Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MECH339 Manufacturing Processes > Additive Manufacturing - Fused Deposition Modelling & Stereolithography > Flashcards

Additive Manufacturing - Fused Deposition Modelling & Stereolithography Flashcards

1
Q

Additive Manufacturing/ Rapid Prototyping technologies are referred to as

A
  • Solid free-form fabrication
  • Direct Digital Manufacturing (DDM)
  • Layered manufacturing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is AM/RP?

A

Technology that quickly transforms a CAD model into a physical part using the computer description of the part shape.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Principles of AM

A
  • Fabrication of complicated 3D geometry without the constraints of traditional manufacturing techniques
  • Reduce high capital costs with production tooling being the longest process in the manufacturing cycle
  • Greatly impacts industry speeding product development cycle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does AM/RP speed development?

A
  • Rapid evaluation of design’s manufacturability
  • Used in design reviews to establish design effectiveness
  • Visualise purposes in client presentations
  • Working prototypes communicated to suppliers for quotas
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Classification of AM/RP processes

A

Subtractive- With traditional prototyping processes material is removed

Additive- Build up of a part adding material incrementally

Virtual- Use of advance computer-based visualisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

7 Categories of AM

A

Standards to classify the range of AM processes by the ASTM group

VAT Photopolymerisation- Liquid photopolymer resin is cured with a UV light source

Material Jetting- Material jetted onto a build platform where it solidified (cured using UV) 3D Polyjet Printing

Binder Jetting- A print head deposits a binder adhesive on a bed of powder based material; 3D Power Printing (3DP)

Material Extrusion- Material is drawn through a nozzle, where it is heated and is then deposited layer by later (FDM)

Powder Bed Fusion- Laser of electron beam melt and fuse material powder (SLS, DMLS, EBM, SLM)

Sheet Lamination- Sheet or ribbons of metal bound together using US welding followed by CNC milling; also LOM (paper with adhesive and cut by blades)

Direct Energy Deposition (DED)- Nozzle deposits molten material(metal, polymer, ceramics) onto build platform; molten with laser,plasma arc or electron beam)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Classification of RP process

A

Additive technologies

  • Fused Deposition Modelling (FDM)
  • Stereolithography (SLA)
  • Selective Laser Sintering (SLS)
  • Direct Metal Laser Sintering (DMLS)
  • Electron Beam Melting (EBM)
  • 3 Dimensional Printing Technologies (3DP)
  • Solid Ground Curing (SGC)
  • Laminated Object Manufacturing (LOM)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

AM/RP Applications

Prototyping

A
  • Primary use of RP is to quickly make prototypes for communication and testing purposes
  • Very useful for testing a design to evaluate its performance
  • Allows to evaluate funcitonality not possible without RP e.g. transparent prototype parts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

AM/RP Applications

Rapid tooling

A

Traditionally the most expensive and time consuming of all manufacturing processes

Indirect tooling- Prototypes are used as patterns for making moulds and dies

Direct tooling- Production tools are cast as net shape tools directly from CAD files

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Characteristics of Tooling

A
  • Toughness and wear resistance
  • Complex geometries
  • Very high dimensional accuracy (0.01 mm or better)
  • Very high surface finish
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What manufacturing processes are Prototypes used?

A

Vacuum casting
Sand Casting
Investment Casting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Rapid Tooling- Direct tooling

A

Hard tooling is made directly from CAD without fabricating a pattern first:

  • Selectively sintering of polymer-coated steel pellets together to produce a metal mould, burn off the polymer binder and infiltrate with copper
  • Development of ceramic composite materials using Direct Shell Production Casting techniques
  • Construct of sand moulds directly from CAD data using sand-like material that is sintered into moulds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Pros of Rapid Tooling

A

Pros
-Less dependant on highly skilled pattern makers

-Reduction of high labour costs

-Shorter lead-times in the production of patterns and moulds using the concept of net shaped tools
ld design possible; chill and cooling channel placement possibly leading to reduced cycle times

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Cons of Rapid Tooling

A
  • Potentially reduced tool life

- Limited material range; often only specialised and propriety materials and processes available

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Rapid Manufacturing applications

A
  • Direct production of functional and saleable products direct from CAD data
  • For short production runs
  • Products which cannot be made by subtractive processes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Pros of Rapid Manufacturing

A
  • Natural progression to produce functional and saleable products directly from CAD data
  • Ideal for short production runs as no tooling is required significant time and cost savings
  • Ideal for producing custom parts tailored to customer specifications
  • Ideal for products that cannot be made using traditional manufacturing processes (subtractive or compressive)
17
Q

Cons of Rapid Manufacturing

A
  • Economic reasons due to high raw material costs
  • Time issue to produce parts quickly for high volume manufacture
  • Long-term performance characteristics with regards to wear and life cycle compared to well established traditional methods of manufacturing
18
Q

Steps to creating AM/RP models

A
  1. Define the part to be built in a CAD environment as a surface or 3D solid model (SolidWorks etc..)
  2. Separate bounding surfaces of the CAD model into a collection of slices (triangular facets) and write on a file using STL-format
  3. Analyse each slice separately to set and compile instructions for the AM/RP machine to manufacture the part
  4. Manufacture the model building up one layer at a time driving a laser or modelling head (depending on the type of process) along a path
19
Q

What is STL?

A

Stereolithography Tesselation Language

20
Q

What is a STL file?

A
  • It is the link between 3D CAD design and the 3D printer hardware
  • The file format contains design data (3D surface as an assembly of planar triangles) to allow deciding object designs into slices (this is a mesh of triangles wrapped around the CAD model)
  • Modern CAD systems include STL output feature
    • Files suitable for rapid prototyping
    • Requires solid-modellers rather than surface-modellers
21
Q

STL format

A

CAD system settings with regards to STL mesh:

  • Triangles that are too large, small file size, prototype with visible facets.
  • Very small triangle mesh, big file size, long processing time, prototype accuracy or resolution not necessarily better
  • Best fidelity a mesh approximately the size of the layers is used by the AM/RP system
22
Q

What is FDM

A

Fused Deposition Modelling- Thermoplastic is spooled and extruded through a heated die constructing the part layer by layer

23
Q

FDM Method

A
  • Filaments of heated thermoplastic or wax are extruded from the tip of an extruder die
  • Lowering the platform which is kept at a lower temperature to apply subsequent layers upon the first; solidification by cooling
  • support structures may have to be built along the way and fastened to part
24
Q

FDM Process characteristics

A
  • Layer thickness is determined by extruder-die diameter (0.13 -0.33mm)
  • Extrusion detail of material (flat ribbon 0.08-0.97mm)
  • Stepped surface finish on oblique surfaces
  • dimensional accuracy between 0.13-0.241mm
  • fair to good surface finish
25
Q

What materials are used for FDM

A

-Polymers- production grade thermoplastics
-Wax
-Desired properties are:
Rigid, dimensionally stable
Good Strength and toughness
High resistance (chemical, UV, abrasion)
Nontoxic (bio-compatible, sterilisable)

26
Q

FDM- Applications

A
  • Detailed models for fit&form testing
  • Prototypes for higher temperature applications
  • Trade show and marketing parts & models
  • Patterns for investment casting
  • Fabrication of specialised manufacturing tools
27
Q

SLA

A

Stereolithography, involves fabricating a solid plastic part out of a photosensitive liquid polymer using a UV laser beam to solidify the polymer.

28
Q

SLA- Method

A
  • Scanning the liquid surface of a bath of photo-sensitive polymer resin with an ultraviolet laser beam that causes the resin to cure in the shape of a layer of the part
  • Lowering the platform by the slice thickness after each new layer is formed at the surface
  • Final curing cycle in a UV oven to complete photo-polymerisation
29
Q

SLA- Process Characteristics

A
  • Layer thickness 0.05-0.5mm
  • Capable of producing hollow and solid prototypes
  • Prototype must be built on a tray for support structure
  • Smooth surface finish
  • Stair stepping and faceting depending on layer thickness
  • 0.025-0.05mm per 25.4mm of part dimension
30
Q

SLA- Materials

A

Photo-sensitive polymers

  • Versatile in allowing to mimic a wide variety of engineering plastics
  • Material spectrum to address requirements such as accuracy, durability, rigidity, flexibility, transparency, colour, temperature or moisture resistance.

Special application resins
-Resins filled with non-crystalline nano-particle for improved strength or detail resolution

31
Q

SLA- Applications

A
  • Functional prototypes- mimic production parts for testing
  • Presentation models- design reviews, presentation, sales, marketing
  • Casting pattern for investment casting of a metal part, also used for sand or plaster casting
  • End use production parts, even assemblies,
  • Rapid tooling used to create limited-run tooling
32
Q

SLA- Variation

A

Micro-sterolithography

  • more highly focused laser (as small as 1 micrometer)
  • layer thickness roughly 10 micrometers
  • photo-polymers with a much lower viscosity to ensure uniform layers

MECH339 Manufacturing Processes (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions