Porcelain is an ancient technology that has been transformed by modern machinery and 3D printing. Designs once impossible to create by hand are now possible using 3D printers. At Shapeways, we launched our very own porcelain process in 2014 that uses your 3D design file to print a mold and cast using our own porcelain material.
As expected with all new technologies, there are limitations. To understand how to optimally design for 3D printed porcelain, it is important to understand the production process as well as the caveats of the material. Read on to learn about each stage of production and find tips on how to design in porcelain to make your finished objects just right.
How is 3D printed porcelain created?
1. 3D printing engineers check your design
Once you place your order, your model file is sent over to our 3D printing engineers who specialize in porcelain. They inspect the model to ensure that the mold of the design can be printed and continue through the production process.
2. The mold is generated and printed
We have developed software that generates a mold of your 3D file. You can imagine the mold as a shell or the negative space of your design. We will also generate a small funnel that will be used to cast your product.
3. The mold is cut and cleaned
Once the model is taken out of the printer, it must be cleaned of all residual support material. In order to completely clear out all of the material, the mold must be cut to reach the interior. Imagine the mold as the “skin” of your model or the negative space. The mold and overall design must be able to hold together in order to eventually cast in porcelain.
4. The mold is reassembled
After the mold has been cleaned out, it must be glued back together in order to cast. This creates a seam where the model has been cut and glued. However, this will later be sanded and repaired by hand.
The exterior funnel will be glued to the mold for the next step in the process, casting.
5. Porcelain is cast in the mold
The porcelain material is poured into the mold through the exterior funnel. The porcelain material within the mold will settle and harden.
6. The mold is removed
Once the porcelain is fully hardened, the mold will be removed and the porcelain model will remain.
7. Model goes into first firing
Immediately after the mold has been removed, the design goes into the kiln for its first firing. This hardens the design so that the model may be repaired and glazed.
8. Model is repaired and hand finished
With the first firing complete, the model is strong enough to repair. There are a few types of repairs that may be performed. First, the porcelain team uses a variety of tools to carefully remove the seam lines left by the mold. Second, if the porcelain has not reached all ends of the mold or has generated any air pockets, these minor imperfections will be patched and repaired by hand.
9. Model goes into second firing
If your model needed to be patched, the product will go in for a second firing. This cycle of repairs and firings can happen a few times in order to get your design just right.
10. Product is glazed
Your design will be hand dipped in a liquid glaze. Any excess glaze on the base of the design will be wiped away in order to avoid the glaze from sticking to the kiln.
11. Glaze firing
Once the base has been wiped clean, the model enters the kiln for the glaze firing. This will solidify the food-safe coating of glaze on the design. In some cases, the model may need to be re-glazed and fired due to unpredictable surface issues, such as small pin holes or patches that were not glazed fully. A re-glaze may cause pooling of glaze on the model.
12. Finished model
The model is then packaged carefully and sent to the distribution center to be shipped off to you.
What do you need to consider before designing in porcelain?
There are two aspects of porcelain to consider before you begin to design your product. First, the glaze that will coat your design. Second, the properties of the production process.
During the glazing process, your model is dipped in the thick glaze liquid. Excess glaze drips off and the base is cleaned so that it may rest on the kiln shelf without fusing to the bottom. While the model is in the kiln the glaze becomes molten. After cooling, the result is a stronger, hardened layer of colored food-safe glass.
FIT AND HOLE CLEARANCE
Our glazes run a thickness of 1 to 2 mm. This means that if precise fit and unobstructed holes are important to your model, ensure you have left at least 2 millimeters of clearance on EVERY wall.
In the image below you can see two differently sized holes. The hole on the left is larger than 5 mm wide. This will allow the glaze to coat the inside without closing the hole. The hole on the right displays a 4 mm hole, the glaze will completely obstruct this hole eliminating the ability for clearance.
UNOBSTRUCTED HOLE OBSTRUCTED HOLE
The same logic applies for lids that fit onto containers. The lid should account for the glaze that will be applied as well as the container itself. Meaning, your design should have at least 4 mm of space between the lid and the container.
Details of a design can get lost under a layer of glaze. It is necessary to consider the depth, height, and width of the detail of before submitting your design. On our porcelain material page, we recommend a minimum of 1 mm height and width of detail. If you are aiming for sharp details, consider making them greater than this minimum.
We have published a previous post depicting examples of details after being glazed in each of our color options. As mentioned, each color has a slight variation of thickness. For the clearest text or imagery, please ensure you accommodate for the glaze.
Adding feet to your standing designs are useful for avoiding fully unglazed bases. While designing these decorative and useful features, there are couple aspects to keep in mind:
The height of the feet should be greater than the thickness of the glaze. Otherwise, the base will be required to go unglazed.
Long spindly feet can break during casting. Please ensure that the height and thickness of the feet are comparable or that the thickness can allow for the feet to fully cast
ROUND vs. SHARP EDGES
Sharp edges and rounded edges will affect how the glaze rests on the model after firing. In the images below, you can see how a sharp edge will split the glaze whereas a rounded edge will allow the glaze to roll over the edge. One is not better than the other; they are merely aesthetically different.
All models must be able to stand on their own, as they will be fired with other models in a single kiln. At this time stilts and supports are not included in the production process. This means that the model must have a base or feet to rest on. With designer-selected orientation, you have the power to determine which side of the model goes unglazed and rests on the kiln during the firing process.
During the upload process, a render is provided to select the top and bottom of your design. Arrows may be selected to rotate the design in the proper orientation. Top and bottom indicators are located on the render image. NOTE: The orientation in the render will be the orientation in production.
The bounding box for porcelain states the limits of how large or small your design can be. These limits are important to consider before taking the time to completely design your item.
Minimum: 40 × 40 × 10 mm
Maximum: 125 × 125 × 200 mm
WALL AND WIRE THICKNESS
In order for a model to cast completely and reach the very edges of the design, walls and wires must be thick enough for the comparable length.
The smaller the model or shorter the wire, the thinner it may be. This is demonstrated in the image below. If the model is 2 mm thin and very short, it is easier for the porcelain to make it to the end of the mold. Otherwise, if the design is long and thin, it is nearly impossible for the porcelain to fill the mold completely.
With extremely thin wires, holes, and walls, cleaning out the mold by hand can cause breaks with insufficient thickness. So it is especially important to consider making these features larger than 3 mm for the best result. This does not increase pricing greatly as porcelain is priced by surface area. Adding thickness does not increase price as it does with other materials.
Elevate your porcelain ideas by using these tips and techniques. Let those details shine through and make sure your design glides through the production process. Once you’ve printed your design, you can begin selling on the Shapeways marketplace!