Multi-material printing for producing a 3D item with interpenetrating layers
The invention provides a method wherein single layers of a wall element, consist of two (or more) strands. One of the strands is located at one side of the layer and another one of the strands is arranged at the other side of the layer. However, at one or more positions these sides may be changed. In this way, e.g. color, reflectivity, transmissivity, and or other optical properties may be controlled. Further, a strong(er) layer may be obtained. Printing becomes more flexible, as the two strands may essentially be printed continuously. There will thus be change positions within the layer where one strand is over the other, or vice versa. In order not to increase layer thickness (at those change positions), as all strands are within the same layer, at the change positions the layer thickness of the strands may be decreased. In specific embodiments, there may be a temporary stop during printing of one of the strands at the change position to provide space for the future strand. A kind of woven structure may be obtained, which may also provide strength. Especially, one of the strands may be transmissive for visible light. This may provide a light transmissive single layer, or a light transmissive wall element.
1 . A method for producing a 3D item (1) on a receiver plate having an x-y plane by means of fused deposition modelling, the 3D item comprising one or more layers of 3D printed material, a first layer part of the one or more layers comprising a first strand of first 3D printed material in a first plane and a second strand of second 3D printed material in a second plane, the first plane and the second plane being parallel to the x-y-plane of the receiver plate, at least one of the first 3D printed material and the second 3D printed material being transmissive for visible light,
wherein the method comprises a 3D printing stage comprising layer-wise depositing 3D printable material to provide the 3D item,
wherein, during the 3D printing stage, the first strand of first 3D printed material and the second strand of second 3D printed material are deposited so that at a plurality of positions in a cross-sectional view parallel to the first plane and the second plane, the first strand and the second strand are available in a configuration wherein the first strand and the second strand are next to each other, either in direct contact or at a non-zero distance,
wherein, at one or more first positions, the arrangement of the first strand and the second strand is swapped relative to each other during 3D printing, wherein at the one or more first positions, four parallel strands of two layers are used to enable the swap.
2 . The method according to claim 1 , comprising providing at least one of the first and second strands in a block-shape way, in a zig-zag way, or in a meandering way.
3 . The method according to claim 1 , comprising providing the first and second strands in a way individually selected from a block-shape way, a zig-zag way, and a meandering way.
4 . The method according to claim 1 , comprising providing the first and second strands at a non-zero distance of each other at one or more second positions.
5 . The method according to claim 1 , wherein one or more of the following applies: (i) providing one of the first and second strands with a reduced strand height (H 1 ) at one or more first positions, (ii) interrupting 3D printing of one of the first and second strands at one or more first positions, (iii) providing the other of the first and second strands with a reduced strand height at one or more first positions, (iv) interrupting 3D printing of the other of the first and second strands at one or more first positions, and (v) reducing the strand height (H 1 ) of one of the first and second strands at one or more first positions by compression when printing the other of the first and second strands at the respective one or more first positions.
6 . The method according to claim 5 , wherein the method at least comprises (v) reducing the strand height of one of the strands at one or more first positions by compression when printing the other of the strands at the respective one or more first positions, wherein printing the other of the strands at the respective one or more first positions is done before a temperature of the 3D printed material of the one strand at the respective one or more first positions is below one or more of the melting temperature and glass temperature of the 3D printed material of the one strand.
7 . The method according to claim 1 , wherein the first 3D printed material and the second 3D printed material differ in composition.
8 . The method according to claim 1 , wherein the first strand and the second strand are configured in average parallel to each other.
9 . The method according to any claim 8 , wherein at least one of the first 3D printed material and the second 3D printed material is black, white, or colored.
10 . The method according to claim 1 , wherein, at one or more first positions within the first layer part, the configuration of the first strand and the second strand changes from a first configuration to a second configuration.