All About Magnetic Iron 3D Printing Filament： Materials, Properties, Definition

Magnetic iron 3D printing is the use of iron-filled plastic filaments to 3D print parts that appear metallic. Printing with this filament is done by a completely different process than the techniques used for powdered metal printing, such as DMLS and SLM, which melt and fuse the bulk metal powder to build metal parts. In contrast, finished parts printed using magnetic iron filament remain a plastic matrix with metal filler. While parts printed with magnetic iron filament have a metallic appearance, their strength and durability are nearly the same as for the parent PLA polymer. Parts printed with these special filaments may be more brittle than standard PLA. Using these filaments to print parts will cause finished parts to be ferromagnetic, meaning that magnetic materials will stick to them. For more information, see our guide to 3D printing.

The composition of magnetic iron 3D printing filament depends on the filament manufacturer. However, in general, the percentage of magnetic iron in a filament is about 5-15% of the total volume or weight of the filament. The remaining volume or weight percentage comprises the base thermoplastic material. Higher percentages of iron lead to a more metallic finish and stronger ferromagnetic properties but will result in more difficult print jobs and brittle parts. Aside from PLA, ABS and Nylon, can also be filled with iron powders to make magnetic filaments.

Despite having a metallic appearance, parts printed with magnetic iron filament do not share many characteristics with actual metals. The list below describes some properties of magnetic iron filaments:

1. They produce parts with a metallic luster.
2. They have ferromagnetic properties (iron and other magnetic materials are  attracted to parts printed with magnetic iron 3D printing filaments).
3. They have strength and properties (mechanical, thermal, electrical, chemical, degree of biodegradability, and recyclability) more similar to the primary thermoplastic matrix material than to the added metal.
4. They have a density of around 1.5x higher than the base polymer filament material.
5. The metal powder particles are abrasive, increasing the wear rate on the printer extrusion nozzle compared to the plastic-only filament.
6. Bridging and support capability is poor because of the increased density of the filament due to the iron powders.

Comparison of Magnetic Iron Filament Properties

Table 1 below shows a comparison of some of the attributes of various 3D printing filaments:

Metal-filled filaments are notorious for being difficult to print, and it’s no different from magnetic iron filaments. The limitations of 3D printing with magnetic iron pertain to print settings and their impact on final part quality. One challenge is that the fine magnetic iron powder particles within the filament abrade the nozzle tip, leading to accelerated wear. 

Another limitation is the poor bridging and overhangs support capabilities of magnetic iron filaments. This limitation is due to the increased density of the filament that results from the addition of metal powders. 

Finally, the metal powder fraction can cause clogs and jams during printing. This means that print settings such as print speeds and feeds, layer thicknesses, and retraction distances must be fine-tuned and optimized to find the best settings for a particular print. Compared to standard filaments, like PLA, magnetic iron filament-printed parts require closer attention to process details to achieve parts with the desired qualities.

Why is Magnetic Iron Used in 3D Printing?

Magnetic iron 3D printing filaments are used in 3D printing to create parts that have metallic appearances without the need for a costly metal 3D printer or traditional metal fabrication processes. Parts with realistic metallic lusters like sculptures, jewelry, ornaments, props, and replicas are some of the most common applications of magnetic iron filaments in 3D printing. Beyond ornamental and decorative parts, parts printed with these filaments are finding increased usage in various sensors and actuators, small motors, and computer storage devices. Though using magnetic iron 3D printing filaments can create parts that look like iron, these parts don’t have the physical or chemical characteristics of iron. By no means should a part printed with magnetic iron filaments be used in place of a metal part unless the part is non-load-bearing or aesthetic only. 

How to Use Magnetic Iron in 3D Printing?

Printing with magnetic iron filaments can be more challenging than printing with standard filaments, but it is not impossible. Listed below are some of the best practices for how to use magnetic iron in 3D printing:

1. Small iron powders present in the filament can abrade and quickly wear out brass nozzles. Use a wear-resistant nozzle made from hardened or stainless steel for metal-filled filaments. Routinely check the wear condition of your nozzle.
2. Standard nozzles have a 0.4 mm diameter orifice. Metal particles tend to clump around the orifice and prevent filaments from feeding. To prevent clumping around the orifice, use a nozzle with a larger orifice (0.5-0.6 mm).
3. Because metal-filled filaments are denser than standard polymeric filaments, they are heavier for a given size filament. This increased weight can lead to drooping or breakage of the filament when the print instructions require bridging a gap or printing an overhang. If it can be helped, avoid printing parts with bridges or overhangs when using magnetic iron 3D printing filament.
4. Since metal-filled filaments are brittle, they can easily snap or crack. This problem can occur  if the filament printing path has too many sharp corners between the spool and the extruder. To solve this problem, minimize the distance between the spool and the extruder – the closer the two are, the better. 
5. Metal powders in the filament make it difficult for the extruder to retract molten material back into the nozzle while printing. This retraction leads to blobs of material at the start and end of a particular print segment. Optimize retraction settings to avoid retraction.

Protoplant, Inc. manufactures a popular magnetic iron-filled filament under the brand name Protopasta. While printer settings for metal-filled filaments will differ based on the manufacturer, the settings that Protopasta recommends for their magnetic iron-filled PLA filament can be considered typical, and are listed in Table 2 below:

Good wall thicknesses for parts printed with magnetic iron filaments are similar to the wall thicknesses for their primary base plastic. For magnetic iron-filled PLA, wall thicknesses are recommended to be 1.5 mm, with 0.8 mm being the absolute minimum.

What is a Good Wall Density for 3D Printing Magnetic Iron?

A “good” infill density for 3D printing with magnetic iron boils down to the desired properties of the final printed part. There is a correlation between wall, or infill density, and the strength of the resulting 3D-printed parts. If maintaining a high print speed is a concern, consider using a lower infill density (15-50%). Lowering the infill density will lead to parts that can potentially bend and break easily due to the brittleness of metal-filled filaments, but printing with high speeds could be used to verify part geometry and aesthetics quickly. Consider using a denser infill (50-80%) for functional, durable parts.

What is the Difference Between Magnetic Iron and PLA in 3D Printing?

The biggest difference between pure PLA printing filament and magnetic iron-filled PLA filament is that magnetic iron-filled PLA is magnetic. These metal powders lead to more brittle parts and print jobs that require more fine-tuning and attention than standard PLA parts. Magnetic iron-printed parts may have a metallic appearance and exhibit magnetic properties, but retain many of the same characteristics and properties as standard PLA.

This article presented magnetic iron 3D printing filament, explained what it is, and discussed the different factors to consider when using it in 3D printing. To learn more about magnetic iron 3D printing filament, contact a Xometry representative.

Xometry provides a wide range of manufacturing capabilities, including 3D printing and other value-added services for all of your prototyping and production needs. Visit our website to learn more or to request a free, no-obligation quote.

Disclaimer

The content appearing on this webpage is for informational purposes only. Xometry makes no representation or warranty of any kind, be it expressed or implied, as to the accuracy, completeness, or validity of the information. Any performance parameters, geometric tolerances, specific design features, quality and types of materials, or processes should not be inferred to represent what will be delivered by third-party suppliers or manufacturers through Xometry’s network. Buyers seeking quotes for parts are responsible for defining the specific requirements for those parts. Please refer to our terms and conditions for more information.