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Additive Manufacturing > 2. Material Extrusion > Flashcards

2. Material Extrusion Flashcards

1
Q

What is the key process of Material Extrusion Additive Manufacturing (MEAM)?

A

Material is selectively dispensed through a nozzle.

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2
Q

What distinguishes MEAM in terms of commonality and cost compared to other additive manufacturing methods?

A

It is the most common and cheapest additive manufacturing method.

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3
Q

How does material deposition work in MEAM?

A

Material is deposited one layer at a time, with the platform moving down after each layer.

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4
Q

What are the stages of material extrusion?

A
  1. CAD Model
  2. Convert model to STL
  3. Setup
  4. Build
  5. Post processing
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5
Q

What are the requirements for a 3D model to be printed in MEAM?

A

The model must be a 3D solid or watertight mesh.

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6
Q

What design considerations should be taken into account when creating a CAD model for MEAM?

A
  • Avoid thin walls
  • Consider support structures (especially for large masses supported by thin stems)
  • Account for moving part tolerances
  • Make appropriate material choices.
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7
Q

What is the purpose of converting a model to STL in MEAM?

A

It converts the model to a triangular surface representation suitable for stereolithography, saving it in .stl format.

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8
Q

What are the key steps in the setup process for MEAM?

A
  • Import the model to software
  • Set the orientation, quantity, process parameters, and support structures
  • The software generates slices and the print path.
  • Additionally, ensure platform leveling, nozzle alignment, material feed, and preheat the base.
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9
Q

Describe the build process in MEAM once the setup is complete.

A

The build process starts with the platform raised to the top; the nozzle stays at the same elevation. The platform lowers as each layer is printed.

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10
Q

What post-processing steps are needed in most AM processes?

A
  • Removal of support structures, which can be by force or dissolved.
  • Painting to improve appearance and strength
  • Polishing through mechanical or chemical methods.
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11
Q

Describe the order of operations in a single spool extrusion system for MEAM.

A
  • Filament is unwound from the spool
  • Filament is led to the extruder
  • Extruder applies torque and pinch to extract the filament
  • Filament is heated by the heater block
  • Heated filament is forced out of the heated nozzle
  • Heated filament is laid down on the model
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12
Q

How does a dual spool system differ from a single spool system in MEAM?

A
  • Two separate spools, heater and nozzle systems
  • Allows for separate build and support material systems
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13
Q

What are the benefits of using soluble support structures in MEAM?

A
  • Easy removal of support material
  • Ideal for complex geometries or hard-to-reach areas
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14
Q

What are the characteristics of integrated (direct) extrusion in MEAM?

A
  • Simpler design compared to remote extrusion
  • Increases the weight of the print head
  • Results in slower print speeds
  • Rarely encounters printing issues
  • Print head acceleration is limited due to extra mass and inertia
  • Print speed is also constrained by nozzle size and material flow rate
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15
Q

What are the features and issues associated with remote (Bowden) extrusion?

A
  • Utilized in printers like the Ultimaker 2
  • Extruder is located away from the print head
  • A Bowden tube transmits mechanical force to the hot end
  • Allows for a faster-moving print head due to reduced weight
  • Can have friction issues within the Bowden tube
  • Potential for distortion of the filament by the filament driver
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16
Q

What is the filament driver and how does it function in MEAM?

A
  • Comprises a toothed or grooved bolt attached to a stepper motor with an adjacent opposing wheel
  • Filament is squeezed between the bolt and wheel
  • The resistance between the bolt and wheel provides torque necessary to retract or feed the filament
17
Q

What are the components of the hot-end in MEAM and their functions?

A

Consists of an aluminum block or barrel, a heating element, a cooling fan, a temperature sensor, a controller, and the print nozzle

18
Q

How does the nozzle size affect printing in MEAM?

A
  • Nozzle diameters range from 0.2 to 0.8mm
  • The size of the nozzle influences print quality and speed
19
Q

What are the temperature ranges for different materials in MEAM?

A
  • General temperature range is from 190 to 280 degrees Celsius
  • PLA should be printed between 190 to 220 degrees Celsius
  • ABS requires a higher range of 230 to 280 degrees Celsius
20
Q

What are the two types of XYZ movement systems in MEAM?

A
  • Cartesian
  • Delta
21
Q

What characterizes the Cartesian movement system in MEAM?

A
  • Moves in straight lines
  • Utilizes fixed rods, timing belts, pulleys, and stepper motors for movement
  • Known for precise movement
  • The accuracy of the stepper motor is crucial for print quality
  • Typically, the print head moves in the X and Y directions, while the print bed moves in the Z direction
22
Q

How does the Delta movement system operate in MEAM?

A
  • Features a triangular layout with three vertical rods
  • Carriages on the rods move in the Z direction
  • Movement of a carriage results in the nozzle moving in X, Y, and Z directions simultaneously
23
Q

What is the purpose of heating the build platform and chamber in MEAM?

A
  • Heated systems accommodate a wider range of materials
  • Materials expand when heated, so a heated chamber reduces warping and cracking
  • A heated build plate improves adhesion of the part during printing and facilitates easier removal after printing
24
Q

What are the limitations of non-heated systems in MEAM?

A

Limited to printing with certain materials that do not require a heated environment to prevent warping or cracking.

25
Q

What is GCODE and its role in MEAM?

A
  • GCODE is produced by software to instruct the printer’s actions
  • It includes commands for movement, position, speed, and extrusion amounts
26
Q

What does the GCODE line

‘G1 X10 Y10 Z0.5 F1000 E0.5’

instruct the printer to do?

A

‘G1’ = Move command

‘X10 Y10 Z0.5’ = Move to this position

‘F1000’ = Move at this speed (in mm/s)

‘E0.5’ = Extrude this amount of material

27
Q

How is the E value for extrusion determined and what is the formula for the volumetric extrusion rate (VE)?

A
  • Determined by the layer height (H), nozzle diameter (W), and the length or nozzle position (L)
  • The volumetric extrusion rate (VE) is calculated by multiplying the nozzle diameter (W) by the layer height (H) and the nozzle speed (F):

VE = W * H * F

28
Q

What are infill structures in the context of MEAM?

A
  • The internal structure of the printed part
  • Different types of infill can significantly influence the properties and performance of the part
29
Q

How does the type of infill affect a printed part in MEAM?

A
  • Each infill type can change the part’s strength, flexibility, and other mechanical properties
  • The choice of infill pattern can also affect the aesthetics of the part
30
Q

What impact does infill density have in MEAM?

A
  • Infill density directly affects the strength of the part
  • A higher infill density usually results in a stronger part but increases print duration and material usage
  • Conversely, a lower infill density reduces print time and material usage but may reduce the part’s overall strength

Additive Manufacturing (9 decks)

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