Direct mold milling
Since summer 1999, a new technology for mold making has complemented the capacities of Direct Croning®. "Direct mold milling or Direct milling of the molding material" creates mold segments, whose size greatly extends the current building space of laser-sintering machinery. At present, at ACTech, there are two plants for mold segments up to an outer size of 2.4 meters. The manufacture of large-sized car body structures, which are executed, for example, as die-casting parts in later series production, or true-to-size casting blanks, that reduce the machining time for molds to a fraction, are only some examples of how to use this new technology.
Combinations for success
Even in this procedure, we dispense with the time- and cost-intensive fabrication of modeling equipment. The mold is directly milled in a molding material block. The size of the generated casting molds is only limited by both the mechanical strength of the molding material used and the available milling machine. Finally, the production of prototypes for sand casting only depends only on the available pouring capacity.
The potential of laser-sintering in combination with other manufacturing techniques makes it possible to fabricate not only large, but also very complex castings as prototypes or in small series in a short time and at low cost.
“Direct mold milling” – the procedure
The procedure to directly mill the molding material was developed at ACTech GmbH in order to also fabricate sand casting-molds of greater size. A Patent for the procedure was applied for under the title of “ Procedure and equipment for direct fabrication of a lost mold for metal castings ” in Germany in 1998 and Europe-wide in 1999. Additionally, a patent for the technology was applied for in Japan, the USA and Canada.
Further patents were granted for the development of new milling cutters for direct mold milling.
Characteristics
The procedure can be performed without drafting angles and rounding, and even undercuts may be produced to a limited extent. The accuracy of the mold segments milled amounts to within a few tenths of a millimeter.
The 5 axis-CNC-milling machines run at ACTech allow sizes up to 2,400 x 1,400 x 800 mm for an individual mold segment. However, it is also possible to build greater casting molds by cutting the required mold into segments. If specific dimensions of the casting blank are particularly significant for the entire function, then they can also be measured and, if necessary, corrected, during mold assembly.
Advantages
- Procedure can be done at low cost and quickly
- Any size casting molds can be built
- All materials usual for sand casting may be poured
- Commensurable results are available even at the test stage due to near-series dimensioning of the gate and feeder systems
- High accuracy
- Almost any contour is feasible in combination with laser-sintering of Croning®-molding material
Development
Self-engineered tools for high productivity in direct mold milling
CNC machining center of the type FZ 2000x1000
(GEISS)
(Years of manufacture: 1999 and 2003)
Technical data sheet “Annex 1.pdf” (German 75KB)
Technical data sheet “Annex_2.pdf” (German 79KB)
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