A spool of thermoplastic filament is first loaded into the printer. Once the nozzle has reached the desired temperature, the filament is fed to the extrusion head and in the nozzle where it was heated to its well above glass temperatureand around its melting point(click click sound and blobs) . The extrusion head is attached to a 3-axis system that allows it to move in the X, Y and Z directions. The melted material is extruded in thin strands and is deposited layer-by-layer in predetermined locations, where it cools and solidifies. Sometimes the cooling of the material is accelerated through the use of cooling fans attached on the extrusion head. To fill an area, multiple passes are required (similar to coloring a rectangle with a marker). When a layer is finished, the build platform moves down (or in other machine setups, the extrusion head moves up) and a new layer is deposited. This process is repeated until the part is complete.
not on first layer solution: fine tune cooling fan on extruder head
Mesh Bed Leveling: Virtualy create a 3d virtual plate to allow computing compensation of flex and curve on the print platform on the fly, traditional z level adjustment,grid-based adjustment presume print platform to be a perfectly even and sometimes tilted surface, which is engineering wise difficult in reality. Manual leveling, automated leveling with probe (prusa i3 MK3)
extremely vicious for printers with 2 nozzles, especially when z is not leveled.
Glass Fiber/ Carbon Fiber (Stiffness and weight, here prints were composed with multiple Nylon layers and reinforced with Carbon Fiber layers together, sole Carbon Fiber have extreme layer adherance difficulty, the machanism is when carbon fiber printed out it will melt its way into the part below it. )Markforged
Metal FDM (In Thermoplastic FDM, printed layers are heated to its glass transition temperature, which makes it soft and fusible when next layer is added. Metal doesn't do that, it is either hard and collide the print head or imaging what happent when you use a soldering gun on solder)
Cold Wedling (Aceton)
Gap Filling (Cotton swab Aceton, fill the gap with epoxy XCT-3D, autobody filler, Aceton with ABS, and sand)