Metal Filled

Most 3D printers ship with brass nozzles that are relatively soft. Since metals can be abrasive in general, brass nozzles can easily wear out when used with metal filled filaments. Upgrading to a wear-resistant nozzle will help reduce the wear significantly. Another aspect to consider while upgrading is the nozzle size. Although it is possible to print with standard 0.4mm nozzles, metal particles tend to clump around the orifice and can cause clogging over extended periods of use. Nozzle sizes of 0.5 – 0.6 mm seem to work better for metal filled filaments. It is also good to periodically check the nozzle orifice for any visible wear. Worn out nozzles can otherwise result in inconsistent extrusion and reduced overall quality of the printed parts.

Metal filled filaments are quite heavy, which has an impact on their bridging performance. When the molten plastic is extruded across either side of the bridge, it droops excessively and eventually breaks before it can complete the bridge. This means that parts with lots of large bridging regions will be very difficult to print.
Simplify3D Version 4.0 added several new features related to bridging, including one that allows you to completely customize the direction of this bridging fill. If you have a part that requires bridging and there is no way to avoid it, you might find that there is a specific fill angle that will work best for this material. The software also allows you to customize the exact speed and extrusion rate used for the bridges, so you can experiment to find what works best for your material. Other successful methods would be to add support structures to support any potential overhangs, or consider using a dual extrusion system with a dissolvable support structure such as PVA. Simplify3D includes a feature called Dense Supports, which allows you to use this PVA material very sparingly, only at the interface between the supports and the part, so this can be a great option as well.

Metal filaments are very brittle in general. This affects the final parts, but it also applies to the raw filament itself which needs to be pulled into the printer as it is extruded. If you follow the filament path from the spool, all the way to the extruder, check for any sharp angles or curves which may put too much stress on the filament. We found that many printers included sharp bends that had a tendency to cause the filament to snap in the middle of printing. You may notice this happens more as the toolhead moves around during the print, since different toolhead positions may put more stress on the filament as it bends to move to the new location. One great way to avoid this is the change the location where the filament spool is mounted. Start by mounting the spool on top of the printer and try to minimize the distance from the spool to the extruder.
Additionally, a strong filament guide tube that limits the bend in the filament path will prevent most breakages.

Like wood filled and other composites materials, retractions with metal filled filaments can be rather challenging. The presence of metal powder makes it difficult for the nozzle to contain the suction pressure in the melt chamber during retraction. This will frequently lead to blobs at the beginning and end of each printed segment, where the extruder was trying to start or stop the plastic extrusion. Simplify3D has several features that can be a big help in this situation. The first is a unique feature called Coasting, which will automatically reduce the pressure in the nozzle right before the end of a print segment. This greatly reduces oozing when moving to the next print segment, so it can be a great option to consider. You can also try setting the “extra restart distance” to a negative value of -0.1 or -0.2mm, as this can help with the blobs that may form at the start of each segment. For more tips on how to reduce these blobs, please refer to our Print Quality Guide: How to Reduce Blobs and Zits.