Making the Cut by J.A. Schmidlin Richel, Inc   (Cleaner Times - August 1997)

They want it all. Today, more than ever, manufacturers require flexibility, innovation and quality in the equipment they purchase. Major purchases must not only meet today’s demands, but be flexible enough to meet the unknown challenges of tomorrow. Waterjet cutting technology has risen to the challenge. It is proving itself as flexible, accurate and fast. Manufacturers utilizing this technology find themselves on the cutting edge.

Waterjet technology is easily understood. The systems operate on the basic principle of erosion. Water-pressurized to 60,000 psi and focused in a narrow orifice, as small as .003" - is directed at a material and clearly passes through without shredding or crushing the material.

Low pressure tap water, the essential ingredient, must meet certain standards. The water is subjected to a deionization process or reverse osmosis system. Simplified, this process removes solids such as iron and calcium and can often be accomplished with a water softener. The water then passes through a filtration system which removes particles down to 0.45 microns. Such purification is essential to maintain the pumps and high pressure seals. Without it, mineral deposits would clog vital elements in the system.

The purified water enters an intensifier pump where it is pressurized up to 60,000 psi. After these three steps - deionization, filtration and intensification - the waterjet is ready to perform.

For products such as paper, plastic, foods, rubber, insulation and corrugated cardboard, water alone will penetrate the material. For harder materials such as metals, glass and stone, an 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 only water using an orifice as small as .003" while harder materials may require the addition of an abrasive and an orifice up to .016".

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 steadfastly diffuses the force projected by the high pressurized nozzles. The water, once turned into a cutting tool, reverts back to its placid state.

Methods of controlling the cutting path range from basic mechanically-controlled motions to sophisticated Computer Numerical Control (CNC) motion systems. The multi-directional cutting capabilities and optional multiple cutting heads further increase the cutting capabilities and flexibility of waterjet technology.

The list of materials which a waterjet system will penetrate is seemingly endless. To date, applications have been used with foam, GIO phenolic, steel, armor plating, urethane, titanium, kevlar, aluminum, linen phenolic, brass, neoprene, copper, glass, stainless steel, spectra, fiberglass, corrugated cardboard, acrylic, ceramic tile, wood, rubber, glass, marble and granite.

The erosion process can be controlled such that it creates no burring or rough edges which often eliminates the necessity of additional finishing operations. The only start holes are those drilled by the waterjet, and parts can be optimally placed to fully utilize a piece of material.

The spectrum of applications for waterjet cutting ranges from the delicate to the stalwart. FDA regulations allow the use of waterjet technology in cutting food items such as cakes, French fries, steak, poultry and fish. Waterjets have proven themselves as both efficient and sanitary.

On the other extreme, abrasive waterjet systems (AWJ) bombard armor plating used in the assembly of M1 tanks and Bradley fighting vehicles. In between lies a wide spectrum of other applications. Artists, interior designers and shipbuilders are among the many who are embracing waterjet technology. Industries such as paper, textile, aeronautics and steel are routinely incorporating the technology into their manufacturing process.

Waterjet technology is performing old tasks in a new efficient manner. Complex and intricate designs and mosaics made of tile, stone and glass - often used in decorative surfaces and corporation logos - are now executed with the aid of a waterjet. Many of the projects would have been impossible to create without a waterjet because of the intricacy of the design and the fragile nature of the materials.

Watetjets are also helping ease the burden of rising medical costs. It’s a technology helping technology.

Waterjet technology placed a Florida specialty stone manufacture on the cutting edge. An interior designer with a special project in mind brought to the stone manufacturer a sketch of a detailed medallion and border. The medallion, with its intricate swirls and fine details, were intended for the entry hall of a client’s home. Marble was the preferred material. Delicately thin swirls chiseled from marble - a nightmare even by Michelangelo’s standards.

The stone firm confidently accepted the challenge, their confidence backed by their waterjet capabilities. The firm and interior designer worked together to refine the medallion and border. Content with their initial version, the medallion was entrusted to a waterjet computer programmer. Their vision was scanned and digitized into the computer which would eventually direct the waterjet cutting nozzles.

Preliminary plans rapidly became the blueprint for this creation. The paper concept was ready for execution in rock. The interior designer and client strolled through the marbleyard. Before them their palette, a stone spectrum of color. Here they selected the materials that would eventually constitute their vision.

Returning to the computer, the precise shades of the marble selected were added to the computer image of the medallion which began to take life. Technicians went onsite to take actual measurements; the border alone would be nearly 300 linear feet with the six foot medallion resting inside.

Fabrication followed. Controlled by the computer, the waterjet nozzles were lowered over the marble and began the process so common in nature: erosion. The water combined with garnet bombarded the marble exacting out the swirls quickly and accurately.

Where other cutting methods would have cracked or exploded the materials, the waterjet left a piece to the puzzle, accurate and intact. Several months and approximately 450 pieces later, fabrication of the medallion and border were complete. Marble border pieces in three different colors were assembled into six by eight inch modules and labeled for installation. The medallion, done in six different colors of marble and highlighted with Lapis Lazuli, assembled in one piece. The puzzle, packed and mapped, was ready for shipment.

Onsite, the border modules and medallions were installed, leveled and polished. Gone now are the computers, the water, the abrasives and the tools. The work of art embellishing the entryway takes its place among those pieces hanging on the walls. The subtle colors, the richness of the marble and lapis combine for an understated, elegant appearance. An interior designer’s vision, now cast in stone.

Currently under national scrutiny is the high cost of medical care. Much of the credit for our longer life span goes to medical technology that allows the medical profession to accurately diagnose problems before irrevocable damage has been done to critical life systems. Such technology is found in MRI (Magnetic Resonance Imaging) equipment. It provides medical professionals with a view of any part of the body without the use of dyes or invasive surgical procedures.

The manufacturer of one type of MIR set out to find a way to produce the equipment at a lower cost. Enter the waterjet and a group of trained professionals who fully understood how to maximize savings with their waterjet technology.

The original design of the MRI equipment made use of three thicknesses of aluminum. Normal assembly required half-inch, five-eighths inch and three-quarter inch parts. The half inch sheets were set up and appropriate parts were cut from it. Remaining scrap from the half-inch sheet was discarded. The process was repeated with the five-eighths inch sheets and once again using the three-quarter inch aluminum. After frequent set-ups, a minimum number of parts had been cut and a large pile of scrap was left to haul away.

The manufacture of the parts for the MRI, a waterjet cutting facility, was quick to realize that this process was not fully utilizing the capabilities of a waterjet. Waterjet machines are noted for their ability to "nest" parts (place snugly together) thereby reducing the amount of material scrapped. This method also allows for a reduction in set-up time since more parts are cut from a single sheet of material

Waterjet technicians consulted with the MRI engineers about the necessity of using three different thicknesses of aluminum. Engineers agreed that although three thicknesses were specified in the original design, it would be appropriate to use a single thickness of five-eighths inch for specified parts previously cut from the half-inch and three-quarters inch aluminum.

Waterjet programmers latched onto the new design specifications. Their computers were reprogrammed to nest parts and fully utilize the 74 x 74 inch aluminum plates. Like a parsimonious midwestern housewife, nothing was laid to waste. Large rings, used as end plates to cap off the machinery, took up the major portion of the sheet of material. The previously unused corner pieces and center sections from the rings were recaptured by delegating smaller required parts to be cut from those areas.

The final result was a substantial savings, in excess of $100,000 annually. The savings were generated from a combination of factors. Material, previously relegated to the scrap pile, was being used to create viable parts which reduced the price of material per part. The increased use of five-eighths inch aluminum allowed for the purchase of larger quantities of that size material which reduced the cost of material due to quantity discounts. More savings were reaped as a result of fewer set-ups, meaning a reduced average cutting time for the job.

However, the lesson has not ended. Since the implementation of changes to the MRI parts, the engineers have increased their waterjet technology savvy. Understanding the capabilities of the waterjet has allowed them to reengineer existing equipment as well as new designs to make use of waterjet technology. Nesting has become an integral part of the designs. Blueprints now arrive at the parts manufacture clearly marked as "cut with waterjet only", a clear indicator of the adoption of this growing technology.

Life might seem simpler in a two-dimensional world; everything easier to comprehend with no corners to hide the unknowns. But waterjet technology is ready and comfortable with the reality of a multi-dimensional world. Its five-axis cutting capabilities are putting other cutting methods to shame. Five-axis waterjet equipment utilizes water-only or abrasives. It is the water-only equipment operators that pioneered the technology originally for applications in the automotive industry. The days of the boxy black Model T Ford are treasured, but gone. Today’s consumers want aerodynamic curves, performance and reliability - aesthetically packaged.

The needs of the automotive industry became a mecca for waterjet cutting applications. Radiator hoses, gaskets, molded fiberglass body parts such as bumpers and door panels, headliners, fitted carpet and sleek dashboards are only a few of the components that comprise today’s vehicles. These parts are all molded to a specific shape and require trimming around the edges and / or the cutting of holes within the shape. Trimming and cutting of holes in oddly shaped parts are criteria that present challenges to traditional cutting methods. Although not impossible, it normally requires multiple set-ups of a part. Producing the part utilizes an expensive labor resource rather than equipment resources. The five-axis waterjet will cut and trim in one pass, requires less use of labor resources and completes the job significantly faster than traditional methods.

Five-axis waterjet cutting equipment is best described as a robotic arm with the ability to twist and cut on any required plane. Freed from the constraints of horizontal and vertical cutting, the five-axis roams freely about a part. Its lightweight design allows it to change directions rapidly with the resulting motion being more akin to sculpturing than cutting. But cutting is what it does best, as rubber, wood, glass, carpet, composites and various metals melt away under the high pressured jet. Each robotic arm can cut at speeds up to 2000" / minute. In tandem, the arms operate at unbelievable speeds in a superbly choreographed dance, with the computer controlling their speed and placement.

Normal cutting tolerances for many of the automotive applications is low. However, high tolerance equipment is available, as well as gantry style setups and systems that make use of abrasives. The aerospace industry is increasingly utilizing waterjet technology. Much like the automotive industry, it requires the trimming and cutting of irregularly shaped, specially molded parts, the forte of waterjet cutting equipment.

Waterjet cutting technology effectively meets the challenges posed by a variety of today’s manufacturing needs. It goes beyond traditional cutting methods in providing quality materials in a cost effective manner. It is hard to compete with a methodology that is so flexible and effective. Waterjets - why walk when you can fly?