Nylon refers to a class of thermoplastic polymers with variations in mechanical, thermal, and chemical properties. Nylons are among the most popular materials used by engineers and manufacturers due to their variability and tendency for high strength and wear resistance.
Using Nylon as a 3D printing material allows you to create robust prototypes and take advantage of the wide range of properties across different formulations. In this post, you’ll discover today’s options for printing with Nylon and learn top tips for successful outcomes.
Types of Nylon
A number of different nylons exist for both FDM and SLS 3D Printing. Below are the current most popular formulations which vary in mechanical properties and print settings.
This material is designed to meet as many high-performance 3D applications as possible. A unique blend of nylons and co-polyesters, Alloy 910 has the highest tensile strength of most all 3D printing materials and is compatible with mid to high end machines.
This material ‘bridges’ the gap between a number of different mechanical properties. Nylon Bridge has moderately high tensile strength and a low frictional coefficient with easier print settings compared to other similar materials.
This material is used with lower-end machines that can’t achieve the temperature requirements needed for other nylons. Nylon 230 is extruded at 230C making it compatible with printers that don’t utilize metal hot ends.
PA11 (polyamide 11) has greater flexibility than its commonly used neighbor PA12, with similar tensile strength and thermal properties. A great material for applications where a degree of flexibility is necessary.
PA12 is a robust material applicable to a wide range of engineering applications. With moderate stiffness and high tensile strength, PA12 is a popular material for both prototyping and directly printing end-user products.
Storing Nylon Filament
Nylon filaments are hygroscopic meaning they readily absorb moisture. Moisture in filament adversely affects printing results so it’s important to keep your material dry. To store your filament, use an air-tight container with desiccant.
You might be familiar with the small (inedible) silica gel packets that your filament ships with and these are included to reduce moisture in the packaging. For small quantities of filament, a few of these packets mixed into your container will help to keep nylon filament dry. For larger quantities, rechargeable desiccant beads can be a more economical option. These include indicator beads that change color when the desiccant is saturated and are often be heated to make the desiccant useful again.
Drying Wet Filament
If your filament has been exposed to a humid environment for as little as a few hours, there’s a good chance it’s absorbed a significant amount of moisture. There are a few ways you can go about drying filament if you expect it’s wet.
The Oven Method
The easiest way to go about drying your filament is to bake it in the oven. To dry nylon bridge, we set the oven to 200F for 2 hours. The temperature you heat your filament to will depend on your specific material. A good rule of thumb is to refer to the glass transition temperature of your specific material and then bake the material 20F below its glass transition.
For those that would prefer to be conservative, going further below the glass transition temperature of the material and extending the baking time will produce similar results. It’s important to unspool your filament and wrap it into coils prior to baking. Spools are often made with low-temperature thermoplastics like LDPE which will deform in the oven.
Taulman3D is the leading supplier of Nylon FDM filaments and has designed a device to dry Nylon filament for you. Material is encased in a small bucket and heated by an incandescent bulb which removes excess moisture. Refer to Taulman3D’s graphic below or visit their website directly.
When printed correctly, Nylon has exceptional mechanical properties, but there are a few things to keep in mind when prints aren’t producing the results you’d expect.
The most common cause of printing issues with Nylon is moisture laden filament. Moisture laden filament will hiss and steam while being extruded from the nozzle. It will also exhibit excessive stringing and poor bonding between layers. Below is an image of the same material printed with the same settings. One batch was dried for an hour in the oven at 200F and the other was left in a humid environment.
Low Extrusion Temperatures
Adequate extrusion temperatures are important to ensure strong layer bonding with FDM printing and this is especially true when using Nylon. When printed at low extrusion temperatures, Nylon will pull apart and separate between layers. If your prints are exhibiting these properties, it’s a good indication that you need to increase your extrusion temperatures.
Iterate upwards by 5C until the layers begin to adhere properly. Decreasing print speeds can also improve layer adhesion by giving the extruded filament more time to fuse to the material below.
SLS Printed Nylon
SLS (Selective Laser Sintering) has historically been a costly technology accessible only to large corporations, and it works by sintering together powderized material. Formlabs recently announced the Fuse 1 which lowers the cost and knowledge barrier required to use SLS printing.
The Fuse 1 offers results comparable to those produced by more costly industrial grade machines at a fraction of the price. Units will begin shipping in late 2017 with both PA11 and PA12 offered as compatible materials.