Assigning Multiple Materials When 3D Printing a Part in GrabCAD Print

With many 3D printing technologies on the market, only one reigns supreme when it comes to building parts with multiple materials at one time – Stratasys PolyJet. We find that many people get very excited about multi-material printing (and rightfully so), but they seem to quickly get intimidated by the process (NOT rightfully so). In this article, I want to show how easy it is to work with multi-material builds by applying multiple materials using Stratasys PolyJet printers. Spoiler alert – it is just as easy as FDM.

To set the backdrop to this topic, Stratasys has revamped its line of PolyJet printers which involved expanding the capabilities of their printers including making the multi-material capabilities more accessible to a wider range of users. This was done by increasing the number of materials that can be printed on machines like the J8 series line of 3D printers. There was also the introduction of the J55 Prime, a full-color, 5-material, office-friendly PolyJet machine.  Stratasys also released the J35 Pro, a 3-material stablemate to the J55 Prime which dropped the cost of entry into multi-material printing. Because of these newer developments, I wanted to put together a short overview of how to assign material properties to parts within Stratasys’s PolyJet software – GrabCAD Print.

How Multi-Material PolyJet Works

Before jumping into how to set up multi-material parts, and in hopes of not oversimplifying a very amazing series of technical achievements, I will attempt to summarize in one paragraph the very complex subject of how PolyJet technically works to produce multi-material parts. PolyJet works like a run-of-the-mill color inkjet photo printer, but instead of ink, PolyJet technology sprays highly controlled tiny droplets of plastic resins to print a 2D image. This 2D image (or slice as we call it) is not printed on paper like a photo printer but instead printed on a build plate. After the slice is printed, it is exposed to a UV lamp that converts the liquid resin into a solidified plastic as opposed to the ink air drying on paper.

The next image, or slice, is printed directly on top of the last image, or slice, with the UV lamp catalyzing the resin layers and bonding the two layers together. This is repeated many times to build thickness to the part resulting in a three-dimensional object. The controlled deposition of these droplets (up to 360,000 drops per square inch) allows for the precise blending of resins with different properties ranging from color, durometer, and transparency to alter the characteristics of the part being printed. This allows for the simultaneous production of multiple parts with multiple materials at one time or printing a single part with multiple properties with full-color textures, overmolds and varying transparencies.

Applying Material Properties in GrabCAD Print

Now that we have a baseline on how PolyJet can develop parts from a mixture of materials, let’s look at how we assign these materials in the software. Don’t worry, it is far easier to do this than understanding my previous paragraph.

Full Color from SOLIDWORKS
(J5, J7, or J8 series)

Set your colors in SOLIDWORKS by applying color to the body or to the face. Save your SOLIDWORKS file. Next, ensure your printer is loaded with the following materials VeroWhite, VeroCyanVivid, VeroMagentaVivid, and VeroYellowVivid. Open your SOLIDWORKS file in GrabCAD Print and you are done. See, I said it would be easy. One thing to note, if you’re using a J35 Pro, the J35 opens a colored part while having VeroBlack and VeroWhite loaded, it will convert the colored part to grayscale.

Grayscale from SOLIDWORKS
(Connex3, J3, J5, J7, J8 series)

Set your grayscale colors in SOLIDWORKS by applying color to the body, or face, before saving the file. Ensure your printer is loaded with the following materials VeroWhite and VeroBlack before opening your SOLIDWORKS file in GrabCAD Print. In GrabCAD Print, you should see on-screen exactly what the part looked like in SOLIDWORKS.

Here is a video blog on using the Split Line command to make logos and adding text on parts that you can apply colors to.

Changing Color Using the Color Picker
(J5, J7, or J8 series – J35 Pro Grayscale only)

With a “color loadout” in the printer (Cyan, Yellow, Magenta, and White), it is easy to adjust the color of the parts using the Color Picker. Simply move the adjustment sliders to present different hues (colors), values (light or dark), and saturation (vibrancy) of the color you want. This is a very intuitive process and allows for quickly manipulating the color of rigid parts. The same is true for grayscale if you have Black and White loaded in the 3D printer, you can use the Grayscale dropdown rather than the Color Picker option.

Applying Transparency Using the Color Picker
(J3, J5, J7, J8 series)

Just like choosing colors for parts, if you have a clear material loaded in the 3D printer, you can also gain access to a slider for Transparency in the Color Picker (or Grayscale dropdown if only using Black and White). Simply adjust the slider to increase the transparency of the part. You can also apply a color to the part to add a transparent hue.

Changing Durometer Using the Color Picker
(J3, J5, J7, J8 series)

Another use of the Color Picker dropdown (or the Grayscale dropdown if working with black and white), is when you are working with a clear or white rubberized material, you can utilize the Shore-A Level slider to adjust the durometer of the part, note that because the rubberized material is either clear or white it will affect the color of the part the softer the durometer that is chosen.

Changing Durometer Using Digital Materials
(Connex3, J3, J5, J7, J8 series)

It is also possible to change the durometer of a part by using the Digital Materials drop-down option. This allows the user to select specific materials that they wish to blend. When compatible materials have been selected a series of available blends are presented. Hovering over the blends will enable a pop-up window that gives information about the material properties of the blend. It is important to note that the color representations (grayscale in the image below) are not representative of the color of the print but are graphically shown in a graduated scale to indicate a variation in properties. Digital materials can be used to create specific blends for color, transparency, and durometer.

Improving Impact Resistance using Digital Materials
(Connex3, J3, J5, J7, J8 series)

Another ability to use rubberized materials in Digital Material blends is that some combinations will allow for materials labeled as “PP-Like”. This means the blended material exhibits impact properties similar to polypropylene – making these PP-Like blends great for snap fits and items that may require additional flexibility.

While I have not covered all the methods to apply multiple materials and material properties in GrabCAD Print, I hope I have at least shown enough to take the mystery out of setting up parts for multi-material PolyJet printing. If you have additional questions or want to learn more about PolyJet or GrabCAD Print, please feel free to reach out to TriMech’s 3D Printing Team.