Mark Technical Ceramics
Temperature-resistant marking of ceramic green bodies - CerTrace®
Why do you need temperature-resistant marking of ceramic green parts?
What does CerTrace® stand for?
WZR uses word marks to indicate the different topics WZR is dealing with. Besides CerPrint (3D printing of ceramics), CerCoat® (ceramic coatings) or CerChek® (testing and evaluation of ceramics), the term CerTrace® was chosen for the temperature-resistant marking of ceramics. For this purpose, WZR has developed special inks that are applied to green bodies and are still very clearly visible after the sintering process.
Which ceramics can be labeled with CerTrace®?
We could gain positive experience with the following points:
- Structural ceramics based on Al2O3
- Structural ceramics based on ZrO2 (Y-TZP)
- Refractory ceramics
- Ceramic shells for investment casting
How can ceramic green bodies be labeled?
Basically, a distinction must be made between manual and machine marking. We have developed inks that can be written on the green body very easily with a pen. This type is particularly suitable for marking samples or specimens, mostly in the laboratory.
In order to mark serial products, an automated marking is much more reasonable. For this purpose, printers that print an ink on the surface are suitable. There are two different printing principles: Drop on Demand (DoD) and Continuous Inkjet (CIJ).
What are the possibilities for automated marking of ceramic green bodies?
In principle, both DoD and CIJ printers can be used for marking green parts. For this purpose, we, at WZR, have developed inks for both printing systems, since there are ceramic components for both types of printers which require the respective technology.
In industrial use, the printers must be integrated into the production process. For this purpose, the connection to the database of the process control is important in order to print the correct marking. It is important to decide whether the marking is printed in plain text or as a code (bar code or data matrix code). This includes the decision how much data should be stored in the label:
- With plain text an alphanumeric character can be printed, in connection with a database production data can be assigned (e.g. “Product 4.213, Batch 9445, #443”)
- With a barcode / barcode it is possible to read the labeling automatically, the best known example is the supermarket checkout. A relatively small number of characters is stored, which in turn, in conjunction with a database, make information about the production process available
- A data matrix code can be used to encrypt a much larger amount of information, so that information about the component can also be stored directly in the code. The QR code is widely used to make Internet pages directly accessible for a cell phone
How do drop-on-demand (DoD) printers differ from continuous inkjet printers? (CIJ)
DoD printers for processing ceramic inks typically use piezo print heads, which have a large number of individual nozzles that can be individually controlled. This is where the name comes from: Drops are generated on demand and shot onto the surface. Here, it is necessary that the distance between the print head and the surface to be marked is in the range of approx. 5mm and is kept constant within narrow limits. If this can be guaranteed, the print image is very sharp, a resolution of 600x600dpi can be used.
CIJ printers work fundamentally different: the ink is sprayed continuously (“continuous”) in a jet. This jet is deflected in such a way that individual drops produce the print image. On closer inspection, these drops can be seen in the print image. The greater the distance between the print head and the surface and the faster the printing speed, the more this effect becomes visible. Basically, the print image is less detailed compared to DoD printers. However, the distance between the print head and the surface can vary greatly without the print quality deteriorating significantly. In addition, the print heads are much more robust compared to DoD print heads, which is why CIJ printers have become particularly popular in industrial environments where dust accumulates.