Is it possible to 3D print multiple 0.1 mm high layers with a 0.4 mm diameter nozzle in FDM while ensuring fidelity to the set layer height? The raster width is set at 0.4 mm and I am not touching that. The part thickness is 3 mm, so 30 layers of 0.1 mm have to be deposited for the completion of the print job. My polymer is PLA.
If not, should I be using a 0.2 mm diameter nozzle for this purpose?
Can a 0.4 mm print nozzle print rasters with higher width (0.5 mm, 0.6 mm, etc.)?
Yes, absolutely. I believe the original sample file that came with the Ender 3 (0.4 mm nozzle) was sliced for 0.1 mm layer height. As long as your printer can get decently precise Z positioning at 0.1 mm increments, it should be able to do it.
I've never used smaller nozzles but they pose challenges that make them unattractive. It's hard to flow material through such a small opening, so you have to go slow and use narrow line widths. This may make sense for really small parts, but even then there are tradeoffs.
Yes, you can print lines wider than the nozzle, up to at least the width of the flat end of the nozzle, and with slightly reduced quality, even beyond that. Lost in Tech on YouTube has several videos showing his results doing this with very wide lines, up to nearly 2 mm if I recall. For 25% to 50% over the nozzle width, it's no problem at all, and a lot of people even recommend doing that. Wider lines improve overhang quality and part strength, but may compromise the ability to print fine detail.
The general consensus for nozzle diameter versus layer height is to limit the layer thickness to eighty percent of the nozzle diameter. For a 0.4 mm nozzle, one usually limits the layer to 0.3 mm. The printer on which the nozzle is installed will determine the minimum layer thickness, often a typical value of 0.10 mm. I have printed successfully to 0.10 mm layer thickness with a 0.40 mm nozzle.
The linked site says just about the same as above, but also provides useful information regarding appearance, speed, strength, etc.
With a "next size up" nozzle of 0.6 mm, you'd want to limit the layer height to 0.48 mm but you might get away with 0.50 mm layers as there is some wiggle woom.
For 0.8 mm nozzle, you can get your 0.60 mm layers as the max for that nozzle is 0.64 mm.
The article also references that one can print wider than nozzle dimensions by increasing the extrusion factor, which may go by other terms, depending on the slicer used.