Table 5.

Patents on FDM technology.

Type	Authors, Number of Patent	Bullet Points
Filament storage and printer heads	Mark et al. (2017) US9815268 [140]	The ironing lip of the nozzle that, when in contact with melted material, “irons” it onto the layers of the part, i.e., presses it as the nozzle or plate are moving relative to each other. Hence, flat compressed cross-sections of the initially circular extruded composite are created. The resultant shapes can be regulated by the controller that lowers the nozzle by 1/2 or 1/3 initially circular extruded filament’s diameter
	Mark and Gozdz (2015) US9126367 [139]	The patent was built specifically for the composite filaments to be printed by FDM The temperature in the nozzle is higher than melting temperature of the polymeric matrix and lower than melting temperature of the added fibers The fibers are presented in the paper to be continuous or semi-continuous
	Pax and Schmehl (2014) US20140044823 [137]	The heater has an integrated safety system that can regulate the temperature of the heater and maintain the safe operating temperature of the extruder
	Swanson et al. (2013) US8465111 [138]	The print heads are supposed to be loaded into the receptacles There is a voice coil mechanism below the receptacle that is controlled to be moved along z-axis such that the head is in the active state when lowered and in the passive state (no filament extrusion) when in the upper position.
	Taatjes et al. (2012) US8157202 [135]	The container for the filaments has a circuit board required for the communication between the printer and the container providing information about the type and amount of the filament in the container.
	Comb et al. (2012) US8153182 [136]	The deposition head is supposed to be installed into the head mount An adjustable head mount is designed to prevent damage to the printer head and secures from undesirable shaking
Support materials	Hopkins et al. (2012) US8246888 [142]	Carboxyl and phenyl monomers are added to the support material making it soluble in the aqueous alkaline solution (ph7–13) It is also claimed that the material becomes less susceptible to cracking
	Tafoya (2013) US8505560 [143]	A tank with the aqueous solution to remove the support material The temperature control is integrated to provide required conditions for material removal
Novel technique	Lewis et al. (2016) US20160346997 [141]	The rotation of the deposition head can control the alignment of the fibers (or other high-aspect-ratio additives) in the material The higher the rotational velocity the more inclined to the direction of the extrusion the fibers are.
Auxiliary measures	Paul and Batchelder (2012) US8222908 [144]	Capacitive detector that induces an electric field is used When the extruded material goes through the electric field the capacitance value rises The detected capacitance value is dependent on the volume, diameter of the extruded filament and the moisture content in it. Hence the concentration of the moisture and lack of material (due to nozzle clogging and other issues) can be detected
Biotechnology	Boehm et al. (2013) US20130326878 [145]	Production of dental prosthesis using FDM