Over the last several years, 3D printing has become the go-to way to prototype and test designs inexpensively and quickly. 3D printing is not only quick, but it enables creating models with complex shapes very easily compared to other model making techniques. It has created a simple and quick way to transform a computer model into a real-life object in-house, in a matter of hours or even minutes. One of the major advantages of 3D printing is its relatively inexpensive cost and speed, but printing with plastic isn’t always ideal for a purpose — especially when that part is going to be taking a beating. To get the best of both worlds, you can use 3D printing to cast metal parts and get your metal part quickly and inexpensively.
The first step in this process is to create or identify a 3D computer model of the object that will be cast. This can be done by either designing your part in CAD (computer aided design) software or by simply downloading it online (one of our favorite sources is Thingverse). Now that you know what you’re going to make, the next step is to get the part printed out using a 3D printer. I recommend that you use PLA and not another plastic such as ABS because PLA is non-toxic and how well it melts away when making the sand mold. If you don’t already have access to a 3d printer you can easily use an online service like Shapeways, who will send you the part within a couple of days. Next comes the fun part of casting the part.
The next steps are difficult to explain without visuals so here’s an Instructables article by user Haus Page that delves much further into this process. In his article, he writes about a couple ways to create molds. The first technique demonstrates how to create a simple mold on a flat surface. This is ideal for a cast that’s flat and doesn’t need detail on one of its sides. In the second technique, Page illustrates what to do for more complex parts. This is where printing in PLA comes in particularly handy. This method is similar to how jewelers cast jewelry.
After building the mold, the part is melted away inside of the mold using an oven. The intense heat melts the PLA right out and the mold quickly takes the shape of the 3D printed part Next you melt down the metal with the help of a kiln or a furnace. The liquid metal is poured into the mold and after some clean up and cooling the part is complete.
Now that your 3D printed part has gone from plastic to your choice of metal, what are the drawbacks of doing this? First, any blemishes from the print will show up on the surface of the cast, typically the layer lines or anything else that wasn’t cleaned up perfectly on the part. Of course, some minor details may also be lost depending on the resolution of the sand that was used for the mold, but that is rarely very noticeable. If that doesn’t deter you then give it a shot and unleash even more ability out of 3D printing. If you’re interested in learning more, Adam Savage, of MythBusters fame, visited Artisan’s Asylum in Somerville, MA (not far from our office) to interview and walk through this exact process on his Tested YouTube channel. Check out their video below if you’re looking for more exposure to using 3d printing to cast metal parts or just want to watch an interesting and educational video!