Additive manufacturing system of powder starting material and method of producing a component

Abstract

This invention relates to an additive manufacturing system for powder starting materials, utilizing an electron beam gun as an irradiation device. The system includes an improved shielding against ionizing radiation (especially X-rays). By using the additive manufacturing system according to this invention, a compact and lightweight build-up area shielding is achieved.

Description

[0001] This invention relates to an additive manufacturing system for powder starting materials, comprising an electron beam gun as an irradiation unit. The system includes improved shielding against ionizing radiation, particularly X-rays. Background Technology

[0002] Prior art has known apparatus and methods for additive manufacturing of workpieces, also known by the term additive manufacturing (AM). It is also expressed as "generative manufacturing technology" or "3D printing." Raw materials can be in powder or liquid form. Powder processes include, for example, selective laser melting (SLM), selective laser sintering (SLS), or electron beam melting (EBM). The raw materials are composed of plastics or metals.

[0003] In processes involving powdered raw materials, the material is applied in a layer to a lowered working surface for segmented melting or sintering. The working surface is then lowered by one layer. Another layer is then applied over the first layer, repeating the same procedure as the first layer. The sections to be melted or sintered are selected, and the three-dimensional workpiece is built up layer by layer.

[0004] Compared to laser processes, systems operating under electron beam melting (EBM) processes use one or more electron beam guns as radiation sources. When using such systems, X-rays, in addition to the expected heat, are generated when the electron beam strikes the powder surface, necessitating shielding against ionizing radiation. To prevent ionizing radiation, especially X-rays, the system walls are typically and laboriously coated primarily with lead or steel. These coatings require a minimum thickness to reliably absorb ionizing radiation. This makes the system very heavy and therefore difficult to maintain. Furthermore, these thick coatings incur considerable costs. In addition, lead poses physiological problems.

[0005] Purpose of the invention

[0006] Starting from these problems, the object of the present invention is to provide an additive manufacturing system including an electron beam gun, by which the disadvantages of prior art devices are overcome. In particular, the object of the present invention is to provide an apparatus that can be made into a smaller and lighter shielding element without impairing the manufacturing process, and to provide a method for producing components using the above-described apparatus. Summary of the Invention

[0007] This objective is achieved using an additive manufacturing system and a method for manufacturing components. Variations of the preferred embodiments are the subject of the appendices.

[0008] An additive manufacturing system for powder starting materials according to the present invention includes:

[0009] - A vacuum chamber, comprising:

[0010] + At least one construction area with a construction platform,

[0011] + At least one powder storage container is located at the side end of the construction area.

[0012] + At least one powder coating assembly, horizontally arranged and movable between at least one powder reservoir and at least one construction platform, to dispense powder starting material from at least one powder reservoir onto at least one construction platform, wherein the powder coating assembly traverses the construction area at least once in each powder dispensing process, and

[0013] - At least one electron beam gun, associated with at least one construction area.

[0014] Its features

[0015] - At least one construction area is surrounded by a shielding element resistant to ionizing radiation, the shielding element comprising four walls, two of which can be formed by the walls of a vacuum chamber.

[0016] - The multiple walls of the shielding member on at least two sides along the moving direction of at least one powder coating assembly are composed of an upper component and a lower component.

[0017] in

[0018] The upper component is rigidly connected to the vacuum chamber and is formed of 2 to 11 horizontally spaced metal plates. It has a clear height above the construction platform, allowing the powder coating assembly to move horizontally through the construction area.

[0019] The lower component is connected to a vertical movable frame and is formed of 2 to 11 horizontally spaced refractory metal sheets. These refractory metal sheets are arranged in an interlocking manner with multiple metal sheets of the upper component and are attached to the movable frame in a radiopaque manner.

[0020] - The lower component can move relative to the upper component on a vertical line between a closed position and an open position, wherein the lower component has multiple refractory metal sheets.

[0021] + In the closed position, the arrangement is such that the lower edge of the refractory metal sheet engages with a groove structure on the surface of the construction area, simultaneously forming a labyrinth structure, and the upper edge of the refractory metal sheet engages with multiple metal sheets of the upper component, simultaneously forming a labyrinth structure, and

[0022] + When in the open position, it no longer moves between the multiple metal plates of the upper component to allow the powder coating assembly to move horizontally through the construction area.

[0023] The additive manufacturing system according to the present invention may be equipped with multiple electron beam guns covering multiple individual areas of a larger build platform, or it may be equipped with multiple build platforms with one or more electron beam guns associated with each of the aforementioned build platforms. The latter configuration provides the advantage that, in this case, only a single vacuum chamber must be evacuated.

[0024] In the context of this case, the aforementioned construction area is understood to refer to the area within the vacuum chamber of the additive manufacturing system where the construction platform is located, on which the powder starting material is bombarded with an electron beam and the components are built.

[0025] The powder coating assembly can be, for example, a scraper or a coating roller. Powder for the next layer of the component, supplied from a powder reservoir, is uniformly distributed onto the surface of the construction platform or onto a layer already applied to the surface by the powder coating assembly. For this purpose, the powder coating assembly travels through the entire construction area once. This movement occurs at least to the end of the construction platform, but generally to an end position entirely at the opposing wall, because an excess powder collection container or another powder reservoir is usually attached there. As a result, it is impossible to attach any equipment to the area of ​​movement of the powder coating assembly, especially above the construction platform. However, this is the location of an X-ray radiation source, which occurs when an electron beam strikes the powder surface.

[0026] In the additive manufacturing system according to the invention, the problem solved is to use an anti-ionizing radiation shield directly around the build area, which can be raised synchronously with the movement of the powder coating assembly. Therefore, it is unnecessary to provide a shield covering the entire outer wall of the system; a shielding surface much smaller than this shielding surface is sufficient, as the shielding surface is arranged closer to the origin of radiation. Thus, a considerable amount of weight can be saved simply by reducing the surface area.

[0027] However, in this case, if the outer wall's shielding surface is simply designed in the same way, albeit at a reduced size, there will still be the problem of having to move a considerable mass. In addition to mechanical stress (which would require a corresponding stabilizing mechanism), the construction process will also be slowed down because the movement of heavy mass cannot occur as quickly as the movement of powder coating components.

[0028] To address this issue, the anti-ionizing radiation shielding component of the present invention is not made of a solid plate, which would require complete movement and thus necessitate a vacuum-sealed passage in the top plate of the vacuum chamber. Instead, the shielding component is divided into two parts: an upper part fixed to the top plate of the vacuum chamber and a movable lower part. As a result, only the parts within the movement range of the powder coating assembly need to move. Furthermore, the solid plate is replaced by a plurality of thin plates spaced far apart, allowing the plates of the upper and lower parts to move in an interlocking manner. This interlocking arrangement forms a labyrinthine structure, ensuring no direct beam path, and the radiation is reflected multiple times at the multiple interlocking metal plates, thus slowing it down.

[0029] Furthermore, the thin plate of the movable lower part is made of refractory metal. When discussing "refractory metal sheet" in this context, it is understood to be a sheet made of a mixture or alloy containing more than 50% by weight, for example, more than 60%, more than 70%, more than 80%, more than 90%, more than 95%, and especially more than 99% by weight of refractory metal. In this context, refractory metal is understood to be high-melting-point metals such as titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten. Besides their high melting point, these materials are primarily characterized by high density and, most importantly, a high ionizing radiation absorption coefficient. Thus, shielding performance comparable to that of a conventional thick lead or steel layer on an outer wall can be achieved with a thinner sheet. Here, the superior temperature resistance of refractory metals compared to lead is particularly important, meaning that the shielding part can be moved closer to the radiation point and therefore requires a smaller surface area. In addition, lead has insufficient mechanical stability, which would prevent it from being attached to a movable frame in sheet form, and for mechanical reasons, it cannot be allowed to reach higher temperatures. Steel provides better stability in this respect, but due to its lower absorption coefficient, it must be made thicker and therefore heavier.

[0030] The refractory metal sheet of the lower component is preferably composed of tungsten, molybdenum, rhenium, tantalum, and / or mixtures or alloys thereof. Tungsten, molybdenum, tantalum, and / or mixtures or alloys thereof are particularly preferred. The alloys and mixtures may preferably be made of copper.

[0031] The upper component of the non-movable shielding element does not necessarily need to be made of refractory material and can be made of other metals for cost reasons. However, if the vacuum chamber maintains a very low temperature, or if very high temperatures are inevitably generated due to the processing of metal powder, it is still desirable to manufacture the sheet metal of the upper component from refractory metal. In this case, the same refractory metal as the lower component can be used. In design variations, the metal sheet of the upper component is made of stainless steel, copper, refractory metals, and / or mixtures or alloys thereof.

[0032] It has been proven advantageous to design the individual plates of the upper component with a length that decreases from the outside to the inside. In this case, multiple lower edges are evenly aligned, and multiple upper edges are offset in steps. This makes it easier to attach multiple metal plates to the top plate of the vacuum chamber.

[0033] The number of plates in the upper and lower components depends on the electron beam gun and the power of the ionizing radiation generated by it, as well as the metal used. Based on the absorption capacity of the selected metal, 2 to 11 plates have proven to be optimal. For safety reasons, the number of plates should be preferably chosen such that one more plate is installed than is necessary for shielding.

[0034] For cost reasons, the shielding element can preferably be manufactured from commercially available standard-sized individual refractory sheet components. Preferably, at least two joints are provided in each layer of refractory sheet, and these sheets do not overlap to avoid tilting caused by distortion due to thermal expansion. These individual sheets may have gaps of up to 50 mm, 40 mm, 30 mm, or 20 mm at the aforementioned joints. The gaps are preferably from 5 mm to 25 mm, and most preferably from 10 mm to 20 mm. Multiple joints between two consecutive layers of refractory sheet within the upper and / or lower components are respectively misaligned to avoid free beam paths.

[0035] The plurality of refractory metal sheets in the lower component preferably each have a thickness of 0.1 to 20 mm. The thickness of the sheet can be 0.1 to 20 mm, 0.5 to 15 mm, 1 to 10 mm, 2 to 8 mm, or 3 to 6 mm. The thickness can be, in particular, up to 20 mm, up to 15 mm, up to 10 mm, up to 8 mm, or up to 6 mm. In particular, the thickness can be at least 0.1 mm, at least 0.5 mm, at least 1 mm, at least 2 mm, or at least 3 mm.

[0036] In addition to the refractory metal sheet, the lower component may also include one or two layers of stainless steel sheet as the innermost layer for additional heat protection. These stainless steel sheet layers can therefore be arranged in a double layer, with a smaller distance between them than the refractory metal sheet. The stainless steel sheet primarily contributes to heat protection, and also contributes to radiation protection to a lesser extent. This measure protects the more expensive refractory metal sheet from heat, thus extending its service life. On the other hand, the cheaper stainless steel sheet can be replaced more frequently.

[0037] The metal sheets of the upper component preferably each have a thickness of 1 to 100 mm. The thickness of the metal sheets can be 1 to 100 mm, 2 to 75 mm, 3 to 50 mm, 4 to 25 mm, or 5 to 15 mm. The thickness can be particularly at most 100 mm, at most 75 mm, at most 50 mm, at most 25 mm, or at most 15 mm. In particular, the thickness can be at least 1 mm, at least 2 mm, at least 3 mm, at least 4 mm, or at least 5 mm. The thickness of the metal sheets of the upper component is preferably designed to match the refractory metal sheet of the lower component, such that the upper and lower components absorb nearly the same amount of radiation. The metal sheets in the upper component do not necessarily need to have a uniform thickness. For example, the metal sheets can also be made thicker on the outer side of the stacked sheets than on the inner side.

[0038] Ideally, when the refractory metal sheet of the lower component engages with the metal sheet of the upper component, there should be a gap of 1 mm to 50 mm between them. Therefore, the distance between the refractory metal sheets is, for example, 1 mm plus the thickness of the metal sheet in the component plus 1 mm. In any case, the distance between the multiple sheets should be much smaller than the height of the sheets to reliably function as a radiation trap. The distance between the sheets should ideally be at least half the distance between the upper and lower components when they are engaged in the closed state. In this way, multiple reflections can be maximized in the generated ray labyrinth.

[0039] Multiple corresponding grooves are formed on the top surface of the construction area. When the shielding member is closed, the lower edge of the thin plate of the lower component is engaged with the corresponding grooves in the same way that its upper edge is in the lower edge of the thin plate of the upper component. Thus, a labyrinth is also created on the bottom side of the lower component of the shielding member to prevent radiation from escaping.

[0040] In one specific embodiment, the refractory metal sheet of the lower component has a density of more than 10 grams per cubic centimeter (at 20°C).

[0041] The ionizing radiation shielding can be constructed in two different ways. In any case, the shielding includes four walls that surround and thus shield the construction area. Two of these walls can be formed from the outer walls of the vacuum chamber, and therefore a shielding material is typically provided. This material can also be a common material, such as lead and steel, but preferably not lead, but refractory metal or steel. In this case, these two walls are not shielding walls in the direction of movement of the powder coating assembly. The wall in the direction of movement of the powder coating assembly is therefore designed in a two-part configuration with an upper part and a lower part, so that the shielding can be raised to allow passage of the powder coating assembly.

[0042] However, it is preferable to use four separate walls as shielding elements. This will generate the minimum distance to the radiation point on all sides, thus necessitating the use of the minimum shielding material surface area and mass.

[0043] Ideally, all four walls of the masking component consist of an upper part and a lower part. This is particularly advantageous because not every type of powder coating assembly or its drive unit can incorporate two fixed walls. In the case of, for example, a scraper, such powder coating assembly or its drive unit guides and / or drives laterally, so all four walls must be raised to allow the scraper to cross the build area. Therefore, the powder coating assembly offers greater design freedom.

[0044] In the design variant, the attachment of the refractory metal sheet of the lower component to the non-transmissive movable frame includes a spacer bolt fastening with two different diameters. The first diameter is adjusted to match a hole in the refractory metal sheet. The second diameter of the aforementioned spacer bolts is larger on the outside of the hole, such that radiation passing through the hole is shielded by the spacer bolt, in the same way as the shielding method used in non-perforated areas by the refractory metal sheet.

[0045] In a preferred design variant, the powder coating component is either a scraper or a roller.

[0046] The method for producing a component using an additive manufacturing system according to the present invention includes the following steps:

[0047] a) Provide an additive manufacturing system according to the present invention.

[0048] b) Provide powder starting material in at least one powder reservoir, and evacuate the vacuum chamber.

[0049] c) Move the lower part of the shield to the open position.

[0050] d) Dispensing powder starting material from at least one powder reservoir onto at least one construction platform by horizontally moving the powder coating assembly across the construction area at least once.

[0051] e) Move the lower part of the shield to the closed position.

[0052] f) To produce a layer of the component by irradiating the powder starting material with at least one electron beam gun.

[0053] g) Repeat steps c) through f) until the component is complete.

[0054] Depending on the design of the powder coating assembly and the coating process, the powder layer can be applied by a simple one-time movement or by a reciprocating movement. In the latter case, the masking element remains open until the powder coating assembly has returned to its starting position after the second movement. Only after this point does the masking element lower and irradiation begin.

[0055] Irradiation occurs only when the shield is closed. The electron beam gun stops operating as soon as the shield is opened. Attached Figure Description

[0056] Figure 1 This is a perspective cross-sectional view of an additive manufacturing system according to the present invention in a closed state at the starting position.

[0057] Figure 2 It is a three-dimensional cross-sectional view of the construction area surrounded by shielding components.

[0058] Figure 3 yes Figure 1 A three-dimensional cross-section of the system in the open state before the powder coating component enters the construction area.

[0059] Figure 4 yes Figure 1 A three-dimensional cross-section of the system in the open state with the powder coating component within the construction area.

[0060] Figure 5 It comes from Figure 1 A three-dimensional cross-section of the system in a closed state after the powder coating components have left the construction area again. Detailed Implementation

[0061] Figure 1 This shows a perspective cross-sectional view of an additive manufacturing system according to the present invention. A build area (2) is provided in a vacuum chamber (1), and a single build platform (3) is provided in the build area (2). This shows the upper starting position at the start of build. A powder reservoir (4) is provided on the left and right sides of the build area (2), each having an adjacent slot to receive excess powder. In this example, a powder coating assembly (5) with a scraper suspended from a movable beam transports some powder from the powder reservoir (4) to the build platform (3) in the build area (2). The build platform (3) is slightly larger than one layer of the component required, ensuring uniform coating across the entire surface of the build platform (3). Excess powder is transported beyond the opposing powder reservoir (4) into a slot, and from there to a collection container. Figure 1 In the middle, the powder coating component (5) is in the starting position on the left.

[0062] An electron beam gun (6) is embedded in the top plate of the vacuum chamber (1) above the construction area (2). The entire construction area (2) is surrounded on all four sides by a shield (7), which consists of an upper component (8) and a lower component (9). Since the powder coating assembly (5) is still in the initial position, the shield (7) is in the closed state. Figure 2An enlarged view of the construction area (2) surrounded by the shielding element (7) is shown again. In the example shown here, the upper component (8) consists of four stainless steel metal sheets (10) having a thickness of 30 mm on the outer side and 20 mm on the inner side at a distance of 13 mm. The lower component (9) consists of three pure tungsten refractory metal sheets (11) having a thickness of 3 mm at a distance of 30 mm. The density of the refractory metal sheets (11) is therefore 19.25 g / cm³. The refractory metal sheets (11) of the lower component (9) are arranged in an interlocking manner within the metal sheets (10) of the upper component (8) and overlap with the metal sheets (10) by 45 mm.

[0063] The metal sheets (10) of the upper component (8) are each adjusted in size to be slightly shortened from the outside towards the construction area (2). This makes it easier to attach these metal sheets to the stepped support at the top plate of the vacuum chamber (1) by bolts. The refractory metal sheets (11) are attached to the movable frame (12) and can be lifted above the frame (12). In the closed position shown here, the lower edge of these refractory metal sheets engages in a groove structure (13), which forms the edge region of the construction area (2). The groove structure (13) is adjusted in size similar to the structure of the upper component, i.e., in this example, multiple 13 mm wide grooves are milled into the surface of the vacuum chamber (1) at a distance of 20 mm around the construction platform (3), because the distance between the grooves and the multiple sheets corresponds, and the thickness of the web between the multiple grooves corresponds to the thickness of the multiple sheets.

[0064] To produce a component, the powder reservoir (4) is filled with a powder starting material (e.g., filled with titanium powder), and the system is moved to... Figure 1 The starting position is shown, and the vacuum chamber (1) is evacuated. To produce the first layer of the component, titanium powder is then transported from the powder reservoir (4) to the construction area (2) using a powder coating assembly (5). Just before the powder coating assembly (5) begins to move, or when the powder coating assembly (5) has almost reached the closed shielding member (7), the lower part (9) of the shielding member (7) is lifted by a movable frame (12) and pushed into the upper part (8) to open the range of motion of the powder coating assembly (5). The electron beam gun (6) stops operating during this period. This situation is... Figure 3 As shown in the image. At this moment, the shielding element (7) is in the open state, and the groove structure (13) can now be clearly seen.

[0065] Figure 4 The powder coating assembly (5) is shown when it traverses the construction area (2) and distributes titanium powder onto the construction platform (3). Figure 5The powder coating assembly (5) is shown momentarily after traversing the construction area (2). Once the powder coating assembly (5) has left the construction area (2) again, the lower component (9) descends to the closed position again. The lower edge of the refractory metal sheet (11) re-engages into the groove structure (13). The powder coating assembly (5) then continues to move to the end position behind the right-side powder reservoir (4), thereby discharging excess titanium powder into the collection tank. Once the shielding element (7) closes again, the electron beam gun (6) can be activated, starting with the first layer of written data.

[0066] After the first layer has been written, the process starts again in the other direction. In a system with only one powder reservoir (4), the powder coating assembly (5) may remain in a position beyond the build area (2) until the layer is written and the lower part (9) of the shield (7) is lifted again, and the powder coating assembly (5) may only move back to the starting position after this to obtain new powder, or move back to the starting position momentarily by reciprocating motion after crossing the build area (2) before the shield (7) closes.

[0067] Explanation of reference numerals in the attached figures

[0068] 1 Vacuum Chamber

[0069] 2 Construction Area

[0070] 3 Construction Platform

[0071] 4 Powder Storage

[0072] 5 Powder Coating Components

[0073] 6 electron beam guns

[0074] 7 shielding components

[0075] 8 upper parts

[0076] 9 Lower Components

[0077] 10 Metal Sheets

[0078] 11 Refractory Metal Sheets

[0079] 12 frames

[0080] 13-groove structure

Claims

1. Additive manufacturing system for powder starting material, comprising: - a vacuum chamber (1) comprising: + at least one build area (2) with at least one build platform (3); + at least one powder reservoir (4) arranged at a side end of the build area (2); + at least one powder application assembly (5) arranged horizontally movable between the at least one powder reservoir (4) and the at least one build platform (3) to distribute powder starting material from the at least one powder reservoir (4) on the at least one build platform (3), wherein the powder application assembly (5) traverses the build area (2) at least once per powder distribution process; and - at least one electron beam gun (6) associated with the at least one build area (2); characterized in that - the at least one build area (2) is surrounded by a shielding (7) against ionizing radiation, which shielding comprises four walls, wherein the four walls are each formed by a wall of the shielding (7) or two walls are formed by a wall of the shielding (7) and two walls are formed by a wall of the vacuum chamber (1); - the four walls of the shielding (7) are at least on both sides in the direction of movement of the at least one powder application assembly (5) composed of an upper part (8) and a lower part (9), wherein + the upper part (8) is rigidly connected to the vacuum chamber (1), formed by 2 to 11 horizontally spaced metal sheets (10) and has a clear height above the build platform (3) to allow horizontal movement of the powder application assembly (5) through the build area (2), and + the lower part (9) is connected to a vertically movable frame (12) and formed by 2 to 11 horizontally spaced refractory metal sheets (11), which refractory metal sheets (11) are arranged in meshing fashion with the metal sheets (10) of the upper part (8) and attached to the movable frame (12) in a radiopaque manner; and - the lower part (9) is movable in a vertical line relative to the upper part (8) between a closed position and an open position, wherein the refractory metal sheets (11) of the lower part (9) + in the closed position are arranged so that the lower edges of the refractory metal sheets engage a groove structure (13) on the surface of the build area (2) and at the same time form a labyrinth structure and so that the upper edges of the refractory metal sheets engage the metal sheets (10) of the upper part (8) and at the same time form a labyrinth structure; and + in the open position are no longer moved between the metal sheets (10) of the upper part to at least allow horizontal movement of the powder application assembly (5) through the build area (2).

2. The additive manufacturing system of claim 1, wherein, The refractory metal sheets (11) of the lower part (9) have a density of more than 10 g / cm3 at 20°C.

3. The additive manufacturing system of claim 1 or claim 2, wherein, The refractory metal sheets (11) of the lower part (9) consist of tungsten, molybdenum, rhenium, tantalum and / or alloys thereof.

4. The additive manufacturing system of claim 1, wherein, The metal sheets (10) of the upper part (8) consist of stainless steel, copper, refractory metal and / or alloys thereof.

5. The additive manufacturing system of claim 1, wherein, When the shield (7) uses four separate walls, all of the four walls of the shield (7) are composed of an upper part (8) and a lower part (9).

6. The additive manufacturing system of claim 1, wherein, The radiopaque attachment of the fire-resistant sheet metal (11) of the lower part (9) at the movable frame (12) comprises a spacer bolt fastening having two different diameters, wherein a first diameter is dimensioned to match an aperture in the fire-resistant sheet metal (11) and a second diameter, which is larger outside the aperture, so that radiation passing through the aperture is shielded by the spacer bolt fastening in the same way as it is shielded by the non-perforated area of the fire-resistant sheet metal (11).

7. The additive manufacturing system of claim 1, wherein, The fire-resistant sheet metal (11) of the lower part (9) each has a thickness of 0.1 mm to 20 mm.

8. The additive manufacturing system of claim 1, wherein, The metal sheet (10) of the upper part (8) each has a thickness of 1 mm to 100 mm.

9. The additive manufacturing system of claim 1, wherein, The fire-resistant sheet metal (11) of the lower part (9) and the metal sheet (10) of the upper part (8) each have a spacing of 1 mm to 50 mm relative to each other when engaged.

10. The additive manufacturing system of claim 1, wherein, The powder application assembly (5) is a doctor blade or a roller.

11. A method of manufacturing a component by using an additive manufacturing system, comprising the steps of: a) providing an additive manufacturing system according to any one of the preceding claims; b) providing a powder starting material in the at least one powder reservoir (4) and evacuating the vacuum chamber (1); c) moving the lower part (9) of the shield (7) to the open position; d) distributing the powder starting material from the at least one powder reservoir (4) onto the at least one build platform (3) by moving the powder application assembly (5) horizontally at least once completely across the build area (2) between the at least one powder reservoir (4) and the at least one build platform (3); e) moving the lower part (9) of the shield (7) to the closed position; f) irradiating the powder starting material by the at least one electron beam gun (6) to generate a layer of the component; and g) repeating steps c) to f) until the component is completed.

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