Design for Additive Manufacturing (DAM)

Forewords 0 : This is in progress (last update 18-oct-2017)
Following the "release early/often" habit, you will see here a live draft of what is mean to be a comprehensive guide, as I will find time to write it.

Forewords 1 : Why I'm sharing this ?
Because I think it can be useful.
Even more when I see in the Standardization Roadmap for Additive Manufacturing of the ASTM that among the identified gaps there is a need for design guidelines.
The roadmap provides a snapshot of the current additive manufacturing standards landscape and identifies 89 “gaps” – 19 of them high priority – where no published standard or specification currently exists to address a particular industry need.
Among them :
Gap D1 Additive VS Substractive,
Gap D2 Additive Processes,
Gap D3 Process-Specific Design Guidelines,
Gap D4 Application-Specific Design Guidelines,
Gap D5, Gap D10 Design for Assembly.

Like any process (e.g. Injection Molding), there are some guidelines to follow to effectively design for Additive Manufacturing (3D printing). This personal collection of best practices and know-how is build on more than 7 years of experience, that I acquired mostly from the field.

Forewords 2 : Why I'm sharing this freely ?
Free does not equal with no-value, the opposite is also true (pricey does not equal with high-value).
Because I prefer to have impact rather than to be rich, and that seem natural after being used to apply the open/libre-software philosophy.
If I extrapolate from some consulting that have been sold, this page is worth between 1 to 2€ per minute you will spend here, so yeah it is worth something to keep browsing (or to hire me for advice/training).

With the wonders of the digital age it cost me almost nothing but time to publish and distribute knowledge here, while using an old media/strategy like a book would mean paper/investment/obsolescence. So, like Wikipedia, my bet is to rely on your generosity (see the yellow button up right, that's my open-source Patreon), supports will allow me to spend more time writing this or making illustrations.

Here we go.

26 Rules to DAM (I first presented these during FAB 12 in Shenzen, summer 2016)

Rule #0 : A correct 3D file

Check that the model is "watertight", have only one clean shell per volume (no inner walls or intricate things), at manufacturing scale, and oriented for manufacturing (if possible).

And we will see that orientation is the art of finding the best compromise. Sometimes it is easy (thanks to design anticipating the process), and sometimes it is tricky.


Rule #2 : 45° to avoid support
This one is the first I learned, from this guide : http://reprap.org/wiki/File:FFFDesignGuide.pdf
(Y)

#Gravity (T)
But if you think about what will happen, and you have control of wether you want support or not, some people have been clever using gravity at their advantage.
(better looking that with the steps the shape would have otherwise)

#modèle ≠ résultat
that allow me to introduce this other principle
the parameters


#Le cas du pont (H)

#trou pas débouchant = pont
évite plein de support
se nettoie bien

#Orientation pour limiter les supports

#Motifs et support
rectiligne : plus simple à enlever mais à éviter sur les hauteurs, risque de flambage, adaptation de l'orientation à vérifier
nid d'abeille : moins facile à enlever mais plus homogène (orientation motif vue de dessus)

#Ou on dessine les supports

#Grille / trame en Z
essayer de travailler avec un multiple de la hauteur de couche par rapport à la dimension finale souhaitée (sinon approximation possible)

#Grille / trame XY
idem

#épaisseur mini : 2*extrusion (ou 0.8 - 1.0mm en général)


#
Orientation / maximiser la surface de contact avec le plateau
dans la mesure du possible

#
Orientation / résistance
vertical vs horizontal
Efforts are made to produce parts that are more isotropic, maybe one day this rule will be less applicable.

#
Orientation / sens impression et mouvement / friction

#
Orientation / tolérance XY
trous plus petits à compenser
coins arrondis

#
Orientation / motif de remplissage
angle à adapter selon orientation XY de la pièce sur le plateau (ex. poignée folda, ou fine parois avec remplissage)

#
Les motifs de remplissage
hexagone : résistance
ligne : couvrir surface (ou moins de matière à surface identique)
/!\ concentrique : à éviter si pente < 45° /!\ #on peut obtenir un résultat différent du modèle 3D en jouant avec les réglages cas du vase forme pleine ou du roulement "quick-print-gear-bearing" -> le résultat ne ressemble pas forcément au modèle 3D (rappelez-vous du sapin du début)

# attention à l'accumulation de température / beware of heat build-up
trouver un compromis entre laisser refroidir les petites zones à risque, et ne pas créer d'obstacles

#Contexte d'usage
à prendre en compte pour proposer un compromis

#Tolérance et emboitement
0,2mm comme valeur de départ
varie selon procédé/machine/réglages

#Densité > Cavité (FFF/FDM)
pour les autres techno où les volumes sont plein, il est intéressant de penser comme en injection : épaisseur minimum constante (donnant par exemple des structures "lattices" en 3D)

#hauteur max pièces fines et/ou peu surface contact (FFF/FDM)
150mm
au-delà risque important de décrochage par le mouvement (malgré le peu d'efforts, effet levier)

#Cas d'équerre : renforcement / orientation / 45°

#Cas d'axe en place
cf plateforme (ponts)
ou double rotules (45°)

#Post-processing
(astuce: prévoir un chanfrein de 0,5×0,5 mm à la base
chimique
mécanique
vernis / peintures
http://www.fabbaloo.com/blog/2017/8/27/a-great-guide-to-3d-print-post-processing
www.fabbaloo.com/blog/2017/9/5/9-ways-to-dramatically-improve-the-finish-quality-of-your-3d-prints

Other relevant ressources :

i.materialise tutorials : https://i.materialise.com/tutorials#3dPrinting
3D Hub tutorials
Sculpteo tutorials & ebooks
Colorfabb : https://learn.colorfabb.com/

(Open-Badge potentiel : Fabrication Additive / théorique : évaluer la faisabilité d'un modèle 3D)

Sélection d'applications

Veille :  https://mensuel.framapad.org/p/OE3D

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