2. Material Extrusion Flashcards
What is the key process of Material Extrusion Additive Manufacturing (MEAM)?
Material is selectively dispensed through a nozzle.
What distinguishes MEAM in terms of commonality and cost compared to other additive manufacturing methods?
It is the most common and cheapest additive manufacturing method.
How does material deposition work in MEAM?
Material is deposited one layer at a time, with the platform moving down after each layer.
What are the stages of material extrusion?
- CAD Model
- Convert model to STL
- Setup
- Build
- Post processing
What are the requirements for a 3D model to be printed in MEAM?
The model must be a 3D solid or watertight mesh.
What design considerations should be taken into account when creating a CAD model for MEAM?
- Avoid thin walls
- Consider support structures (especially for large masses supported by thin stems)
- Account for moving part tolerances
- Make appropriate material choices.
What is the purpose of converting a model to STL in MEAM?
It converts the model to a triangular surface representation suitable for stereolithography, saving it in .stl format.
What are the key steps in the setup process for MEAM?
- 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.
Describe the build process in MEAM once the setup is complete.
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.
What post-processing steps are needed in most AM processes?
- Removal of support structures, which can be by force or dissolved.
- Painting to improve appearance and strength
- Polishing through mechanical or chemical methods.
Describe the order of operations in a single spool extrusion system for MEAM.
- 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
How does a dual spool system differ from a single spool system in MEAM?
- Two separate spools, heater and nozzle systems
- Allows for separate build and support material systems
What are the benefits of using soluble support structures in MEAM?
- Easy removal of support material
- Ideal for complex geometries or hard-to-reach areas
What are the characteristics of integrated (direct) extrusion in MEAM?
- 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
What are the features and issues associated with remote (Bowden) extrusion?
- 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
What is the filament driver and how does it function in MEAM?
- 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
What are the components of the hot-end in MEAM and their functions?
Consists of an aluminum block or barrel, a heating element, a cooling fan, a temperature sensor, a controller, and the print nozzle
How does the nozzle size affect printing in MEAM?
- Nozzle diameters range from 0.2 to 0.8mm
- The size of the nozzle influences print quality and speed
What are the temperature ranges for different materials in MEAM?
- 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
What are the two types of XYZ movement systems in MEAM?
- Cartesian
- Delta
What characterizes the Cartesian movement system in MEAM?
- 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
How does the Delta movement system operate in MEAM?
- 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
What is the purpose of heating the build platform and chamber in MEAM?
- 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
What are the limitations of non-heated systems in MEAM?
Limited to printing with certain materials that do not require a heated environment to prevent warping or cracking.
