But sometimes using glue to get a printed part on metal just won't cut it....
So why would you want to print on metal?
Well, there is things like copper and aluminium foil that are quite usefull for decorative purposes but also to add features like shielding against heat or sunlight.
In the model making world you might want to add some supports or mounting featured to a sheet of brass sheet...
Anyway....
If you every tried to print on some metal you have noticed that even with sanding the surface and a heated bed adhesion is a pain in the behind.
PETG does work great "out of the box" but isn#t always the easiest material to print.
If you wanted, for example, to print with PLA on a sheet of brass you would have to cheat...
So how do we get the adhesion we require???
I found a simple and neat trick to make most plastic we use in our printers stick to basically any metal - the important first layer that is...
Things you might need:
Fine sand paper
Acetone or alcohol - to clean the surface but soapy water and a brush will do as well
Metal primer or galvanising spray
Preparation:
Give the metal surface to print on a light sanding.
You want oxides and such to disappear to get shiny surface.
If you only print in certain areas you can use a mask.
Clean the surface with acetone, alcohol or soapy water - the later only if it won't mean to wrinkle the sheet....
Dry off and apply one coat of primer or galvanising spray.
What's the difference?
Primer you can get in clear but it might not always stick properly to copper and brass - test first.
Galvanising spray bonds well on all metals and provides a rougher surfece, unless you go for the shine aluminium or chrome look sprays - avoid those please.
Getting the sheet on the bed can be done in various ways.
A bit of sticky tape around the edges if the sheet or print won't cause lift off.
Or using a glue stick, place the sheet and turn the heat on for about 20 minutes to set the glue - it won't create a permenent bond and pops off after the print.
Do not use double sided tape as the glue will cause a bad mess with the heated bed and printing cold might not work.
How actually print?
Needless to say you should heat you bed before you start the print.
Metal loves to cool down on the surface, so you might want to do some tests to determing if and by how much you have to increase the bed temp.
You can use some blue painter's tape - if the plastic prints fine on there you know the bed temp is good without messing up the metal sheet.
First layer, depending on the material, should be printed rather thin, like .015mm, very slow, about 20mm/s MAX and if possible with a slightly higher temp than the rest of the print.
As a rule of thump: Go half the usual first layer speed with about 5° more than usual.
Do NOT print with a raft, brim or such things and avoid support structures starting from the build platform.
For very thin sheets of foil it really helps use a glue stick before placing the foil on the bed....
The following layers can be printed as normal.
Embedding metal foil for decorations or as a logo....
It can be nice to have some shiny metal foil embedded in the surface of a print, rather than sticking them on top.
Placement though can be rather tricky....
There is many ways of getting it right but here is the one I prefer:
Do a print of paer than has your design in the right place and size.
Cut it out
Now use your 3D printer to create just a very thin brim, like 0.1mm.
Place your paper inside the brim and use a marker to trace where the metal bits need to be.
Peel the brim off and use a gluestick to get the metal foil placed correctly.
Use a first layer height of MORE than the thickness of your metal foil.
For example: If you use 0.1mm brass sheets you want to have a first layer height of at least 0.2mm.
Extrusion rate is a critical factr here if you don't have the metal spaces reflected in your 3D design!
No big deal for some small starts and such but a logo covering a larger area means you extrude far too much plastic to get a clean and smooth first layer.
Try to find find a rate that won't produce too much mess while still properly sticking to the bed in exposed areas.
Do only 2 or 3 solid infill layers at the bottom - less is better than more
The fill infill should start early to create a smooth surface.
Even if your design is rather thin it is better to add at leas one fill layer with less than 60% infill rate than to print it all solid - otherwise you might not get a smooth top surface and smeared perimeters.
Alternative method, for thinker foil or metal sheets:
0.1mm thicknees is on the limit and if the designs are larger it can be a pain to get a good first layer.
Far better, especially if you use ready made decorations that are thicker is to remove those areas from your print design.
If you have a scanner or used your ownd designs it is quite easy to do with a vector graphic.
Let's say you logon shall be made from .5mm thick aluminium.
No chance to have this on the bed from the start.
But your print desing has these shapes as empty spaces.
Means you can add a pause before the first full layer starts.
Place you designs in the empty shapes and secure them in place with a bit of glue stick magic on the bed.
Having the surface to be printed on sanded and with a coat of primer or galvanisng spry makes sure things bond well.