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Lesson 12 MJ and BJ - Coggle Diagram

- - - - Flow
        
        Suspending particles in carrier liquid
        
        Dissolving materials in solvent
        
        Melting of solid polymer
        4.Mixing formulation of monomer or prepolymer with polymerization initiator
    - - Materials must be converted into small discrete droplets from a continuous volume of liquid
        
        depends on material, hardware, and process parameters
        
        Any addition or changes to the material may drastically change the droplet formation behavior
    - - How the droplet drop, impact and substrate wetting or interaction needs to be account for in the movement of print head or substrate
        
        If smaller droplets break off from main droplet during flight, material will be spread over a larger area than intended --> not well defined boundaries
        
        If droplet splashes --> formation of crown
    - - When the phase changes occurs is important as it affects droplet's interaction with substrate and final deposition created
        
        Because non uniform solidification --> warpage and undesirable results
    - - droplets interact differently with own material as compared to metal plate substrate
        
        Each layer must be fully bonded to previous layer
        
        Addition of new layers does not damage previous layer
        
        Can be resolved by smoothen the surface periodically
    - - clogging of nozzles can occur
        
        Needs to be monitored and maintained
        
        Purging and Cleaning Cycles
        
        Complex sensing systems to identify and compensate malfunctioning or inconsistent nozzles
        
        Replaceable nozzles
    - - Can be improved by producing many small droplets very close together
        
        but
        
        Difficult due to limitations in manufacturing processes and overlapping of thermal and pressure differentials to drive adjacent nozzles
        
        multiple passes over the same area can be done
  - - - constant pressure
        stream break into droplet
        droplets of uniform mass achieved by pertubing jet at fixed frequency close to spontaneous droplet formation rate
        charging droplet to deflect and position the droplets by electric field
        remaining droplets are collected in gutter and is recycled
    - - droplet produced directly from nozzle individually
        
        formed by individual pressure pulses which was created at specific times by thermal, electrostatic, piezoelectric, acoustic or other actuators
- - - - Fabrication of ceramic parts
        
        Green parts subjected to thermal decomposition to remove polymer binder
        
        Furnace temperature increased until ceramic's sintering temperature
        
        Sometimes an infiltrant is used that reacts to form a ceramic binder
        
        Another possibility is to infiltrate a metal to form a ceramic-metal composite
    - - Fine powders does not flow well enough to spread into defect-free layers
      - The need for isotactic pressing due to inadequate green part density severely limits the types of part shapes capable of being processed.
      - Slurry-based working material which is deposited over the build area using ink-jet printing can be used to counteract this.
      - After the slurry dries, binder is selectively printed to define the part shape.
      - Repeated step for each layer, --> increase build time.
    - - Start with metal oxide powders, following the binder jetting process for ceramics up to the sintering step, a hydrogen atmosphereis introduced while in the furnace
      - Cause a reaction to occur between hydrogen and oxygen atoms in metal-oxide, which converts it into a metal
      - After reduction, metal particles are sintered to form a metal part.
- - - - BINDER JETTING
        
        Faster than MJ
        
        Enables material composition that MJ can't achieve easily
        
        Better quality ceramic and metal parts produced
        
        Able to print in colours
        
        No support structures required as parts are self-supporting in powder bed
        
        Increased multiple parts to be produced at one time
    - - Allows for multiple material parts and colour
      - capable of using multiple print head to increase printing speed
      - Lower cost as machine can be assembled from standard parts
      - Better accuracy and surface finishing than binder jetting