Rapid tooling
The term Rapid Tooling (German: rapid tooling) describes an application of additive manufacturing process for the production of tools (English tool ) or tool components in the tooling or mold , in particular of plastic injection tools .
The main reason for using an additive manufacturing process to manufacture a tool or tool insert is the possibility of integrating internal, conformal cooling channels into them. Such generatively manufactured tools or tool inserts are characterized by improved cooling performance compared to tools made from solid material. This results in reduced cycle times and improved component quality through reduced thermal distortion .
Combinations of conformal cooling and temperature control in one mold are also possible: At Miele, for example, both heated and cooled zones are integrated into the mold for the manufacture of vacuum cleaner tops. The medium should act as a conformal cooling at around 15 ° C, while at around 50 ° C it ensures the high-gloss look of the visible surfaces. One also speaks of a "thermal differentiation" in the tool.
This effect can also be increased by using parallel cooling in the tool insert: with parallel cooling, more coolant is brought to the cavity or the surface of the molded part than with simple, contoured cooling with a long cooling channel. With a long cooling duct, the cooling capacity decreases continuously with the distance. Furthermore, with parallel cooling, each cooling loop is supplied with fresh cooling medium, which results in more targeted cooling. The result is dynamic and even cooling. This increases the desired effect - in terms of part quality and cycle time reduction.
Temperature control medium
The linchpin is a clean cooling medium. One speaks of “inoculated water”, which is a chemical solution that circulates in a closed system and is free of particles, suspended matter or germs. A corrosion inhibitor in the pH range from 7.5 to 10 (Ferrofos 8579 from Kurita) is often common . The dispersant component of this medium prevents deposits on the pipe walls and thus guarantees the formation of an optimal corrosion protection film. This requirement arises from the cooling channels. They are sometimes very small in cross-section and it must be ensured that the channels do not clog.
Options for conformal temperature control
- Basis: temperature medium in a closed system with corrosion inhibitor
- Integration of mold inserts with conformal temperature control channels
- Optional heat dissipation and supply
- Close to the contour distance to the cavity at approx. 2-3 mm
- Less warpage, sink marks and rejects
- Cycle time reduction of 10 to 30%
Individual evidence
- ^ Online Kunststoffe 10/2011, Carl-Hanser-Verlag, Munich , 2011, pages 157–159