FIELD

[0001] The present invention relates to 3D-printing or additive manufacturing. In particular, the present invention relates to a 3D-printing gas duct system, a 3D- printhead, a 3D-printer and a 3D-printing method.

BACKGROUND

[0002] In the field of additive manufacturing or 3D-printing an additive manufacturing machine is also called a 3D-printer. In 3D-printing objects or workpieces are built/created/generated by subsequent depositing layers (beads or strands) of build material onto each other. This build material may be plastic material and in particular, the depositing process may be the FFF process. The build material supplied to the 3D- printer may be filament or granulated material.

[0003] The 3D-printer usually comprises a 3D-printhead that moves in three dimensions by means of a motion system (e.g. a gantry system) the 3D-printhead is fixed to by means of a fixation. Also, there are 3D-printers that comprise at least one 3D-printhead that moves in two dimensions and a printbed (the surface or structure on/to which the workpiece(s) are created) that moves in the third dimension. Also, there are 3D-printheads that are mounted to a conventional industrial robot such that the 3D- printhead can realize complex trajectories. The 3D-printhead generally comprises an extruder to apply the (build) material to build up the workpiece.

[0004] In the field of FFF printing, the 3D-printhead conventionally may comprise a liquefier to heat up the build material. Sometimes the 3D-printhead further comprises a melt pump or positive displacement pump downstream the liquefier. Build material

(the material from which the workpiece is created) is fed to the liquefier and subsequently (if applicable) to the melt pump. In the 3D-printhead said build material is heated up to a temperature it can be deposited. In particular, the build material is heated up in the liquefier and deposited through a material nozzle having a material opening. The material nozzle is connected to the liquefier or melt pump. The hot deposited build material forms a deposited strand that in turn forms one layer or part of a layer of the workpiece being built. The heated and plastic-state build material leaves the printhead, or more particularly, the material nozzle trough said material opening to form the workpiece(s). The print head may use any known technology such as positive displacement pumps, material feed units (e.g. friction wheel units), screw extruders, gear pumps, liquefiers, tube liquefiers, or any combination of these.

[0005] The deposited build material or deposited strand subsequently cools down after its deposition. This cooling, and in particular, how fast said cooling happens has direct impact on the properties of the workpiece being build. If the just extruded or deposited build material cools down fast, it solidifies fast. This e.g. has the consequence that it tends not to melt together so much with the previous layers the just deposited strand of build material is applied to. Consequently, the so-called 'inter- layer-bond' is reduced. However, the just deposited strand has less time to move or change its position due to gravity influences (e.g. in printing an overhanging geometry) since the deposited strand cools down quickly and thus solidifies quickly and gravity is less influential on the just deposited strand. Hence, an increased accuracy in printing overhanging geometries may be achieved. Further, the use of a support structure or support material (commonly known) may be at least reduced if not avoided. However, as mentioned above, the inter-layer-bond between the different and subsequent deposited strains is reduced because the time to melt together is reduced due to the fast cooling.

[0006] On the other hand, if the just deposited strand of build material cools down slowly, the inter-layer-bond is strengthened by having time to melt together. However, printing an overhanging geometry in a situation in which the just deposited strand of build material cools down slowly, the so printed geometry has time to shift due to gravitation influences because not only the just deposited strand is in a plastic state but also the strands it was deposited onto due to longer period of cooling down. However, up to date the inter-layer-bond cannot be controlled satisfactory by means of a cooling rate.

[0007] Also, on a printhead several sections have to be kept at quite opposing temperatures. For example, in an FFF-printhead some sections of the printhead have to be kept at a high temperature in order to keep the build material in a plastic or depositable state. However, other sections of the printhead have to be kept at a considerably lower temperature than the aforementioned section. For example, if the printhead comprises a feeding mechanism, it may be of advantage that the build material has a temperature around room temperature and thus is far lower than the temperature at which the build material is in a plastic state. Also, the can be other parts of the printhead where it is advantageous or necessary to have a temperature in the range of room temperature. Since printheads are desirably designed to be compact the sections with quite opposing temperatures are usually located in close proximity to each other and may interfere in an unwanted way with each other.

[0008] Object of the present application is to overcome the aforementioned drawbacks and to provide a 3D-printing gas duct system, a 3D-printhead, a 3D-printer and a 3D-printing method that contributes to the improvement of the part quality of printed workpieces by controlling a gas flow at and/or around the material nozzle or material opening.

[0009] This object is solved by a 3D-printing gas duct system, a 3D-printhead, a 3D- printer and a 3D-printing method according to the appended independent claims. Preferable embodiments are subject to the features of the appended dependent claims.

[0010] A 3D-printing gas duct system according to an aspect of the present application comprises a gas supply, a gas duct and at least one nozzle with a nozzle opening. The gas duct connects the gas supply with the at least one nozzle and further comprises at least one interface between the at least one gas nozzle and the gas supply. The gas supply provides gas that is ultimately provided in the vicinity of the material opening. The gas is guided from the gas supply to the gas nozzle by the gas duct via the interface. This may have the advantage that the gas may be guided to a material nozzle where the gas can have influence on build material that is being deposited or was deposited. Further, this may have the advantage that the interface provides flexibility in the setup of the gas duct system. [0011] An FFF-printing gas duct system according to an aspect of the present application comprises a gas supply, a gas duct and at least one gas nozzle with a nozzle opening. The gas duct connects the gas supply with the at least one gas nozzle. The FFF-printing gas duct system further comprises a gas extraction having at least one extractor having an extraction opening and an extraction duct, wherein the at least one extraction opening is located in the vicinity of the nozzle opening. This may have the advantage that the gas can be provided by the gas nozzle and the gas extraction can subsequently or simultaneously extract the gas. Consequently, a gas atmosphere in the vicinity of the gas nozzle and the extractor may be controllable more precisely and thus the quality of the workpieces may be increased.

[0012] With an FFF-printing gas duct system according to another aspect of the present application the at least one interface is located between the at least one nozzle and the gas supply and/or between the extraction opening and the extraction duct. This may have the advantage that the interface provides flexibility in the setup of the duct system.

[0013] A gas duct system according to another aspect of the present application comprises at least one gas supply, at least two gas ducts and at least one gas nozzle, wherein the at least one gas nozzle is connected with at least one of the gas ducts. This may have the advantage that the use-flexibility of the system is increased.

[0014] A gas duct system according to another aspect of the present application comprises a gas supply for each of the at least two gas ducts. This may have the advantage that the gas flow in each of the gas ducts can be controlled individually. This may have an advantage in a case in which e.g. one gas duct is used to influence the build material and the other gas duct can be used to e.g. cool parts of a 3D- printhead the gas duct system may be attached to.

[0015] With a gas duct system according to another aspect of the present application, the at least one nozzle and/or extractor is detachable from the gas duct or the extraction duct at the at least one interface. This may have the advantage that the use- flexibility of the system is increased since e.g. different shapes of gas nozzles and/or extractors may be used dependent on a specific (momentarily) print-situation.

[0016] With a gas duct system according to another aspect of the present application, the at least one gas nozzle is fluidically connected with the gas duct at multiple points. This may have the advantage that the gas flow within the duct system, and the gas nozzle in particular, may be rendered less turbulent.

[0017] With a gas duct system according to another aspect of the present application, the nozzle opening or emitting characteristics is/are adjustable. This may be a pre-set adjustment or a variable adjustment. The emitting characteristics may include the shape of the gas flow exiting the nozzle opening and/or the direction of the gas flow. This may have the advantage that the gas flow exiting the nozzle opening may be set according to a print-situation. This may further have the advantage that the gas flow may be directed precisely to the area needed, without for example, influencing with a heated part of the printhead the gas duct system is mounted to. In other words, a cooling of the printhead in an undesirable area (e.g. the material nozzle or the at least part of a hot end) by the air current as by-product of the cooling of the deposited build material may at least be reduced. Further, the cooling rate in view of a print-speed and/or material properties of the build material may be chosen. For example, in the case of a high print-speed it is beneficiary to focus the emitting characteristics of the gas flow in order to at least punctually achieve a high cooling rate. In case the print- speed is slow, the heated parts of the print head have an increased temperature influence on the deposited build material than at higher print-speed. A variable adjustment (emitting characteristic and/or volume flow) may advantageously help compensating for the impact of changing print-speed.

[0018] With a gas duct system according to another aspect of the present application, the gas duct system may comprise at least one sensor. This may have the advantage that data regarding the gas in the gas duct system may be collected. This data may e.g. concern temperature, pressure, mass flow, flow rate, humidity, gas properties, gas composition, etc. [0019] With a gas duct system according to another aspect of the present application, at least one of the gas duct, the gas nozzle, the extractor or the extraction duct is movable. This may be a movability with respect to the rest of the system. This may have the advantage that the gas duct, gas nozzle, the extraction duct or extractor may be positioned and controlled variably. Hence, advantageously positioning at least one of the above in a specific (momentarily) print-situation to guide the gas flow in an advantageous manner.

[0020] A gas duct system according to another aspect of the present application, further comprises at least one temperature system for cooling and/or heating a gas within the gas duct system. This may have the advantage that the temperature of the gas within the gas duct system may be controlled. Consequently, an influence of the gas on the build material may be controlled more finely.

[0021] A 3D-printhead according to another aspect of the present application comprises a fixation and a gas duct system according to any of the aspects mentioned above. This may have the advantage that workpieces produced by means of said 3D- printhead may have an increased quality due to e.g. influence on said inter-layer-bond.

[0022] A 3D-printhead according to another aspect of the present application further comprises a nozzle changer. This may have the advantage that a gas nozzle and/or extractor may be changed e.g. during a print with respect to a specific (momentarily) print-situation.

[0023] With a 3D-printhead according to another aspect of the present application, at least the gas nozzle and/or the extractor is moveable with respect to the fixation. This movability may be a rotation and/or a linear movement. This may have the advantage that a position and/or orientation of said gas nozzle and/or said extractor may be controlled with respect to a specific (momentarily) print-situation.

[0024] A 3D-printer according to another aspect of the present application comprises a gas duct system and/or a 3D-printhead according to any of the aspects mentioned above and further comprises a nozzle changer and/or a nozzle magazine. This may have the advantage that a gas nozzle and/or an extractor may be changed e.g. during a print with respect to a specific (momentarily) print-situation.

[0025] According to a 3D-printing method of another aspect of the present application the method comprises controlling at least one feature of at least one gas nozzle and/or extractor in the vicinity of a build material nozzle. This may have the advantage that workpieces produced by means of said 3D-printing method may have an increased quality due e.g. to influence on said inter-layer-bond.

[0026] With a 3D-printing method according to another aspect of the present application, said at least one feature is for example the volume flow of the gas flow and/or the emitting characteristic of the gas flow provided by said at least one gas nozzle. This may have the advantage that workpieces produced by means of said 3D- printing method may have an increased quality due e.g. to an even more detailed influence on said inter-layer-bond.

[0027] With a 3D-printing method according to another aspect of the present application, said at least one feature is controlled using data of a print trajectory. This may have the advantage that the method may take specific (momentarily) print- situations in account and said at least one feature may be controlled accordingly.

[0028] With a 3D-printing method according to another aspect of the present application, said controlling comprises an adjustment of a nozzle opening of the at least one nozzle. This may have the advantage that workpieces produced by means of said 3D-printing method may have an increased quality due e.g. to an even more detailed influence on said inter-layer-bond.

[0029] With a 3D-printing method according to another aspect of the present application, said controlling comprises exchange of the at least one gas nozzle and/or extractor with another gas nozzle and/or extractor. This may have the advantage that a gas nozzle and/or an extractor may be changed e.g. during a print with respect to a specific (momentarily) print-situation.

[0030] With a 3D-printing method according to another aspect of the present application, said controlling comprises moving the gas nozzle and/or the extractor. This may be a rotational movement and/or a linear movement. This may have the advantage that a position and/or orientation of said gas nozzle and/or said extractor may be controlled with respect to a specific (momentarily) print-situation.

[0031 ] The above aspects may be freely combined. The aspect of the above methods may be combined with the aspects of the above gas duct system and/or the above aspects of the 3D-printhead and/or the above aspects of the 3D-printer and vice-versa.

[0032] For a better understanding of the invention the latter will be explained in view of the appended figures. The gas mentioned in this application may be at least one of air, any technical gas, an inert gas. An above-mentioned ventilator for providing the gas current may be or comprise a gas source supplying e.g. inert gas.

[0033] The figures respectively show in very simplified and schematically depiction:

[0034] Fig. 1 an example of the effect of a slow cooling of deposited build material.

[0035] Fig. 2 an example of the effect of a rapid cooling of deposited build material.

[0036] Fig. 3 an example of a 3D-printing gas duct system.

[0037] Fig. 4 an example of an FFF-printing gas duct system having a gas duct and an extraction duct.

[0038] Fig. 5 an example of a gas nozzle head with multiple openings.

[0039] Fig. 6 an example of a gas nozzle head with a ring nozzle opening.

[0040] Fig. 7 an example of a gas nozzle head with ring segment nozzle openings. [0041] Fig. 8 an example of a gas nozzle head with linear nozzle openings.

[0042] Fig. 9 a cross sectional view of the gas nozzle head depicted in fig. 5.

[0043] Fig. 10 an example of a gas duct system with multiple channels.

[0044] Figs. 11 to 14 examples of ring nozzles and their respective emitting characteristics.

[0045] Fig. 15 a schematic example of a rotatable gas nozzle and extraction nozzle.

[0046] It is to be noted that in the different embodiments described herein same parts/elements are numbered with same reference signs, however, the disclosure in the detailed description may be applied to all parts/elements having the regarding reference signs. Also, the directional terms / position indicating terms chosen in this description like up, upper, down, lower downwards, lateral, sideward are referring to the directly described figure and may correspondingly be applied to the new position after a change in position or another depicted position in another figure.

DETAILED DESCRIPTION OF THE FIGURES

[0047] Fig. 1 depicts an example of the effect of cooling of deposited build material 800 by a schematic cross section of deposited strands of build material 800. In fig. 1 no cooling or relatively less cooling was applied to the strands of deposited build material 800. Consequently, the individual strands of deposited build material 800 had more time to form the inter-layer-bond. The strands are deposited from the bottom upwards. In detail A the strands are deposited straight upwards and in detail B the strands are deposited in an overhanging geometry. This inter-layer-bond is depicted as the dashed line 810 between the individual strands of deposited build material 800 (best to be seen in detail A of fig.1 ). Since there is no or relatively less cooling in this example, the strands have more time to form the inter-layer-bond since the last deposited strand of build material 800 cooled down relatively slowly and there was consequently more time that the just deposited strand of build material could coalesce with the strand that was deposited before. Hence, a length 815 of this inter-layer-bond is relatively long and thus the deposited strands of build material adhere together relatively strongly.

[0048] In detail B of fig. 1 the effect of no cooling or relatively less cooling is depicted in a case where an overhanging geometry is printed. Here, gravity has more time to interfere with the intended geometry since there is no cooling or relatively less cooling. The relatively great length 815 of the inter-layer-bond is here of disadvantage since the overhanging geometry is prone to deformation due to the influence of gravity.

[0049] Fig. 2 depicts another example of the effect of cooling of deposited build material 800 by a schematic cross section of deposited strands of build material 800, similar to fig 1 . However, in fig 2. more cooling as in fig. 1 was applied. Best to be seen in detail A of fig. 2, there is also an inter-layer-bond 820 between the individual deposited strands of build material 800. However, in fig. 2 a length 825 of the inter- layer-bond is shorter than depicted in fig. 1. This is because of the cooling of the deposited strand of build material 800, giving the different layers of deposited build material less time to adhere together. Hence, there is less force needed to separate the individual strands of deposited build material in comparison to the strands of deposited build material depicted in fig. 1 having a greater length 815 of the inter-layer- bond. However, when an overhanging geometry is printed with the increased cooling (detail B of fig. 2) the geometry is less prone to be affected by gravity. With other words, the cooling of the deposited strands of build material helps the printed geometry to stay in the intended shape. The effects of figs. 1 and 2 were already mentioned above.

[0050] Fig. 3 depicts a schematic view of a gas duct system 10. The gas duct system

10 comprises a gas supply 20, a gas duct 30 and a gas nozzle 40 having a nozzle opening 45. An interface 50 is located between the gas nozzle 40 and the gas duct 30.

The interface 50 is optional. The gas supply 20 may be at least one among a ventilator, an inert gas source, a compressed air supply. The orientation or layout or shape depicted in fig. 3 is random and the system may have any layout or form that is desired or needed. Usually a 3D-printhead the gas duct system is mounted to will dictate a major part of the layout of the gas duct system. A gas (i.e. an inert gas or air) is supplied by the gas supply 20 and guided via the gas duct 30 and the interface 50 to the gas nozzle 40 and exits the gas duct system 10 and in particular the gas nozzle 40 via the nozzle opening 45.

[0051] Fig. 4 depicts a schematic view of an FFF-printing gas duct system 11. The gas duct system 11 comprises a gas supply 20, a gas duct 30 and a gas nozzle 40 having a nozzle opening 45. An interface 50 is located between the gas nozzle 40 and the gas duct 30. The system further comprises a gas extraction 60 with an extraction duct 70 and an extractor 80 having an extraction opening 85. An interface 50 is located between the extractor 80 and the extraction duct 70.

[0052] In the gas duct system 11 , gas is supplied into the gas duct 30 by the gas supply 20. The gas flows from the gas supply 20 via the interface 50 to the gas nozzle 40 and leaves the gas nozzle 40 via the nozzle opening 45. Due to a negative pressure in the gas extraction 60 the gas that left via the nozzle opening 45 is sucked at least partially into the extractor 80 and further into the extraction duct 70 via the interface 50. The interfaces 50 are each optional and may be applied to the system independent from each other.

[0053] Downstream of the extraction duct 70 may be a gas treatment system located that treats the recovered gas and further provides it back to the gas supply 20 in order to establish a cycle. The gas treatment system may comprise at least a filter and/or a gas sensor. The gas duct 30 and/or the extraction duct 70 may comprise at least a sensor connected thereto. The at least one sensor may detect at least among a gas flow, temperature, pressure, composition.

[0054] Fig. 5 depicts a gas nozzle head 35 including three interfaces 50, a nozzle opening 45 and extraction opening 85. Both, the nozzle opening 45 and extraction opening 85 are ring shaped and also concentric. The interfaces 50 connect the openings 45 and 85 with (not shown) gas and extraction ducts. Flere, there are three interfaces 50 shown, however, the only has to be one duct per opening. In other words, each opening 45 or 85 needs to communicate at least with one respective duct (gas duct 30 or extraction duct 70). Flere, the opening having the smaller diameter is depicted as the extraction opening 85 and the opening having the larger diameter is depicted as the nozzle opening 45. However, this might be interchanged and the nozzle opening 45 can have the smaller diameter.

[0055] Fig. 6 depicts a nozzle head 35 similar to the nozzle head depicted in fig. 5. Here, the nozzle head 35 comprises two interfaces 50 being connected to a gas nozzle 40 having a nozzle opening 45. The nozzle opening 45 may of course be in communication with only one interface 50.

[0056] Fig. 7 depicts two gas nozzles 40, each in communication with an interface 50 and a nozzle opening 45. Here, the nozzle opening is in the form of a ring segment. Here, two gas nozzles 40 are depicted, however there can be one gas nozzle 40 having an interface 50 and a nozzle opening 45 and one extractor having an interface and an extraction opening.

[0057] Fig. 8 depicts two gas nozzles 40 similar to fig. 7. However, here the nozzle openings 45 have the shape of a straight line. The nozzle openings 45 are connected each to a gas nozzle 40 and an interface 50. Here also, corresponding to the above regarding fig. 7, one of the openings depicted in fig. 8 may be an extraction opening. The openings of figs. 7 and 8 do not have to be embodied in pairs, at least one of the openings has to be embodied.

[0058] Fig. 9 depicts a cross sectional view of the nozzle head 35 depicted in fig. 5.

The nozzle head 35 comprises a build material nozzle 41 being surrounded by the extraction opening 85 and the nozzle opening 45. The ring shaped nozzle opening 45 is connected to the gas nozzle 40 and at least one interface (not shown). The also ring shaped extraction opening 85 is located between the build material nozzle 41 and the nozzle opening 45. The extraction opening 85 is connected to an extractor 80. Fig. 9 schematically depicts two area X and Y or emitting characteristics. Essentially areas X and Y are areas of different pressure levels (e.g. air pressure). In area X the pressure level X is due to the extraction performed by means of extraction opening 85 and extractor 80 lower than in area Y. In area Y the pressure level is higher than in area X and also to the ambient area due to the gas (e.g. air) that is conveyed into the area X by means of the gas nozzle 40 and nozzle opening 45. The extension of both areas X and Y are heavily influenced by a shape of the openings 45 and 85 and are not as sharp as schematically depicted in fig. 9. They are also heavily dependent on the emitting characteristics. This will be explained in further detail below in view of figs. 11 to 14. Gas conveyed via the nozzle opening 45 into the area X will be extracted in the are X via the extractor opening 85 (respectively indicated by the arrows). The current of gas originating at the nozzle opening 45 and drain in the extractor opening 85 influences the material deposited via the build material nozzle 41 as descried above.

[0059] Fig. 10 depicts a gas duct system 10 comprising two gas ducts 30 and 31 . The gas duct 31 comprises a nozzle opening 45b. In the gas duct system 10 the nozzle opening 45b may be used to cool a part of a 3D-printhead the gas duct system 10 is mounted to. The gas duct system 10 further comprises another gas duct 30 that is connected via an interface 50 with a gas nozzle 40 having a nozzle opening 45a (not visible in fig. 10 because it is located on the opposite side of gas nozzle 40). Here, the nozzle 40 is connected to the gas channel 30 via two interfaces 50. Here, the nozzle opening 45a has the ring shape as depicted in fig. 6. Each gas duct 30 and 31 may have an own gas supply that is independently controllable. The gas duct system 10 depicted in fig. 10 may also comprise the nozzle head 35 of fig. 5 instead of the gas nozzle 40. In this case there would be a third duct, the extraction duct, connected to the extraction opening.

[0060] Figs. 11 to 14 depict each a nozzle head 35 corresponding to fig. 6. Figs. 11 to 14 depict different emitting characteristics of the regarding nozzle openings 45. Each figure depicts a nozzle head 35 having two interfaces 50, a gas nozzle 40 and the nozzle opening 45. The area Y or emitting characteristic of each nozzle opening 45 is different and dependent on the nozzle opening 45. In fig. 11 the area Y or emitting characteristic of nozzle opening 45 is essentially straight downwards with regard to the nozzle head 35.

[0061] In fig. 12 the area Y or emitting characteristic of nozzle opening 45 is focused towards the center of the nozzle opening 45 and downwards with regard to the nozzle head 35. [0062] In fig. 13 the area Y or emitting characteristic of nozzle opening 45 is spread outward from the nozzle opening 45 and downwards with regard to the nozzle head 35.

[0063] In fig. 14 the area Y or emitting characteristic of nozzle opening 45 is also focused towards the center of the nozzle opening 45 and downwards with regard to the nozzle head 35. However, here considerably more than depicted in fig. 14. All emitting characteristics are depicted as areas, however, this is for simplicity reasons since every gas flow has a certain drag and even if very focused, the gas flow will have drag and consequently result in an area of gas flow.

[0064] In fig. 15 the schematic design of a gas duct system 10 is depicted mounted to a schematically depicted 3D-printhead 90 comprising a build material nozzle 41 . The 3D-printhead 90 is fixed to a motion system via a fixation (not shown). The gas duct system 10 comprises a gas nozzle 40, a nozzle opening 45, an extractor 80 and an extraction opening 85. The gas nozzle 40 and extractor 80 are rotatable (indicated by the double arrow) on a turning circle TC and about an axis Z that passes through the center of the build material nozzle 41 and the turning circle TC. In other words, are the turning circle TC and the build material nozzle 41 in the depicted example concentric. The gas nozzle 40 and the extractor 80 may also be controlled to rotate independent from each other about the turning circle TC or may have each an own turning circle. The gas nozzle 40 and extractor 80 are also rotatable with respect to the fixation of the 3D-printhead 90. Consequently, the at least one of the openings 45 and 85 may be positioned based or dependent on the print trajectory of the build material nozzle and thus optimally with respect to the respective print trajectory.

[0065] If the build material nozzle 41 follows a print trajectory as this is commonly known, it is possible to position both openings 45 and 85 based on the current orientation of the print trajectory as needed and/or desired. In other words, the openings 45 and 85 may be positioned with respect to the print trajectory as needed and/or desired. The controlling or positioning of the openings 45 and 85 may be. based on data of the print trajectory. Also, openings may be controlled separately from each other. Also, there may be an alternative that comprises at least one of the rotating openings 45 or 85.

[0066] In all figures like reference sings are used for like or similar parts/elements as in the other figures. Thus, a detailed explanation of such part/element will only be given one for the sake of brevity. The extraction openings and nozzle openings may have any shape that is desired and/or needed. The nozzle openings throughout the entire disclosure may be configured to have a variable emitting characteristic.

[0067] The embodiments depict possible variations of carrying out the invention, however, it is to be noted that the invention is not limited to the depicted embodiments/variations but numerous combinations of the here described embodiments/variations are possible and these combinations lie in the field of the skills of the person skilled in the art being motivated by this description.

[0068] The scope of protection is determined by the appended claims. The description and drawings, however, are to be considered when interpreting the claims. Single features or feature combinations of the described and/or depicted features may represent independent inventive solutions. The object of the independent solutions may be found in the description.

[0069] All notations of ranges of values in the present description are to be understood as to also comprise and disclose all arbitrary sub-ranges therein, e.g. the disclosure 1 to 10 is to be understood that all sub-ranges starting from the lower limit 1 up to the upper limit 10 are also comprised and disclosed, i.e. all sub-ranges starting with a lower limit of 1 or bigger and end with an upper limit of 10 or smaller, e.g. 1 to 1 ,7, or 3,2 to 8,1 , or 5,5 to 10. Only one digit after the comma is described, however the same applies mutates mutandis to any given number of digits after the comma.

[0070] It is further to be noted that for a better understanding parts/elements are depicted to some extend not to scale and/or enlarged and/or down scaled. Reference sign list

10 3D-printing gas duct system

11 FFF-printing gas duct system

20 gas supply

30 gas duct

31 gas duct

35 gas nozzle head

40 gas nozzle

41 build material nozzle 45 nozzle opening 45a nozzle opening 45b nozzle opening

50 interface

60 gas extraction

70 extraction duct

80 extractor

85 extraction opening

90 3D-printhead

800 deposited build material

810 inter-layer-bond

815 length of inter-layer-bond

820 inter-layer-bond

825 length of inter-layer-bond

X area / emission characteristic

Y area / emission characteristic

TC turning circle