In what way does geometry affect build rate in power bed fusion? June 09, 2015 12:40PM |
Registered: 9 years ago Posts: 2 |
Re: In what way does geometry affect build rate in power bed fusion? June 09, 2015 02:25PM |
Registered: 10 years ago Posts: 869 |
Re: In what way does geometry affect build rate in power bed fusion? June 09, 2015 06:17PM |
Registered: 9 years ago Posts: 2 |
Quote
cdru
What you see as the "beam width" is actually the laser moving back and forth very rapidly within that strip. Why it takes multiple passes instead of scanning the entire layer as a single pass I don't know. It may be due to the design of that printer. From the tech specs of that printer, beam has a focus diameter of 100 μm (0.004 in) and a scan speed of up to 7.0 m/s (23 ft./sec). Using a focus diameter of 100um, in 1 second it could fill in an area up to 7m x 100μm, or 700mm^2.
You'd have to know the total area of all layers being printed, or a total volume of the entire print to compute how long it would take to sinter the material with a best-case scenario of no overscanning, no travel time, and optimal material properties. You'd have to add in the recoat time for each layer times the number of layers to be printed. How you would figure out the area/volume to be printed without looking at the model is going to be difficult for anything but the most primitive of shapes. But you can probably approximate it by using an overall bounding box and get somewhat close.
It's also going to depend if the object is being printed out as a vector or a raster image. Imagine you are printing out a section of thinwall tube. You want it only 100μm thick. It could theoretically print with just a single pass of the laser just the width of the beam so it could print extremely fast per layer if the beam only has to trace the diameter of the tube. If it has to scan back and forth the entire area of the tube, there is much more area that would need to be covered even though it's not sintering anything in that area so would be much slower. However it would be easier to compute paths as you're just scanning the model not tracing it.