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TYPES OF MANUFACTURING PROCESSES-
1. FORMING
2. JOINING PROCESSES
3. REMOVAL PROCESSES
4. ADDITIVE MANUFACTURING
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The really old way: Take a block of material and carve it
out
The more modern way:
You want to make a sphere...
Generate 3D model
Generate CNC program
Machine away unwanted material
If possible, recycle waste
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*Generate a 3D model*Software slices the 3D model into thin
slices
*Machine builds it layer by layer
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Advantages:
Process is Independent of Part FeatureNo Blanks are RequiresTool
less processEasily Automation Possible
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*Video
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1)STEREOLITHOGRAPHY
Thin layers of UV sensitive liquid polymers are
solidified through the use of a laser.
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Stereo lithography is a photo polymerisation process.
Three main photopolymer systems used are acrylate , epoxy and
vinyl ether.
Layer thickness-Each layer is 0.076 mm to 0.50 mm (0.003 in to
0.020 in.) thick
Scanning time is 500-25000 mm/s.
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Time to complete a single layer-
where Ti = time to complete layer i; Ai = area of layer i; v =
average scanning speed of the laser beam at the surface; D =
diameter of the spot size, assumed circular; and Td = delay time
between layers to reposition the worktable
Part Built Time
di
i TvD
AT
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Once the Ti values have been determined for all layers,
then the build cycle time is:
where Tc = STL build cycle time; and nl = number of layers
used to approximate the part
Time to build a part ranges from one hour for small parts
of simple geometry up to several dozen hours for complex
parts
Total Time
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Benefits-
No milling or masking steps needed.
Can be highly accurate
Only one material needed for build and support
Downsides-
Requires post curing of material
Long term curing can lead to warping
Can have brittle parts with a tacky surface
Support structures are often needed
Material is toxic and light sensitive
Benefits and downsides
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Heated thermoplastics are extruded through nozzles ,
extruded material hardens as it cools.
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Benefits-
Can use standard engineering thermoplastics (ABS) Can use
multiple materials (One for bulid & support) Can produce water
tight parts Parts are hardened very quickly
Downsides-
Poor layer uniformity Delamination of extruded layers can be
problematic Parts can have a rather coarse surface finish
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Molten/liquid plastics printed along with wax support
structure.
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Lasers used to selectively sinter/fuse layers of powdered
materials.
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SLA- Excellent surface finish suitable for presentation, master
models and light functional testing.
FDM- Good combination of strength and surface finish at
affordable price and lead time.
3DP- Suitable for general purpose parts for initial design stage
with a quick delivery
SLS- Range of materials available, soft like rubber to strong
like metal. SLS Nylon suitable for snap and living hinge
features
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Architecture and Design
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There is a quote in AM-
IF U CAN DRAW IT WE CAN PRINT IT
We are pushing our limits . Manufacturing is not the
barrier to the entry , actually the design is the
barrier to the entry.
THATS THE POWER OF TECHNOLOGY
And it marks the beginning of next industrial
revolution.
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Jane Chu, Sarah Engelbrecht, Gregory Graf, David W. Rosen,
(2010) "A comparison of synthesis methods for cellular structures
with application to additive manufacturing", Rapid Prototyping
Journal, Vol. 16 Iss: 4, pp.275 283
Francis J. Quail, Thomas Scanlon and Matthew Strickland(2010)
Development of a regenerative pump impeller using rapid
manufacturing techniques ,Rapid Prototyping Journal Volume 16
Number 5 2010 pp 337344
Tomaz Brajlih, Bogdan Valentan, Joze Balic, Igor Drstvensek,
(2011) "Speed and accuracy evaluation of additive manufacturing
machines", Rapid Prototyping Journal, Vol. 17 Iss: 1, pp.64 75
wohlersassociates.com/terms.html
additivemanufacturing.com/
www.ge.com/stories/additive-manufacturing
www.docstoc.com/docs/71023917/ADDITIVE-MANUFACTURING-AND-THE-ENVIRONMENT
www.arptech.com.au/slshelp.htm
