DfAM: How to Reduce Support Removal Time for FDM

It’s no secret that Additive Manufacturing is a powerful tool, allowing engineers to create organic geometries and build parts in a completely unique process. One factor that enables these one-of-a-kind part builds is soluble support material. However, in an additive technology like Fused Deposition Modeling (FDM) soluble support material can increase build time, the material cost of the part, and the amount of time that must be dedicated to the post-processing support removal step.

When designing a part, it is always important to understand the process in which the part will be produced, and the case is no different with Additive Manufacturing. The classic approach to additive is very siloed, sectioning off designing, building, and post-printing as separate steps, with the latter usually left as an afterthought.

However, post-printing is an integral part of the overall additive workflow, so it is important for all three of these steps to be considered in order to effectively streamline production, and ultimately improve scalability. This article will take a deeper look at support removal and how your part orientation, support settings in the slicing software, and part design can affect support material usage and removal. Using these tips combined with PostProcess Technologies’ DECI or BASE Support Removal systems for FDM will decrease your overall part cycle time.

Figure 1

Part Orientation

Depending on the geometry of your part, orientation can play a huge role not only in the part’s strength but also in the amount of support material that is used during the print step. Below you’ll find a simple example of how orientation can affect the amount of support material required.

Figure 1 shows a L-bracket printed on its end, and Figure 2 shows the same L-bracket printed flat on its side. In the below screenshots from the GrabCAD Print software, the green represents the model material of the part while the orange represents the support material required to print the part in that orientation. As you can see in the example below, build time is reduced by about 58% and support material usage is reduced by about 91% just by changing the build orientation of your part. This translates to a shorter overall part cycle time, as well as a lower part cost for you.

Figure 2

To determine if you have effectively minimized the support material needed for a printed part, you can use slicing software like Stratasys’s GrabCAD Print or Insight (if you have a Stratasys FDM printer) to preview the build and estimate the amount of time and material required. If you use Insight, there is also an Automatic Orientation function that will allow you to select the “Minimize supports” method. By choosing this option, you will see a couple of different orientation alternatives to minimize your support material usage. It’s important to keep in mind that this method in Insight does not always work, but it should always be able to help you figure out if you are on the right track. Especially if you have a complicated part, this software component is ideal for showing you options to minimize your support material usage.

Slicing Software Support Settings

Figure 4

When you cannot alter or change the design of the part, there are still things you can do to help reduce the amount of required support material in your build. In Insight, for example, if you have a part as shown in Figure 4, you can change how much support material is used by altering the “Grow Support” setting. By default, the software is set at “Small only”. However, in some cases you can modify it to “No.” See Figure 5 and 6 for the before and after results (in this case, the red is model material and the gray is support material).

By changing this setting, you eliminate the support material that grows from the bottom of the feature (in this case a hole) to the build platform. In the end, it comes to about a 10-minute reduction in build time (6% overall reduction) and 0.141 inᶟ reduction in support material (15% overall reduction) for this single part.

Figure 5
Figure 6

Part Design

Figure 7

The final option for reducing support removal time is to be strategic with your part design by maximizing on the benefits of whatever print technology you are using. With FDM, you can take advantage of self-supporting angles and, in combination with your part orientation, reduce the amount of support material needed. In some cases, this can help to strengthen your printed part.

So, just what is a self-supporting angle, and how do you know what the value of that angle is? A self-supporting angle is the angle from a line parallel with the build platform, to the feature being supported (see Figure 7).

In general, the angle is 45⁰. With that said, any overhanging geometry that has an angle of less than 45⁰ will require support material. However, to get specific, the actual value is in the support settings in GrabCAD print, and if you are using a Stratasys printer, in Insight. The actual value will vary based on the printed model material and the slice height that the printer is set at. For example, on a Stratasys Fortus 450mc, loaded with ASA material and printing at a slice height of 0.010”, the part will have a self-supporting angle of 43⁰, whereas Nylon 12CF is 50⁰. So that angle could change slightly when changing materials and/or slice heights.

While designing a part to be printed on an FDM printer it’s essential to understand what orientation the part will be printed in, and where you may be able to utilize tricks like self-support angles in your part design. Remember, this will help reduce the support material needed and help make the support removal process that much faster. Below is a self-supporting example that will illustrate how effective this can be in saving printer build time, support material usage, and ultimately reducing the time it takes to remove the support material.

Figure 8
Figure 9

Just like with any tool, it takes time and practice to design parts that take advantage of what Additive Manufacturing can bring to your engineering or design teams. As you start to look at the lifecycle of designing, building, and post-printing, explore the product offerings of PostProcess Technologies, specifically the DECI and BASE systems as solutions for FDM. Both of these systems are built with our proprietary Volume Velocity Dispersion (VVD) technology, which has been developed specifically for additive manufacturing to remove support material more efficiently and streamline workflows overall.

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