In additive manufacturing, powder residues accumulate constantly throughout the operating process. The valuable powders are subject to the most stringent of quality requirements and should be reused in the printing process. To reduce rejects to an absolute minimum, the powders are processed. 3D printers have an internal or external powder processing unit that uses ultrasound to screen out clumps and other contaminants. The screens are adapted to meet the individual requirements of each powder processing unit.
- Microscope images of sieved powder and powder with impurities or lumps
- The pictures show the good grains (left) and the screened-out oversize grains (right) in the same resolution/enlargement
- This is metal powder that has been reprocessed after the printing process with Telsonic ultrasonics. During the screening process, a separation efficiency of almost 99% is achieved.
- There is practically no usable powder in the reject powder.
How does ultrasonic screening work?
In principle, an ultrasonic screening system always consists of three components: a generator, a converter and a matching screen resonator with installation frame. The generator converts the normal mains voltage into high-frequency voltage and transmits it to the converter. This in turn converts the high-frequency voltage into ultrasonic oscillations using the piezoelectric effect, which then cause the screening frame to oscillate via the resonator. The oscillations are transferred to the screening fabric and distributed evenly there. The screen oscillations, which vary in the range between 33 and 37 kHz, reduce the frictional resistance between the material to be screened and the screening fabric. This ensures efficient cleaning of the screens without particles getting stuck, increases throughput, optimizes the separation efficiency and speeds up the recycling process.
