How to Succeed When 3D Printing With Metal PLA

There are a lot of different PLA composite materials out there, many of which use metal. Filaments like Steelfill, CopperFill, or Magnetic Iron PLA are really cool to print with and can create some amazing ornate prints, but there are some steps you'll need to take first before taking the plunge and printing with metal-infused PLA.

Note!

Metal-infused PLA does not make the filament take on the material properties of the metal it is infused with. Don't expect to take your stainless steel-PLA carabiner and use that to go rock climbing. These filaments are purely for decorative purposes, and in fact the powdered metal in the plastic actually makes it more brittle than the plastic alone.

Step 1: Use the Right Nozzle

Most 3D printers come with a brass nozzle, which is great for thermal conductivity and having easy and quick extrusion. But brass is soft for a metal, and any sort of metal based PLA is going to wear down your brass nozzle. The harder metal within the PLA will scrape away at the nozzle orifice, taking your pristine 0.4mm nozzle potentially up to a 0.5mm nozzle by the end of the roll. There are however, abrasive resistant nozzles you can usually swap into your printer, like stainless steel, hardened steel, or the Olsson Ruby.

"Wear Resistant" nozzles, are usually brass with a nickel plating, so while they are designed to resist any problems, when you start printing with ColorFabb Steelfill, that plating is going to disappear.
Stainless steel nozzles are a good step up from brass, and will last you a decent amount of time, but still aren't the best you can put in your hotend.
Hardened steel nozzles aren't as good as brass when it comes to conducting heat, but a little hotter extruder temperature and it will make up for it, and the hardened steel is resistant enough to potentially last years printing abrasive materials.
The Olsson Ruby is the end-all-be-all nozzle, designed to withstand almost anything you can throw at it. Specifically designed to print boron-carbide filament, this nozzle will last almost forever.

Changing your nozzle is really simple and will expand your material printing capabilities

Step 2: Make sure your first layer is right

Making your first layer right is a two-part process: you need to make sure your bed is level, and you need to make sure the nozzle is the right distance from the bed. Some printers now come with auto-leveling features or specific leveling routines, so follow the instructions provided with your printer.

Leveling the Bed

In most cases, 3D printer bed surfaces are leveled using three or four screws attaching the bed to a carriage. Tightening or loosening these screws changes the plane the bed is on, if your bed itself isn’t bent. In general, though, the procedure to level a bed is:

Move your print head out of the way of the bed to prevent it from crashing if it’s too close.
Home the Z axis. This will move the nozzle to as close to the bed it can get. If there’s room between the nozzle and the bed, perfect. If there isn’t room, tighten the screws under the bed until there’s about 1mm of space.
Move the print head above one of the three or four screws and insert a piece of paper between the bed and the nozzle.
Gently loosen the screw until there is a very slight amount of resistance between the bed and the nozzle. Just enough to notice, but not enough to require force to move the paper out.
Repeat this with the rest of the screws. The key is to get the same resistance at all points; this means your bed is level.

Adjusting Nozzle Distance

Now that the bed is level, you need to make sure the nozzle is at the right distance from the bed.

Make sure your bed material of choice is applied at this point.
Start a print with a skirt that covers the entire area of the bed.
Watch how the filament is laid down. Is it really smearing out the sides of each pass and looks like it’s bubbling up against each other? You’re much too low, and should bump it up a little bit at a time. Is there a clear distinction between each pass of the skirt? You’re too far away and need to lower the nozzle.
You can either turn each screw the same amount and continually test until the skirt comes out okay or you can change the Z Offset in MatterControl and typing in your desired change. Keep it to 0.02mm at a time until you find the right distance.

Knowing how to level your bed is incredibly helpful.

Step 3: Print bed and adhesion.

Just like regular PLA, all the same adhesion techniques apply. From kapton tape, to hairspray, to gluestick. Whatever you use when you're printing regular PLA will work just fine here. Be careful when printing on a surface like BuildTak or PEI, as the metal-infused PLA is a more brittle than regular PLA, and any sort of wrenching on a part to separate it may break it.

Step 4: Calibrating your print temperature.

For metal PLAs, I generally print at 215 degrees Celsius and a bed temperature of 60 degrees Celsius.
You may need to fine tune your printer to get results you are happy with, and you can do that by adjusting temperatures up or down 5 degrees at a time.
Since these filaments are PLA based, you need to be careful of how high your printing temperature goes. Too high and you risk ugly overhangs or drooping. Do some experimenting with small parts to gauge what works best on your printer.

Step 5: Layer Cooling Fans

Just like regular PLA, layer cooling fans are a must. Too little cooling, and all your overhangs and bridges will have some drooping. Whether it's a proper layer cooling fan mounted to your printhead or a desk fan to the side of your printer, you'll need something running. Print with your cooling fans at 100% if you have them and you're good to go.

Step 6: How To Change Filament

Changing to a metal-PLA from any other isn't any different than usual, just heat up your printer to the previous printing temperature and extrude the metal-PLA through it. This should melt out all of the old filament, and keep running it until the new filament runs through. When you are done printing with metal-PLA, it's the same procedure of heating it up to whichever material runs hotter (so if your new material is ABS, heat it up to ABS temperature), and then extrude the new material.

Changing filament the right way will save you a lot of headache diagnosing clogs.

Step 7: Print Speeds

The print speed for metal PLAs are comparable to regular PLA, or just a little slower. The powdered metal in the filament makes the filament more brittle than regular PLA, so any sort of strain or kinking to the raw filament will cause the filament to break. Make sure that the filament path from spool to extruder is well constrained, and by that I mean a straight path to the extruder, to decrease the chance of it breaking before it can be extruded. In some cases, you may be able to print at all the same speeds as regular PLA.

Step 8: Regular Maintenance and Care

Some other quick tips that should prove helpful:

Regularly clean the extruder gear and check the tension. As the drive gear presses down on the filament, it chews it just a little bit in order to move it. Gradually the teeth of the gear fills and it won’t be able to extrude or it’ll underextrude. A toothbrush or a small wire brush can make quick work of this filament dust. Some extruders have adjustable tensioners, and you can tune that too to get extrusion to work and not bite into the filament too hard.
1. If you aren’t able to extrude ASA at all and your hotend is at temperature, your nozzle might be clogged. Check out our video on how to unclog a nozzle to help walk you through the steps of clearing it.

And that’s it! It’s a lot of information to process, but altogether you should have enough to work from to get started printing metal infused PLA and printing it successfully.

Step 9: Post Processing

There are a couple different ways to go about post-processing metal PLA:

Use a rock tumbler. Now this doesn't have to be anything expensive, you can just get one online or a cheap one from a hardware store, but it's essentially a motor that rolls a small container with your part inside it and some abrasive material. You'll also need to buy "media" which is the actual substance that is abrasive to wear down and polish the 3D print. If you choose this method, make sure your print doesn't have any small protrusions or these may break off, because you will be leaving it in the tumbler for the better part of a week.
If you're using magnetic iron PLA, you can rust it! This is as easy as scuffing you model with some steel wool or a wire brush to open up more surface area to accept the solution you're about to make. In a container big enough to fit your 3D print, mix water, salt, hydrogen peroxide, and vinegar in no specific ratio, and leave it overnight, or at least a couple days.
Much like other filaments, you can sand and polish your 3D print. Start off with a low 80 grit to really break down the layer lines, and progressively move up to 1000 or 2000 grit before using some polishing compound to really make it shine.
An easier and much simpler method for a quick post-process is burnishing. Use some steel wool and the back of a smooth piece of metal, like a spoon, to just polish the outer surface of the model to make it shine. This won't break down the layer lines, but it will at least make for a really pretty print.

Step 10: Support Settings

Be careful with your support settings, and even consider using some small air gap tests, because support material is a bit more prone to welding to your part. Since your print is much more brittle than regular PLA, any torque or force applied to the rest of the model in trying to remove support could actually break pieces off. Go easy on your 3D print, and do some testing before committing to a 24 hour supported print.