I have been printing 3D parts for some time in molten wire and SLA / LCD photosensitive resin. This subject only concerns molten wire parts, (still the most widespread technology) ... although some techniques can certainly be applied to resin parts ... to see!
My pieces must be functional, that is to say not only to be beautiful in appearance but above all functional with resistance to mechanical resistance over time.
The majority of 3D prints by makers (users of 3D printers) concern knickknacks and for them, only the surface aspect and the finish.
The subject of 3D prints is therefore not often mentioned by the maker community (as long as the arm of his GI Joe or Sankogu stands alone and is beautiful, the maker is happy ... )
So I looked for some surface treatment avenues to post surface treatment of 3D printed parts in order to improve their resistance and / or appearance.
Indeed, the weak point of 3D printed parts is their anisotropy and a lack of mechanical cohesion: even if the part seems "perfectly well printed" to you, it will still present a HIGH risk of layer detachment in the direction in which it was printed.
Some have shown that the direction of printing (= the positioning of the part during printing) has a huge influence on the mechanical resistance of the part and thata 3D printed part did not have at all the mechanical properties of a plastic part injected or machined in the equivalent mass ... (but we suspected it ...):
Listing (dynamic) of the post processing techniques of the printed parts that I could find (for the moment) and that I will try to experiment for some
1. Treatment with fiberglass or carbon and epoxy or polyester resin
The solution certainly the heaviest but probably the most effective: we use the 3D part as a permanent "mold" by applying one or more layers of glass or carbon fibers
- it's heavy work,
- need to master the technique,
- incompatible or hardly compatible with small parts or parts with too small details or too complex a shape (the main purpose of 3D printing is to print "complexity")
2. Re-melt the plastic with acetone
Passing one or more layers of acetone on the ABS parts or soaking them will reshape the surface of the part and ensure better cohesion. It's quite easy, cheap and efficient.
- can only be used with ABS (and derivatives)
- removes any details from the room
- requires mastering the technique (quenching time / number of layers VS details to keep / thickness of the part)
3. The "ABS soup" or polystyrene: homemade resin
Close to technique 2 but which can be used on all plastic parts (a priori), it consists in melting ABS in acetone to obtain a resin applicable to any surface. Fairly easy to implement.
Some on this forum do the same thing with polystyrene it seems to me but I no longer remember the solvent?
- less homogeneous solution 2
- need ABS
- requires experience to know the number of layers
- almost free
I prepared a small pot yesterday (with a 3mm ABS coil from 2014 ...) that melted well overnight I added a few strands (at random) this morning.
I will test the application on a carbon PLA part
4. "Conventional" two-component resin treatment
Between 1 and 3 with a resin (epoxy or polyester or other if you have any suggestions?) Which is not loaded with fiber or plastic.
- more expensive than 3
- held over time?
- must be applied in a short time (open time of the two-component resin)
5. Treatment with 405 nm photosensitive resin
Apply one (or more) layer (s) of resin dedicated to resin 3D printers and put the part in the sun. Very easy to set up. I will test.
- quite expensive (photosensitive resin is at best 35 € per kg)
- homogeneity with the unknown parts
- little known mechanical properties (we do not yet know what resins for the general public are)
- resin is brittle especially if overexposed to UV (use of the room outdoors)
6. Treatment with "glue"
Suggested by some internet users ... I don't really believe it but it's a solution. Use glue, neoprene, cyano ... to strengthen the surface ...
- probably quickly overpriced
- held over time?
7. Redesign of the part in the oven with an inert material
The technique consists of passing a part in the oven for a certain period of time in order to recast it. All in an inert powdery material. The idea seems good but my first experience was not that great in terms of results: 3d-printers / marvelous-technological-advancement-but-t16549-30.html # p412108
The technique is obviously limited to the parts entering your furnace ... and to massive parts ... (100% inflill filling ... which was not the case with my parts ... but the surface aspect was not improved anyway).
To be continued...