A waterjet pressurizes water and creates a high velocity stream of water, called a jetstream that erodes material. Waterjet machine tools use high-pressure pumps to force water through a tiny orifice inside a nozzle, creating a narrow, high velocity jetstream. In the case of abrasive waterjets, fine abrasive particles (typically garnet) are pulled into the jetstream within the nozzle. A computerized motion control system moves the nozzle and the jetstream from the nozzle erodes a thin line from the material. Pure waterjets (without abrasive) are generally used to cut soft materials like food and foam, while abrasive waterjets are used to cut hard materials like steel. Abrasive waterjets can cut virtually any material, metal and nonmetal, from carbon fiber to copper, glass to granite, titanium to tungsten and practically anything in between.
Waterjet systems can vary, but most are made up of a high-pressure pump, a cutting table that holds the work material, a nozzle that emits the jetstream, an X-Y motion system to move the nozzle and a PC-based controller. OMAX tables are water-filled tanks with slats that hold the material. The material can be submerged under the water, making the cutting quiet and clean. OMAX waterjets have hoppers that hold and dispense abrasive during the cutting process.
Most of the maintenance on an abrasive waterjet involves servicing the pump and the cutting head. The exact type and frequency of maintenance will depend on how the machine is used (pump pressure, type of material cut, etc.) the specific components (pump type, nozzle type, accessories) and the water quality. The nozzle needs to be changed out fairly frequently to ensure precision cutting. Changing out a nozzle takes just a few minutes. Our MAXJET 5i nozzle is warranted to last 500 operating hours. The wear components in the cutting head need to be changed out occasionally. This takes approximately 10 minutes. The high pressure pump needs regular servicing. Our direct drive pumps are very easy to service and, depending on the pump model, a rebuild typically takes 1-2 hours. Accumulated abrasive and work material particles need to be regularly removed from the tank. This work can be automated by using a Solids Removal System that continually removes sludge without taking the waterjet machine offline, or the sludge can be shoveled out manually, which requires draining the tank. The table slats should be inspected for wear at least once a month and rotated or replaced when worn. We provide free hands-on training including waterjet maintenance for our customers. We also provide online videos and manuals with step-by-step maintenance instructions for our pumps, cutting heads and accessories.
There are four main factors that contribute to the exceptional speed and precision of OMAX JetMachining Centers:
OMAX incorporates an advanced cutting model into the controller which automatically creates the optimal cutting path. It varies speeds and accelerations so that no time is wasted going more slowly than necessary. In addition, the OMAX controller automatically takes advantages of many speed-up tricks that would be too difficult and cumbersome for a human to program. For example:
The OMAX controller automatically adds corner passing on corners that will allow for it. This can result in speed increases from 5 to 25%, depending on the geometry of the part. This process is automatic, and does not require additional work or knowledge from the operator.
The OMAX controller automatically adjusts the speeds and accelerations around curves and corners to optimize the tool path for speed, precision, and square corners. This makes it very fast and easy to program the machine, and allows the parts to be machined as quickly as possible while still maintaining the highest tolerances.
The OMAX controller selects the optimal pierce speed, and length, based on an advanced piercing model. This greatly speeds up the otherwise slow process of piercing the material, automatically and optimally.
There are also tools such as the "optimal stack height calculator", which can be used to greatly speed up some categories of parts.
2. Superior X,Y positioning system
All OMAX waterjet machines are designed for high precision machining. A combination of precision mechanics, rigid construction, and precision velocity control from the software insures the highest degree of precision in the machined parts, even in shops where vibrations from other tools such as punch presses or fork-lifts driving by may exist.
3. Superior direct drive pump technology
OMAX pumps are highly efficient, so 33% more horsepower makes it to the nozzle than in the competing intensifier pump designs. This means that for the same horsepower rating, the OMAX system's pump will cut much faster, and at a significantly lower cost.
4. Superior nozzle technology
OMAX MAXJET and MiniJet nozzles are designed for maximum precision, life, and cutting speed.
What to do with that used abrasive tends to fall into three categories: disposing, recycling, and repurposing. In most cases, used abrasive from a waterjet can be thrown out with other non-toxic garbage since garnet is a non-reactive, natural substance. However, if the abrasive has been used to erode toxic material and is contaminated with particles of toxic material such as lead or beryllium, it can't be simply thrown out with the trash and must be treated as toxic waste. A service that will periodically collect and properly dispose of your used abrasive can be employed to simplify this process.
Cutting Material with an Abrasive Waterjet
Cutting speed for abrasive waterjets is affected by multiple factors, including material type, material thickness, desired edge quality, part geometry, pump horsepower and more. Compared to other cutting processes, abrasive waterjets cut 5-10 times faster than wire EDM when cutting material less than 1 inch thick, and generally not as fast as plasma and laser cutters.
If you'd like us to run a cutting time and cost analysis for your part in your specific material, contact us today for a free test cut.
The high-level answer is that abrasive waterjets can cut through 12 inches of most materials. Many of our customers report cutting material even thicker than that. Most abrasive waterjet cutting, however, is done in material that is 3 inches thick or less. Cutting thicker than that usually reduces the tolerance that can be maintained and increases the amount of time to cut a part. We can run a free time and cost analysis of your part and specific material type and thickness on an OMAX machine.
It's easier to answer what materials can't be cut with a waterjet. An abrasive waterjet can cut virtually anything, but we don't recommend cutting tempered glass with a waterjet because it will probably shatter. And while an abrasive waterjet can cut food, we don't recommend that either because of the abrasive. Many food processing companies do use pure waterjet machines (rather than abrasive waterjets) to cut food. Waterjet can cut aluminum, brass, bronze, carbon fiber composite, ceramic, copper, fiberglass, glass, granite, Kevlar, marble, stainless steel, titanium, tungsten and a lot more.
Yes. Dual pressure piercing allows for piercing of glass with minimal risk of cracking. OMAX waterjet machines come standard with dual pressure capabilities. OMAX Machines also have a special "brittle mode" that works in conjunction with low-pressure piercing to slowly raise the pump pressure during the pierce to avoid a sudden shock to the material by a rapid change in pressure. Using these techniques reduces the risk of cracking, making glass cutting into a very profitable venture.
Table accuracy for OMAX line waterjets is ±0.0010" and for MAXIEM line waterjets is ±0.0030". The repeatability for the tables in both lines is ±0.0010". Be aware that more than just the X-Y accuracy of a table goes into the final accuracy of a part cut on an abrasive waterjet. This is due to the nature of the cutting tool on an abrasive waterjet, a high velocity stream of water and abrasive known as the jetstream. Unlike rigid cutting tools, the jetstream bends as it moves and the lower part of the jetstream doesn't behave exactly like the upper part. The width changes and deforms and it tapers as it cuts. All of these things change with different materials, different thicknesses, different cutting speeds and a range of other factors. The control software on all OMAX abrasive waterjets uses an advanced cutting model that takes all of these factors into account and for each cutting job and optimizes the cutting parameters to make accurate parts every time. To get a precise measurement of accuracy for any abrasive waterjet system, get some test cuts done with your part designs and material and measure them.
If you'd like a free test cut of your part on an OMAX machine, contact us today.
- Abrasive waterjets can cut virtually any material, including glass and reflective materials, and a wide range of material thicknesses. Some OMAX customers report cutting material up to 18 inches thick.
- Abrasive waterjet machining is a cold cutting process and creates no heat-affected zones (HAZ), therefore it doesn't change the material properties or leave heat-hardened edges.
- Set-up for cutting jobs on abrasive waterjets is quick and easy.
- Multiples of the same part can be cut at one time from different types of material simply by stacking the various sheets of material on the waterjet.
- No harmful vapors are emitted with abrasive waterjet cutting.
- A waterjet's cutting tool never gets dull.
Waterjet vs. Laser - Laser generally can only cut material that is up to 1½ inches thick. Waterjet can cut most materials at 12 inches thick, sometimes even thicker. Reflective materials such as aluminum, bronze and copper are difficult and sometimes even impossible to cut with laser. Waterjet has no difficulty cutting materials with reflective properties. Laser cutting leaves a heat-hardened edge that is problematic when doing secondary operations. When rough cutting parts with a laser and then finishing them on a CNC mill, that heat-hardened edge has to be removed which wastes material and slows down the finishing process. With waterjet cutting, there's no heat-affected zone (HAZ), maximizing material usage and making secondary operations like tapping and beveling much easier than if cut with a heat process.
Waterjet vs. Plasma - While plasma cutting is typically faster than waterjet cutting, the cut edge quality of waterjet is far superior. Plasma cutting leaves a rough edge that usually requires some clean-up. Waterjet can do a much more precise cut than plasma, often eliminating the need for any edge clean-up. Since plasma cutting works by melting the material, it's not a good option for materials that don't melt easily, such as granite, or for materials that are destroyed by melting, such as laminates. Waterjet is a cold cutting process with no heat-affected zone (HAZ), and does not change the material properties.
Waterjet vs. Wire EDM - Waterjet cutting is 5-10 times faster than wire EDM cutting. Abrasive waterjets can cut virtually any material, but wire EDM is limited to conductive materials. Both processes cut with high precision.
Yes. The OMAX control software allows for up to 100 user-specified home locations, which provides multiple tooling locations on a single machine. The OMAX Precision Optical Locator (POL) accessory lets you zoom in on a part to locate a feature or edge and mark that as a reference point on the tool path. The software will automatically rotate the tool path to match the placement of the part on the table. The optional A-Jet articulated cutting head makes it possible to cut countersinks and bevels.
Yes, abrasive waterjets with OMAX premium software can perform etching in material.
Operating an OMAX Waterjet
After about one day of training, you can make simple parts. Three days of training are provided for extra proficiency (learn more at Training). Optional follow-up training is available and recommended after a few months of use, to increase skills and productivity.
A number of factors go into calculating waterjet operational costs, including but not limited to consumable parts, pump horsepower, water supply cost, whether the machine is running one cutting head or two, abrasive cost, the type and thickness of the material being cut and the desired edge quality. Because of all these variables, the specific answer is, it depends on what you're doing with the waterjet. However, a very general operating cost range to run an OMAX waterjet is UDS $25-35 per hour, not including labor cost.
At operating pressures above 60,000 PSI (4,137 bar) more maintenance is required and unplanned downtime can increase dramatically. Ultra-high pressures result in higher operating costs due to accelerated metal fatigue in high pressure components used in pumps and plumbing. For this reason, waterjet cutting machines usually operate most economically and reliably in the range of 60,000 PSI (4,137 bar) or less.
Prudent machine shops calculate their service prices based on the price per part. OMAX software is the most accurate in the industry at predicting the cutting time and cost for a specific part. The cost data can be used for internal accounting reports or customized to include labor and other overhead costs to create a customer quote, all within the Intelli-MAX software.
If you'd like us to run a cutting time and cost analysis for your part in your specific material, contact us today for a free test cut.
For most locations in the U.S. and Canada, the answer is “no”. Most of the water that comes from a city's water supply in these countries can be used in an abrasive waterjet without any treatment. For those areas that fall into the exception, waterjet owners can save significant time and money by conditioning the water, no matter what brand of waterjet machine they're running. OMAX recommends all waterjet purchasers get a water quality analysis before buying. The water should be tested for "total dissolved solids" (TDS), not just for bacteria. Dissolved minerals in the water can do a lot of damage to the high-pressure equipment. Even if the parts per million of dissolved solids in your water initially tested within the allowable limit (typically at or below 250 ppm), you should periodically retest. Water quality can change when there is unusual weather or your water department switches reservoirs.
While there are many methods used to hold work material in place while cutting with a waterjet, the simplest and most common way is to place a plate of material onto the cutting table slats, anchor it down with weights and if space allows, secure the plate in the X and Y directions with clamps. OMAX offers material holding kits specifically designed to fit the dimensions of OMAX waterjet tables for high precision cutting. The kit includes track assemblies and vertical load clamping arms and mounts into the slat bed.
Cutting under water is typically used to reduce the noise and splash and to eliminate airborne dust. However cuts can be made above water if desired, with no loss in performance.
Typically as the thickness of the part increases, the ease of obtaining precision decreases.
Both pure waterjet and abrasive waterjet cutting involve pressurizing water and focusing a narrow jetstream through a nozzle at a high velocity. In the pure waterjet cutting process, it's the water that cuts a very thin line through the work material by erosion. In abrasive waterjet cutting, abrasive particles (typically garnet) are added to the high-pressure stream of water inside the nozzle, and it's the tiny abrasive particles that do the erosion, or cutting. Pure waterjet cutting is used for soft materials like foam and rubber, and to cut food, which needs to remain free of abrasive particles. Abrasive waterjet cutting is used for hard materials, and also for cutting thick soft material.
This depends on the kind of work you want to do. If working in very thick metal, get a pump that is capable of putting a lot of horsepower to the nozzle. Although a smaller pump can machine thick metal, a larger pump will be faster, and therefore more practical. If cutting mostly thin metal, or doing water-only cutting, get a smaller pump. Smaller pumps are often cheaper, cost less to run, are easier to maintain, more reliable, and are quieter. Bigger pumps, however, allow faster cutting.
Note: It is very important to understand that it is horsepower at the nozzle that is important, not the size of the motor turning the pump. This is important because many pumps have big motors driving inefficient pumps, while other pumps have smaller motors running efficient pumps.
For example, a 50 hp (37 kW) intensifier pump will typically only put 30 hp (22 kW) to the nozzle, while a 30 hp (22 kW) crankshaft pump will put 28 hp (21 kW) to the nozzle. Examine the price and maintenance differences between the two types of pumps, and the lower horsepower pump quickly starts to look like the better choice:
Comparison with English units 50 hp intensifier = 30hp at nozzle = 20 hp lost to inefficiencies
30 hp crankshaft pump = 28 hp at nozzle = only 2 hp lost
Comparison with Metric units
37 kW intensifier = 22 kW at nozzle = 15 kW lost to inefficiencies
22 kW crankshaft pump = 21 kW at nozzle = only 1 kW lost
The amount of electricity lost as efficiencies can have a significant effect on operating cost. For example, if electricity costs $0.10 per KWH, and you are wasting 15 KWH per hour, then you are losing $1.50 per hour to heat. In addition, because Intensifiers require additional cooling water, you are losing even more in the cost of cooling water.
The more horsepower that makes it to the nozzle, the faster you can cut. The trade-off with a higher horsepower pump is cost, efficiency, a larger kerf width, and sometimes a slight loss in precision. However, a high horsepower pump can almost always be run at lower pressures to reduce the operating cost and maintenance, and then run at higher pressures for special jobs that would otherwise try your patience.
The intensifier pump is not as efficient and is more costly to operate than the direct drive pump. It has pressure ripples and is noisy. The direct drive pump is quieter, uses less water and power and is more straightforward to maintain. It is the better option for environments where operating costs and profitability are important.
With the OMAX Mini-Jet nozzle, the kerf width is 0.020" (0.5 mm) wide, which is 0.010" (0.25 mm) smaller than a standard OMAX MAXJET nozzle. For even smaller cuts, the 7/15 MAXJET5 nozzle has a kerf width of only 0.015” (0.38 mm). You can make parts as small as you like, but exceptionally small parts may require special fixturing to prevent them from falling into the tank. OMAX offers several methods for fixturing such small pieces. OMAX "waterjet brick" is especially popular for detailed work.
About OMAX Company
Because nobody else made a waterjet that was precise, easy to use, fast to setup and program. Traditional waterjets have been used for applications such as cutting diapers, but nobody made a machine tool for the machine tool market. The abrasivejets that were available for machine tool work were very low tolerance, and built from a variety of custom configurations. OMAX brought precision, ease of use, and a standard product line to the market.
OMAX develops complete waterjet systems, not just individual components. We design, manufacture and test each system as a complete unit at our USA headquarters in Kent, Washington before delivering to a customer. We even develop the CAD/CAM software and the motion control software for our waterjets, so everything works together, seamlessly. We have decades of waterjet industry experience and the largest waterjet research and development team in the world.
If you have questions that weren't answered, let us know.