CNC Stone Carving

Published: General // Published 24.05.2023

Water doesn't flow, water sculpts", as per the great Gian Lorenzo Bernini, a famous Italian architect, and sculptor from the 17th century.

Did the creator of Baroque sculpture know that one day, man would shape stone with amazing dexterity, even without touching it with his hands?

We have no answer to this question, but Bernini's remark is truer today than ever since water jets are more popular for stone carving of any kind.

"A water drop will pierce the stone not by force, but by tenacity..."

If you want to understand the force of water, we must go back in time before Bernini, to the 15th century. It was then that Giordano Bruno made it clear that stone itself does not resist the association between the power of water and its strength.

Since then, mankind has waited 400 years for the invention of machines to carve the stone. Today we have them, as a combination of sophisticated software and waterjet machines. All these machines, which perform everything from simple cutting operations to true stone carving, use a water jet at extreme pressure or a water jet mixed with an abrasive substance as a 'knife'.

In the mid-19th century, the water jet was used in mining and as an industrial cutting tool only around 1930, but for soft materials only (such as paper, or plastic). The late 1950s mark the debut of the first cutting system with a high-pressure water jet, suitable for hard materials. Further iterations led to the introduction of a nozzle with 0.051 mm in size, and 480 MPa operating pressure. It was later (1987) that the industrial waterjet cutting system was patented.

The operation of current cutting systems is based on 2 methods: abrasive water suspension cutting and waterjet control cutting.

Water suspension cutting has 2 components: water and abrasive. Such a combination allows deep and fast cuts, more efficient compared to traditional systems. Cutting control became necessary for the industry with the debut of jet cutting because reliability and accuracy were essential. This led to a move from mechanical pantographs to basic CNC systems, based on the 1952 NC milling machine (John Parsons) running G-code. It wasn't until the early 1990s that nozzle positioning systems were developed, with standard PCs for controlling the speed at each point of the path.

The software designed to control the machine (OMAX) was licensed by the company Flow International, so waterjet cutting machines became precision tools for the stone industry, but also other materials such as metals, leather, rubber, textiles, ceramics, composite materials, food, paper. Note that all of these are softer compared to materials with à hardness value of 7.5 - 8 on the Mohs scale (e.g.: quality glass and diamond cannot be cut). The current technology allows waterjet cutting machines to cut metals up to 15 cm thickness, and up to 46 cm thickness for other materials.

How does water carve stone?

With excellent features even for Bernini, the system meets the following requirements:

1. high-speed water stream at 210-620 MPa, possibly with abrasive particles, delivered by a high-pressure pump.

2. applied for a wide range of materials: from soft & temperature sensitive to very hard ones

3. nozzles made of extremely hard materials (e.g., tungsten carbide)

4. tape compensation of less than one degree

5. nozzle distance from the workpiece of 3.2 mm

Different speeds produce different quality cuts.

Yet, considering the carving executed on multiple axes, Ingersoll-Rand Waterjet Systems has developed a 5-axis cutting system. This is a CNC system, with 2 software applications: CAD for drawings and CAM for translating them into G-code or M-code instructions for the machine. A CNC configuration includes a controller, one or more spindle motors, servo or stepper motors, servo amplifiers, frequency converter, vacuum pumps, clamping systems, a work table, and many accessories.

Rendering - the dream on screen

From dream to reality the link involves the rendering. The photos that convert vision into reality are essential elements for interior design. Here, experts play with sizes, colors, textures, and lights, to satisfy even the most demanding needs. Due to complex software, real-time rendering reveals angles that would otherwise remain hidden, plus hard-to-guess transparencies, blends colors as desired, and sharpens and expands volumes. Dynamics, highlighted as defining element, allows clients to touch their dreams, right before their eyes.

Inspired by the success and driven by technology, the future "paints" and "sculpts" according to new principles, reviving Caravaggio's chiaroscuro, Monet's brushstrokes, and Bernini's baroque!