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Additive Manufacturing > Introduction > Flashcards

Introduction Flashcards

1
Q

When was the first commercial AM system sold?

A

1988 first commercial system sold

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2
Q

How old is the AM industry?

A

industry is only ~27 years old

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3
Q

What is the current state of the AM market?

A

Global market for AM products and services grew 34.9% (CAGR) to $3.07 billion in 2013*

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4
Q

How many industrial AM systems were sold in 2013 globally?

A

~10,000 industrial AM systems sold, current total of ~70,000 worldwide

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5
Q

How many personal AM systems were sold in 2013 globally?

A

~73,000 personal AM systems sold, current total of ~140,000 worldwide

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6
Q

Mention 6 other names for Additive Manufacturing

A
  1. 3D Printing
  2. Layer Manufacturing
  3. Solid Freeform Fabrication
  4. Tool-less Manufacture
  5. Digital Manufacturing
  6. Freeform Fabrication
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7
Q

What is the ASTM definition for additive manufacturing?

A

AM - Process of joining materials to make objects from 3D Model Data. usually layer upon layer, as opposed to subtractive manufacturing methodologies. Synonyms: Additive Fabrication, Additive Processes, Additive techniques, Additive Layer Manufacturing, Layer Manufacturing and Freeform Fabrication.

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8
Q

In how many and in which distinctions are manufacturing processes classified? Who coined these distinctions and when?

A

Marshal Burns (1993) coined the three distinctions of the manufacturing process:
1. Subtractive
• Material removed from a solid block until the desired shape is reached (e.g. CNC machining)

  1. Additive
    • Material manipulated so that successive pieces of it combine to make the desired object
  2. Formative
    • Mechanical forces applied to material to form it into the desired shape (includes bending and moulding)
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9
Q

Give an example of a subtractive manufacturing process

A

CNC machining

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10
Q

What happens during a subtractive manufacturing process?

A

Material removed from a solid block until the desired shape is reached (e.g. CNC machining)

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11
Q

What happens during a formative manufacturing process?

A

Mechanical forces applied to material to form it into the desired shape (includes bending and moulding)

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12
Q

Give an example of a formative manufacturing process

A

moulding

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13
Q

Which distinction best describes AM?

A

AM is an additive process, whereby parts are built, layer by layer, directly from a CAD file

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14
Q

What requirement does AM eliminate compared to other processes?

A

Eliminates requirement for tooling

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15
Q

What is the generic process chain for AM?

A

A. FILE PREPARATION

  1. Create 3D CAD Model
  2. Generate .stl file
  3. Check and repair .stl file

B. BUILD SET-UP

  1. Orient parts
  2. Generate supports*
  3. Slice part horizontally*

C. PHYSICAL

  1. Build part layer by layer*
  2. Remove supports*
  3. Postprocessing*

*Process specific

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16
Q

What’s the standard file format of CAD files for 3D Printing?

A

.stl

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17
Q

What are the characteristics of the .stl file format?

A
  1. Original format for Stereolithography
  2. Provides a standard format for use on most machines
  3. Approximates the part surface into a series of tessellated triangles
  4. Some loss of accuracy during triangulation
  5. Very difficult to edit – ‘dumb’ data
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18
Q

Are new formats for printing 3D structures emerging?

A

Yes

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19
Q

Why do we need to build support structures when 3D Printing?

A

Most processes require some form of support structure for over-hanging geometries

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20
Q

Characteristics of support structures for AM?

A
  1. Thin lattices to be broken off easily
  2. They are made of Separate (weaker) support material
  3. They can be water-soluble
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21
Q

Which systems are self supporting?

A

Powdered-polymer systems are self-supporting; other processes self supporting up to a certain angle.

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22
Q

What is often overlooked when discussing AM?

A

The requirement for proper post processing of the product.

23
Q

Mention 6 post-processing processes.

A
  1. Post-curing
  2. Infiltration
  3. Support removal
  4. Bead-blasting
  5. Machining
  6. Polishing
24
Q

According to which factors are AM systems classified?

A

Classification off systems, based on:

1. Materials 
(metals, polymers, ceramics)
2. Processing Method 
(laser-based, photo-cure, jetting)
3. Speed
4. Size
5. Cost
25
Q

By what is choice affected when in comes to AM process selection?

A
  1. Required Accuracy
  2. Mechanical Properties
  3. Application
  4. Surface Finish
  5. Number of parts required
  6. Component size and complexity
  7. Cost
  8. And don’t forget - it isn’t always appropriate to use AM.
26
Q

What are the uses of layer-manufacturing?

A
  1. Rapid Prototyping (RP) – create a likeness of a part
  2. Rapid Tooling (RT) – create a part indirectly
  3. Additive Manufacturing (AM) – create end-use part directly
27
Q

What is Rapid Prototyping used for?

A

Rapid Prototyping (RP) – create a likeness of a part.

  1. It’s a tool for communicating ideas.
  2. It creates a representation of a part that will ultimately produced by some manufacturing process.
  3. Low cost method by which a part or product can be visualised or used to some degree.
  4. This implies that there are different types of prototype
28
Q

What are the three historical stages of prototyping?

A
  1. Manual prototyping (thousands of years old)
    - Un-sophisticated
    - Craft/skill-based Labour intensive
  2. Virtual prototyping (since mid 1970s)
    - Test, analyse and modify computer models
    - Skilled, and often time-consuming, process
    - More chance of ‘getting it right’
  3. Rapid Prototyping
    - Automated (semi-automated) production of physical prototypes
    - Quicker, and more complex
    - Still skill-based?
29
Q

What are the specific benefits of Rapid Prototyping?

A
  1. Reduced costs/ lead times (no tooling)
    a. Communication between departments
    b. Quicker time to market
    c. Customer trials pre-production
    d. Tendering processes
    e. Higher number of design iterations – better quality parts
    f. Less design restrictions (e.g. draft angles etc.)
  2. CAD can often be used for marketing purposes
  3. BUT… Need to be careful – don’t start prototyping things we can’t put into series production!
30
Q

Mention two conventional methods for tooling.

A

machining - casting

31
Q

What are the disadvantages of conventional tooling?

A
  1. High cost
  2. Long lead-times
  3. Few design iterations
32
Q

What is Rapid Tooling?

A

Rapid Tooling (RT) – create a part indirectly

33
Q

What are the different forms of Rapid Tooling?

A

A. Direct Rapid Tooling: Direct production of tool from sliced CAD data

B. Indirect Rapid Tooling: Production of a master or pattern from which the tool is produced; E.g. for silicon rubber moulding

34
Q

What are the applications of Direct Rapid Tooling?

A
  1. Often used for production of tools for injection moulding
  2. Carbon fibre lay-ups
  3. Some forms of Direct RT also suitable for die casting
35
Q

What are the Specific benefits of Direct Rapid Tooling?

A
  1. Higher geometrical complexity (E.g. conformal channels)
  2. Shorter lead times & lower cost
  3. Mass reduction
  4. Functionally graded materials (E.g. hard-wearing surface & thermally conductive heating/cooling channels)
36
Q

What is the definition of a conformal channel?

A

Conformal cooling channel is a cooling passageway which follows the shape or profile of the mould core or cavity to perform rapid uniform cooling process.

37
Q

Characteristics of Conformal channels?

A
  1. Can be used for heating and/or cooling
  2. Increase rate of heating/cooling
    a. Increase cycle times
  3. Control temperature distribution within mould
    a) Improve consistency of moulding
    b) Difficult geometries (e.g. thin channels)
38
Q

Why is tool mass reduction important?

A

Tool mass reduction:

  1. Reduces energy and time to heat/cool a mould.
  2. Increases effective thermal diffusivity of a tool.
  3. Reduces material use and build time
39
Q

What are the limitations of Rapid Tooling?

A
  1. Material choice
  2. Surface finish
    (Post-finishing is generally required)
  3. Geometrical accuracy
  4. Depending on material/process, can still be limited to small to medium volume manufacture
  5. Software systems (e.g. Functional grading)
  6. Knowledge of how to use them!
40
Q

What is hybrid tooling?

A

Often combinations of technologies are used to get best solution, e.g.:
• AM core and machined cavity combines internal complexity and best A-surface finish
• Layer manufactured tools often post machined
• Machined tools may include layer manufactured inserts for engineering changes

41
Q

How is AM for Direct Manufacture originally known as?

A

AM for Direct Manufacture, originally known as Rapid Manufacturing

Rapid’ implies evolution from Rapid Prototyping, rather than defining speed

Speed and cost are also important, but it is normally the ‘high added- value’ aspects which would lead us to choose AM

42
Q

Is AM a new industrial revolution as many people claim?

A

More appropriate to class AM as ‘another tool in the tool- box’, e.g.:
• Injection mould some parts
• CNC machining for others
• AM where appropriate

43
Q

What are the benefits of AM for Direct Manufacture? (5)

A
  1. Increased Design Freedom (Less DfMA criteria)
  2. Personalisation (production runs of n=1)
  3. Optimisation (Weight, strength, airflow, heat transfer): possible as a result of increased geometric complexity.
  4. Part consolidation/moving parts (less assembly time - better performance)
  5. Supply chain: Localised manufacture, just-in-time production, no need to have so many spare parts
44
Q

What are the issues that we need to currently overcome in AM for direct Manufacture?

A

A. MATERIALS
(cost, range, long term material properties)

B. INTEGRITY OF PARTS
(Mechanical properties, accuracy, tolerances, repeatability, surface finish and stair-stepping)

C. SYSTEMS
(Machine cost, build speed, build volume, automation)

D. SOFTWARE

E. TRAINING

45
Q

What are broader issues to deal with in terms of AM for direct manufacture?

A
  1. INTELLECTUAL PROPERTY
    - Who owns the data if I design something and upload it to a service bureau?
    - Piracy - lessons to learn from Music Industry?
  2. LIABILITY
    - Who is liable if I build a part at home, use it on my car, and end up injured?
  3. PREVENTION OF DUBIOUS USE
    - How?
46
Q

What are the future trends for Direct Manufacture AM?

A
  1. Wider range of materials as large manufacturers become more involved
  2. More diverse system sizes, and faster speeds
  3. Full-colour parts
  4. Fully automated systems
  5. Integrated electronics / multi-functional parts]
  6. Increased crossover between ‘hobbyist’ and ‘workplace’ systems
  7. More suitable CAD systems for range of users
47
Q

Mention some example developing fields for AM

A
  1. Medical: Surgical planning aids - Bone implants, tissue engineering scaffolds, knee joints (Regulation is a problem so far!)
2. Integrated electronics
Fully integrated electronic and mechanical components, e.g. 
• Actuators
• Batteries
• Strain gauges
48
Q

Mention some common mistaken perceptions about AM

A
  1. There are no restrictions on what we can make
  2. We can make things that are impossible by any other method
  3. The mechanical properties are not good enough
  4. These 3D Printers are going to become as common and useful as personal computers
  5. Everyone will have a 3D Printer in their home
  6. Any time something breaks, we’ll be able to fix it using our 3D Printers
49
Q

Please discuss the following statement

“There are no restrictions on what we can make with AM”

A
  1. Short answer is – of course there are!
    • Minimum feature sizes, tolerances, structural integrity, support/powder removal etc.
  2. What we actually mean is, we can produce complex geometries more easily, but we still have to work with process/ system/ material boundaries
50
Q

Please discuss the following AM statement

“We can make things that are impossible by any other method”

A

No, but we can make things that are impossible to manufacture economically using traditional techniques

51
Q

Please discuss the following AM statement

“The mechanical properties are not good enough”

A
  1. Early systems designed purely for prototyping (OK, properties were not always great…)
  2. Range of properties is still limited, but many processes now compete favourably with ‘traditional’ techniques, for a number of properties
  3. Is there any such thing as an ‘awful’ set of properties? Mainly we mean ‘they’re not what I’m used to’ - Give me a set of properties, there is always an application
  4. Do people always know what properties they actually need?
52
Q

Please discuss the following AM statement

“These 3D Printers are going to become as common and useful as personal computers”

A 
A. Before personal computers, we:
1. Wrote letters
2. Kept budgets
3. Read books
4. Searched for information
5. Stored photos
PC just makes this more efficient!

B. Before 3D Printers, we:
Well, we didn’t make all that much stuff for ourselves…

53
Q

Please discuss the following AM statement

“Everyone will have a 3D Printer in their home”

A
  1. Prices ARE coming down, and more and more systems available… but that doesn’t mean we’ll all buy one
  2. People who will actually have them in their home:
    a) Hobbyists, including those who simply like tinkering, or the challenge of making the system better
    b) People with children… (and who quite fancy the idea of one?)
  3. Most likely to be a surge in purchases, largely due to all the media hype
54
Q

Please discuss the following AM statement

“Any time something breaks, we’ll be able to fix it using our 3D Printers”

A

Currently:
• Quality of parts is generally not production standard
• Range/colour of materials, to give ‘exact fit’
• Availability of data
• Motivation – it’s simply easier for someone else to do it!

~ Most likely to see increasing numbers of stores providing 3D Printing services as well as 2D

~Service industries will make better use (e.g. car manufacturers license Halfords to produce replacement parts in-store)

Additive Manufacturing (9 decks)

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