The invention relates to a method (200) for providing a printable melt (12) for operating a printhead (100) for a 3D printer.

According to the invention, the method (200) comprises the following steps: filling (210) a cavity (40) with printable material (10) using a supply device (2), closing (220) an opening cross-section (21) of a piston bushing (4) by advancing a piston (3) from a starting position (3a) in the direction of a nozzle (8) of the printhead (100), converting (230) the material from a solid phase (10) to a liquid phase (12) via a plastic phase (11), solidifying (240) the material (10, 11, 12), ascertaining (250) a spring constant of the liquid phase (12), and preparing (260) the liquid phase (12) for a printing process.

The invention also relates to a printhead (100) for a 3D printer for carrying out the method (200) according to the invention.

The present disclosure includes a method for determining a melt strength includes extruding one or more polymers to form the polymer film, passing the polymer film at least partially around a measurement roll coupled to a force measuring device, at least partially around a chill roll downstream of the measurement roll, and through a nip defined between two nip rolls, and measuring a force exerted on the measurement roll by the polymer film using the force measuring device. The polymer film is at least partially molten when contacting the measurement roll. A system includes an extruder, a measurement roll couple to one or more load cells, a chill roll coupled to a drive motor, at least two nip rolls downstream of the chill roll, and a take-up roll downstream of the nip rolls. The load cells measure a force exerted by the molten polymer film on the measurement roll.

The present disclosure relates to a 3D printer (1) for 3D printing of a construct. The 3D printer (1) has a print bed (2). The 3D printer further comprises at least one actuating tool head (3) with an extrusion element (4), wherein the extrusion element and the print bed are movable in relation to each other. The 3D printer also comprises at least one sensor (5) arranged to sense a force applied to the print bed (2) by the extrusion element (4), or vice versa. The 3D printer additionally comprises a control element (7) arranged to detect when the sensed force exceeds a predetermined value and to record a position of the print bed or extrusion element related to the detection that the predetermined value is exceeded. The present disclosure also relates to corresponding methods and computer programs.

A method for adapting a pressing force of at least one blade of a granulating machine for granulating material strands, such as plastic material strands. The granulating machine has a force generating means for pushing the at least one blade with the pressing force against a perforated plate of the granulating machine. The method includes the steps of specifying a blade pressing force; determining a hydrodynamic force, such as axial pressure force, which is generated by rotation of the at least one blade and acts on the at least one blade towards the perforated plate; determining the pressing force on the basis of the specified blade pressing force and the determined hydrodynamic force; and providing the determined pressing force to adapt the pressing force prevailing in the granulating machine. Also disclosed are a corresponding computer program product, a controller, a granulating machine, and a method for granulating material strands.