WO2013087609A2

WO2013087609A2 - Manufacturing method for a permanent magnet, moulding system and permanent magnet

Info

Publication number: WO2013087609A2
Application number: PCT/EP2012/075049
Authority: WO
Inventors: Adriana Cristina URDA
Original assignee: Siemens Aktiengesellschaft
Priority date: 2011-12-13
Filing date: 2012-12-11
Publication date: 2013-06-20
Also published as: EP2605253B1; CN103157794B; CN103157794A; WO2013087609A3; DK2605253T3; EP2605253A1

Abstract

It is described a method for manufacturing a permanent magnet, the method comprising: separating, by a separator (107, 207), a mould volume into a first compartment (109, 209) and a second compartment (111, 211); filling a first material (119, 219) into the first compartment (109, 209); filling a second material (121, 221) into the second compartment (111, 211); compacting the first material and the second material, wherein the separator is shaped such that a shape of the first compartment corresponds to a target shape of the magnet.

Description

DESCRIPTION

Manufacturing method for a permanent magnet, moulding system and permanent magnet

Field of invention

The present invention relates to a method for manufacturing a permanent magnet, to a moulding system for manufacturing a permanent magnet and to a permanent magnet, wherein the per^¬ manent magnet may in particular be used in a rotor of an electric generator.

Art Background

It may be known to produce a rectangular magnet from a magnet powder in a rectangular shape/frame/press. After sintering the rectangular magnet, it is grinded/cut into the desired magnet shape using different cutting or shaping methods.

EP 2 017 859 Al discloses a method for manufacturing of mag^¬ net poles, wherein a vitrifiable base material powder is filled into a mould, the mould is closed with a plate, the mould with the powder is placed in a magnetic field and the plate is pressed such onto the powder as to establish a com^¬ pact and the compact is sintered. WO 2010/066251 Al discloses a permanent magnet rotor for a machine and a manufacturing method of a permanent magnet ro^¬ tor, wherein a permanent magnet is formed in an inner opening of a sleeve between a first cap and a second cap. It has been observed that conventional manufacturing methods for manufacturing a permanent magnet require a lot of expen^¬ sive magnet material and require a number of shaping steps in order to achieve a target shape of the permanent magnet. There may be a need for a permanent magnet, a method and a moulding system for manufacturing a permanent magnet, wherein the manufacturing is simplified and less expensive magnet ma- terial is wasted.

The need may be met by the subject-matter of the independent claims. The dependent claims specify particular embodiments of the present invention.

Summary of the Invention

According to an embodiment of the present invention it is provided a method for manufacturing a permanent magnet, the method comprising separating, by a separator, a mould volume into a first compartment and a second compartment; filling a first material into the first compartment; filling a second material into the second compartment; compacting the first material and the second material, wherein the separator is shaped such that a shape of the first compartment corresponds to a target shape of the magnet.

The permanent magnet may in particular be or comprise a neo- dymium magnet (also known as NdFeB magnet), i.e. an alloy of neodymium, iron and boron to form the d₂Fei₄B tetragonal crystalline structure. Further, the magnet may comprise Dy (Dysprosium) between 0% and 10% wt . The permanent magnet may have high coercivity (i.e. resistance to being demagnetized) and may have a high saturation magnetization of between 1 and 2 Tesla. The permanent magnet may for example be used in an electromechanical machine, such as an electrical generator, in particular for an electrical generator of a wind turbine. In particular, the generator may be an outer rotor generator in which the magnet (rotating with the rotor) is placed radially outwards from a stator. The separator may be a physical solid structure such as a bent sheet, bent metal piece or the like. The separator may have at least partially a curved shape. The separating the mould volume may be achieved by arranging the separator within the mould volume. The separator may comprise one or more separation walls. The separator may be adapted to con^¬ fine the first material within the first compartment and to confine the second material within the second compartment. Thus, the separator may be tight for the first material as well as for the second material.

The first compartment may have a volume which is between 5 and 100 times larger than a volume of the second compartment. The first compartment may be partly delimited by the separa- tor and may be partly delimited by a portion of a mould wall. Alternatively, the first compartment may entirely be confined or delimited by the separator.

The second compartment may partly be delimited by the separa- tor and may partly be delimited by a mould wall. The target shape of the magnet may be different from a cuboid shape. The target shape of the magnet may resemble a cuboid having two rounded edges. The target shape of the magnet may have a mir^¬ ror symmetry. The target shape of the magnet may have a translational symmetry along a depth direction, wherein the depth direction (in particular parallel to a filling direction) may be perpendicular to a height direction and a width direction of the mould or the mould volume. The first material may be filled into the first compartment along a filling direction which may be along the depth direction. The second material may be filled into the second com^¬ partment along the filling direction. The compacting the first material and the second material may be achieved by applying pressure to the first material and the material, in particular along the filling direction. The first material may also be referred to as active (magnet) material, wherein the second material may be also referred to as a dummy material not contributing (or contributing less between 0% and 20%) to the magnetic properties of the final- ized and manufactured permanent magnet.

When the first material is filled into the first compartment the first material may be in the final desired target shape of the magnet (in particular when disregarding shrinking which may occur during compacting and/or sintering) . Thus, after compacting the first material and the second material no grinding, machining or other shaping process after the compacting need to be necessary, in order to obtain the permanent magnet having the desired target shape. In particular, it may be omitted to remove some of the first material from the compacted product. Thereby, a waste of material may be reduced. Further, the manufacturing method may be simplified, since no grinding or machining or shaping steps may be required .

According to an embodiment of the present invention the manu^¬ facturing method further comprises placing the separator into the mould volume, in order to form the first compartment and the second compartment, wherein the mould volume has in par- ticular a cuboid shape.

The separator may be placed into the mould volume by shifting or moving the separator along the filling direction into the mould volume. The separator may have a at least partially curved shape. A portion of the separator may comprise a flat shape. Thereby, separating the mould volume into the first compartment and the second compartment may be easily

achieved . According to an embodiment of the present invention the sepa^¬ rator is shaped such that the first compartment has a shape resembling a cuboid having two rounded edges extending in a depth direction, wherein the separator has in particular a constant thickness.

The shape of the first compartment may at least partially be defined by the shape of the separator. In particular, the first compartment may be partly or entirely enclosed or sur^¬ rounded by the separator. The first compartment and also the second compartment may comprise a mirror symmetry, wherein the mirror plane may be oriented parallel to a plane spanned by the height direction and the depth direction. In particu^¬ lar, the mirror plane may be arranged at a half of an extent in the width direction of the mould volume or mould.

Thereby, a permanent magnet having a suitable shape to be used as a rotating magnet in an electrical generator may be manufactured .

According to an embodiment of the present invention the sepa^¬ rator is shaped such that an extent of the first compartment in a height direction decreases towards both ends in a width direction, the height direction and the width direction being in particular transverse, further in particular perpendicular to a filling direction along which the first material and/or the second material is filled into the respective compart- ment .

In particular, the separator may be shaped such an extent of the second compartment in the height direction increases to^¬ wards both ends in the width direction. In particular, a sum of the height of the first compartment and the height of the second compartment (the minimal height being in particular 1% to 10% of the height of the mould volume) may be constant across the width direction. Thereby, in a central portion the height of the first compartment may be constant and in outer portions (along the width direction) the height may decrease in a symmetric (with respect to the mirror plane) way.

Thereby, an appropriate shape of the permanent magnet may be achieved when such a separator is used in the manufacturing process .

According to an embodiment the separator is made of separator material comprising any kind of material that can be shaped in an easy manner. E.g. a think layer of plastic material can be used as separator material, since it is easy to shape. A steel sheet is also an option since it is more firm (tight, solid) compared to the plastic sheet. The separation sheet will be removed before sintering, so it does not need to be a high temperature resistant material.

If the separator needs to be kept in place, then this has to be a non-magnetic material, with the magnetic permeability close to 1.

According to an embodiment of the present invention the first material is a ferro magnetic powder material, in particular a high grade NdFeB powder material, which has a remanence and/or coercity and/or energy product that is between 2 and 10 times higher than that of the second material. The ferro^¬ magnetic powder material may comprise tiny particles or grains having a size between 1 ym and 20 ym. The tiny parti^¬ cles of the ferromagnetic powder material may comprise small crystalline grains.

The remanence or remanent magnetization is the magnetization left behind in a ferromagnetic material after an external magnetic field is removed.

The coercivity is the intensity of the applied magnetic field required to reduce the magnetization of the ferromagnetic powder material to zero after the magnetization of the ferro^¬ magnetic powder material has been driven to saturation.

Thus, the first material may be a high grade neodymium mate^¬ rial suitable as serving for a rotating magnet of a genera^¬ tor. In contrast, the second material may be a low-grade ma- terial (and/or having more impurities), in particular much cheaper than the first material. In particular, the second material may be selected not to affect (or affect to a smaller extent) the magnetic properties of the final product comprising the first material and the second material.

According to an embodiment of the present invention the first material comprises Fe in a mass ratio between 50 % and 75 %, Nd in a mass ratio between 15 % and 35 %, Dy in a mass ratio between 1 % and 15 %, and B in a mass ratio between 0% and 2 o

o ·

Thereby, a high grade neodymium permanent magnet may be manu- facturable. The first material may primarily affect the mag- netic property of the finished manufacturing product. In par^¬ ticular, magnetic properties of the finished product may evolve to between 70 % and 100 % from the first material.

According to an embodiment of the present invention the sec- ond material comprises a plastic material, in particular a thermosetting or/and a thermoplastic material, in particular expoxy. Alternatively or additionally, the second material comprises Fe in a mass ratio between 75 % and 100 %, Nd in a mass ratio between 0 % and 30 %, Dy in a mass ratio between 0 % and 10 %, and B in a mass ratio between 0 % and 1 %.

The second material may have between 0 % and 30% Nd and in particular 0% Dy.

The plastic material may comprise a polymer material. In par- ticular, the plastic material may comprise carbohydrates. The thermosetting material may cure or crosslink or solidify upon application of heat. The thermoplastic material may solidify by lowering the temperature. Thereby, for the second material a low-cost material may be used. In particular, for the second material a material may be used which affects the magnetic properties of the manufac^¬ tured product only between 0 % and 20 %. Thus, the finished permanent magnet may exhibit magnetic properties which are mainly governed by the first material shaped according to the shape of the separator (and/or a portion of the mould) into the target shape.

Thereby, removing the second material from the finished prod^¬ uct may not be required and also machining, polishing, grind^¬ ing or shaping the first material after compacting may not be required, in order to achieve desired magnetic properties of the finished product.

According to an embodiment of the present invention, the mould volume is delimited by a mould wall, wherein the mould wall provides an (closable) opening for filling in the first material and/or the second material into the mould volume. The mould wall may for example comprise five flat surfaces, in particular made of a metal, such as iron or steel. The planes of the mould wall portions may be oriented perpendicu^¬ lar to each other. The opening may be a rectangular opening having a width being equal to the width of the mould and hav^¬ ing a height being equal to the height of the mould. Thereby, filling into the first compartment and second compartment the first material and the second material, respectively, may be simplified. Further, the mould may be manufactured in a sim- pie manner.

According to an embodiment of the present invention the com^¬ pacting comprises applying pressure, in particular via (or through) the opening, to the first material and the second material.

In particular, a stamp or a plate may be arranged in the opening, the plate just fitting into the opening and a pres^¬ sure may be applied by excerpting a force onto the plate in the filling direction or depth direction. Different magnitudes of pressure may be applied. Further, a constant or varying pressure may be applied for a predetermined duration. Thereby, the first material and the second material may ef- fectively be compacted. The compacting may comprise that the tiny particles forming the powder material partially adhere to each other such that they stick together. Thereby, the shape of the first material filled into the first compartment may be maintained even if the separator is removed.

According to an embodiment of the present invention applying pressure comprises: applying pressure of a first magnitude to the first material and the second material; then removing the separator; and then applying pressure of a second magnitude to the first material and the second material, wherein the second magnitude is between 2 times and 50 times greater than the first magnitude. The pressure of the first magnitude may just be high enough such that the particles of the ferromagnetic powder material (i.e. the particles of the first material) stick together and adhere to each other such as to maintain the shape of the first material filled into the first compartment even if the separator is removed.

Applying the pressure of the second magnitude may even fur^¬ ther press the particles of the ferromagnetic powder material together such as to permanently (also when finally removed from the mould) maintain the shape defined by the first com^¬ partment. Thereby, the pressure of the second magnitude is in particular selected such that the resulting finished product may be used as a magnet of a wind turbine generator. According to an embodiment of the present invention the re^¬ moving the separator comprises drawing the separator out of the moulding volume, in particular in a direction opposite to the filling direction. The drawing the separator out of the moulding volume may be performed at a constant velocity along an unchanging direc^¬ tion. Thereby, the removing process may be simplified. In other embodiments the separator may be maintained between the first material and the second material, in particular in a case, wherein the separator comprises separator material not affecting (or only to a minor degree) the magnetic prop- erties of the final product. Thereby, the manufacturing method may even be simplified. An actuator, such as an elec^¬ tro motor may be used for removing the separator out of the moulding volume. According to an embodiment of the present invention the method further comprises sintering the first material; and/or magnetizing the first material. Sintering may be performed without applying additional pressure to the first material and the second material. In particular, sintering is per- formed below the melting temperature of the first material, such as to maintain micro magnets comprised in the ferromag^¬ netic powder material of the first material. Sintering may be performed between 10 hours and 36 hours, for example.

Thereby, the temperature may be adjusted to increase to be constant or to decrease, in particular in a cyclic manner.

The magnetizing may be in particular performed after the sintering. Thereby, the sintered product may be subjected to a strong magnetic field providing a homogenous magnetic field across the extent of the sintered product.

The final product may be used as an outer rotor magnet in particular for a direct drive wind turbine generator. The target shape of the magnet may be selected such that unde- sired torque ripples waves are reduced.

According to an embodiment of the present invention the sec^¬ ond material filled into the second compartment surrounds be^¬ tween 30% and 100% of an outer surface of the first material filled into the first compartment.

The second material may also serve as a protection layer or protection cover to protect (at least a portion of) the first material from corrosion and/or oxidation or other physical degradations or chemical degradations of the first material. This protective effect may be in particular achieved, when the second material surrounds the first material. On the other hand, when the second material only partially surrounds the first material, the first material may be protected in an exposed area (when used a magnet in a generator) , further the separator may be produced in a simple manner. It should be understood that features individually or in any combination disclosed for a method for manufacturing a permanent magnet may also (individually or in any combination) be applied to a mould system for manufacturing a permanent mag^¬ net or a permanent magnet (according to an embodiment of the present invention and vice versa.

According to an embodiment of the present invention it is provided a mould system for manufacturing a permanent magnet, the mould system comprising a mould having a mould volume; a separator, for separating the mould volume into a first compartment and a second compartment; an actuator for compacting the first material and the second material; wherein the sepa^¬ rator is shaped such that a shape of the first compartment corresponds to an target shape of the magnet.

The mould may be high pressure resistant and also resistant to heat treatment during a sintering process. The sintering may for example be applied at a temperature between 500 °C and 1500°C, for example. The pressure or maximal pressure applied to the first material and the second material filled into the mould volume may for example amount to between 50 MPa and 200 MPa.

The mould system may comprise a number of different separa- tors which are differently shaped in order to manufacture differently shaped permanent magnets. The shape of the second compartment taking together with the shape of the first compartment may have a cuboid shape. The first material filled into the first compartment and the sec^¬ ond material filled into the second compartment may be pressed within the cuboid mould and then sintered.

After the sintering and magnetization no grinding or machining may be necessary, because the desired active material shape has already been formed due to the shaped separator. Advantageously, pressing the cuboid shaped or rectangular mould is much easier than pressing an irregular shaped mould having the shape of the desired target shape of the permanent magnet. Pressing or applying pressure to a cuboid shaped mould may obtain the best uniformity of the density of the first material. Thereby, the quality of the permanent magnet may be improved.

According to embodiments of the present invention scraping or grinding or machining the sides of the finished product to form the geometrically desired shape may not be necessary anymore. Instead, the target shape or desired shape is achieved within or inside the finished cuboid block of the produced magnet by layering the different powders in a rec^¬ tangular or cuboid mould frame. Further, coating or protect- ing or applying a protection layer to the finished block of the first material and the second material may be avoided, since the second material located on top of at least a por^¬ tion of the first material is not really active (in the mag^¬ netic sense) and is not used for the magnetic flux produc- tion. Further, grinding of the active first material due to oxidation on the outer layer of the magnet may not be neces^¬ sary anymore, as a protective passive layer (formed by the second material) may surround at least partially the active material .

In case, the separator between the first material and the second material is removed, diffusion in the boundary between the two different materials may occur during sintering. Thus, the final active shape (after sintering) of the first mate^¬ rial may not accurately resemble the actual or initial target shape. However, these discrepancies may be controlled by se^¬ lection of process parameters, or for example by maintaining the separator or another separating material in between.

According to an embodiment of the present invention it is provided a permanent magnet, in particular manufactured ac^¬ cording to one of the embodiment described above, the magnet comprising: a first material shaped in a target shape differ^¬ ent from a cuboid; a second material at least partially sur^¬ rounding the first material, wherein an outer shape of the magnet is a cuboid. It has to be noted that embodiments of the invention have been described with reference to different subject matters. In particular, some embodiments have been described with ref^¬ erence to method type claims whereas other embodiments have been described with reference to apparatus type claims. How- ever, a person skilled in the art will gather from the above and the following description that, unless other notified, in addition to any combination of features belonging to one type of subject matter also any combination between features relating to different subject matters, in particular between features of the method type claims and features of the appa^¬ ratus type claims is considered as to be disclosed with this document .

The aspects defined above and further aspects of the present invention are apparent from the examples of embodiment to be described hereinafter and are explained with reference to the examples of embodiment. The invention will be described in more detail hereinafter with reference to examples of embodi^¬ ment but to which the invention is not limited.

Embodiments of the present invention are now described with reference to the accompanying drawings. The invention is not restricted to the described or illustrated embodiments. Brief Description of the Drawings

Fig. 1 schematically illustrates a perspective view of a mould system according to an embodiment of the present invention;

Fig. 2 schematically illustrates a perspective view

mould system according to another embodiment the present invention; and

Fig. 3 schematically illustrates a perspective view of a permanent magnet manufactured using the mould system of Fig. 1 or Fig. 2 according to an embodiment of the present invention.

Detailed Description Fig. 1 schematically illustrates a perspective view of a mould system 100 according to an embodiment of the present invention. The mould system 100 comprises a mould 101 formed by five mould wall portions from which only the wall portions 103, 104, 105 and 106 (but not a back wall portion) are il- lustrated in Fig. 1. The mould wall portions of the mould 101 enclose a cuboid mould volume which is divided or separated by a separator 107 into a first compartment 109 and a second compartment 111. Together the first wall compartment 109, the second compartment 111 and the separator 107 are arranged within the mould volume.

The mould 101 extents in a width direction 113 by an extent w which may amount between 100 and 120 mm, for example. Fur^¬ ther, the mould 101 extends in a height direction 115 to an amount h between 18 and 20 mm. Further, the mould 101 extends in a depth direction 117 to an amount d which is for example between 60 and 70 mm. The mould 101 is adapted for manufacturing a permanent magnet (such as the one illustrated in Fig. 3) which may be utilized within in particular an outer rotor electrical generator for a wind turbine.

In a first method step for manufacturing the permanent magnet the separator 107 is placed within the mould volume of the mould 101. Thereby, the first compartment 109 and the second compartment 111 are formed. In particular, the first compartment 109 has a shape resembling or being equal to a target shape of the permanent magnet to be manufactured. In a next manufacturing step a first material 119 is filled into the first compartment 109, wherein the first material is a neodymium material supplied in a powder form.

Further, a second material 121 is filled into the second com- partment 111, wherein the second material 121 is different from the first material 119. In particular, the second mate^¬ rial 121 may be a plastic material or for example a powder of small iron particles. In particular, the first material 119 and the second material 121 is filled into the mould volume of the mould 101 along the depth direction 117 which may also referred to as a filling direction.

Thus, while into the first compartment 109 an active magnet powder is filled, into the second compartment 111 a non- active dummy powder is filled.

For filling in the different material the mould 101 comprises an opening 123 which has the form of a rectangle having the width w and the height h. Thus, the opening 123 allows fill- ing in the different materials across the entire extent of the mould 101 in the lateral directions, i.e. the width di^¬ rection 113 and height direction 115. 1 b

After filling the tool materials into the mould 101 a plate is placed into the opening 123 (wherein the plate is not il^¬ lustrated in Fig. 1) and a pressure (using actuator 114) is applied to the first material and the second material.

Thereby, the constituents or particles of the first material 119 and the second material 121 stick to each other and ad^¬ here to each other such as to maintain the shape defined by the separator 107 and the mould wall portions of the mould 101.

In particular, the separator has a shape resembling a cuboid having two rounded edges 125. At the rounded edges 125 the separator 107 has a curved shape, while in the portion 127 the separator has a flat or planar shape.

The manufactured magnet comprises an upper surface 129 of the first material and an upper surface 131 of the second mate^¬ rial covering the surface 129 of the first material. Thereby, the first material 119 is protected by the second material

121 covering the upper surface 129 of the first material. The smallest thickness of the cover layer of the second material amounts to Δ being between 0.5 and 2 mm, in particular about 1 mm, in particular between 1/50 and 1/5, further in particu- lar between 1/20 and 1/10, of the height h.

After having applied the pressure to the first material and the second material 119, 121 filled into the first compart^¬ ment 109 and the second compartment 121 a sintering process is applied involving heat treatment below the melting tem^¬ perature of the first material 119.

Afterwards a magnetization is applied for example in the height direction 115 such that the magnetic field lines of an external magnetic field are co-linear with the height direc^¬ tion 115. According to another embodiment the separator 107 is withdrawn in a direction opposite to the filling direction 117 before applying a further pressure step. After the further pressure step a sintering step and a magnetization step may be applied. Finally, the manufactured end product may be re^¬ moved from the mould 101 and may be connected to a rotor of an electric generator.

As is evident from Fig. 1 the separator 107 only partly sur- rounds the first compartment 109. In fact, also the mould wall portions 104 and 106 and 105 partly enclose or surround the first compartment 109.

Fig. 2 schematically illustrates another embodiment 200 of a moulding system in a perspective view. Elements or components similar in structure and/or function to elements or compo^¬ nents illustrated in Fig. 1 are labelled with the same refer^¬ ence sign differing only in the first digit. The mould system 200 illustrated in Fig. 2 comprises a mould 201 having mould wall portions 203, 204, 205, 206. The mould 201 may have a similar size as the mould illustrated in Fig. 1. Differing from the moulding system 100 illustrated in Fig. 1 the moulding system 200 illustrated in Fig. 2 comprises a separator 207 that entirely surrounds the first compartment 209 in the width direction 213 and the height direction 215. Thus, also the second compartment 211 surrounds the first compartment 209 entirely in the width direction 213 and the height direction 215.

Thereby, it may be achieved to essentially completely sur^¬ round or cover the first material 219 comprised or arranged or filled into the first component 209 by the second material 221 filled into the second compartment 211. Thereby, the first material 219 may be effectively protected against oxi^¬ dation or corrosion. The resulting permanent magnet from the manufacturing methods using either the mould system 100 illustrated in Fig. 1 or the mould system 200 illustrated in Fig. 2 may be magnetized in the height direction 115, 215, respectively .

The upper surface 229, 129 or the upper surface 131, 231 of the resulting permanent magnet may be opposite to a stator of an electric generator, when the permanent magnet is used as a permanent magnet of an electrical generator.

Thereby, the thickness of the second material 221 above the upper surface 129, 229 of the first material 119, 219 may amount to Δ which may be in between 0,5 and 2 mm, in particular about 1 mm. This thickness Δ may be small enough such that a gap between the upper surface 131, 231 of the permanent magnet and the stator may be maintained. In par- ticular, the second material at least partially covering the first material 119, 219 may not (or only slightly, e.g. 0% to 20%) interfere or affect the magnetically property of the re^¬ sulting permanent magnet, in particular the magnetic proper^¬ ties may be governed by the material and the shape of the first material 119, 219.

Fig. 3 schematically illustrates a perspective view of a per^¬ manent magnet 300 manufactured using the mould system of Fig. 1 or Fig. 2 according to an embodiment of the present inven- tion.

The permanent magnet 300 comprises a first material 119 shaped in a target shape (defined by surface 126 of the sepa^¬ rator and surface 104 of the mould) different from a cuboid and a second material 121 at least partially surrounding the first material, wherein an outer shape of the magnet is a cu^¬ boid 124. Dimensions of the magnet 300 can be taken from Figs. 1 or 2. In particular the surface (defining a border or interface between the first material 119 and the second mate- rial 121) is curved providing rounded edges of the magnet 300. It should be noted that the term "comprising" does not ex^¬ clude other elements or steps and "a" or "an" does not ex^¬ clude a plurality. Also elements described in association with different embodiments may be combined. It should also noted that reference signs in the claims should not be con strued as limiting the scope of the claims.

Claims

1. Method for manufacturing a permanent magnet, the method comprising :

separating, by a separator (107, 207), a mould volume into a first compartment (109, 209) and a second compartment (111, 211);

filling a first material (119, 219) into the first com^¬ partment (109, 209);

filling a second material (121, 221) into the second compartment (111, 211);

compacting the first material and the second material; wherein the separator is shaped such that a shape of the first compartment corresponds to a target shape of the mag- net.

2. Method according to claim 1, further comprising

placing the separator into the mould volume, in order to form the first compartment and the second compartment, wherein the mould volume has in particular a cuboid shape (w*h*d) .

3. Method according to claim 1 or 2,

wherein the separator is shaped such that the first compart- ment has a shape resembling a cuboid having two rounded edges (125) extending in a depth direction (117), wherein the separator has in particular a constant thickness.

4. Method according to one of the preceding claims,

wherein the separator (107, 207) is shaped such that an extent (hi) of the first compartment (109, 209) in a height di^¬ rection (115) decreases towards both ends in a width direc^¬ tion (113), the height direction and the width direction being in particular transverse, further in particular perpen- dicular to a filling direction (117) along which the first material and/or the second material is filled into the re^¬ spective compartment.

5. Method according to one of the preceding claims,

wherein the separator is made of separator material compris^¬ ing xxx.

6. Method according to one of the preceding claims,

wherein the first material is a ferro magnetic powder mate^¬ rial, in particular a high grade NdFeB powder material, which has a remanence and/or coercity and/or energy product that is between 2 and 10 times higher than that of the second mate- rial.

7. Method according to one of the preceding claims,

wherein the first material comprises Fe in a mass ratio be^¬ tween 50 % and 75 %, Nd in a mass ratio between 15 % and 35 %, Dy in a mass ratio between 1 % and 15 %, and B in a mass ratio between 0% and 2 %.

8. Method according to one of the preceding claims,

wherein the second material comprises a plastic material, in particular a thermosetting or/and a thermoplastic material, in particular expoxy and/or

wherein the second material comprises Fe in a mass ratio be^¬ tween 75 % and 100 %, Nd in a mass ratio between 0 % and 10 %, Dy in a mass ratio between 0 % and 10 %, and B in a mass ratio between 0% and 1 %.

9. Method according to one of the preceding claims,

wherein the mould volume is delimited by a mould wall (103, 104, 105, 106), wherein the mould wall provides an opening (123) for filling in the first material and/or the second ma^¬ terial into the mould volume.

10. Method according to one of the preceding claims,

wherein the compacting comprises:

applying pressure, in particular via the opening (123), to the first material and the second material.

11. Method according to the preceding claim, wherein applying pressure comprises:

applying pressure of a first magnitude to the first ma^¬ terial and the second material; then

removing the separator; and then

applying pressure of a second magnitude to the first ma^¬ terial and the second material,

wherein the second magnitude is between 2 times and 50 times greater than the first magnitude.

12. Method according to one of the preceding claims,

wherein the removing the separator comprises drawing the separator out of the moulding volume, in particular in a direction opposite to the filling direction (117),

the method in particular further comprising:

sintering the first material; and/or

magnetizing the first material.

13. Method according to one of the preceding claims,

wherein the second material filled into the second compart- ment surrounds between 30% and 100% of an outer surface of the first material filled into the first compartment.

14. A moulding system (100, 200) for manufacturing a permanent magnet, the moulding system comprising:

a mould (101, 201) having a mould volume;

a separator (107, 207), for separating the mould volume into a first compartment (109, 209) and a second compartment (111, 211);

an actuator (114, 214) for compacting the first material and the second material;

wherein the separator is shaped such that a shape of the first compartment corresponds to an target shape of the mag^¬ net .

15. Permanent magnet (300), in particular manufactured ac^¬ cording to one of claims 1 to 13, the magnet comprising:

a first material (119, 219) shaped in a target shape (126) different from a cuboid; a second material (121, 221) at least partially sur^¬ rounding the first material,

wherein an outer shape of the magnet is a cuboid (124) .