- Printed Parts Peel or Warp
Why Parts Warp
In general, 3D printed parts warp because of thermal deformation. When plastics heat up, they expand. When the plastics cool, they shrink. Because Fused Filament Fabrication (FFF) almost always involves thermoplastics, this happens with almost every FFF 3D printer.
Many parts warp simply because of the material limitations of FFF 3D printers combined with part design not optimized for 3D printing. This article will offer suggestions for both the system and part design to help combat warping in parts.
System Solutions for Warping
To help minimize warping, please consider the following system options:
- Keep the print bed and printing environment warm during printing. These two strategies keep the part at temperature, so it doesn’t cool, therefore, no warping. To keep the most heat in during printing, keep the visor and printer lid closed.
Note: Please take caution when introducing any type of heating element to the printing environment. Markforged cannot be responsible for any damage done to the printer or parts as a result of heating elements that are introduced to the printing environment.
- Apply a thick layer of glue under the entire base of your part. This will help the part better adhere to the print bed and will help ensure better surface contact.
- Let the part cool completely before removing it from the print bed. This will minimize the amount of flex and warping that will occur during the removal process.
Design Solutions for Warping
When 3D printed parts warp, it’s because of a thermal moment formed around the edge of a part. This thermal moment is caused because when FFF printers lay down filament, they are heating the plastic until it is semi-fluidic and then cooling it down after it is extruded. When most materials cool, they want to shrink. In the case of FFF 3D printers, this means that each “line” of material will want to contract lengthwise. Usually, this is not enough to break adhesion with the build plate, but this force builds up as more layers are added, making the part warp. This is especially common with long, thin parts.
To help minimize warping, please consider the following design options:
- Use rounded corners rather than sharp corners. Sharp corners create stress concentrations, so corners are the most common geometries that induce warping. Adding a fillet to these corners reduces the stress concentrations because the sharp corner gets rounded off, and the stress gets distributed. In general, creating cross sections that are more round in shape when contacting the build plate will reduce warping
- Use the Brim feature. This reduces warping or curling for two reasons. One, the part has an “extended” bottom surface, meaning that the contact with the build plate is larger than it would be normally. Two, any warping that occurs transfers to the brim, which will take the worst of it. The brim additionally gives a better surface for support structures to adhere to.
- Design fillets or custom brims onto your part. Sometimes, due to odd build plate contact point geometries, parts will still warp just because the brim may not be large enough or curved enough. In these unique cases, it may be necessary to CAD your own brim. What is suggested in these scenarios is to add thin, round “dots” to all of the corners of your part, which will provide more surface area contact with the build plate at key points where warping occurs.
- Print in a good orientation for 3D printing. The worst shapes to 3D print are shapes with larger cross sections as you go up, and shapes with sharp corners after long, straight segments. Try to get the largest face on the bottom because parts tend to warp as the cross section gets larger on top of stacked layers. Additionally, the more surface area you have contacting the build plate, the better, because a larger surface area will hold better.
- Use Fiber. This essentially forces the bottom layers to be flat, making it almost impossible for them to warp. If you’re doing this, however, remember to balance the composite by creating a sandwich of fiber at a top and bottom surface of your part to optimize for torsional strength.
- Use Onyx, if possible. Onyx does not deform nearly as much under heat. This means that it warps much less than our standard nylon, and creates much more dimensionally stable parts.