PROCESS PARAMETERS – FUSED DEPOSITION MODELING
The most commonly use 3D Printer is Fused Deposition Modelling (FDM) or Fused Filament fabrication (FFF). Here is some fundamental knowledge that one need to know for a good print.
Printer Parameters ;There are many parameters that can be adjusted on most Desktop size FDM printers to achieve an accurate print. for a good material flow, build speed, extrusion speed and nozzle temperature control are few parameters that need to play with. To get a really high resolution print for FDM, there are two key parameters ; nozzle diameter and layer height. By having smaller nozzle diameter and lower layer height are the generally the solutions for smooth surface parts. most of the desktop size 3D printer machines offer a 200 x 200 x 200 mm build platform/bed/chamber. The build chamber size can even be bigger up to 1000 x 1000 x 1000 mm. As for us we have as big as 300 x 300 x 300 mm and therefore for big components we opt breaking a design into few components
Warping : warping is the unavoidable issue for 3D Printing. as different sections of the print cool at different rates creating internal stresses that can lead to warping or distortion. heated bed and adhesion such as glue play an important role in sticking a part down and limiting the likelihood of warping occuring.
layer adhesion: filament is glued and pressed against the previous layers to create the bonding between layers. layer adhesion is a crucial part of FDM printing process in order to create a solid part and cohesive part. The hot extruded material melts and re-melts the previous printed layers. The downward force and the partial remelting of the underlying material enables bonding of the new layer. This also means that FDM deposited in an oval shape rather than a circle. Apparently, this cause inherent anisotropic behaviour, rougher surface finish promoting to a stress concentration at these small valleys lead to crack when subject to load.
Support Structure ; Support structures is prerequisite for a successful printing. All overhanging structures that are shallower than 45 degrees to the ground plane required support. This is because new layer cannot be deposited onto thin air without a structure than can support it. support is part of the printed object and normally in a lattice structure that is removed after the printing. Although it is possible to print overhangs that are less than 45 degrees due to inherent sickness of the molten filament, the angled surface begins to suffer in quality. for accurate print, maintaining the 45 degrees is highly recommended. The drawback is that support detrimental the surface quality resulting rougher surface finish. anyway, half an hour post processing will do.