Field of the invention

[0001] The present invention concerns a system for additive

manufacturing a component, such as a mechanical part or workpiece, a constituent or a part of a mechanical or electrical system, up to a prototype or a product.

Description of related art

[0002] The recent evolution of the domain of additive manufacturing (AM) provides excellent tools not only for rapid and cost-effective manufacturing of prototypes and products but also for a single on-demand component, for a pre-production series of components and for a

production of a limited number of components. In particular, there is an increasing interest in manufacturing high-value added components, i.e. components that are manufactured according and conforming to given quality standards and technical requirements so as to allow a use in high- demanding and normative application fields.

[0003] In an additive manufacturing process, a manufacturing anomaly (e.g. non-intended variation of the structural or material properties of the final manufactured component) could arise due to a mismatch of

manufacturing parameters, an inconsistency in the 3-dimension (3D) model of the component, an incorrect application of a material layer, a flaw in the material powder, or a bad thermal management resulting in hot spots and related geometrical or material defects.

[0004] Depending on the relevance and of the typology of the variation as well as depending on the applied quality standards and technical requirements, the manufacturing anomaly can represent either an acceptable imperfection or an unacceptable flaw (i.e. defect) which could potentially lead to a malfunction or a premature mechanical failure of the component.

[0005] A non-destructive test of each manufactured component can thus provide a solution to this novel exigence.

[0006] US2014159266 discloses a monitoring procedure for an additive manufacturing procedure permitting to detect defects in the manufactured component by means of an eddy current sensor located on a recoater. The quality of the uppermost solidified material layer is evaluated by

considering a preceding eddy current scan of deeper-lying solidified material layers.

[0007] EP3238865 discloses an inspection system for inspecting a part while the part is being produced by an additive manufacturing technique. To that effect, the inspection system comprises an additive manufacturing apparatus having a build tray. The additive manufacturing apparatus is configured to fabricate said part layer-by-layer on the build tray. The inspection system further comprises an automated exchangeable tool holder carrying a manufacturing tool configured to deposit, add or weld layer-upon-layer of material to form a cross-section of said part. The tool holder and the build tray are configured to move relative to one another along a path defined by a build program. An inspection device is attached to the tool holder and is configured to scan a layer of said material in situ and detect defects in said layer once said layer is deposited, added or welded. The tool holder alternately arranges the manufacturing tool and the inspection device for scanning and detecting defects as soon as the additive manufacturing of a layer is completed. [0008] Switching the manufacturing tool with the inspection too! and positioning the inspection too! relative to the recently-added layer of material is performed by rotating the too! holder so that the inspection too! is In the working position. The switching operation has the

disadvantage to disrupt the speed of the additive manufacturing process.

Brief summary of the invention

[0009] An aim of the invention is to provide a system for additive manufacturing capable to assess a manufacturing quality in a more efficient and faster way with respect to the knowns systems. [0010] In particular, the system does not require switching between the inspection tool and the manufacturing tool, which enables inspection with a minimum penalty on the part manufacturing speed.

[0011] A particular aim is to provide a system for additive

manufacturing capable to assess a manufacturing quality of a

manufactured component that is more simple, timesaving and cost- effective than knowns systems.

[0012] According to the invention, these aims are achieved by means of the additive manufacturing apparatus of claim 1 and the method of claim 27. [0013] The proposed solution provides a system capable of assessing a manufacturing quality by scanning a portion of the additive material and/or of the solidified part of the component which is, or is likely, involved in the current solidification operation. This solution avoids a data- and time-consuming scan of additive material not involved in the manufacturing, as well as a re-scanning of unmodified solidified portion of the component, without having to access a 3D model of the component.

[0014] The proposed solution further provides a solution for simplifying the mechanical conception of the combined additive manufacturing and quality control apparatus. The co-integration of the quality control device (detection device) with the head used for solidification and/or application of functional agents also increases the quality of the readings. It also offers an efficient way to make measurements before and after the solidification process.

[0015] The solidification may be a single-step process or may involve multiple steps. The proposed solution cans be used to assess the quality of each of the steps, as described in the embodiments.

[0016] In one embodiment, the detecting device is configured to sense additive material and/or solidified additive material within and/or close to the solidification area. This solution provides a scan of additive material involved in the (current) solidification process, as well as a scanning of just solidified additive material.

[0017] The additive manufacturing system differs from the one described in EP3238865, in that it does not require a tool holder to change the distances between the part under construction and the

manufacturing/inspection tools.

[0018] It should be noted that sensing functions and part manufacturing functions are simultaneous during most of the process (except in some regions at the edge of the build surface due the spatial offset between the inspection tool and manufacturing tool). This stands in contrast with the additive manufacturing system described in EP3238865, where the manufacturing and inspection phases are necessarily sequential. Indeed, effective part solidification can only occur when the tool head positions the manufacturing tool close to the area being solidified, and effective inspection can only occur when the tool head positions the inspection tool close to the additive material and/or solidified additive material.

[0019] In an embodiment, both the manufacturing tool and the inspection tool (detecting device) of the additive manufacturing system remain at an essentially constant distance to the additive material and/or solidified additive material (e.g. fixed distance to the powder bed in the case of a powder-based additive manufacturing technique). This differs fundamentally from the additive manufacturing system described in

EP3238865, where the very purpose of the tool holder is to change the distance between tools (inspection and manufacturing) and additive material (e.g. powder bed). If layer by layer inspection data is desired with a system according to EP3238865, such distance changes of the

inspection/manufacturing tools achieved by the tool holder occurs at each layer.

[0020] In one embodiment, the detecting device comprises a

combination selected between: an eddy current sensing unit, a capacitive sensing unit, an emitting-receiving unit or an optical sensing unit

comprising at least an optical sensing element sensitive to visible and/or infrared (IR) and/or ultraviolet (UV) radiations (e.g. a camera providing a 1 D or 2D images in one or several bands of the IR-UV range). Alternatively or complementarily, the optical element(s) can provide a 3D image (e.g. depth map, time-of-flight, disparity image). In the case of a use of an optical detection device, the detecting device is not only provided with at least one optical sensing element providing an (1 D or 2D or 3D) image, but also with one or more illumination sources providing the related IR-UV lights, the source(s) being continuously or selectively activated for providing a uniform illumination during the scan.

[0021] This solution provides an accurate detection of material property of various additive materials, e.g. additive material comprising magnetic metal, nonmagnetic metals (e.g. aluminium), and/or (positive) functional agents (adjuvants).

[0022] The (positive) functional agents can provide the function of:

holding the part together before sintering (binding agent, e.g. resin, binders); and/or

decrease locally the quantity of energy required for solidify the additive material, notably by decreasing the sintering or solidification temperature (accelerant agent); and/or

locally increase the energy uptake by the powder bed; and/or colouring the (solidified) material (colouring agent, e.g. pigments).

[0023] In one embodiment, the additive material is a powder material and the detecting device is configured to provide a density, sizes of particle, particle distribution, and/or a purity thereof. These material properties permit to verify the conformity, respectively an early detection of an unconformity (a flaw) in the powder material, potentially or likely leading to a manufacturing anomaly.

[0024] In one embodiment, the detecting device is configured to provide a porosity, a density, a distribution, an integrity, and/or a homogeneity of the (given portion of the) of solidified additive material.

[0025] In another embodiment, the detecting device is configured to provide a density, a distribution, or a homogeneity of the functional agent of the additive material, notably of the binding agent acting as an adhesive to bond (stabilize the particles of) powder material.

[0026] In another embodiment, the detecting device is configured to provide a density, a spatial distribution, or a spatial homogeneity of a functional agent selectively deposed by the head according to the CAD file (3D model of the component) or being already deposited on the entire additive material.

[0027] Another category of functional agents can be selectively deposited around the part being produced or in zones of the powder bed not part of the piece being produced (negative functional agent). Such (negative) functional agents could be used to decrease the binding between grains in order to facilitate the de-caking of the parts, locally inhibit sintering (e.g. by increasing the sintering temperature) or decrease the energy uptake by the powder bed.

[0028] Combinations of positive and negative functional agents can be used to help creating special conditions in the zones of the powder bed that will become the surface of the part, by a chemical reaction and/or by respective their surface tensions and/or by their respective rheological properties.

[0029] In another embodiment, the detecting device is configured to provide information about a non-conformity in an intermediate step of the additive process. Examples of such intermediate steps could be correct evaporation or state change of one or more functional agents, notably on binding agent.

[0030] In one embodiment, the system further comprises a

manufacturing supervisor for detecting manufacturing anomalies, and preferably to assess the detected anomalies as either an acceptable imperfection or an unacceptable flaw (i.e. defect) in the provided additive material and/or the functional agent and/or the component being manufactured, such as a crack, the presence of porosity, or a delamination, or an insufficient quantity of functional agent.

[0031] In one embodiment, the dispenser of additive material is mechanically fixed to the head and the detecting device is configured to sense additive material (e.g. in form of powder material or of a wire) leaving and/or passing though the dispenser. This solution provides a simple, timesaving and cost-effective early scan of additive material.

Brief Description of the Drawings

[0032] The invention will be better understood with the aid of the description of an embodiment given by way of example and illustrated by the figures, in which: Fig. 1 shows a schematic view of a first embodiment of an additive manufacturing system capable to detect a defect within a component, according to the invention;

Fig.2 shown details about the scanning area provided by the additive manufacturing system of Fig.1 ; Figs.3a, b show details about a first and a second embodiment of a detection device of the additive manufacturing system of Fig.1 ;

Fig. 4 shows a schematic view of a second embodiment of the additive manufacturing system; Figs.5 and 6a-b show details about the scanning area and a first and a second embodiment of the detection device of the system of Fig.4;

Fig. 7 shows a schematic view of a third embodiment of the additive manufacturing system;

Fig. 8 shows a schematic view of a fourth embodiment of the additive manufacturing system;

Fig. 9 shows a schematic view of a fifth embodiment of the additive manufacturing system; Fig. 10 shows a schematic view of a sixth embodiment of the additive manufacturing system

Detailed Description of possible embodiments of the Invention

[0033] The invention concerns an additive manufacturing system configured to manufacture a component by an additive manufacturing (AM) process, i.e. by selectively processing additive material to make (manufacture) the component, notably according to a 3D model of the component, typically layer by layer.

[0034] The additive manufacturing apparatus creates a component (e.g. (part or workpiece) according to a given 3D model of the component, e.g. with a geometry read from a CAD file, by successively solidifying selected portion of the component.

[0035] By solidification, it is meant any process of binding a base material (supplied as a powder or another form) into a sufficiently solid state to be removed from the machine, notably from the support thereof. This can include sintering and welding the additive material, notably the particles of the additive material. This can also include binding and stabilize the particle of the additive material by adding a functional agent(s) (e.g. binding agent) with or without an application of energy. The solidified additive material (e.g. green parts) can then be subjected to additional treatments in order to achieve its final properties (in particular mechanical properties), such as sintering, hot isostatic pressing or others.

[0036] The processing of the additive material can notably comprise providing energy for selectively solidify the additive material, together and/or to (a portion of) the component.

[0037] The joining process can be based on a powder bed fusion (PBF) or on a direct energy deposition (DED).

[0038] Examples of processes based on powder bed fusion are known under the denomination or commercial name of: direct or selective metal laser sintering, direct metal production, selective laser melting, laser metal fusion, electron beam melting.

[0039] Examples of process of direct energy deposition are known under the denomination or commercial name of: direct metal deposition, laser engineer net shaping, laser consolidation or deposition, and shape metal deposition.

[0040] Alternatively or complementarily, the processing of the additive material can comprise selectively providing a functional agent (e.g. binding agent, (typically in form of a liquid) for solidifying additive material. The binding agent permits a stabilization of the particles of the additive material constituting a first (provisional) solidification of the dunked additive material, notably by evaporation or by polymerization. A second (final) solidification of the component can be provided in a second stage, where the particle of the (entire) solidified additive material can be definitively bind together (sintered) together while the functional agent (e.g. binding agent) can be decomposed, notably by means of a thermal process, e.g. by means of a furnace.

[0041] The exemplary additive manufacturing system 1 of Figure 1 is based on a powder bed fusion.

[0042] The system 1 comprises a support 10 configured to support the component to be manufactured, such as a platform, a work flat or a base plate. Advantageously, the support 10 comprises a planar surface 101 (i.e. a surface being substantially flat) on which the component can be

manufactured.

[0043] Preferably, the system 1 is configured to provide a horizontal fixation of the support 10 (notably of the planar surface 101 thereof) on or above a reference surface (preferably a flat surface, e.g. a table and a floor) on which the system and/or the support is placed. According to the invention, horizontally means any direction with an angle of 90° +/-10° with respect to the gravity direction.

[0044] The system 1 and/or the support can be also configured to provide a vertical movement of the support (notably the planar surface 101 thereof) with respect to the reference surface on which the system and/or the support is placed. This arrangement provides a vertical adaptation of the support (notably of the planar surface on which the component is manufactured, layer-by-layer) for (substantially keeping the new solidified portion of the component at a given height. According to the invention, vertically means any direction with an angle of 0° +/-10° with respect to gravity direction.

[0045] The embodiment of Figure 1 comprises a dispenser 110

configured to (iteratively) provide additive material on or above the support 10 for covering the entire, already solidified portion of the component. In this embodiment, the support 10 takes a form of a material bed (not illustrated), e.g. an (top-opened) container, configured to retain the additive material for enabling the manufacturing of the component.

[0046] In particular, the dispenser 110 can be configured to provide a layer of additive layer in form of a powder (metal) material 3 on or above (all) the solidified portion of the component, independently from the 3D model of the component. The dispenser can thus have a form of a recoater (e.g. powder spreader or power roller) 110.

[0047] In the embodiment of Figure 1, the (additively) manufacturing of the component is enabled by a head 12 providing energy at selected portion of the additive material laying on or above the support 10 so as to solidify this portion of additive material.

[0048] The head 12 is configured to provide energy 121 generated by an energy source 120 for solidifying the additive material by a thermal process, notably by melting or sintering the (energized) additive material. The energy source can be a laser or an electron beamer. The energy source 120 can be part of the system, and, preferably, mechanically fixed to the head 12.

[0049] The head 12 is configured to provide the energy (within) a solidification area 125 so as to solidify uniquely the additive material located in the solidification area, together and/or to a close portion of the component. The solidification area 125 can be a point-shaped, a spherical shaped or other-shaped volume. The solidification area 125 can have a volume less than 1 mm x 1 mm x 1 mm, preferably less than 0.5 mm x 0.5 mm x 0.5 mm.

[0050] The solidification area is spatially correlated with the position of the head 12, e.g. spatially located at a given relative position with respect to the head 12. Preferably, the solidification area is positioned along a line passing through the head and perpendicular to the support, notably to the planar surface 101 thereof. The relative distance between the head 12 and the solidification area is typically less than 3 cm.

[0051] In order to successively position and/or move this solidification area on or above the additive material laying on the support, the head 12 is moveable with respect to the support 10.

[0052] The head is relatively moveable along at least a direction 122. Preferably, the head 12 is moveable within a plan substantially parallel to the support 10, notably to the planar surface 101.

[0053] The head is moveable according to at least one direction 122 (substantially) parallel to the support 10, notably to the planar surface 101. Preferably, the head is moveable at least within a plan, advantageously this plan being substantially parallel to the support. Notably to the planar surface 101 thereof.

[0054] The system can be configured to provide an approaching movement between the head and the support 10 by means of a head being further movable toward and/or away from the support and/or by means of a support being moveable toward and/or backward the support. Preferably, the approaching movement is, or comprises, a translation perpendicular to the planar surface 101 of the support 10.

[0055] The system comprises a head controller configured to control a relative movement between the head 12 and the support 10. The controller is configured to provide a sequence of relative positioning and/or relative movements for solidifying a selected portion of the additive material 3 with a portion of the component (i.e. already solidified additive material 210), according to the 3D model of the component. The solidification of the selected portion of the additive material 3 will then provide a new solidified portion of the component.

[0056] The system of figure 1 comprises a detecting device 14 measuring a given material property of the provided additive material 3 and/or of the solidified additive material 210 (e.g. manufacturing component) so to permit an early detect (e.g. determine, infer, recognize, estimate) a manufacturing anomaly.

[0057] The detecting device 14 is moveable over the support to provide a given material property at various positions with respect to the solidified additive material 210 and/or the support by sensing:

a portion 31 of the additive material 3 and/or by

a portion 22 of the solidified additive material 210.

[0058] As illustrated in Figure 1, this relative movement of the detecting device is efficiently provided by mechanically fixing the detecting device to the head 12 so as to provide a common movement of the head and of the detecting device. In particular, the mechanically fixing provides a given relative positioning between the detecting device and the solidification area, this all long of the manufacturing of the component. [0059] In particular, the detecting device 14 can thus be configured to sense:

a target portion 31 of the additive material 3 and/or by a target portion 22 of the solidified additive material 210;

wherein the target portion 31 and the target portion 22 are located at a predefined relative position with respect to the head, notably with respect to the solidifying area 125, as illustrated in Figure 1 and 2.

[0060] In the embodiment of Figure 1, the detecting device 14 is configured to sense one or both these target portions 31,22 by sensing a material property of material and/or surface thereof within a single sensing volume 146 encompassing one or preferably both these target portions 31,22.

[0061] The sensing volume can be obtained by sensing a plurality of superposed plane surface, preferably parallel to the planar surface 101 of the support.

[0062] As the detecting device 14 is fixed to the head 12, the sensing volume can be thus move with the movement of the head 12, so as to provide a spatial correlation between the sensing volume and the position of the head, this all long the manufacturing of the component.

Advantageously, the sensing volume 146 can be spatially correlated with the position of the solidification area 125, notably the sensing volume (146) encompassing or being close to the solidification area 125.

[0063] Advantageously, the detecting device is configured to

(substantially) center the sensing volume 146 at:

the center of the solidification area 125, as illustrated in Figure 2; within the solidification area 125, or

close (i.e. a distance less than 1 cm) to the solidification area 125. In particular, with respect of the movement 122 of the head 12 the detecting device can be configured to (substantially) center the sensing volume 146:

in front of the solidification area (i.e. along and forward the moving direction 122 of the head) so to detect unsolidified material, or behind (i.e. backward the moving direction 122 of the head) the solidification area so to detect solidified material.

[0064] This arrangement permits to efficiently scan additive material being, or likely being involved in the current solidification process (e.g. in the current layer solidification).

[0065] This solution permits to efficiently scan both the premise

(additive material within or close the solidification area) and the effects (just added portion) of the joining process providing by the system 1.

[0066] The detecting device 14 comprises one and preferably a

combination of:

an eddy current sensing unit 143 comprising at least an eddy current sensor 1430, 1431; and/or

a capacitive sensing unit 144 comprising at least a capacitive sensor 1440, 1441; and/or

an emitting-receiving unit 145 comprising at least an

electromagnetic emitter 1451 and at least an electromagnetic receiver 1450, 1452, and/or

an optical sensing unit comprising at least an illumination source and at least an optical sensing element sensitive to visible light and/or to infrared radiation and/or to ultraviolet radiation.

[0067] The eddy current sensing unit 143 comprises a single eddy current sensor (EC) or a plurality of eddy current sensors (ECs) so to sense a circulating flow of electrons, or currents, within a scanned conductor in response of an emitted (excitation) magnetic field.

[0068] An eddy current sensor can be configured to generate the excitation magnetic field with a single, given excitation frequency.

Alternatively, an eddy current sensor can be configured to generate the excitation magnetic field with a set of given excitation frequencies by means of an array of emitting elements (e.g. emitting/sensing elements).

[0069] Advantageously, the eddy current sensing unit 20 is configured to create a time-varying, local magnetic field and to measure the induced magnetic field, or field variations in a localized manner (notably less than 3mm x 3mm x 3mm, advantageously less than 1 mm x 1 mm x 1 mm).

[0070] The material property provided by the eddy current sensing unit scanning a portion of the new solidified cross section is function of the electromagnetic properties (such as, but not limited to, its electrical conductivity and magnetic permeability) of the scanned portion, that depends on the integrity (absence of crack or non- uniformity within the solidified mass) and of the particular shape of the sensed portion.

[0071] The eddy current sensing unit can operate in a frequency range within 10 kHz-100 MHz [0072] The capacitive sensing unit 144 comprises a single capacitive sensor or a plurality of capacitive sensors. The capacitive sensing unit 144 is configured to create a time-varying local electric field and to measure induced electric field in a localized manner, notably less than 3mm x 3mm x 3mm, advantageously less than 1 mm x 1 mm x 1 mm . [0073] The capacitive sensing unit 144 can operate in a frequency range within 100 KHz - 10 GHz.

[0074] The emitting-receiving unit 145 comprises:

a single electromagnetic emitter and a single electromagnetic receiver, or

a single electromagnetic emitter and a plurality of

electromagnetic receivers; or

a plurality of electromagnetic emitters and a plurality of electromagnetic receivers.

[0075] The emitting-receiving unit 145 is configured to emit an electromagnetic wave and to receive an electromagnetic wave in the same frequency range. The received electromagnetic waves can be reflected waves and/or passing-trough waves.

[0076] In one embodiment, the electromagnetic receiver(s) can be configured to measure an electrical parameter of the electromagnetic emitter(s) (such as a detuning and/or a change in the tuning of the emitter), the electrical parameter being modifiable by material properties in the vicinity of the electromagnetic emitter(s).

[0077] The frequency range can be located within 100 MHz - 100 GHz.

[0078] The optical sensing unit comprises at least an optical sensing element sensitive to visible and/or infrared (IR) and/or ultraviolet (UV) radiations providing a 1 D, a 2D or a 3D image. The optical sensing element can be, or comprises, a camera or an image sensor. The optical sensing unit can be provided with a single optical sensing element being sensitive to one or several bands of the visible, IR and/or UV range. Alternatively, the optical sensing unit can comprises a plurality of optical sensing elements, each element being sensitive to one or several bands of visible, IR and/or UV range.

[0079] The optical sensing unit can comprise one or more illumination sources providing the related visible, IR and/or UV lights. The optical sensing unit can be configured to continuously or selectively activate the illumination source(s) for providing a uniform illumination during the acquisition of the 1 D, a 2D or a 3D image.

[0080] The sensing elements of the detecting device 14 are

advantageously configured to measure the same sensing volume 146 or overlapping volumes encompassing the sensing volume 146, either simultaneously or sequentially.

[0081] A combination of the above-mentioned units will provide an accurate detection of material property of various additive materials being constitute or comprising one or a combination of:

a magnetic (metal) material;

a nonmagnetic (metal) material (e.g. aluminium);

a dielectic material, such as a binding agent;

a coloured material (pigments).

[0082] The above-mentioned units can be arranged in an array 140 being fixed on the head.

[0083] The different sensing elements of the detecting device 14 can be arranged in a 1-dimensional (1 D) array, or on a multiple-dimensional (2D, 3D) array. A magnetic sensing element can be placed behind capacitive sensors to provide measurements from the same volume simultaneously. [0084] The array is advantageously shaped so as to have a (preferably central) overture or passage. As illustrated in the exemplary embodiments of Figure 2 and 3, the array can take a linear, circular-, annular- (0-) or a hole-shaped array 140', 140". The array can be U-shape, V-shape, or C- shape.

[0085] Alternatively, the detecting device 14 can comprise a

combination of linear arrays, multidimensional arrays and/or one or more single sensors provided with an overture or passage.

[0086] These configurations permit a fixation of the array around a delivering element 129 of the head (e.g. an element configured to deliver, notably focus or spray, the energy/binding agent provided by the head) so as to scan the material within the solidification area 125.

[0087] The sensing elements of the above-mentioned units are advantageously spatially arranged and/or interposed in the array 140‘, 140" so that each unit provides a substantial homogenic sensing over the entire sensing volume 146.

[0088] The detecting device is advantageously configured to provide a (first) material property of the provided additive material (i.e. before solidification), notably by sensing the target portion of additive material, i.e. the additive material within the scanning volume 146.

[0089] In the illustrated embodiment of Figure 1, this (first) material property is: a density distribution, a maximal size of particles, a minimal size of particles, a mean size of particles, a particle size distribution, or a purity of the powder material within the scanning volume 146, or a combination thereof. [0090] Alternatively, or complementarily, the detecting device is configured to (sequentially or simultaneously) provide a (second) material property of the solidified additive material, notably by sensing the target portion of solidified additive material, i.e. the solidified additive material within the scanning volume 146.

[0091] Alternatively, or complementarily, the detecting device is configured to sense material properties of the solidified layer underneath (non-solidified) additive material, notably underneath powder additive material supplied by the dispenser, e.g. the recoater.

[0092] In the illustrated embodiment of Figure 1, this (second) material property is: a porosity, a density, a distribution, an integrity, or a

homogeneity of said target portion (22) of the solidified additive material, or a combination thereof.

[0093] Preferably, the detecting device 14 can be configured to simultaneously sense (e.g. within a time lapse less than 100 ms) the target portion of the additive material and the target portion of the component so as to avoid a slowing down of the solidification process.

[0094] Figure 4 shown a second embodiment of the system 1 wherein the detecting device 14 comprises at least a detecting array 141, preferably a pair of detecting array 141, 141 ', located laterally with respect to a terminal portion of the head and/or to the provided energy.

[0095] As illustrated in the Figure 5, a pair of detecting array 141, 141 ' permits to sense the additive material in front 146 and behind 146' the solidification area 125 , preferably close to (the centre of) the solidification area 125. [0096] Advantageously, the detecting device 14 comprises more than a pair of detecting arrays 141, 141', each detecting array being located laterally with respect to the delivering element 129 of the head 12.

[0097] Advantageously, each of the plurality of detecting arrays is located radially with respect to (the direction of) the energy delivered by the head, preferably at a constant relative angular position.

[0098] The detecting device 14, by means of the plurality of detecting arrays 141, 141 ', can be further configured to provide a cumulative scanning volume (i.e. a scanning volume constituted by the scanning volume 146, 146' provided by the entire detecting arrays) centered at the centre (or at least within) the solidification area 125.

[0099] Alternatively or complementarily, the system can be configured to selectively activate:

a sub-set of sensing element of each detecting arrays; and/or one or a pair of the plurality of detecting arrays

(e.g. by means of the head controller 13) according to the (current) direction 122 of the movement of the head.

[00100] These arrangements provide an efficient (consistent) coverage of the target portions 31, 22 of the additive material not only along a single direction of movements but also along various directions of the head with respect to the support (e.g. head moving within a plane parallel to the support).

[00101] As illustrated in the exemplary embodiments of Figure 6a and 6b, the detecting array of the plurality of detecting arrays doesn't need any more to have an ouverture or passage, so it can take a round-, a square- , a rectangular-shape, or another (full) shape. [00102] The sensing elements of the above-mentioned units are

advantageously spatially arranged and/or interposed in (each) the array 140', 140" so that each unit provides a substantially homogeneous sensing over the entire sensing volume 146, 146'. [00103] The exemplary embodiments illustrated in Figure 7 and 8 related to a system 1 enabling an additive manufacturing based on a direct energy deposition. The system 1 is thus provided with a dispenser mechanically fixed to the head so that the dispenser is moved above the support 10 with the head. [00104] In the embodiment of Figure 7, the system 1 is provided with a dispenser 111 fixed to the head 12 so as to provide the additive material in form of (metallic) powder material 33 on or above the support (10) close (at a distance less than 1 cm) to the (centre of) the solidification area 125 provided by the head 12. [00105] In this arrangement, the target portion of the additive material can be advantageously a portion 32 of the additive material being provided or to be provided by the dispenser 111 fixed on the head.

[00106] The detecting device 14 can thus be configured to sense a portion of the additive material 33 leaving, passing through and/or temporary stored by the dispenser 111.

[00107] The portion 32 of the additive material being provided or to be provided by the dispenser 111 is advantageously sensed by one (or preferably a combination) of the above-described eddy current sensing unit 143, the capacitive sensing unit 144 and the emitting-receiving unit 145. [00108] The target portion 32 can be sensed by a single unit or by a single array of the above-described units 143, 144, 145 located in, close or near the dispenser 111.

[00109] Alternatively, the target portion 32 can be sensed by a plurality of physically separated units or arrays of the above-described units 143,

144, 145, located axially or radially with respect to the direction of the delivery of the additive material. In particular, the plurality of physically separated units or arrays can be configured to cooperate, e.g. an

electromagnetic receiver of a first unit/array can be configured to receive an electromagnetic field emitted by an electromagnetic emitter of a second unit/array.

[00110] The sensing of the target portion 22 of the solidified additive material 210 can be provided by one or more of the above-described units 143, 144, 145 and/or arrays 140, 140', 140", 141, 141 ', 141 ", located around, radially, or in front and/or behind the delivering element 129.

[00111] This solution provides a simple, timesaving and cost-effective early scan of additive material.

[00112] In the embodiment of Figure 8, the dispenser 112 fixed to the head 12 provides the additive material in form of (metallic) wire 34. [00113] In this embodiment, the target portion of the additive material is a portion 32 of the additive material being provided or to be provided by the dispenser 111 fixed on the head, i.e. a portion 32 of the (metallic) wire 34. [00114] The detecting device 14 is configured to sense a portion of the wire 34 leaving, passing through and/or temporary stored by the dispenser 1 12.

[00115] As previously described, the target portion 32 of the wire 32 can be sensed by means of :

a single unit/array located in, close or near the dispenser 112 or by a plurality of physically separated units or arrays located axially or radially with respect to the longitudinal axis of the wire 34.

[00116] The sensing of the target portion 22 of the solidified additive material 210 can be provided by one or more of the above-described units 143, 144, 145 and/or arrays 140, 140', 140", 141, 141 ', 141 ", located around or radially with respect to the delivering element 129.

[00117] The solutions illustrated in the Figure 7 and 8 provide a simple, timesaving and cost-effective early scan of additive material.

[00118] The exemplary embodiments illustrated in Figure 9 and 10 related to a system 1 enabling a particular additive manufacturing based on a binder jet, i.e. a use of a binding agent for solidifying additive material.

[00119] The additive system 1 of the figure 9 is configured to selectively provide (e.g. spraying) a functional agent, notably the binding agent 123, on additive material laid on or above the support 10, by means of the head 12.

[00120] The binding agent is a specific class of functional agent which permits a first (provisional) solidification of the additive material (also called green part) being provided with the binding agent (additive material wetted by the binding agent) typically by evaporation, reticulation, cross- linking, UV-curing or other means of hardening of a resin.

[00121] Depending on the binding agent, the evaporation can occur at ambient temperature or can be facilitated/ promoted/enabled by heating the additive material, e.g. by heating the support 10.

[00122] Additional process steps, involving the application of energy, typically as heat, light (IR to UV typically) or a reagent can be used during the additive manufacturing process..

[00123] Reticulation can optionally be provided by locally (selectively) applying energy, e.g. as ultraviolet light, notably by the same head.

[00124] A separate (final) solidification of the component is typically provided in a later stage, where the metal particles of the (entire) solidified additive material are joined together/sintered by a successive, additional process generally enhancing the mechanical properties of the part. [00125] The embodiment of Figure 9 thus comprises a dispenser 110 configured to (iteratively) provide additive material (notably in form of a powder material) 3 on or above the support 10 for covering the entire, already (provisional) solidified portion of the component 211. The dispenser can thus have a form of a recoater (e.g. powder spreader or power roller) 110 providing additive material in form of a powder material 3.

[00126] In this embodiment, the support 10 takes thus a form of a material bed (not illustrated) for retaining the additive material on and above the component. [00127] In this embodiment, (one of the) material property provided by the detecting device 14 is advantageously a density, a distribution, or a homogeneity of the binding agent sensed in the target portion 23 of the (provisional) solidified additive material (wetted additive material) or a combination thereof.

[00128] This property permits an early verification of the conformity of the dunked additive material, respectively a detection of a unconformity (a flaw) thereof, potentially or likely representing a manufacturing anomaly.

[00129] Alternatively or complementarily, the material property provided by the detecting device 14 can be related to the reagent used during the additive manufacturing process, notably for providing information about a correct application of this reagent.

[00130] Advantageously, a contrast agent can be added to the functional agent (e.g. the binding agent) and/or to the reagent, the contrast agent being detectable by the detecting device. This contrast agent assists in detecting the spatial distribution of the functional agent and/or reagent and/or correct wetting of the powder (wetting corresponding to the CAD file of the part, respectively of the negative of the CAD part).

[00131] The contrast agent can be a magnetic and/or metallic agent, preferably a magnetic agent (ferromagnetic, paramagnetic or

superparamagnetic particles in the size range of 1 nanometer to 10 micrometer).

[00132] The contrast agent can be an adjuvant providing a specific electromagnetic response, a ferromagnetic substance or a substance with high dielectric constant, a substance with a specific response as a function of the frequency of the electromagnetic field in the range DC-GHz, a radio isotope.

[00133] The contrast agent can be a coloured material, such as pigment.

[00134] Advantageously, the contrast agent 123 can be added to the functional agent 123 prior to the delivery on a selected portion of the additive material laid on or above the support 10. This solution facilitates and/or promotes and/or enables a detection of the above-described material property of the binding agent by one or a plurality of the above- described units and/or arrays, in case of a binding agent having no, or poor, ferro/magnetic properties.

[00135] Another advantageous use of such a magnetic agent is that its electromagnetic properties can change depending on its state, helping to derive information about the correct application of intermediate process steps. For example, the relaxation mechanism of the magnetization of the particles is different when in solution or bound to a surface, leading to different electromagnetic properties.

[00136] Example states are: loose base material (powder or other additive material); compacted powder (higher density); wet powder material (wetted completely or partially by a functional agent); solidified by a binder (referred to as green state); solidified with organic components evaporated (brown state), sintered. These states are separated bay process steps with potential for malfunction, leading to off-specification states that should be detected.

[00137] Advantageously, the functional agent can be conductive (e.g. contain water with a sufficient concentration of ions) in order to increase the conductivity of the powder in the wet state compared with the dry state.

[00138] Advantageously, the conductivity of the functional changes during curing, evaporation or state/phase change of the functional agent, thereby enabling the control of the quality of intermediates steps.

[00139] Advantageously, the functional agent can colour the powder (i.e. lead to a change in absorption / reflectivity in the IR-UV range).

[00140] Advantageously, the functional agent is engineered to change colour (and/or change the colour of the powder-agent mixture) in reaction to state changes.

[00141] Advantageously, the functional agent contains fluorescent and/or luminescent molecules or particles reacting to one or several wavelengths.

[00142] Advantageously, the fluorescent molecules are chosen to exhibit a change in properties (such as fluorescence intensity or lifetime) with state changes.

[00143] Advantageously, functional agents can react to create a specific condition at the interface between zones containing different functional agents (e.g. in what will become the surface of the part) that can be measured by the detecting device. Such a specific condition may be a change in colour, or a concentration of contrast particles (magnetic or fluorescent).

[00144] The additive system 1 of the figure 10 is configured to selectively provide (e.g. spraying) additive material 3 with the functional agent (e.g. binding agent) 123 (locally wetting the additive material) on or above the support 10, by means of the head 12.

[00145] In this arrangement, the detecting device 14 can be configured, alternatively or complementarily) to sense a portion of additive material with the binding agent 123 being provided and or to be provided (e.g. sprayed) by the head.

[00146] The above-described embodiments of the system 1 are

advantageously provided with a manufacturing supervisor 15 configured to detect a manufacturing anomaly based on the material property/ies provided by detecting device 14, notably a delamination and/or a crack in the solidified additive material 210, 211.

[00147] The manufacturing supervisor 15 can be configured to detect a manufacturing anomaly based on one of, or a combination of:

a comparison of the provided material property/ies with a given reference material property; and/or

a difference between the provided material property/ies from a given expected material property; and/or

a deviation of the provided material property/ies from a given material property range.

[00148] Advantageously, the manufacturing supervisor can be

configured, in response of a detection of a manufacturing anomaly, to control:

the dispenser 110, 111, 112, and/or

the head 12, and/or

the head controller 13

so as to trigger a manufacturing action on a given portion of the additive material and/or on a given portion of the solidified additive material 210, 211.

[00149] The manufacturing supervisor is configured to trigger the removal of the material with parameters which are off-specification, and renewed application of additive material (notably of powder additive material) and/or of functional agent (e.g. binding agent), as well as recoating and sintering steps, depending on the embodiment.

[00150] The manufacturing action can be one or a combination of:

an interruption of the additive manufacturing of the component; or

a modification of a parameter of the dispenser so as to modify a property of the provided additive material and/or of additive material to be provided; and/or

a modification of a parameter of the head so as to modify a property of the delivered energy 121 and/or of the binding agent 123 and/or of the additive material with the binding agent 123.

[00151] The support can be fitted with standardized reference defects or reference part in order to calibrate the detecting device 14 and/or the manufacturing supervisor. [00152] According to another aspect of the invention, the detecting device 14 can be alternatively fixed to another moveable element of the additive manufacturing system (i.e. an element being moveable with respect to the support 10), such as a dispenser (e.g. recoater). Numerical references used in the drawings

1 Additive manufacturing (AM) system

10 Support

101 Planar surface

1 10 Recoater

1 1 1 Powder nozzle

1 12 Wire feed

12 Head

120 Energy source

121 Energy

122 Moving direction

123 Binding agent

125 Solidification area

126 Nozzle

127 Channel

129 Delivering element

13 Controller

14 Detection device

140-140·' Detection array

141-141'" Detection array

143 Eddy current sensing unit

1430, 1431 Eddy current sensor

144 Capacitive sensing unit

1440, 1441 Capacitive sensor

145 Emitting-receiving unit

1450, 1452 Receiver

1451 Emitter

146, 146' Sensing volume

15 Supervisor

2 Component

210 Joined part

21 1 Solidified additive material with binding agent

22 Portion

23 Portion Additive material

Laid additive material

Delivering / to be delivered additive material

Powder

Wire