S.Senthikumar, B.E.,M.E., Assistant Professor Department of Mechanical Engineering LIQUID BASED RAPID PROTOTYPING SYSTEMS
Oct 24, 2015
S.Senthikumar, B.E.,M.E.,Assistant Professor
Department of Mechanical Engineering
LIQUID BASED RAPID PROTOTYPING SYSTEMS
Introduction
Most liquid-based rapid prototyping systems build parts in a vat of photo-
curable liquid resin, an organic resin that cures or solidifies under the
effect of exposure to laser radiation, usually in the UV range.
The laser cures the resin near the surface, forming a hardened layer.
When a layer of the part is formed, it is lowered by an elevation control
system to allow the next layer of resin to be similarly formed over it.
Vat - A large open vessel for holding or storing liquids
This continues until the entire part is completed.
The vat can then be drained and the part removed for further processing, if
necessary.
There are variations to this technique by the various vendors and they are
dependent on the
type of light or laser
method of scanning or exposure,
type of liquid resin,
type of elevation and optical system used.
Introduction
Liquid-Based Rapid Prototyping Systems
3D Systems’ Stereolithography Apparatus (SLA)
Cubital’s Solid Ground Curing (SGC)
D-MEC’s Solid Creation System (SCS)
CMET’s Solid Object Ultraviolet-Laser Printer (SOUP)
Teijin Seiki’s Soliform System
Autostrade’s E-Darts
Meiko’s Rapid Prototyping System for the Jewelry Industry
Other Similar Commercial RP Systems
Two Laser Beams
Rapid Freeze Prototyping
Microfabrication
CompanyProductsAdvantages and DisadvantagesProcessPrincipleApplicationsExamplesResearch and Development
CompanyProductsAdvantages and DisadvantagesProcessPrincipleApplicationsExamplesResearch and Development
3D Systems’ Stereolithography Apparatus (SLA)CompanyCompany
3D Systems was founded in 1986 by inventor Charles W. Hull andentrepreneur Raymond S. Freed.
Amongst all the commercial RP systems, the StereolithographyApparatus, or SLA® as it is commonly called, is the pioneer with itsfirst commercial system marketed in 1988.
It has been awarded more than 40 United States patents and 20international patents, with additional patents filed or pendinginternationally.
3D Systems Inc. is currently headquartered in26801 Avenue Hall,Valencia, CA 91355, USA.
3D Systems’ Stereolithography Apparatus (SLA)ProductsProducts
3D Systems’ Stereolithography Apparatus (SLA)
3D Systems’ Stereolithography Apparatus (SLA)
3D Systems’ Stereolithography Apparatus (SLA)
3D Systems’ Stereolithography Apparatus (SLA)Advantages Advantages
(1) Round the clock operation - continuously and unattended round the clock.
(2) Good user support.The computerized process serves as a good user support.
(3) Build volumes. The different SLA machines have build volumes ranging from small tolarge to suit the needs of different users.
(4) Good accuracy. It has good accuracy and can thus be used for many application areas.
(5) Surface finish. Can obtain one of the best surface finishes amongst RP technologies.
(6) Wide range of materials. There is a wide range of materials, from general-purposematerials to specialty materials for specific applications.
(1) Requires support structures. Structures that have overhangs and undercuts must
have supports that are designed and fabricated together with the main structure.
(2) Requires post-processing. Post-processing includes removal of supports and other
unwanted materials, which is tedious, time consuming and can damage the model.
(3) Requires post-curing. Post-curing may be needed to cure the object completely and
ensure the integrity of the structure.
3D Systems’ Stereolithography Apparatus (SLA)DisadvantagesDisadvantages
Creates three-dimensional plastic objects directly from CAD data.
The process begins with the vat filled with the photo-curable liquid
resin and the elevator table set just below the surface of the liquid resin
(see Figure).
The operator loads a three-dimensional CAD solid model file into the system.
Supports are designed to stabilize the part during building.
The translator converts the CAD data into a STL file.
The control unit slices the model and support into a series of cross sections
from 0.025 to 0.5 mm (0.001 to 0.020 in) thick.
3D Systems’ Stereolithography Apparatus (SLA)ProcessProcess
3D Systems’ Stereolithography Apparatus (SLA)ProcessProcess
3D Systems’ Stereolithography Apparatus (SLA)
Computer
3D CAD Model
STL File
SYSTEM
Slice file
Support Information
CONTROL SYSTEM
Optical Reflector
Laser Movement (X-Y)
Elevator Movement (Z)
The computer-controlled optical scanning system then directs and
focuses the laser beam so that it solidifies a two dimensional cross-
section corresponding to the slice on the surface of the photo-curable liquid resin
to a depth greater than one layer thickness.
The elevator table then drops enough to cover the solid polymer with
another layer of the liquid resin.
A levelling wiper or vacuum blade (for ZephyrTM recoating system) moves
across the surfaces to recoat the next layer of resin on the surface.
The laser then draws the next layer.
3D Systems’ Stereolithography Apparatus (SLA)ProcessProcess
This process continues building the part from bottom up, until the system
completes the part.
The part is then raised out of the vat and cleaned of excess polymer.`
3D Systems’ Stereolithography Apparatus (SLA)ProcessProcess
3D Systems’ Stereolithography Apparatus (SLA)ProcessProcess
The main components of the SLA system are
a control computer,
a control panel,
a laser,
an optical system and
a process chamber.
3D Systems’ Stereolithography Apparatus (SLA)ProcessProcess
The workstation software used by the SLA system, known as
3D Lightyear
3dverifyTM Module
ViewTM Module
MERGE Module
VistaTM Module.
Part ManagerTM Module
SliceTM Module
ConvergeTM Module
Maestro includes the following software modules
3D Systems’ Stereolithography Apparatus (SLA)ProcessProcess
3dverifyTM Module
This module can be accessed to confirm the integrity and/or
provide limited repair to stereolithography (STL) files before part
building without having to return to the original CAD software.
Gaps between triangles, overlapping or redundant triangles and
incorrect normal directions are some examples of the flaws that
can be identified and corrected
3D Systems’ Stereolithography Apparatus (SLA)ProcessProcess
ViewTM Module.This module can display the STL files and slice file (SLI) in graphical form. The viewing function is used for visual inspection and for theorientation of these files so as to achieve optimal building.
3D Systems’ Stereolithography Apparatus (SLA)ProcessProcess
MERGE Module.
By using MERGE, several SLI files can be merged into a group
which can be used together in future process.
3D Systems’ Stereolithography Apparatus (SLA)ProcessProcess
VistaTM Module
This module is a powerful software tool that automatically generates
support structures for the part files.
Support structures are an integral part to successful part building, as
they help to anchor parts to the platform when the part is free floating
or there is an overhang.
3D Systems’ Stereolithography Apparatus (SLA)ProcessProcess
Part ManagerTM Module
This software module is the first stage of preparing a part for
building.
It utilizes a spreadsheet format into which the STL file is loaded and
set-up with the appropriate build and recoat style parameters.
3D Systems’ Stereolithography Apparatus (SLA)ProcessProcess
SliceTM Module.
This is the second stage of preparing a part for building.
It converts the spreadsheet information from the Part ManagerTM
module to a model of three-dimensional cross sections or layers.
3D Systems’ Stereolithography Apparatus (SLA)ProcessProcess
ConvergeTM Module
This is the third and last stage of preparing a part for building.
This is the module which creates the final build files used by the
SLA.
3D Systems’ Stereolithography Apparatus (SLA)ProcessProcess
• confirm the integrity and/or provide limited repair to stereolithography (STL) files before part building3dverifyTM Module3dverifyTM Module
• This module can display the STL files and slice file (SLI) in graphical formViewTM ModuleViewTM Module
• several SLI files can be merged into a group which can be used together in future processMERGE ModuleMERGE Module
• module is a powerful software tool that automatically generates support structures for the part files.VistaTM ModuleVistaTM Module
• This software module is the first stage of preparing a part for building. Part ManagerTM ModulePart ManagerTM Module
• This is the second stage of preparing a part for building. SliceTM ModuleSliceTM Module
• the third and last stage of preparing a part for building. ConvergeTM ModuleConvergeTM Module
3D Systems’ Stereolithography Apparatus (SLA)
PrinciplePrinciple
The SLA process is based fundamentally on the following principles:
(1) Parts are built from a photo-curable liquid resin that cures
when exposed to a laser beam (basically, undergoing the
photopolymerization process) which scans across the surface of the
resin.
(2) The building is done layer by layer, each layer being scanned by
the optical scanning system and controlled by an elevation
mechanism which lowers at the completion of each layer.
3D Systems’ Stereolithography Apparatus (SLA)
There are many types of liquid photopolymers that can be solidified by
exposure to electro-magnetic radiation, including wavelengths in the gamma rays,
X-rays, UV and visible range, or electron-beam (EB)
The vast majority of photopolymers used in the commercial RP systems,
including 3D Systems’ SLA machines are curable in the UV range.
UV-curable photopolymers are resins which are formulated from
photoinitiators and reactive liquid monomers.
PrinciplePrinciple PhotopolymersPhotopolymers
3D Systems’ Stereolithography Apparatus (SLA)
There are a large variety of them and some may contain fillers and
other chemical modifiers to meet specified chemical and mechanical
requirements
The process through which photopolymers are cured is referred to as the
photo polymerization process.
PrinciplePrinciple PhotopolymersPhotopolymers
3D Systems’ Stereolithography Apparatus (SLA)
Polymerization is the process of linking small molecules (known as
monomers) into chain-like larger molecules (known as polymers)
When the chain-like polymers are linked further to one another, a
cross-linked polymer is said to be formed.
Photopolymerization is polymerization initiated by a
photochemical process whereby the starting point is usually the
induction of energy from the radiation source
PrinciplePrinciple PhotopolymerizationPhotopolymerization
3D Systems’ Stereolithography Apparatus (SLA)PrinciplePrinciple Layering Technology, Laser Layering Technology, Laser
and Laser Scanningand Laser Scanning
The important component of the building process is the laser and its
optical scanning system.
The key to the strength of the SLA is its ability to rapidly direct
focused radiation of appropriate power and wavelength onto the
surface of the liquid photopolymer resin, forming patterns of solidified
photopolymer according to the cross-sectional data generated by the
computer
3D Systems’ Stereolithography Apparatus (SLA)PrinciplePrinciple Layering Technology, Laser Layering Technology, Laser
and Laser Scanningand Laser Scanning
In the SLA, a laser beam with a specified power and wavelength is sentthrough a beam expanding telescope to fill the optical aperture of a pair ofcross axis, galvanometer driven, beam scanning mirrors. These form theoptical scanning system of the SLA.
The beam comes to a focus on the surface of a liquid photopolymer, curinga predetermined depth of the resin after a controlled time ofexposure (inversely proportional to the laser scanning speed).
The solidification of the liquid resin depends on the energy per unitarea (or “exposure”) deposited during the motion of the focused spot onthe surface of the photopolymer
3D Systems’ Stereolithography Apparatus (SLA)PrinciplePrinciple Layering Technology, Laser Layering Technology, Laser
and Laser Scanningand Laser Scanning
There is a threshold exposure that must be exceeded for thephotopolymer to solidify.
To maintain accuracy and consistency during part building using theSLA, the cure depth and the cured line width must be controlled.
As such, accurate exposure and focused spot size become essential.
3D Systems’ Stereolithography Apparatus (SLA)PrinciplePrinciple Layering Technology, Laser Layering Technology, Laser
and Laser Scanningand Laser Scanning
Parameters which influence performance and functionality of the partsare the
•physical and chemical properties of the resin,•the speed and resolution of the optical scanning system,•the power, wavelength and type of the laser used,•the spot size of the laser,•the recoating system, and•the post-curing process.
3D Systems’ Stereolithography Apparatus (SLA)ApplicationsApplications
cost justifiable methods for reducing time to marketlowering product development costsgaining greater control of their design process and improving productdesign
The range of applications include:(1) Models for conceptualization, packaging and presentation.(2) Prototypes for design, analysis, verification and functional testing.(3) Parts for prototype tooling and low volume production tooling.(4) Patterns for investment casting, sand casting and molding.(5) Tools for fixture and tooling design, and production tooling.
3D Systems’ Stereolithography Apparatus (SLA)ExamplesExamples
•QuickCast technology•rapid tooling by investment casting stereolithography mold halves tocreate the hard tool.•first built a SL model of the cover - found a clearance problem•Pro/MOLDESIGN software•The turnaround time for the second set of tooling was only four weeks,•and the cost for “QuickCast Tooling” was only $5000 per tool set,compared to the $33 000 quoted for machining a single tool.•Ford was able to start durability and water flow testing 18 monthsahead of schedule, with costs reduced by 45% and time savings of morethan 40% achieved.
Ford Uses Stereolithography to Cast Prototype Tooling
3D Systems’ Stereolithography Apparatus (SLA)ExamplesExamples
Black & Decker Saves a Year by Using Stereolithography toPrototype their Improved Shearer/ShrubTrimmer PowerTool
Bose Saves Five Weeks Using Stereolithography Over Traditional Hard Tooling
3D Systems’ Stereolithography Apparatus (SLA)Research and DevelopmentResearch and Development
3D Systems’ research focus is on improving process and developing newmaterials, and application, especially rapid tooling
Bose Saves Five Weeks Using Stereolithography Over Traditional Hard Tooling
SGC
Topic Team Date RemarksCUBITAL’S SOLID GROUND CURING (SGC)
Team 6 : Nos 6,16,26
D-MEC’S SOLID CREATION SYSTEM (SCS)
Team 6 : Nos 36,46,56, 66
CMET’S SOLID OBJECT ULTRAVIOLET-LASER PRINTER (SOUP)
Team 7 : Nos 7,17, 27
TEIJIN SEIKI’S SOLIFORM SYSTEM Team 7 : Nos 37,47, 57
AUTOSTRADE’S E-DARTS Team 8 : Nos 8,18,28
MEIKO’S RAPID PROTOTYPING SYSTEM FOR THE JEWELRY INDUSTRY
Team 8 : Nos 38,48, 58
RAPID FREEZE PROTOTYPING& MICROFABRICATION
Team 9 : Nos 9,19,29
Seminar Topics
Thank you
A photoinitiator is any chemical compound that decomposes into freeradicals when exposed to light. Photoinitiators are found both in nature (inphotochemical smog) and in industry (for example, in plastics production).In nature, photoinitiators are present throughout the atmosphere. For instance,nitrogen dioxide is produced in large quantities by gasoline-burning internalcombustion engines. NO2 in the troposphere gives smog its brown colorationand catalyzes production of toxic ground-level ozone. Molecular oxygen (O2)also serves as a photoinitiator in the stratosphere, breaking down into atomicoxygen and in order to form the ozone in the ozone layer.In industry, photoinitiators are primarily used topromote polymerization reactions, notably in the productionof polyethylene plastic. There are a handful of medical applications as well; forinstance, benzoyl peroxide creams are commonly prescribed as acnemedication.
PhotoinitiatorFrom Wikipedia, the free encyclopedia