In the past, creating metal designs has posed several challenges. One major concern with most designs is the impact of the heat generated by cutting methods. Often, the heat results in hardening and discoloration of the material, which is unacceptable in highly visible architectural projects. Thin metals often warp, and replicating intricate designs onto metal is futile.

The Technology

Waterjet systems operate on the basic principle of erosion. Water, pressurized to 60,000 pounds per square inch (PSI) and focused in an orifice as small as .003 inch, is directed at a material and cleanly passes through without shredding or crushing the material.

For products such as paper, plastics, foods, rubber, insulation, and corrugated cardboard, water alone will penetrate the material. For harder material, such as the metals, glass, and stone often used in architectural applications, an abrasive, usually garnet, is added to the cutting process.

In either case, the highly pressurized water or pressurized water/abrasive is passed through a narrow orifice in a cutting head positioned above the material to be cut. The size of the orifice is adjusted to suit the material density. Easily penetrated materials can be cut with water using an orifice as small as .003 inch, while harder materials may require the addition of an abrasive and an orifice up to .016 inch.

The water leaving the orifice reaches speeds up to Mach 2.5 before striking the material to be cut. Materials lie on support grates, held on tables which vary in size. Below the support grates, a pool of water diffuses the force projected by the highly pressurized nozzles.

Methods of controlling the cutting path range from basic mechanically controlled motions to sophisticated computer numerically controlled (CNC) motion systems. The multidirectional cutting capabilities and optional multiple cutting heads further increase the cutting capabilities and flexibility of waterjet technology.

The erosion process can be controlled to the extent that it creates no burring or rough edges, which often eliminates the necessity of additional finishing operations. The only start holes, those drilled by the waterjet, are nearly invisible in the final design.

AWJ creates a minimum kerf, allowing parts to be placed closely together. Thus, expensive material can be fully utilized, and the amount of setup time for those parts is reduced.

The Importance of Programming

The key factor in AWJ cutting is the accuracy with which the original design is programmed into the software controlling the cutting heads.

(photo courtesy of Creative Edge Corp, Fairfield, IA)

Abrasive waterjet cutting for

ARCHITECTURAL

APPLICATIONS

TECHNOLOGY EASES DESIGN CONSTRAINTS

Here, science meets art. Experienced operators bring to the project a knowledge of the characteristics of a material. Their choices can make or break the economics of a project.

Cutting speed is one variable that programmers must control. AWJ systems have a range of speeds, from 0.1 to 300 inches per minute (IPM). When selecting the speed, programmers take into consideration the material and its thickness, the tolerance required, and the edge quality on the finished piece. Some materials, such as stainless steel and granite, are cut slowly. On difficult-to-cut materials, the machines are programmed to cut at speeds as slow as 0.3 IPM. Other materials such as carbon steel, brass, aluminum, and marble pose little opposition to the stream of water and garnet. These materials can be cut faster and still maintain the desired tolerances and edge quality.

Aesthetics Embrace Functionality

Successful fabricators of architectural designs meld these variables to produce quality products in economical ways. The recent increased use of decorative ornamental railings in home and commercial applications is one example.

Railings used to be deemed functional but rarely attractive. Today, durable metals such as brass, steel, stainless steel, and aluminum can be cut to match an infinite number of artistic designs. Details as small as 1/32 inch can be created.

The example in the Lead-in photograph is part of a railing system based on traditional designs. Attention was given to recent building codes that restrict openings to 4 inches or less. The basic panel units are 2 feet, 6 inches square and cut from 3/4 inch aluminum. The material is cut at 6 to 8 IPM.

After cutting, the back edge is touched up with a sanding tool. A slower cutting speed would entirely eliminate any sanding. However, this manufacturer felt that the economics of the extra sanding step outweighed the cost of a slower cutting speed.

Adding to the attractiveness of design is the absence of weld seams in the corners. The panels are mounted to the supporting structure by means of an inner telescoping sleeve. The junction is then welded or grouted.

AWJ technology can be adapted for special configurations often found when turning corners and in stairwells. Adjustments can be made through the computer program.

(photo courtesy of Creative Edge Corp, Fairfield, IA)

Figure 1

Formidable Stainless Steel

An intricately executed mural (see Figure 1) exemplifies the potential of a waterjet when working with stainless steel. Traditionally thought of as difficult to machine and easily warped, stainless steel has been avoided in architectural decor applications.

Here, AWJ cutting has provided intricate detail. Featured is highly complex filigree silhouette cutting.

This project took nearly six weeks to complete. Nearly half of that time was spent programming the piece-through patterns. The actual cutting time was about one week, with the remaining time spent on assembly and packing. Although programmed to cut at 10 IMP, this AWJ rarely reached that speed on this design, because it slows as it starts and stops with each intricate cut.

This project is located outside and has a satin finish on the stainless steel. The corten steel retains its original factory finish, which gives portions of the mural a rust-like appearance.

Making a Grand Entrance

Today, entryway floors are receiving more attention than ever. The vestibule is intended to set the tone of what lies within, and many architects want more than traditional tile, carpet, or wood. Floor medallions, typically composed of swirls and possessing a mosaic appearance, must be durable to foot traffic as well as maintainable. Expensive materials are often combined for an elegant effect.

The example in Figure 2 combines three types of marble: beige creama marfil, red rojo alicante, and rosa verona. The insignia uses a brass outline as a highlight. This piece is extremely tolerant of foot traffic and is maintained in the same way as the tile surrounding it, being subjected to occasional waxing and polishing.

(photo courtesy of Creative Edge Corp, Fairfield, IA)

Figure 2

Once again, programming was the key to a successful creation. Each seam was programmed to allow enough room between pieces for grout to be placed in the joints, but not so much as to create sloppy-looking junctions. The brass, being a more expensive metal, was conserved by cutting the design from a 1/4 inch sheet. One-half-inch studs were drilled and tapped into the back of the brass motif as spacers intended to level the 1/4- inch brass with the 3/4-inch marble. The gaps on the underside were filled with epoxy in the final assembly.

This particular piece was assembled at the manufacturer, crated, and shipped, ready for installation. Often, larger pieces are mapped, labeled, and crated in sections for final assembly on site.

Flexibility in Cutting

Flexibility is the key characteristic of AWJ technology when it comes to architectural applications. It has provided designers with a wide-ranging palette of materials.

Almost anything that can be drawn can be recreated, cut, and fabricated. Imagination, rather than limitations of cutting technology, is the only constraint.