BASF Forward AM Ultrafuse® Metal - Tips and Tricks on How to be Successful

When starting a printing process, the goal is to get the best possible final part. However, in order to achieve that, it is essential for certain guidelines to be respected. In this article, we will touch on the important steps required to produce the best possible printed metal part with BASF Forward AM’s Ultrafuse® Metal material. Let’s begin with the tips and tricks to successfully print using BASF Forward AM Ultrafuse® Metal.

What are Ultrafuse® Metal Filaments?

Ultrafuse® Metal filaments are metal-polymer composite filaments specifically designed for Fused Filament Fabrication (FFF) printing. The non-slip outer surface of Ultrafuse® filaments has been optimized for printing on both Bowden and direct drive FFF extruders. With high metal contents of around 90% by mass, combined with even distribution of tailor-made metal powders within the binder matrix, Ultrafuse® metal filaments provide both dependable performance and help to reduce the risk of printing defects, therefore, increasing final part success rates. 

When compared to other fine metal powder methods like Selective Laser Melting (SLM), Direct Metal Laser Sintering (DMLS), Direct Metal Deposition (DMD), and Binder Jetting, Ultrafuse® filaments bind metal particles within a robust polymer system at high density to reduce potentially harmful fine metal particle exposure.  And because there is no need to unpack the printed parts out of raw powder within the build chamber, operators have minimal exposure to fine metallic particles.

BASF Forward AM offers two metal filaments as part of its portfolio: Ultrafuse® 316L and Ultrafuse® 17-4 PH. 

Which leads to the question, when should you use what material? Ultrafuse® 17-4PH is the cost-effective, all-rounder stainless steel, shows high mechanical load resistance and is suitable for almost all metal applications, only beaten by Ultrafuse® 316L when it comes to corrosion resistance. If you want to check which part is made from 316L or 17-4 PH, simply use a magnet. If it sticks, it is 17-4 PH. If it doesn’t, the part is made out of 316L.

General Important Setting and Guidelines

Before we delve into the most important tips and tricks, be sure to review the table below. In it, you can find a brief summary of how to successfully work with metal filaments.

Suggested Printing Parameter

The selection of printing parameters during the slicing process is critical for part quality and printing time. The suggested parameters seen in the table below serve as a starting point for new users looking to begin printing quickly. As with any manufacturing process, each part presents specific challenges and can benefit from tuning and optimization in order to achieve the highest possible quality.

• Nozzle Size: 0.3 - 0.8mm
  • Varies depending on the level of detail required and print time
• Line Width: ±10-20% Nozzle size
  • Recommended
• Retraction Distance: 1.5mm / 5.0mm
  • Direct / Bowden extruder
• Retraction Speed: 45 mm/s
  • Recommended
• Layer Height: 0.10 - 0.25 mm
  • No more than 60% of the nozzle size is recommended
• Outlines: 1-3
  • Too many outlines can result in wall separation
• Infill Density (Solid Part): 105% Lines
  • Rectilinear types have shown to produce higher densities
• Infill Overlap: 20-35%
  • Overlap between the infill and the walls must be ensured
• Infill Type (hollow): >60% gyroid, grid, or triangle
  • Minimum infill above 60% for best results, but lower values possible with testing
• Infill Line Direction: [45, -45]
  • Recommended
• Nozzle Temperature: 235°C - 245°C
  • Calibrate to ensure actual temperature matches slicer temperature settings
• Bed Temperature: 90°C - 105°C
  • Calibrate to ensure actual temperature matches slicer temperature settings
• Cooling: None
  • Part cooling generally increases warpage but can be helpful during bridging
• Max. Print Speed: 45 mm/s
  • Slower printing speeds produce denser, more accurate results
• Extrusion Rate: Max 8cm3/h
  • By nozzle size 0.4mm lower rates recommended
• Scaling: XY 120%, Z 124%
  • See Shrinkage and Oversizing Factor

Design Guidelines

Developing and choosing the right design is crucial for a high-quality and functional 3D printed object. It is also important to remember that the guidelines are often recommendations, not limitations. And many guidelines are driven by the needs of the D&S process.

• Part Size: The maximum green part footprint cannot exceed X 100, Y 100, Z 100 mm in order to fit on the ceramic plates supporting the parts throughout debinding and sintering. Larger parts are achievable; however, they can suffer from warpage while printing and often require longer development times. The most successful size for new users is X 60, Y 60, Z 60 mm.
• Unsupported Walls: To minimize the chance of collapse and distortion, unsupported wall height to width ratios below 6:1 have been proven to be the most effective. Although easily printed, ratios above 6:1 resulted in cracking and even part collapse.

Mono Extrusion for Metal Only - 2.5D

• Overhangs: >35°
  
  • Should be avoided by the part desigh
• Support Structure: Mandatory for successful printing
• Support Material: Printed from the same material
• Support Removal: Subtractive removal from the metal part via sawing, milling, drilling, and filing
• Shrinkage Plate: Potentially requires CAD, separate print job, assembly finalized at the D&S service partner
• Separatable Live setter (support structure plus shrinkage plate): Requires CAD, separate print job, error-prone finalization of the part assembly

   

The Big Three

There are three big topics that should always be considered when printing Ultrafuse® Metal Filaments: Twist and Deformation after Debinding and Sintering, Shrinkage Plate and Green Part Preparation.

Twist and Deformation after Debinding and Sintering

When using Ultrafuse® Meta Filaments, an uncommon feature must be used in the slicer. The printing history of the individual layers leaves an invisible internal tension in the green part. This is especially true for contour-following lines as they introduce a spring-like tension that follows the thermal history of the extruded line. Parts with thin features or many contour lines suffer the most from deformation during the sintering process (Figure 2). The trick is to print the contours with alternating directions. This compensates the for the tension, and the parts are not deformed after sintering.

Shrinkage Plate as a Live Setter

The second important tip is to be aware of is the Shrinkage Plate. During the sintering process, the metal particles fuse together and up to 20% shrinkage occurs. During shrinkage, the contact area of the part is affected by friction as a counterforce. The coefficient of friction depends on the mass distribution of the part and the design ratios of the part, which appear stretched or deformed (Figure 4). To compensate for the static friction effects, a separate plate made of the same material, known as a shrinkage plate (Figure 5), is used to enclose the entire contour area of the bottom of the part. The desired part sees only the shrinkage of the plate and no additional static friction. The component leaves the sintering process free of distortion and with higher accuracy (Figure 6). For a debinding and sintering service partner, the shrinkage plate is coated with a sinter-inactive material to prevent diffusion and bonding of the shrinkage plate with the desired metal part.

Green Part Preparation

During the debinding process, the polymer and thermoplastic matrix is removed leaving only stainless-steel powder with a small amount of plastic to hold the part’s shape. Tiny gaps between the part and the support surface of the furnace can exert critical shear forces on the part, leading to cracking and collapse. To successfully survive processing, all part surfaces must be absolutely planar and flat. A glass print bed and the use of Magioo ProMetal are the first steps in the right direction. Each part should be checked for planarity before debinding and sintering and, if necessary, flattened using sandpaper or other subtractive methods.

We hope that by utilizing these tips and tricks, all your metal parts will be printed as expected. For more information and additional tips and tricks, be sure to check out BASF Forward AM’s Metal User Guideline. Until then, happy printing!