Method for obtaining good adhesion of semi crystalline polymers to the build plate during fdm printing

A method for producing a 3D item by means of fused deposition modelling, wherein:

• the method comprises a 3D printing stage comprising layer-wise depositing 3D printable material, to provide the 3D item comprising 3D printed material on a receiver item, wherein the 3D item comprises a plurality of layers of 3D printed material;
• wherein:
• the printable material comprises a semi-crystalline polymer;
• the 3D printable material has (i) a melting temperature range, ranging from a first melting temperature TM1 to a second melting temperature TM2, wherein TM2>TM1, and (ii) a crystallization temperature range, ranging from a second crystallization temperature TC2 to a first crystallization temperature TC1, wherein TC2>TC1;
• the 3D printing stage comprises guiding the 3D printable material through a printer nozzle at a nozzle temperature TN;
• wherein TN>TM2;
• the method comprises during a first sub-stage of the 3D printing stage:
• depositing 3D printable material on the receiver item having a first receiver item temperature TB1, to provide n1 first layers on the receiver item;
• wherein TB1≥TM2;
• the method comprises during a second sub-stage of the 3D printing stage:
• cooling n12 first layers of the n1 first layers selecting a second receiver item temperature TB2 of the receiver item, wherein TB2≤TB1, and one of:
• (i) selecting TB2<TM2, or
• (ii) the n1 first layers comprise a first subset (s11) comprising n11 first layers and a second subset (s12) comprising the n12 first layers, wherein the first subset (s11) of n11 first layers is in contact with the receiver item, wherein the second subset (s12) of n12 first layers is configured on top of the first subset (s11), wherein cooling the n12 first layers comprises actively cooling the second subset (s12) comprising the n12 first layers of the n1 first layers to a temperature below TC2 and selecting the second receiver item temperature TB2 of the receiver item, wherein TB2≥TM2;
• and
• the method comprises during a third sub-stage of the 3D printing stage:
• depositing 3D printable material on the previously deposited n1 first layers, to provide n2 second layers thereon.