By Benjamin Becker |Jan.14, 2013

Today's current 3D printed ceramics have several factors which can limit the design of ceramic components. Some of the typical constraints of 3D printed ceramics are:

  • Minimum and Maximum Bounding Box (build envelope of the component

  • Objects must have a flat base

  • Minimum Material Drain Hole

  • Minimum Wall Thickness

  • Minimum Component Density

  • Maximum Overhang Allowances

  • Unsupported Struts (Columns)

  • Objects within Objects

  • Objects must have glaze applied

  • Objects are not suitable for high temperature applications ( > 1000F / 540C)

  • Large sections must be located lower in the model

  • Fabrication time of 3 to 4 weeks

Minimum and Maximum Bounding Box

With the current capabilities of 3D printed ceramics there is the minimum and maximum bounding box constraint (component size) that applies. These minimum and maximum component sizes can hinder the design of a component and require expensive processing such as bonding of the ceramics (in the case of larger parts) or the impossibility of fabricating the part. With current commercial capabilities typical minimum size for components must be no less than 120mm (x + y + z ), with a minimum wall thickness of 3mm. A component's size is limited to a maximum of 400mm, along with the minimum 6mm wall thickness requirement.

In comparison, the latest 3D printed ceramics breakthrough allow for component sizes as small as 38mm (x + y + z), with a minimum wall thickness of 1mm. The largest un-bonded part that can be produced is still being evaluated but parts as large as 1500mm, with a minimum wall thickness of 3mm are possible.

Objects Must Have a Flat Base

Due to the nature of fabrication technologies surrounding 3D printed ceramics, components must have a flat surface to rest on during the fabrication process. This is another limited factor which could cause a designer to sacrifice original design intent, or for an artist to compromise on their vision. Components that are long and slender are nearly impossible, and entirely round parts are something the designer cannot consider.

With the newest 3D printed ceramic fabrication methods, the designer or artist no longer has to sacrifice their vision. Components can have as many rounded and slender geometries as required without needing to consider what works best for a machine's needs. Spheres, Spiral-Shapes, Crescents, and Ovals are just a few of the geometric shapes that are now possible.

Minimum Material Drain Hole

One drawback of current 3D printed ceramics is the requirement that a drain hole be present on a hollow component for the ceramic building material to exit after fabrication. In many design situations this hole may be difficult to place, once again causing the designer to sacrifice by changing or completely removing feature(s).

Unless the object is a complete sphere, no drain holes would be required for the new ceramic 3D printing process. Complete spheres would require a minimum 5mm support hole depending on the size.

Minimum Wall Thickness

Using current technology, minimum wall thicknesses are required for 3D printed ceramics due to the structural requirements during the printing operation. Objects must be self-supporting to allow for handling post-print. As the object becomes larger, the minimum wall thickness also increases. The object can become unnecessarily thick because of the minimum wall thickness restrictions imposed on a design in order to minimize breakage of the object pre-firing.

While wall thickness restrictions do exist, the imposed requirements are drastically reduced. Minimum wall thicknesses can be as little as 1mm, and accommodate thicknesses up to 25mm depending on the geometry of the part and its application.

Minimum Object Density

Currently the designer has to be concerned not only with the design intent of an object, but also with the structural integrity of the object pre-firing (i.e. its "green" state). Manufacturers recommend a minimum 5% object density, which is determined by the object's material content and the total space consumed by the object. Once again the design is limited by what is structurally required to manufacture the object instead of only design intent.

Advances in ceramic 3D printing technology allows for a lower object density (around 2 %). This lower density requirement stems from the minimum wall thickness being approximately 1mm depending on the design, and the process by which the object is fired.

Maximum Overhang Allowances

Objects that have overhangs, such as those with "T" shapes, may encounter manufacturing issues because of the structural requirements of a 3D printed ceramics. When the object is handled in its green state, the ceramic particles are smashed together, much like wet sand, and can easily be broken apart. Large overhangs will break apart from the base, which makes the object impossible to fabricate reliably. Another alternative with objects that have large overhangs is to fabricate two pieces separately and bond them post-print. Although this is a viable alternative, there is added cost and reduced part strength.

The requirements using the latest ceramic 3D printing process allows for virtually any amount of overhang on a part. There is no need to build your model as if it were a sandcastle in order to meet manufacturing requirements.

Unsupported Struts (Columns)

Traditional ceramic 3D printing suggests unsupported struts or columns greater than 20mm in length are not recommended. Struts longer than 20mm can collapse during fabrication due to the lack of support during the green state, once again limiting the designer's intent. This essentially makes long and slender pieces impossible to create.

Developments in the ceramic 3D printing process allows for many geometries currently limited by a machine's manufacturing capabilities. Long, slender columns supporting larger objects are allowed. Keep in mind that internal stresses may cause the part to be weak, which could result in breakage.

Objects Within Objects

Some limitations that are present with current 3D printed ceramics exist with most any ceramic manufacturing method such as objects within objects (ex: ball within a whistle). This situation leads to either a two-piece design where the whistle body is split into two halves, or a different material choice which may not suit the application.

Objects Must Have Glaze Applied

Many 3D printed ceramics require the application of glaze on the object. Some users prefer ceramic objects without the glaze either for cost savings, or to allow for end-user application of the object's finish.

New 3D printed ceramic manufacture allows for objects to be supplied to the customer without the application of glaze. If the glaze is not requested by the end-user, the ceramic object cannot be approved as safe for contact with food.

Objects are not suitable for high temperature applications ( > 1000F / 540C)

Current 3D printing ceramic technology limits the object's environmental temperature to approximately 1000 F / 540C. After this temperature, the ceramic material begins to deform and mechanical failure can result after a short period of time.

Using high quality materials such as high alumina technical ceramics, the latest ceramic 3D printing process allows for the ceramic object to be exposed to temperatures of 3000 F without deformation and minimal degradation of mechanical properties. This allows for a much wider range of temperatures in demanding thermal applications.

(Image credit: M.A. Ganter | Open3DP)

Large Sections Must be Lower in Model

Large sections of a model must be located in the lower portion of the object near the base in order to be fabricated. With current ceramic 3D printing, issues arise if larger (and ultimately heavier) sections of the model rest above a smaller section (think box on top of a pole). During fabrication the box would cause the pole to break due to the lack of strength of ceramics in their green state.

The latest ceramic 3D printing technology allows for objects to have larger sections above smaller and more slender bases. This is possible due to the unique dispensing and molding techniques.

Lead Time of 3 to 4 Weeks

Ceramic 3D printing vendors have lead times typical of 4 weeks or more. In today's fast-paced world, more time spent waiting for a part could lead to lost opportunities and ultimately revenue. Other technologies claim micron layer thicknesses, but fail to disclose that the fabrication process will often take days to complete at this fine of a resolution.

With recent developments in ceramic 3D printing technology, standard lead times are now as little as 7-10 business days. Expedite service is available which can reduce the lead time to 5 business days. The reduced lead time can help get your latest design out the door faster and into the customer's hands.

 

 

 

 

 

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Posted in 3D Printing Technology

 

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Christian B. wrote at 1/21/2014 7:45:44 PM:

Currently all of the 3D print services I've found have the x+y+z=400mm maximum limitation. Does anyone know of a commercial printer (like Shapeways, Sculpteo, I-Marialise or Ponoko) which can print larger ceramic pieces? Thanks!

Jianhui Hong wrote at 6/30/2013 4:57:44 AM:

Benjamin, I would like to talk to you about making high temp burner parts. Could you send me an email to jhong@webster-engineering.com. Thanks, Jianhui

Daniel wrote at 5/22/2013 2:31:06 AM:

Dear Benjamin Nice information. Could you let me know if you have some experience in medicla parts? Thank you

Benjamin Becker wrote at 2/28/2013 2:44:11 AM:

The lowest temperature we have exposed the ceramics to is 0 deg. F. We have never tested the use of these ceramics in very low temperatures, and this could present a problem in terms of internal stresses in the ceramic part. Please contact me at benjamin.becker@hotendworks.com and we can discuss your application in more depth to determine feasibility.

Eva wrote at 2/25/2013 1:06:17 AM:

Would you happen to know what the minimum temperature is that the ceramics can withstand? (liquid nitrogen application)

M.A. Ganter wrote at 1/14/2013 7:04:27 PM:

nice image taken from Open3DP w/o credit. I took that pic and it is student work from the Univ. of WA.



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