Just an idea for the next - and ultimate !! - generation of 3D printers :
1 - FDM is perfect for multi-materials, from PLA to peek, but the layers aspect is a severe drawback.
2 - UV SLA is perfect for precision and surface aspect.
But cleaning, resin purges and toxic fumes are severe drawbacks.
I don’t talk about the painting of the production, if needed.
But a solution merging the two technologies is totally doable today—all the pieces are on the board.
An hotend for the FDM, 5 axis and UV printer end to cover the FDM surface, concealing the print lines, and doing a precise and nice painting final layer.
That’s going to be way out of most people’s league for the first prototypes.
But Bambu will take an option, with this kind of solution, before other models take over the market.
And BambuLab likes game-changer ideas.
You’re really talking about a combination of a CNC painter and a modern UV flatbed printer.
That alone would be a novel product path - no need to shoehorn it into the same box as a FDM printer.
Something that you just put a finished 3D print into, it scans, then coats with colored UV resin to the final dimensions and appearance would be a cool product idea.
This may take off one day, but no one has this running at scale from a manufacturing perspective
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That is an expensive amount of ‘ink’ to use. It is this which would require the 5-axis head as you suggest this process occurs after the FDM process has completed. The FDM model would need to be cool for the UV to start. Again, 5-axis tech is rare and far more so for UV.
Bambu have made some bad zigs when the industry zigs, so this could be true.
I like that you are thinking out of the box, but this one is a solution too far. At least for a few years.
Layer lines are annoying, there are current and future solutions though.
Current:
Traditional resin printing has an excellent resolution, far better than FDM. For many the disadvantages out way the advantages though. This is also gaining full colour capabilities, albeit in much higher end, note consumer products.
Future:
Technically some current slicer and printers have this.
Multiple nozzle sizes in a single printed model.
The smooth surfaces would use a 0.2mm nozzle, 0.4mm for outer walls and surfaces and 0.6 or 0.8mm for infill.
This gives a far cleaner outer appearance and a stringer internal structure which prints faster.
This has been promised by Bambu Lab for a couple of years.
I like the idea of doing the bulk of the print in one colour then like you said use some sort of 5 axis approach to painting the outer surface with the final colour and detail one colour at a time.
Even with just fdm there would be quite a few speed advantages .
UV printers with rotary attachments already have quite a lot of the hardware needed for your hybrid approach.