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Patent Searching and Data


Title:
LAYERED MANUFACTURING PROCESS, FORMING DEVICE AND DATA CARRIER
Document Type and Number:
WIPO Patent Application WO/2015/185502
Kind Code:
A1
Abstract:
Layered manufacturing process for a layer-by-layer manufacturing of a 3D product (10) comprising the steps of providing a CAD model and a 3D forming device which comprises a first ejector for supplying a layer of build material and a second ejector for supplying a layer of support material (20) and a control electronics for converting the provided CAD model into a CAM model. After inputting the CAD model, the CAD model is converted to the CAM model which comprises the steps of defining a build model to be formed by the build material and defining a support model to be formed by the support material. Subsequently, the 3D product is formed by forming a build and support structure. Finally, the support structure is removed. The removal is enhanced by the presence of embedded discrete multi-layer filler bodies (50) in the volume of the support structure.

Inventors:
KLEIZEN HERMANUS HENDRIKUS (NL)
KLEIZEN GERARDUS HERMANUS (NL)
Application Number:
PCT/EP2015/062148
Publication Date:
December 10, 2015
Filing Date:
June 01, 2015
Export Citation:
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Assignee:
GRUNDEL INVEST B V (NL)
International Classes:
B29C67/00
Foreign References:
US20020171177A12002-11-21
US5503785A1996-04-02
Attorney, Agent or Firm:
HOLLAAR, C. (2280 GE Rijswijk, NL)
Download PDF:
Claims:
CLAIMS

1 . Layered manufacturing process for a layer-by-layer manufacturing of a 3D product comprising the steps of:

- providing a CAD model of a 3D product to be manufactured by the layered manufacturing process;

- providing a 3D forming device for forming the product, in which the 3D forming device comprises:

a platform for supporting the 3D product;

a first ejector for supplying a layer of build material;

a second ejector for supplying a layer of support material;

a control electronics for converting the provided CAD model into a CAM model;

- inputting the provided CAD model into the control electronics;

- converting the CAD model to the CAM model comprising the steps of:

defining a build model to be formed by the build material; and

defining a support model to be formed by the support material;

- forming the 3D product by a layer-by-layer forming process to form a build structure and support structure according to the respective defined build and support model;

- removing the formed support structure from the formed build structure to obtain the 3D product,

characterised in that the support model is defined by a volume of support material including at least one embedded discrete multi-layer filler body, such that the support material completely surrounds the at least one filler body, which filler body comprises a filler material which differs from the support material, such that the support structure to be formed is filled with the at least one discrete multi-layer filler body of the filler material.

2. Layered manufacturing process according to claim 1 , wherein a plurality of filler bodies form a filler element, wherein the filler element comprises a plurality of filler bodies which are shackled to form a network.

3. Layered manufacturing process according to claim 2, wherein the filler element has a shape of a container having an outer wall of a network of filler bodies which outer wall encloses an inner space.

4. Layered manufacturing process according to any of the preceding claims, wherein the discrete filler body of the support structure has a size of at most 10 mm.

5. Layered manufacturing process according to any of the preceding claims, wherein at least one filler body has a pre-defined shape which is in particular substantially ball shaped.

6. Layered manufacturing process according to claim 5, wherein the filler body comprises a hull out of filler material, wherein the hull encloses an internal cavity.

7. Layered manufacturing process according to claim 6, wherein the filler material of the hull of the filler body is a mixture of build and support material.

8. Layered manufacturing process according to any of the claims 5-7, wherein the internal cavity is filled with support material, wherein the hull of the filler body comprises at least one opening which provides a fluid communication in between the internal cavity and an environment external of the filler body.

9. Layered manufacturing process according to any of the preceding claims, wherein the CAD model includes a recess having an internal dimension of at most 10mm, wherein the defined support model of the CAM model comprises a recess sub-model which is defined by a recess volume of support material including at least one filler body of filler material which differs from the support material, such that the support structure to be formed inside the recess has a volume which is filled with the at least one discrete filler body of a filler material.

10. Layered manufacturing process according to any of the preceding claims, wherein the formed support structure is removed by supplying a fluid, in particular a solvent, for removing, in particular dissolving, the support material.

1 1 . Layered manufacturing process according to any of the preceding claims, wherein the formed support structure is removed from the build structure by supplying a fluid, in particular a solvent, in particular by using a fluid bed, wherein the fluid bed comprises grains having a density larger than the density of the at least one filler body.

12. Forming device for forming a 3D product by a layer-by-layer manufacturing process comprising:

a platform for supporting the 3D product;

a first ejector for supplying a layer of build material;

a second ejector for supplying a layer of support material;

a control electronics for converting a provided CAD model into a CAM model;, wherein the control electronics comprises a computer program which is programmed to:

- receive the CAD model;

- convert the CAD model to the CAM model comprising the steps of:

defining a build model to be formed by build material; and

defining a support model to be formed by a support material

- provide control instructions to the first and second ejector to form the 3D product by forming respectively a build structure and a support structure based on the defined build and support model;

characterised in that the support model is defined by a volume of support material including at least one embedded discrete muti-layer filler body, such that the support material completely surrounds the at least one filler body, which filler body comprises a filler material which differs from the support material, such that the support structure to be formed has a volume to be formed of support material which volume is filled with the at least one discrete multi-layer filler body of the different filler material.

13. Forming device according to claim 12, wherein the forming device further comprises a cleaning station for removing the formed support structure from the formed build structure to obtain the 3D product, wherein the cleaning station comprises a unit for a removal of the support structure by supplying of a fluid, in particular by dissolving the support structure, .

14. Data carrier which comprises a computer program having instructions that when run on a computer carries out the steps of a layered manufacturing process according to any of the claims 1 -1 1

Description:
Title: LAYERED MANUFACTURING PROCESS, FORMING DEVICE AND DATA CARRIER

The present invention relates to a layered manufacturing process for a layer-by-layer manufacturing of a 3D product, a forming device, in particular a 3D printer, for carrying out the process and a data carrier comprising instructions to carry out the process.

US6.682.684 discloses a method for improving layered manufacturing techniques to improve an objects' surface properties and shorten manufacturing time for support structures. Removable support structures of a secondary material are disclosed which are designed to support a deposition of main material. During the building of layers, the support structures provide support over main material cavities for depositing the main material to form the cavity ceilings, while minimising the time and material required to build the support structures. Minimised support structures include structures formed as columns supported by the cavity floor and angle braces to support the cavity walls. Some supports are supported by the sidewall but not the floor, and other by the floor and not the sidewalls. The support structure of secondary material is in a later step of the layout manufacturing process removed by mechanical, chemical, or thermal means, leaving the main material article. The disclosed minimised support structure is presented as a solution to minimise a required building time. Additionally, the minimised support structure reduces a necessary time for removal.

US2013/0307193 discloses a printing process which allows an improved removal of a support structure from a formed 3D object. A support structure which supports the 3D object is proposed which is provided with 'fine points' at an upper portion. The 'fine points' are small discrete features which are designed to contact the 3D object. The fine points define an interface in between the 3D object and the support structure. The printing process enables in particular a single print material 3D printer to make a support structure that has accurate fine points that reliably support printed 3D objects and that are easily removed from the 3D object with minimal surface flaws to the surfaces of the 3D object that contact the fine points.

US2002/0171 177A1 discloses a system and method for printing and supporting three dimensional objects. A first material, also called a build material, is dispensed for the construction of a 3D object. A second material, also called support material, is dispensed for forming a support structure. An intermediate layer of the support structure may touch the 3D object surface and serve as a release layer for which a third material can be used. The support structure may include a container for retaining a non-self-sustaining support material. The container forms a secondary support and is generally box-shaped having an open top. The use of the container with a non self-sustaining support material allows the 3D object to be easily released by simply upending the container. The supporting structure may also include pillars and membranes that stabilize and support the 3D object. The pillars and membranes may be composed of a mix of build and support material or a separate material. The membranes are connected to the pillars and connect the pillars to the container. This linkage may be continuous or made by serrations.

Despite the known solutions from the prior art, the removal of a support structure after forming the 3D object is still not satisfying. In practise, the step of removing the support structure requires too much time. In particular, the removal of a support structure from a small recess in a 3D object is problematic. Such a small recess may have any shape, e.g. a hollow pipe, a blind hole, a curved passageway etc.

The general object of the present invention is to at least partially eliminate the above mentioned drawback and/or to provide a useable alternative. More specific, it is an object of the invention to provide a layered manufacturing process which reduces a required time for removing a support structure.

According to the invention, this object is achieved by a layered manufacturing process according to claim 1 .

The layered manufacturing process for a layer-by-layer manufacturing of a three- dimensional product comprises several steps. In a first step, a CAD (Computer Aided Design) model of the product to be manufactured is provided. The CAD model represents the 3D product to be obtained. A 3D forming device, also known as a 3D printer, for forming the product is provided. The 3D forming device comprises a platform for supporting the 3D product. The platform and the first and second ejector are movable with respect to each other for building the 3D product in a layer-by-layer manner. The 3D forming device comprises a first ejector for supplying a build material and a second ejector for supplying a support material. The 3D forming device comprises a control electronics for converting the supplied CAD model into a CAM model. Preferably, the control electronics are integrated in a control unit of the 3D forming device. Alternatively, the control electronics may be a standalone control electronics or integrated in a CAD computer application. The CAM model represents the 3D product including features which are provided for manufacturing proposes. In a step, the provided CAD model is inputted into the control electronics. In a next step, the CAD model is converted to the CAM model by the control electronics. In the converting step, a build model to be formed by build material is defined and a support model to be formed by a support material is defined. Subsequently, the 3D product is formed by forming a build structure and a support structure according to the defined build and support model. The build and support structure are formed in a layer-by-layer manner. Thereafter, the 3D product is obtained by removing the formed support structure from the formed build structure.

According to the invention an improvement is provided in that the defined support model comprises a volume of support material including at least one embedded discrete multi-layer filler body. Embedded means that the volume of support material surrounds the filler bodies. In other words, the filler bodies are floating in the volume of support material. The at least one filler bodies forms a part of the volume of support material which has no linkage with a volume of material outside the volume of support material. In this the at least one filler body is not designed with a constructive aim to support the build structure, but serves to enhance a separation of the support structure from the build structure. The filler body comprises a filler material which differs from the support material. The support structure to be formed has a volume of support material which is filled with at least one discrete filler body of a filler material which differs from the support material.

An individual filler body is a multilayer filler body. The filler body is formed in a layer- by-layer manner and extends along several layers. By defining the support model, at least one filler body, preferably a plurality of discrete filler bodies, is implemented in the volume of the support structure. A formed volume of the support structure is filled with the at least one filler body.

According to the invention, the at least one filler body is completely embedded within the volume of support material, such that the support material completely surrounds the at least one filler body. All present filler bodies are completely embedded within the volume of support material. In an embodiment, the discrete filler bodies may be spaced apart from each other within the volume of support material. In an alternative embodiment, the plurality of discrete filler bodies may be shackled to form a filler element. Advantageously, the support structure may be quickly removed by a combination of a mechanical and chemical removal step. In a cleaning process, the support structure may be removed by a mechanical removal of the filler bodies and a chemical removal of the support material. The mechanical removal of the support structure may be enhanced by removing the filler bodies as a whole from the volume of support material. The filler bodies may be ruptured from the support material by the mechanical removal. The support material may be chemically removed by dissolving the support material. In comparison with a homogeneous massive support structure, the presence of the discrete bodies within the volume of support material may allow a faster dissolving process of the support structure, because of the fact that less support material is present in the support structure. Only the support material which binds the discrete bodies needs to be dissolved instead of dissolving the whole support structure.

In comparison with a supporting structure including a fixed structure of pillars and membranes as in US2002/0171 177A1 , the supporting structure according to the invention can be removed quicker, because according to the invention the filler bodies may already be loosened after dissolving the support material which surrounds the filler bodies. Herewith, the supporting structure according to the invention allows a removal without any mechanical removal steps.

The filler body is a discrete body of a relatively small size with respect to the volume of support material. Preferably, the ratio of a total length of the volume of support material with respect to a length dimension of the size of a discrete body is at least a factor 2, in particular a factor 5. In particular, the volume of the support structure comprises a plurality of substantially equally shaped discrete bodies. The wording 'discrete' means that at least one separate individual filler body is defined. The separate filler body is a geometrically delimited feature, like a ball or cubic body . Within the volume of the support structure, the filler bodies may be arranged in abutting engagement to each other or may be spaced apart. Preferably, the filler bodies are substantially equally distributed in the volume of the support structure.

The filler material is a material which differs from the support material. The difference in material allows a selective removal of the filler and support material. In particular, the filler material has an increased mechanical strength with respect to the support material. For example, the filler material may have another melting temperature. The support material differs from the build material. In an embodiment, the filler material is pure build material. Preferably, the filler material is a mixture of build and support material. Preferably, the mixture comprises at least 50% of build material, in particular at least 70% of build material, but preferably 80% of build material.

Advantageously, the presence of the at least one discrete filler body in the support structure allows a relative quick removal of the support structure in comparison with a massive homogeneous support structure out of support material. Advantageously, a removal process including both a chemical and a mechanical removing step, e.g. by using a fluid bed with grains, can be carried out in a short time. The penetration of a solvent and a rupture of portions of the support structure is also enhanced. The physical principle which contributes to the quick removal of the support structure will be explained hereafter by the described embodiments. Advantageously, the layered manufacturing process according to the invention contributes to an easier removal of a support structure for several techniques, like inkjet layering, sintering of metal or ceramic powders, fused deposition modelling FDM, fused filament fabrication FFF, etc.

In an embodiment of the process according to the invention, a plurality of discrete filler bodies together form a filler element. In an embodiment, the filler bodies of the filler element are spaced apart from each other. The filler bodies are embedded in the volume of support material at a distance from each other. In an alternative embodiment, the filler bodies are shackled to form a network which forms the filler element. Adjacent discrete filler bodies may be in abutting engagement with each other or connected to each other to form the filler element. The filler element may obtain each desired shape to fill a recess or a cavity of the 3D product. The filler element may for example be shaped as a container having an outer wall out of a network of filler bodies which outer wall encloses an inner space. The container may have a cylindrical shape. The container may have a cylindrical shaped including a narrow portion to obtain a flagon shape.

The filler element out of the plurality of discrete filler bodies may provide several advantages. The network of filler bodies which forms the filler element provide an advantage in that such a network is relatively open which may contribute to an improved penetration of a solvent in case of a chemical removal of the support structure. Further, the network of filler bodies provide an advantage in that the network of filler bodies can be relatively easily broken away in case of a mechanical removal of the support structure. A formed filler element can be relatively brittle part of the support structure which allows a relative quick removal by breaking a filler body away from the support structure. The filler bodies may for example be broken out of the network by a jetting process. Herewith, the support structure can be removed quickly.

In an embodiment of the process according to the invention the network of filler bodies is string shaped. Preferably, the string of filler bodies is spiral shaped.

Advantageously, the string of filler bodies may form a spatial 3D structure of the filler element which allows a uniform filling of a recess or cavity of the 3D product.

In an embodiment of the process according to the invention, the at least one discrete filler body has a size of at most 10 mm, in particular at most 5 mm and a size of at least 0,2 mm, in particular at least 0,5 mm. The support model can be defined to include such a small filler body for supporting a small recess in a 3D product. Advantageously, the cavity including a volume of the support structure with at least one filler body can be quickly cleaned.

In an embodiment of the process according to the invention, the at least one discrete filler body has a predefined shape. A pre-defined shape means that the shape is preprogrammed in the control electronics. A pre-defined shape can be pre-programmed in the control electronics as a selectable feature. Advantageously, a converting step of the process according to the invention in which a support model is defined can be simplified. A size of a predefined filler body can be selectable via a user-interface or can be adapted by an algorithm in relation to a size of an available volume of a support structure. A limited availability of programmable sizes for e.g. at most 10 mm and pre-defined shapes for e.g. at most five selectable shapes of filler bodies further simplifies the converting step. In an embodiment of the process according to the invention, at least one discrete filler body is substantially ball shaped. Substantially means that the ball-shaped filler body is not perfectly round, but the filler body may have a shape similar to a ball, like e.g. a kidney bean-shape having radial dimensions in three orthogonal directions within a ratio of at most 1 :2 with respect to each other. Preferably, the volume of the support structure is filled with an amount of substantially equally shaped filler bodies. Preferably, all filler bodies are ball- shaped. The ball-shaped filler bodies may have a variety of sizes, but preferably the filler bodies have a substantially equal size.

Advantageously, a ball shaped discrete filler body increases a design freedom to define a support model in a CAM model for a large variety of CAD models. By defining a discrete filler body as a ball, the converting step of the process according to the invention can be simplified. An algorithm to be used by the control electronics to define a support model may be less complex.

In an embodiment of the process according to the invention, the filler body comprises a hull out of the filler material, wherein the hull encloses an internal cavity. The filler body is hollow. Advantageously, the internal cavity within the filler body may increase a brittleness of the filler body, such that the filler body can be removed quicker by a mechanical removal step. The filler material of the hull differs from the support material of the remaining volume of the support structure. The filler material may be pure build material. Preferably, the filler material is a mixture of build and support material -as indicated above- which due to its deviating material properties contributes to a removal of the support structure from the 3D product formed out of build material.

In an embodiment of the process according to the invention, the internal cavity is filled with support material. The hull of the filler body comprises an opening which is in communication with the internal cavity. Advantageously, the opening allows a relatively quick penetration of a solvent to solve the support material. Additionally, the penetration of the support material will lead to an expansion of the support material within the hull. The expansion will cause the hull to break which will further enhance the removal of the support structure.

In an embodiment of the process according to the invention, the internal cavity includes at least one discrete multi-layer sub-filler body, which said-filler body comprises a material which differs from the support material, such that the inner cavity is filled with at least one discrete multi-layer sub-filler body of the filler material. Advantageously, the sub- filler body inside the internal cavity may provide rigidity to the filler body. Additionally, the sub-filler body may further contribute to a quick removal of the support structure.

In a further aspect of the invention, the invention relates to a layered manufacturing process, wherein at least a particular portion of the volume of the support structure is filled with at least one filler body. More in particular, the invention relates to a layered

manufacturing process for manufacturing a 3D product, wherein the 3D product to be formed includes a recess having an internal diameter of at most 10 mm, in particular at most 5 mm, more in particular at most 3 mm. The solution for quickly removing the support structure of support material including a filler body of a filler material as presented above has proven to be particularly advantageous for this category of 3D products. The defined support model of the CAM model of the 3D product comprises a recess sub-model which is defined by implementing the at least one filler body, such that the support structure to be formed inside the recess has a volume which is filled with the at least one discrete filler body of a filler material. The sub-model and filler body may have any characteristic as mentioned above. In particular, the at least one filler body has an outer dimension of at most 10 mm, in particular at most 5 mm, more in particular at most 3 mm.

In an embodiment of the process according to invention, the step of removing the forms support structure from the formed build structure is carried out by liquefying, in particular dissolving or melting, the support structure.

In an embodiment of the process according to the invention, the step of removing the formed support structure from the formed build structure to obtain the 3D product is carried out by a moving fluid. In a step of removing a support structure, a fluid may be jetted against the support structure. Preferably, the support structure is removed by using a fluid bed. The fluid of the fluid bed comprises grains. Preferably, an individual grain of the fluid has a density larger than a density of an individual filler body to be removed from the support structure, which contributes to a removal of the support structure.

Further, the invention relates to a forming device for forming a 3D product by a layered manufacturing process according to the invention. The forming device according to the invention is arranged to carry out the layered manufacturing process according to the invention. The forming device is arranged for forming a 3D products in a layer-by-layer manner.

The forming device according to the invention comprises a platform for supporting the 3D product. The forming device comprises a first ejector for supplying a layer of build material. The forming device comprises the second ejector for supplying a layer of support material. The forming device comprises control electronics for converting and inputted CAD model into a CAM model. The control electronics may be arranged on board of the forming device or may be arranged remote of the forming device. The control electronics may be integrated in a computer, in particular in a computer application for designing a 3D product. The control electronics comprises a computer program which is programmed to receive the CAD model and converting the CAD model to the CAM model. The conversion of the CAD model to the CAM model comprises the steps of defining a build model to be formed by build material and defining a support model comprising a support material. The control electronics are programmed to provide control instructions to the first and second ejector to form the 3D product. The 3D product is formed by respectively a build and a support structure based on the defined build and support model. The forming device according to the invention is improved in that the support model is defined by implementing a plurality of filler bodies into the support model. The support structure based on the defined support model has a volume out of support material which is filled with at least one discrete multi-layer filler body of a filler material which is different from the support material.

In an embodiment of the forming device according to the invention, the forming device further comprises a cleaning station. The cleaning station is arranged to remove the formed support structure from the formed build structure to obtain the 3D product. In an embodiment, the forming device and cleaning station are arranged in a cascade. Once a 3D product including a support structure is formed by the forming device, the 3D product is transferred to the cleaning station. The cleaning station may comprise a reservoir to be filled with a fluid for removing the formed support structure. Preferably, the cleaning station comprises a fluid bed including a fluid, in particular a solvent, and grains. The fluid bed comprises a reservoir for containing the fluid and the grains. Preferably, the type of the grains is arranged in correspondence with the type of filler bodies in the support structure. Preferably, an individual grain of the fluid bed has a higher density than an individual filler body. Advantageously, the arranged fluid bed combines a chemical and mechanical removing step which contributes to a quick removal of the support structure forms according to the process according to the invention from the build structure of the 3D product.

Further, the invention relates to a data carrier, a memory stick, hard disk or the like which comprises a computer program having instructions that when run on a computer carries out the steps of the layered manufacturing process according to the invention.

Further preferred embodiments are defined in the subclaims.

The invention will be explained in more detail with reference to the appended drawings. The drawings show a practical embodiment according to the invention, which may not be interpreted as limiting the scope of the invention. Specific features may also be considered apart from the shown embodiment and may be taken into account in a broader context as a delimiting feature, not only for the shown embodiment but as a common feature for all embodiments falling within the scope of the appended claims, in which:

Fig. 1 shows a flowchart of a layered manufacturing process according to the invention; Fig. 2A and 2B each show in a schematic cross-sectional view an embodiment of a support structure including discrete filler bodies; and

Fig. 3 shows in a schematic cross-sectional view an embodiment of a filler body including a hull which encloses an internal cavity.

The invention relates to a layered manufacturing process for manufacturing a 3D product. In a layered manufacturing process a product is built in a layer-by-layer manner. In the layered manufacturing process the layers are formed or deposited in a flowable state which can be in the form of a series of long beads of extruded material or in the form of a powder. Subsequently, the layers are hardened to obtain a rigid body. Examples of a layered manufacturing process are widely known as fused deposition modelling FDM, which is an equivalent of fused filament fabrication FFF, stereo lithography, selective laser sintering SLS, three-dimensional printing process TDP, etc.. In particular, the invention relates to an inkjet 3D printing process. More in particular, the invention relates to an inkjet- type 3D printing process, in which at least two different types of material are ejected for forming the 3D product.

Figure 1 shows in a flowchart the layered manufacturing process according to the invention.

In a first step (CAD), a CAD (computer aided design) model of a 3D product to be manufactured by the layered manufacturing process is provided. The 3D product is designed to be formed by a 3D forming device. Here, the 3D forming device is a 3D printer which is arranged to print layer-by-layer a volume of a build and support material. The 3D printer has a first ejector, a first printing head, for printing a layer of build material and a second ejector, a second printing head, for printing a layer of support material. The build material differs from the support material. The build material is another kind of material.

In a next step (CE), the provided CAD model is supplied to control electronics of a 3D printer. The control electronics are arranged to receive the CAD model. The CAD model can be inputted by an operator into the control electronics. The CAD model may be supplied to the control electronics by a data carrier, like a memory stick or may be supplied by a computer network.

In a next step (CAM), after receiving the CAD model, the control electronics convert the CAD model to a CAM (computer aided manufacturing) model. In the converting step, a distinction is made in that a build model (B) to be formed by the build material and a support model (S) to be formed by the support material is defined. The support model to be formed is defined by implementing at least one discrete multi-layer filler body (f). Preferably, a plurality of discrete filler bodies (f) is implemented in the support model as a filler element. The support structure has a volume out of support material which is filled with a plurality of discrete filler bodies of a filler material. The discrete filler bodies are embedded in the volume of support material of the support structure.

The filler material of the at least one filler body differs from the applied support material. The filler material may be pure build material. Alternatively, the filler material may be a third material supplied from a third ejector. Preferably, the filler material is a mixture of support and build material, such that the filler material differs from the applied build material for forming the build structure and the applied support material for forming the volume of the support structure. The deviating material properties of the filler material allow a quick removal of the support structure in a later stage of the manufacturing process.

In a next step (P), a build and support structure is formed by the 3D printer according to the CAM model. The build structure is formed according to the defined build model. The support structure is formed according to the defined support model. The formed support structure comprises the at least one discrete filler body as defined by the support model. The formed support structure is heterogeneous. The support structure comprises a volume of support material and at least one embedded filler body. Preferably, the discrete filler bodies are equally distributed about the volume of the support structure.

In a final step of the process (R), the formed support structure is removed from the formed build structure to obtain the 3D product. The step of removal, also called a cleaning step, preferably includes a step of dissolving the support structure by a solvent. The presence of the discrete filler bodies contribute to a faster removal of the support structure. In a chemical removal step, the presence of the discrete filler bodies may increase a penetration rate of a solvent throughout the whole support structure which contributes to an increase of the removal rate. In a mechanical removal step, the discrete filler bodies may form a solid portions which may be broken out of the support structure which further contributes to an increase of the removal rate. Advantageously, a chemical and mechanical removal step may be combined to favour both effects. Such a combined chemical and mechanical removal step may be carried out by using a fluid bed.

The support model including the at least one filler body may be defined in a variety of embodiments. Figure 2A and 2B show in a diagrammatic cross-sectional view an

embodiment of a support structure including a plurality of discrete filler bodies.

Figure 2A shows in a cross sectional view a 3D product 10 out of a build material which comprises a small recess 1 1 , here a blind hole, at a bottom surface 10b. The recess 1 1 has a maximum internal diameter of at most 10 mm, in particular at most 5 mm, more in particular at most 3 mm. The recess 1 1 has a depth-diameter ratio of at least 1 , in particular at least 2, more in particular at least 3.

The recess is filled with a support structure 20. The support structure has a volume which is filled with a plurality of discrete filler bodies 50. The discrete filler bodies 50 are embedded in a volume of support material 21 . The discrete filler bodies 50 are spaced apart from each other. The discrete filler bodies 50 are positioned at a distance from each other. The presence of the discrete filler bodies 50 embedded in the support structure 20 allows a quick removal of the support structure by a step of dissolving the support material. When the support material is solved by a solvent, like a water or ethanol solution, the discreet filler bodies may be loosened from the support structure as a portion, which may increase a removal rate of the support structure in comparison with a massive homogeneous support structure.

Figure 2B shows in a cross sectional view an alternative embodiment of the support structure 20 inside the recess 1 1 . The support structure 20 includes a plurality of filler bodies 50. The discrete filler bodies are shackled to each other and form a mechanical network. The discrete filler bodies 50 are in an abutting engagement with each other. The discrete filler bodies 50 are attached to each other at a dot shaped region.

The plurality of filler bodies form a filler element 60. In a simple embodiment of the filler element, the plurality of filler bodies 50 may be shackled to form a string or a two dimensional network. Here, the filler element 60 has a 3D structure. The filler bodies 50 of the filler element 60 are attached to each other in a side wards and upwards direction. The filler element 60 has a cylindrical shape including an open end at the bottom surface 10b of the product 10 and a closed end at the top surface 10a of the product 10. Herewith, the filler element provides a rigid 3D structure to support a part of the build structure. As illustrated, the filler element 60 has a top surface formed by the closed end which serves to support build material which forms a bottom of the recess.

In between the attached discrete filler bodies 50 of the filler element 60, the filler element comprises clearances which allows a penetration of a solvent. In comparison with a closed filler element, the presence of the clearances contributes to an enhanced penetration of solvent in case that the support structure is removed by a chemical removal step.

Furthermore, the presence of the relatively small dot-shaped connections in between the discrete filler bodies contribute to easier breakout of filler bodies in case that the support structure is removed by a mechanical removal step. Herewith, the support structure 20 formed by the plurality of discrete filler bodies 50 allows a relatively quick removal of the support structure.

Figure 3 shows in a schematic view a preferred configuration of a filler body 50. Preferably, this configuration is a predetermined configuration in a computer program to be implemented in a calculated volume of a support model during a conversion of a CAD model to a CAM model. The computer program which is arranged to define the support model by implementing a plurality of filler bodies may be programmed to calculate in a first step a necessary volume of a support model, wherein the computer program may be subsequently be programmed to fill the calculated volume of the support model with a plurality of filler bodies having this predetermined configuration.

The filler body 50 has a substantially ball shape. In a substantial ball shape, the filler body has preferably a circular or elliptical cross-section, wherein radial dimensions in three orthogonal directions have mutual ratios of at most a factor 2. Here, the shape of the filler body is programmed as a predetermined pure ball shape with a circular cross-section in its three orthogonal directions.

The shown configuration of a filler body in figure 3 comprises a hull 51 . The hull 51 encloses an internal cavity. The hull 51 of the filler body 50 is formed from a filler material which differs from the support material 21 of the remaining volume of the support structure. The hull of the filler body may be made out of build material. Preferably, the hull of the filler body is formed by a filler material which is a mixture of build and support material.

The internal cavity of the filler body is filled with support material. The hull 51 of the filler body 50 comprises at least one opening 53. The opening 53 provides a fluid

communication in between the internal cavity 52 and a surrounding of the filler body. The opening 53 contributes to a penetration of a solvent during a chemical removal step to dissolve the support structure. The opening 53 allows the support material inside the internal cavity to absorb a liquid. The absorption of the liquid will expand the support material which will cause an expansion force to the hull of the filler body. The expansion force may cause the whole 51 to break which will further enhance the removal of the support structure.

It is noted that the term "comprising" (and grammatical variations thereof) is used in this specification in the inclusive sense of "having" or "including", and not in the exclusive sense of "consisting only of".

Features and aspects described for or in relation with a particular embodiment may be suitably combined with features and aspects of other embodiments, unless explicitly stated otherwise.

Although the invention has been disclosed with reference to particular embodiments, from reading this description those of skilled in the art may appreciate a change or modification that may be possible from a technical point of view but which do not depart from the scope of the invention as described above and claimed hereafter. Modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. It will be understood by those of skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. Therefore, the invention is not limited to the particular embodiments disclosed in the above detailed description, but that the invention will include all embodiments falling within the scope of the appended claims. Thus, the invention provides a layered manufacturing process and performing device for forming a 3D product. A support model is defined for forming a support structure which is filled with filler bodies of a filler material. Advantageously, the presence of the filler bodies contribute to an enhanced removal of the support structure from a build structure to obtain the 3D product.