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The Value of Castings

Posted on May 23, 2018 by Cullen Hikene

Last month, we announced the formal launch of our ProdEX casting service. If you primarily know 3Diligent as a 3D printing service provider, you may be curious to know a bit more about castings and how our services might be useful to you and your future projects and programs.

What is casting?

For the uninitiated, casting is the process of pouring liquid material into a mold, then letting it solidify in the mold. Once solidified, the solid part can be removed from the mold and finished as necessary. Castings can be done with a variety of materials. Some of the oldest examples of castings were in metal—you can see examples dating back to the bronze age, but if this is a bronze age technology, what on earth is it doing as part of a digital-fabrication service?

Well, what has changed the game are advancements in material science and the arrival of high fidelity 3D printing.

Material Science

First, let’s talk about material science. While it’s true metals have been cast for a long time, it’s only recently a wave of new materials have become available. Most notable among these are polyurethane resins. Polyurethane is castable at room temperature, which is why you will sometimes see polyurethane casting referred to as RTV casting—Room Temperature Vulcanization. Two parts are mixed together and within a matter of minutes or hours, the liquid solidifies.  There is an incredible range of material properties now possible through casting. Among these are high-temperature resins, food-grade resins, and clear resins. Moreover, polyurethanes are available in a broad range of shore values from the highly pliable to very stiff. Beyond the scope of polyurethane, which is a continually evolving technology, casting is also available for silicone and metal, as it has been for some time.

While material science has allowed casting to become a viable solution for applications it previously was not, this certainly doesn’t tell the whole story as to how casting has become a key technology in the digital-manufacturing space.  That is explained by 3D printing.

3D Printing’s Role in Castings

3D printing, as you may be aware, is the process of taking a CAD file and building a part up, layer by layer (in an additive fashion), until the geometry is complete. The process is capable of processing extraordinarily complex geometries with more or less the same efficiency and ease as it does simple shapes, which makes it a fantastic solution for rapid iteration on complex, organic geometries. The shortcoming of 3D printing is layer-wise fabrication can take a lot of time and the materials 3D printers consume can be quite expensive. As a result, scaling up production with a 3D printer can sometimes prove quite costly from a time and money standpoint. That’s where a happy partnership with casting has been established. There are two ways 3D printing and casting tend to go hand in hand.

The first is in support of the lost wax or investment casting process. In this process, a master or pattern part can be 3D printed. From there, liquid silicone rubber or a ceramic slurry is poured around the part. Once the silicone or ceramic material sets, the master pattern is removed from the mold (either by being cut out of the silicone or melted in a furnace to drip out of the ceramic mold). Either approach leaves a perfectly defined negative space for casting.  From there, the right urethane or metal for the application can be poured into the void.

The second is directly printing a mold. In this approach, one of our 3D printing technologies either fabricates a resin, plastic, or sand mold from the ground up. By printing in these materials, additional material options are made available for pouring into the negative space of the mold. Notable among these is silicone, which can sometimes be difficult to cast in silicone molds. Additionally, this approach can provide a good pathway to larger-scale castings in metal.

The Value of Castings

In sum, casting is an old process made new by recent advancements in material science and the remarkable capabilities of 3D printing. From a practical standpoint, it commonly provides a cost-effective bridge to large-scale production using injection molding or die casting, for instance. It also offers significant speed benefits. Whereas a bulky part may prove time consuming and expensive to 3D print, casting may provide significant savings in terms of cash and time.  In this way, it’s a fantastic technology that provides a perfect complement to our range of offerings.

As you can tell, we are very excited to be offering casting to our customers as part of our comprehensive range of digital-manufacturing technologies. If you have a project or program you think could be a fit, please log into your 3Diligent ProdEX account and submit an RFQ, specifying either molding/casting or Let Vendor Choose as your process.

We are excited to review, quote, and execute your program!

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