High Shear Compaction™
RTI’s sheet fabricating technology is centered on a proprietary process called High Shear Compaction™ (HSC™) which can be used to create films or sheets of virtually any metal, glass, ceramic, or plastic powder. To our knowledge there is no other system comparable to this type of sheet production method.
This process was invented my Mr. Randall C. Ragan. Ragan was awarded the 1992 American Ceramic Society Samuel Geijsbeeck Award in recognition of his efforts leading to developments of singular significance to the ceramic industry. In 1998 he was awarded the IMAPS John A. Wagnon, Jr. Technical Achievement Award.
In terms of today’s technology, HSC™ permits a much wider range of sheet thickness and higher green density than has ever been available with a tape forming process. Conversely, if desired, controlled porosity, low-density sheet stock can also be produced.
Although the system is compatible with organic solvent systems, specially formulated water-based binders are most commonly used. Clean up is simple compared to organic solvents, EPA problems are avoided, and water is the lowest cost solvent system.
Process compatibility is excellent with all types of ceramic materials. Porous tapes have been produced from hundreds of types of materials including alumina, aluminum nitride, ferrites, glass, metal, and organic powders.
Sheets have been successfully produced in thicknesses from 125 microns (0.0049″) to as great as 1.25 centimeters (0.492″). As a result, the process is adaptable to practically any substrate thickness.
Control of the thickness is excellent with tolerances of +/-5 microns being typical.
The binders and the powders are dispersed very well and cannot settle. The resulting dense tapes are isotropic through the width and right up to the edges. The ceramic tapes therefore fire flat. With proper sintering practices the tapes will form to the shape of the setter and will not warp or bow.
Shrinkage can be less than any other film or sheet-forming processes due to tighter green particle packing, resulting in a higher fired density of ceramic and metal articles. Shrinkage upon firing is very repeatable; more so than with doctor blade tape casting, therefore accurate fired dimension control is possible. In fact, one client intentionally varied the green density to adjust for lot-to-lot raw material variations and is thereby able to control shrinkage upon firing so that his hard punching tools need not be changed.
Production rates depend on the sizing of the machinery. The typical rate of production is 30 centimeters per minute (1 ft./min.) but can be up to about 200 centimeters per minute (6.6 ft./min). The width of the tape does not affect the production rate. Cast tape widths from a few inches to over one meter (39 in.) are possible.
Surface finish of the ceramic tape is controlled. Both sides of the tape can be very fine, or different custom finishes can be created on each side.
The installed prime cost is lower than any other known process. The system can be easily run by two technicians with constant quality, as the system is self-regulating. No manual in-process adjustments are required to maintain the quality of the cast tape being produced.
Highly efficient, the system is capable of producing more than 200,000 square meters of ceramic tape per year, with one shift per day operation. The system is scalable from a laboratory size system to very high volume production to ensure the optimum utilization.