Taking a new approach to textured stone materials, North Carolina Granite Corp. has invested in an innovative machine from Pellegrini of Italy. The unit, which is called the Water Storm-Master, can provide a unique waterjet-textured surface, and it can also provide traditional finishes such as flamed, bushhammered and sandblasted.

The machine uses a high-pressure waterjet directed at the surface, which produces cavities of variable depth. The level of texture depends on the structure and composition of the material being processed, and the process can be used on thicker slabs as well as thin stones, since the structure of the treated material does not suffer any loss of strength from the process, Pellegrini reports.

The working head has a nozzle system with six orifices, and the number of orifices in use can be adjusted as needed depending on the desired texture or the hardness of the material being processed. Additionally, the texture can vary based on the slab feed speed.

North Carolina Granite Corp. was one of the first companies to invest in this new technology, and company CEO Bob Ferris described the unit as “an integrated factory in itself.” The machine is equipped for automatic loading and unloading to minimize labor, and all of the operations are controlled by computer. The operator, acting with a PC keyboard, can control all nozzle unit parameters -- the travel speed of the nozzle, the water pressure, the nozzle rotation speed, the rotation direction and the distance of the nozzle from the stone surface. The jets of water exit at a constant angle, and the waterjet has a greater effect when rotating clockwise. Meanwhile, a counter-clockwise motion is effective for softer stones.

The nominal pump operation of the machine is 30,000 psi, which is lower than a typical waterjet pump and serves to limit wear to the pump components, Pellegrini reports. All of the pump components that make contact with the water are made from stainless steel, including the pump head, and the machine also has a lubrication system with a heat exchange system to control the oil temperature.

Ferris said that installing the machine not only added speed to this sector of its operations, but it also provided a “signature texture” for architectural work. Stone can be flamed and then treated with the waterjet to enhance its color as well as provide texture, and the effect can be subtle or aggressive, depending on the client's needs. Because of the many factors involved in creating a specific texture, North Carolina Granite saves the parameters it uses for each project processed on the machine, so it can replicate the finish if replacement stone is needed at a later time.

To maximize water use, the Water Storm-Master has a filtration unit with two filters, a precompression unit and a 5,000-liter tank for filtered water. A soundproof cabin covers the processing machines, and operators can view the process through safety glass.