Minimum
dimensions
Overhangs/
Sloped
surfaces
Cavities Surface
finishing
Mechanical
properties
Cylindrical
shapes Shrinkage Influence of environment
Free-form
surfaces Rib s/webs
M1 Workspace Strong
M2 Material StrongStrong Strong Strong
M3 Slicing Strong Weak StrongStrong Weak Strong Weak Strong Strong
M4 Support Strong Strong StrongStrong Weak Strong Strong
M5 Building
style Weak Weak StrongWeak Strong Weak Strong Weak
Table 12. Relations between LOM manufacturing characteristics and the product features for dashboards
F1 F2 F3 F4 F5 F6 F7 F8 F9 F10
Bounding
box
Minimum
dimensions
Overhangs/
Sloped
surfaces
Cavities Surface
finishing
Mechanical
properties Cylindrical shapesPins Influence of environment
Free-form
surfaces
M1 Workspace Strong
M2 Material Strong Weak StrongStrongStrong Strong
M3 Slicing Weak Weak StrongWeak Strong Strong Strong Weak Strong
Table 13. Reconfiguration package for a headlight to be produced by SLA
Actions Relationships
Domain
Name Goals CostFeatures
Technological
characteristics Weight
Slicing Strong
Support Strong Design Over-dimensi
on thin parts
to make them
compatible with the
need for supports, the
slicing and the material
8 Minimum
dimensions
Building style Weak
Material Strong
Slicing Strong
Support Strong
Manufacturing Orient the
model
to avoid the need for
support on surfaces
requiring best
roughness
5 Surface finishing
Building style Weak
Reconfiguration
Package
Verification
Rotate and
incline the
measuring
head
to obtain best
accessibility to the
overhangs and
the minimum
re-positioning
2 Overhangs/Sloped
surfaces Support Strong

S. FILIPPI ET AL.
12
by weighting the importance of the pieces of information
inside the DGLs-CF data structure, thus leading to a
more effective Redesign/Reconfiguration Package gene-
ration.
Table 13 shows an example of Redesign/Reconfigura-
tion Package generated using the DGLs-CF during the
redesign of a headlight to be built with SLA. The strong-
weak classification - degree of correlation - of the rela-
tionships between technological characteristics and pro-
duct features has been exploited by the DGLs-CF algo-
rithm used to generate this package. Moreover, the clas-
sification has been explicitly added to the package as a
further help for the DGLs-CF users.
6. Conclusions
This paper describes the knowledge base enhancement
and the knowledge management update of a method for
product redesign and process reconfiguration named De-
sign Guidelines – Collaborative Framework (DGLs-CF).
Information collected using different strategies and from
different sources (interviews, previous experiences, do-
cumentation, etc,) is formatted according to the data
structure of this framework. These additional pieces of
information enrich the knowledge base content of the
method and make it tailored on the specific technologies.
The specific characteristics of the RP technologies are in
fact related to the product features and their relationships
are weighted, thus allowing to privilege the actions de-
termined by strong relationships in achieving the final
result of the framework. Moreover, the analysis of these
pieces of information suggested some interesting impro-
vements of the knowledge management inside the DGLs-
CF. An example of application of the DGLs-CF is shown:
the Redesign/ Reconfiguration Package - a list of actions
to be performed on the product (model) and/or on the
process to get the best compatibility between the product
and the manufacturing technology - related to a headlight
to be produced by SLA.
In the future the same activities will be used for gath-
ering data related to other technologies. In the meantime,
this work suggests to evaluate all the parameters in the
four tables of the technologies with respect to those in
the four tables of the product features. In doing this, the
affinity between some classes of technologies and some
classes of products coming from experience could be
confirmed or not.
7. Acknowledgments
Authors would like to thank for her precious help Dr.
Barbara Motyl, researcher at the DIEGM dept. of the
University of Udine, Italy.
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