Cura Ironing: How to Smooth 3D Prints Top Layers

Ironing is a feature within slicing software, and it's easy to know its purpose, importance, and configuration. It enhances the visual appeal of your 3D prints, and you can typically find it in many popular slicers, such as Ultimaker Cura, Simplify3D, and PrusaSlicer. Today, we focus on how to use Cura ironing in 3D printing to achieve a smoother top layer surface. Cura is a powerful and free slicing software, and we've previously discussed many topics related to it, such as vase mode, scaling an STL file, fuzzy skin, tree supports and so on.

How Cura Ironing Works in 3D Printing

3D Printer Ironing

Just as its name implies, the way the nozzle works is similar to how an iron flattens clothes. Once Cura ironing is turned on, after finishing the final layer, the nozzle will use high temperature to smooth out surface wrinkles and bumps. The nozzle moves slowly back and forth over the top of the model and only pushes out a minimal amount of melted material, filling the gaps and holes. This process results in a smooth and polished top layer surface.

When Should I Use Ironing in 3D Printing?

3D Printer Top Layer Rough

(3D print with rough top layers.)

3D printing ironing works well for large-sized and flat-top parts to smooth out imperfections, saving a significant amount of post-processing time. However, it is not suitable for intricate geometries or curved surfaces. The ironing feature increases printing time since the nozzle moves extra slowly while fusing lines and smoothing the surface on the top layers. Additionally, if you do not adjust the Ironing settings properly in Cura, it may lead to clogs in the nozzle and extruder. So whether you need to use ironing depends on your preferences.

Pros of Cura ironing:

  • Smoothes top layer rough.
  • Suitable for flat and large surfaces.
  • Saves time for post-processing.

Cons of Cura ironing:

  • Increases printing time.
  • Not suitable for detailed and curved surfaces.
  • Might cause 3D printer clogs due to incorrect settings.

How to Enable Ironing in Cura

3D Print Ironing

(Cura 5.4 version.)

If your 3D model meets the requirements for ironing, you can enable it in Cura slicer. First, click on the three lines icon next to the search bar in 'Print settings', and select 'All'. This will display all available settings that can be configured. Then, there are two methods that allow you to easily activate it in Cura.

Method 1: Print settings window >> Top/Bottom >> Enable Ironing

Method 2: Use keywords in the print settings search bar, for example, 'iron'. Then, click the checkbox of 'Enable Ironing' to turn on it.

Best Cura Ironing Settings for 3D Printing

Cura Ironing Patterns

When you activate Cura ironing, there will be 7 settings that require slight adjustments. Below is an introduction to these settings:

1. Iron Only Highest Layer: Ironing is only performed on the topmost layer of the 3D print rather than on all flat surfaces. This it can save your time.

2. Ironing Pattern: When choosing the Concentric or Zig Zag pattern as the ironing pattern, the movement of the nozzle on the top surfaces differs. In the Concentric pattern, the nozzle rotates outward from the center. Meanwhile, the Zig Zag pattern is the nozzle moving from one end to the other.

3. Monotonic Ironing Order: When you select the 'Zig Zag' ironing pattern, this setting will appear. It refers to ironing the top in a single direction when printing adjacent lines, which results in a smoother and more consistent surface finish. This also requires more time.

4. Ironing Line Spacing: This controls the distance between each nozzle ironing path. Since there is a small gap between each ironed line, a smaller value for this parameter makes a smaller gap and a smoother result. Its default value in Cura is 0.1mm, which is enough for most surfaces.

5. Ironing Flow: It allows you to control the amount of material extruded by the nozzle during ironing to fill and fuse holes and crevices. If you notice over-extrusion or line scars on the top layer, you can reduce this percentage.

6. Ironing Inset: It is the distance between the internal ironing and the edges of the 3D print. If this value is set to 0, it means ironing the top all the way, including the edges. However, there might be excess filament flowing over the model's edges, due to the nozzle releasing internal pressure. This can result in jagged edges.

7. Ironing Speed: This can be easily understood; it refers to how fast it irons the top lines. It is recommended to use a lower speed to ensure the nozzle has enough time to melt and flatten the top surface. You can start with Cura's default speed, and if the result isn't satisfactory, reduce it to around 30%-40% of the normal printing speed. For instance, if the regular speed of the Anycubic Kobra 2 Pro is 300mm/s, it is advised to set the ironing speed to around 90-120mm/s.