If you have ever printed with polypropylene (PP) in the past, you’ve probably tried utilizing the same printing techniques and strategies for other commonly printed materials such as PLA or PETG and found yourself frustrated at the start (or end) of a print. Although there isn’t a “one size” fits all solution for printing all materials, the approach for printing PP today can be just as simple and easy to implement as other materials you are printing. Below we will walk through a few key tips and tricks for 3D printing with polypropylene filaments.
Bed Preparation
The most critical part of any FFF printing job is starting with good adhesion to the build plate and PP is no different. There is, however, a key difference for how the bed surface is prepared for PP. Put down the roll of blue painter’s tape, PEI or G10 build sheets. As much as we would love for these solutions to work with all materials, the simple truth is that PP just doesn’t have any chemical attraction/adhesion to those materials. Some folks may recommend PP packaging tape but often the adhesives on these tapes leave a difficult to remove adhesive on your build plate and can still have issues with adhesion since not all packaging tapes are the same.
PP takes a different solution for achieving optimal bed adhesion. We recommend starting with a bed adhesive glue stick specifically designed for polypropylene filaments, such as Magigoo products (www.magigoo.com). Magigoo PP is the workhorse of bed adhesion for most all geometries. Simply apply and even coating of the glue across your glass build plate, set your print temperature to 90°C and you are off printing.
If you have a large part that has sharp corners that tends to warp, we recommend upgrading to Magigoo’s PPGF product (at 90°C). This enhanced formulation will provides additional strength for longer more complex parts. Once you finish printing, simply reheat your bed to 90-100°C to help soften the glue and use a metal scraper to remove your part. To clean your build plate, simply run the build plate under hot water and use a metal scraper to remove the residual glue.
Print Settings
Print settings for PP are comparable to any other material, set your nozzle temp to 230 for unfilled PP or 240-260 for filled grades. Brass nozzles that are >0.4mm for unfilled PP are great but we highly recommend >0.6mm hardened nozzles for any fiber-filled grades. Print speeds for all PP materials range from 30-55mm/s, but keep in mind, that as you increase print speeds, you will also have to increase your nozzle temperature to ensure proper material flow.
Bed temperature is just as important as the nozzle temperature when printing with PP. As mentioned above in the Bed preparation section, make sure to use Magigoo PP with a heated first layer temp of 90°C and 85°C for the remainder of the build. Build plate adhesion additions such as rafts or brims can be useful for geometries that are highly prone to warpage. To achieve the best results for these parts, use a brim width of 5-10 layers to ensure a strong hold on the build plate. If a raft is used, be sure to utilize a one-layer gap between the rafter and the first layer of the part to promote easy removal after printing.
If you are utilizing and Ultimaker printer or Cura Software, we highly recommend downloading materials print profiles directly from the Cura Marketplace. These material profiles have already been optimized to ensure you will get the best print quality on your very first print. All Braskem unfilled and fiber reinforced filaments are available for download by visiting the Braskem materials page on the Cura Marketplace
Support Options
Supporting PP requires the use of a compatible supporting material. Because PP has great chemical resistance, this means many of our traditional support materials, like PVA or breakaway materials will not adhere to PP during the print. We recommend utilizing a water-soluble support that IS compatible with PP, Infinite Material Solutions Aquasys 120 is a great option (www.infinitematerialsolutions.com). Print this support material with a gyroid support structure and use hot water to solubilize the material and you have a perfect looking part each time. Be sure to keep your support material dry before printing, moisture will negatively impact how it deposits.
Self-supporting is also a fantastic option for support structures when you are looking for a simple, cost-effective process or only have a single printer nozzle available to print with. For the best results with self supports be sure your slicer software is set to leave a gap of 1 layer thickness between any part surface and support structure. This will ensure the proper level of adhesion without needing to destroy your part to remove the supports after your print is complete. Filled PP materials like Braskem FL900PP-CF, carbon fiber reinforced polypropylene filament, and Braskem FL500PP-GF, glass fiber reinforced polypropylene filament, have great overhang printing performance, and can print without support up to 70 degrees in some cases.
Optimizing Surface Finish
Polypropylene can be printed, and post processed in a number of ways to achieve many various types of surface finishes. Looking for high tolerance smooth surfaces, will depend on layer height. Be sure to keep your layer height as small as possible and dial in your horizontal expansion settings to really optimize the printing accuracy of your part. The smaller the layer height the higher the resolution, however take caution that these reduced layer heights will increase the overall print times of your part. Experiment with test prints to find the right balance of speed and resolution that will meet your specific requirements.
Part Removal
We have all finished prints where we questioned how the parts would be removed from the build plate without breaking the part or without breaking the build plate. Part removal when using PP filaments can be simplified by using one simple step. Reheat your build plate to 80-100°C, this will allow the bed adhesive to soften making part removal much easier. Once the bed has reached the desired elevated temperature, you should be able to carefully work the metal scrapper around the part, gently releasing it from the build plate. This is especially important when using very strong adhesives like the Magigoo PPGF.