Εργαστήριο Μηχανολογίας Ακριβείας και Αντίστροφης Μηχανικής

3d modelling and manufacturing research activities at
the TEI of Crete
Petousis Markos
Dr. Mechanical Engineer
Technological Education Institute of Crete, Mechanical Engineering Department

d modelling and manufacturing research activities at the TEI of Crete
IntroductionIntroduction
The CNC Machining and Prototyping Laboratory of the Mechanical Engineering Department wasThe CNC Machining and Prototyping Laboratory of the Mechanical Engineering Department was
established in 2008 by the TEI of Crete in partnership with European and private funding.established in 2008 by the TEI of Crete in partnership with European and private funding.
Laboratory cover an area of 500 m2.Laboratory cover an area of 500 m2.
Its equipment are the most recent in their field, acquired in 2008.Its equipment are the most recent in their field, acquired in 2008.
It has a facility with 30 computer stations to design and develop products.It has a facility with 30 computer stations to design and develop products.

IntroductionIntroduction
In brief the research technology areas that can be supportedIn brief the research technology areas that can be supported
are:are:
Design and development of new products.Design and development of new products.
Support any activities in the “3d scanning – 3d modellingSupport any activities in the “3d scanning – 3d modelling
– 3d printing – rapid tool making” processes chain.– 3d printing – rapid tool making” processes chain.
High precision mechanical processes.High precision mechanical processes.
Most of the potential users of this lab’s services fall into one ofMost of the potential users of this lab’s services fall into one of
these categories:these categories:
Medical engineering.Medical engineering.
Industries.Industries.
Research and development projects.Research and development projects.
This work is focusing on the research activities andThis work is focusing on the research activities and
achievements of the laboratory, which are in three, interactingachievements of the laboratory, which are in three, interacting
with each other, areas.with each other, areas.

Laboratory Research AreasLaboratory Research Areas
Three dimensional geometric modellingThree dimensional geometric modelling
Support for digital data production.Support for digital data production.
Conformity of three dimensional design models to theConformity of three dimensional design models to the
requirements of international standards (ISO, EN, DIN, etc.).requirements of international standards (ISO, EN, DIN, etc.).
Application of geometric, functional and aesthetic limitations.Application of geometric, functional and aesthetic limitations.
Software tools for computer aided activities: CAD, CAM.Software tools for computer aided activities: CAD, CAM.
Advanced numerical techniques (CAE) to simulate theAdvanced numerical techniques (CAE) to simulate the
functional behaviour of parts with the finite element analysesfunctional behaviour of parts with the finite element analyses
(FEA) method.(FEA) method.
Document and protect the intellectual work arising from suchDocument and protect the intellectual work arising from such
research and development activities.research and development activities.

Reverse EngineeringReverse Engineering
Design and manufacture an identical, similar or completelyDesign and manufacture an identical, similar or completely
different prototype.different prototype.
The geometry of an existing physical item is scanned by a laserThe geometry of an existing physical item is scanned by a laser
scanner creating a cloud of points in space.scanner creating a cloud of points in space.
This cloud of points is transformed into a digital file and then isThis cloud of points is transformed into a digital file and then is
processed with a CAD programme.processed with a CAD programme.
The digital geometric model can be downloaded to the 3dThe digital geometric model can be downloaded to the 3d
printer to make an identical copy of the original.printer to make an identical copy of the original.
The prototype that the 3d printer makes is a fully functionalThe prototype that the 3d printer makes is a fully functional
prototype.prototype.
It can be used for casting, therefore producing products inIt can be used for casting, therefore producing products in
small quantities.small quantities.

LeptomechanicsLeptomechanics
Numeric control is the basis of many modern engineeringNumeric control is the basis of many modern engineering
processes and machinery.processes and machinery.
A program code replaces the individual manual processesA program code replaces the individual manual processes
done by the operator.done by the operator.
AdvantagesAdvantages: Greatest accuracy possible and ability to: Greatest accuracy possible and ability to
continuously produce the same items.continuously produce the same items.
A CNC milling machine can produce:A CNC milling machine can produce:
Flat surfaces, product outlines, inlets, grooves, hollowFlat surfaces, product outlines, inlets, grooves, hollow
surfaces, threads, gears, helical surfaces, freeformsurfaces, threads, gears, helical surfaces, freeform
surfaces, among others.surfaces, among others.
These capabilities make milling machines ideal for the makingThese capabilities make milling machines ideal for the making
of parts, customized machinery, tools, moulding casts.of parts, customized machinery, tools, moulding casts.
A CNC lathe can produce:A CNC lathe can produce:
Axisymmetric objects, flat and hollow surfaces, grooves,Axisymmetric objects, flat and hollow surfaces, grooves,
holes, conical surfaces, threads and other geometries.holes, conical surfaces, threads and other geometries.

Laboratory Research Projects and ActivitiesLaboratory Research Projects and Activities
3d geometric modelling3d geometric modelling  reverse engineeringreverse engineering
3d geometric modelling3d geometric modelling  leptomechanicsleptomechanics
Development and manufacturing of mechanisms for researchDevelopment and manufacturing of mechanisms for research
projects. Most of the parts are manufactured in house.projects. Most of the parts are manufactured in house.
Most of the parts nowadays in the laboratory are 3d printed.Most of the parts nowadays in the laboratory are 3d printed.
This is because of the ease of use of the technology, whichThis is because of the ease of use of the technology, which
doesn’t require codes programming, specialized tools anddoesn’t require codes programming, specialized tools and
significant technical knowledge, to build a part.significant technical knowledge, to build a part.
In 3d printing the build time is related mainly on the part sizeIn 3d printing the build time is related mainly on the part size
and not on its complexity.and not on its complexity.
For these reasons it has been used for the build of very smallFor these reasons it has been used for the build of very small
to very large parts.to very large parts.
CNC only for metal parts.CNC only for metal parts.

Functional mechanisms: Robotic HandFunctional mechanisms: Robotic Hand
All the mechanical parts in the fingers and the palm are 3dAll the mechanical parts in the fingers and the palm are 3d
printed.printed.
The major challenge of this project, was to design parts thatThe major challenge of this project, was to design parts that
can be assembled and have size as closed as possible to thecan be assembled and have size as closed as possible to the
real thing and on the same time have adequate shape to hostreal thing and on the same time have adequate shape to host
the robotic hand mechanism and adequate strength to supportthe robotic hand mechanism and adequate strength to support
the developed on the hand operating loads.the developed on the hand operating loads.
This challenge is the most common in 3d printing projects.This challenge is the most common in 3d printing projects.

Functional mechanisms: Steward PlatformFunctional mechanisms: Steward Platform
Vehicle and flight simulators.Vehicle and flight simulators.
Functional mechanisms: Robotic boatFunctional mechanisms: Robotic boat
Employing a propulsion system based on the locomotion mechanisms of sea organisms such asEmploying a propulsion system based on the locomotion mechanisms of sea organisms such as
cuttlefish and rays.cuttlefish and rays.
The advantage of such a propulsion system is its remarkable maneuverability.The advantage of such a propulsion system is its remarkable maneuverability.
Such systems are employed mainly in unmanned underwater vehicles.Such systems are employed mainly in unmanned underwater vehicles.
The most complex parts of this mechanism were built with the 3d printing technology saving timeThe most complex parts of this mechanism were built with the 3d printing technology saving time
and cost.and cost.
The designers had the ability to experimentally test different design solutions a few hours after theThe designers had the ability to experimentally test different design solutions a few hours after the
geometrical model of each design solutions was completed.geometrical model of each design solutions was completed.

Biomechanics: modelling and simulation of human joints in theBiomechanics: modelling and simulation of human joints in the
computercomputer
Study kinematics and mechanical behaviour with the FiniteStudy kinematics and mechanical behaviour with the Finite
Elements Analysis method.Elements Analysis method.
Intact human knee joint model.Intact human knee joint model.
ACL deficient human knee joint model.ACL deficient human knee joint model.
Reconstructed human knee joint model with a deviceReconstructed human knee joint model with a device
developed and patented by the laboratory researchers.developed and patented by the laboratory researchers.
This FEA model is now experimentally verified.This FEA model is now experimentally verified.

Biomechanics: 3d printed human modelsBiomechanics: 3d printed human models
Doctors involved in each project can acquire information, notDoctors involved in each project can acquire information, not
been able to validate with the geometric models in thebeen able to validate with the geometric models in the
computer.computer.

Biomechanics: Human face anatomyBiomechanics: Human face anatomy
For the development of the 3d geometric model, patients areFor the development of the 3d geometric model, patients are
scanned with the laboratory 3d laser non contact scanner.scanned with the laboratory 3d laser non contact scanner.
Scanned data are converted to a geometric model in theScanned data are converted to a geometric model in the
computer and then in suitable 3d printing model.computer and then in suitable 3d printing model.
The 3d printing models are employed by the Plastic SurgeonThe 3d printing models are employed by the Plastic Surgeon
for the evaluation of each surgical case and the design of thefor the evaluation of each surgical case and the design of the
required surgical procedure.required surgical procedure.

Discussion - ConclusionsDiscussion - Conclusions
Laboratory research activities are in different technological areas, but all have the same focus andLaboratory research activities are in different technological areas, but all have the same focus and
content; developing parts and devices, study their behavior, manufacture them and acquirecontent; developing parts and devices, study their behavior, manufacture them and acquire
information for them no other method can provide.information for them no other method can provide.
Laboratory research activities usually support greater technology areas, but can also be the mainLaboratory research activities usually support greater technology areas, but can also be the main
result on each research project.result on each research project.
3d modelling has been extended far beyond the idea of modelling in a drafting software tool.3d modelling has been extended far beyond the idea of modelling in a drafting software tool.
3d scanning technology provides geometries impossible to model with conventional modelling3d scanning technology provides geometries impossible to model with conventional modelling
methods.methods.
Software tools nowadays are available for different modelling applications and can support almostSoftware tools nowadays are available for different modelling applications and can support almost
any type of modelling project.any type of modelling project.
Customized parts and products development is always required, as well as taking into accountCustomized parts and products development is always required, as well as taking into account
specialized requirements, parameters, issues and technology.specialized requirements, parameters, issues and technology.
Each area has different parameters to be considered.Each area has different parameters to be considered.
In any type of project the only common parameter is the development of the 3d geometry, which isIn any type of project the only common parameter is the development of the 3d geometry, which is
the most important parameter for a project to succeed.the most important parameter for a project to succeed.

Thank you!
Markos Petousis
Dr. Mechanical Engineer
TEI of Crete, Mechanical Engineering Department
Estavromenos, 71 004, Heraklion Crete, Greece
tel: +30 2810 379227
E-mail: petousis@emttu.org

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