One of the most pleasing aspects of 3D printing is changing a fundament rule of manufacturing. Using 3D printing to make soluble cores and tooling makes the process easier, faster and more cost effective. Soluble cores for composites does exactly that by using a 3D print of soluble support material to form a core/mandrel/layup form that can be dissolved in water; the complex becomes now simple and fast. Here’s is how it is done.
First create a CAD file of your tooling or form. It is natural to want to do the part rather than the tooling but remember that you are 3D printing the tool, not the part. Be sure and build in any features or details for the tool that you need to be incorporated into the finished part such as fasteners, gaps or hooks or fittings.
Next, if building the tool on the Stratasys 3D printer, go to the preferences on the modeler configuration. Select invert build materials, select yes and then clink on the green checkbox.
That will build the part in support materials, which will in turn dissolve in the support removal bath that is standard on our clean stations.
For core builds where you are using the soluble support as the build, a general guideline from the Stratasys technical guidelines includes the following notations:
SR-30 (used with most of the ABS materials) is recommended for soluble core applications. SR-30 For lower temperature curing below 93 °C (200 °F), SR-30 is capable of producing nearly any geometry and should be used unless higher temperatures are necessary. SR-100 (used with PC as an example as support for builds, ) can be used for soluble core used at higher curing temperatures above 121 °C (250 °F), SR-100 may be an option. However, part geometry is limited and guidelines for acceptable part designs are currently not available. High temperature applications are not suitable for soluble core use, and alternatives in FDM materials can be utilized. (Call me at 866-499-7500 for how to use Ultem as a sacrificial core material in high temp situations as an example.)
When using the SR-10, building the layers so that material usage is decreased and the core dissolves faster is a good method of increasing output of demolded parts. Decreasing the amount of material in the core build so that it dissolves faster is most efficient, and can be assisted by selecting a layer resolution that is coarser and using sparse build. At the same time, the core must maintain structural integrity while exposed to lay up/winding and curing. To achieve this sparse but sound structure, use a modified Sparse – double dense Part interior style (Modeler > Setup… > Part interior style > Sparse – double dense) so that liquid flow thru the completed part with core areas will assist with quick dissolving of the core materials. Additional steps such as removing the “endcaps” on the core biuild will also assist in liquid flow thru the core and decrease the time needed to dissolve the core.
For more details on how to configer for best build, do the solid outer skin removal and to get expert help with your application, contact us at firstname.lastname@example.org or call 866-499-7500 and ask for Barbara. Additionally we host several webinars on soluble core applications throughout the year – make sure you register for the next one coming up.