• Why buy from Romeo Engineering Inc?
• Why run at 60,000 psi ?
• What makes a good application for a Waterjet?
• What makes a bad application for a Waterjet?
• Why use a Waterjet instead of saws, plasma, laser, EDM, or milling machines?
• How do I decide the best Waterjet vendor?
• How important is water quality?
• What are the water quality specifications?
• Do I need a water softener, de-ionizer, or reverse osmosis?
• What does resistivity/conductivity mean?
• What size nozzle do I need?
• How much abrasive will I need?

Why buy from Romeo Engineering Inc?

Our engineers have been designing and manufacturing waterjets for a quarter of a century. Our machinery has a reputation for being rock solid, easy to use and performing well for a very long time. The equipment is fabricated at our multiple factories located in Fort Worth, Texas USA. We have a full engineering staff complete with degreed & licensed professional engineers, mechanical engineers, electrical engineers, and nano-particle engineers. Need something different? We build much more than X-Y tables. We offer a broader product line of waterjets and factory automation than any other manufacturer in the world.

1. All machines are precision ground on the world's largest grinding machinery. It starts with an all-steel construction that is stress relieved and precision ground flat, straight, and perpendicular in one setup. Our stress relief process has been proven through independent research to be equal or actually better than thermal stress relief. Lesser quality machines may have milled ways which is not as flat, resulting in nozzle movement. Further, many competitve brands are machined in multiple setups because their machine tools are too small to make large machines in one setup. Or, even worse, they may use aluminum extrusion or not even be machined at all. All REI machines are gantry style. They are built to stand on their own without relying on the customer's floor.

2. Vendors often publish static positioning accuracy, which is not as good of a machine's true accuracy becuase machines are expected to move. A better measure of machine accuracy is dynamic accuracy. Less quality machines, such as cantilever design or those anchored to the floor, will be cheaper to build but cannot hold dynamic accuracy at the same acceleration. Most of our models are ball screw driven with 2 pre-loaded nuts for maximum life. Less quality machines will use a single nut with oversize balls or phased tracks, both of which wear prematurely. Even worse, less quality machines will use rack & pinion which have severe backlash problems.

3. Our control system is designed and built by REI from the ground up. Being Microsoft Windows based, hardware and software upgrades are easy. As part of the base model, all of our controllers include air conditioners, pendants, and other necessary items that others consider to be "optional."

4. On the high pressure system, we only use hydraulic-type waterjet pumps. We do not sell or recommend crank pumps (aka direct drive pumps) for several reasons. Our abrasive delivery system (patents pending) is digitally controlled and has excellent feed performance. Our machines are available in 2,3, and 5 axis and are available with multi-head dynamic centerline as an option.

Below 45,000 psi, a waterjet will not cut metal or other hard materials very well. The industry standard is 60,000 psi operating pressure. Pumps are available that are capable of reaching much higher pressure. So why not run at higher pressure? First is safety. The materials and design of 60 KSI components are well understood and commercially available. A failure in a high pressure system at that pressure would be catastrophic and expensive to replace high pressure cylinders. Second is fatigue life. Remember, a waterjet pump must go from a vacuum to full operating pressure several times per minute. It is impossible to prevent fatique forever. Faster cyclic loading and higher pressure cause shorter fatigue life. A KMT brand pump has the longest stroke plunger in the industry (8-inches), so it typically strokes 50 times per minute. Competitive brands have shorter stroke (usually 4 or 8 inches), and so their stroke much faster at over 75 to 100+ strokes per minute. Again, faster stroke means shorter life. Third, pressures higher than 60 KSI causes faster wear on nozzle and other consumable parts. Finally, the cut quality is not much improved and in some cases is worse for several reasons. If you have a need for speed in your waterjet, contact Romeo Engineering Inc for a smarter way.

Waterjets are ideal for any application that requires intricate cutting all the way through the material. They are exceptional for cutting a variety of materials ranging from very hard to very soft. There are few materials that a waterjet is not able to cut (such as diamond and carbide). You can think of waterjets as a liquid grinder that continuously erodes the material. The decision about cutting speed usually concerns the quality of the cut versus speed. The cut will usually have striation (“rooster tail”) along the edge where the water/abrasive eroded away the material. Striation is a function of material, thickness, speed, and nozzle size. Slower cuts usually result in less striation. Faster cuts usually result in more striation.

Good Applications:

1. Soft materials like rubber, thin plastic, or leather
2. Hard materials like steel, tool steel, or stone
3. Exotic materials like ceramic, composites, and glass
4. Food products like pizza, cheese cake, and vegetables
5. Energetic materials like extruded propellant
6. Gummy materials like elastic and cookie dough
7. Multiple layers like stacks of sheet metal or fiberglass
8. Programs that have contoured corners like letters in signs
9. Multiple nozzles to improve production volume
10. Nested parts to reduce scrap waste

1. Depth of cut is not possible. The stream must pass all the way through the material. However, it is easy to cut bevels or contoured surfaces with multiple axis options.
2. Interrupted cuts like tubes and pipe. Materials that have a hard-soft-hard cross sections tend to blow out the bottom surface because the stream becomes unfocused in the soft regions.
3. Very large amounts of perforations like screen mesh. Very high numbers of cycle will wear out valve seals prematurely. Conventional punch presses are a better technology.
4. Low commodity products like scrap metal, scrap tires, and grass. Waterjets add value to your products but they add cost. A good waterjet application will re-coupe operating costs by 1) improving an existing process by making better cuts or increasing production volume 2) eliminating post-processing or 3) making applications possible that were not possible before.

Every cutting technology has advantages and disadvantages. Waterjets are best known for cutting speed and versatility in cutting a wide variety of materials. They are easily adaptable to automated material handling. Like every cutting tool, however, there will be costs associated with tool wear plus the cost of consumable abrasive (if applicable).

• Saws vs. Waterjets
• Band saws and scroll saws are best for rough cutting thick sections and tubular sections
• Unlike waterjets, saws cannot cut intricate contoured shapes or very hard tool steels.
• Saws do not allow nested parts
• Saws cannot cut from the center of a plate.

• Plasma vs. Waterjets
• Plasma offers extremely fast cutting of steel & aluminum
• Plasma offers low cost & no consumable media
• Plasma leaves molten slag leaves very rough edge quality
• Plasma produces a heat affected zone (HAZ)
• In stainless steel, HAZ is a chromium depletion zone which will rust unless heat treated.

• Laser vs. Waterjets
• Lasers can cut faster and more accurately on to ½" thick or less steel
• Lasers provide a clean cutting process
• Lasers cannot cut 4 - 6 inch thick steel
• Lasers cannot cut shiny surfaces like aluminum because the molten slag acts like a mirror which burns optics
• Lasers cannot powder coat laser cut parts without chemical removal of organics
• Lasers cannot cut some combustibles like corrugate & foam (toxic isocyanate)
• Lasers introduce a heat affect zone and degrades material
• Lasers are expensive to support multiple nozzles
• Lasers costs start at $350,000 to $900,000. Waterjets cost $100,000 to $180,000.

• EDM vs. Waterjets
• EDM is more accurate than waterjets. Waterjet accuracy is typically 0.005" whereas EDM accuracy is 0.0001" accuracy
• Waterjets cut much faster.
• Waterjets cut a much larger variety of materials including plastic, stone, rubber and other non-conductive materials.

• Milling Machines vs. Waterjets
• Milling machines can cut a variety of materials with very close tolerance.
• Milling Machines allows accurate depth of cut (X,Y,Z)
• Milling Machines are less expensive to operate (No consumable media)
• Milling Machines are less expensive to buy than waterjets ($45,000 to $100,000)
• Milling Machines cannot nest parts as closely (typical cutter is 3/8" - 1" diameter)
• Must deal with chips
• Milling Machines require substantial clamping or the rotating tool will move the part
• Tool contacts the part, so may have tool breakage and wear
• Must be careful not to distort thin parts
• Milling Machines are less adaptable to automatic feeding (conveyors, indexers, robot arms, etc) because of need for clamping

Here are a few guidelines for choosing a Waterjet System vendor:

1. CNC Chassis Accuracy

There are many ways to produce high pressure water. But the key to accuracy is in the CNC chassis. You must ensure that a machine tool's accuracy is tightly controlled so that the overall desired shape will be dimensionally accurate. Otherwise, circles will be elliptical and squares will be trapezoidal to some degree. If the machine tool is not "tight", then edges will not be straight and there will be poor cut quality. This is especially a problem with cantilever designs or machines driven from one side only. In general the finished part accuracy of most materials will be around 0.005". It is difficult to achieve better due to the nature of high pressure jet mechanics and inherent 21/2 degree draft angle. Here a few guidelines when selecting the chassis.

• Buy a mid-rail gantry - Romeo Engineering uses electronic gearing to drive a master motor and a slave motor for smooth accurate motion. Mid-rail means that the guideways are halfway betweent the floor and the nozzle. High rail machines are prone to high frequency vibration and are generally anchored to the floor. Just .001 inch of amplitude or thermal grown at the floor can mean .005 or more inaccuracy at the nozzle.
• Don't buy a cantilever chassis - Cantilever designs, high-rail gantries, and single-side drives are never accurate. Cantilever arms have notoriously poor "chatter" during rapid acceleration/deceleration. This causes excessive "rooster tail washout" especially in smaller circles and corners. Cantilevers are less expensive than gantries because the manufacturer saves costs of the additional motor, amplifier, rails, etc. But YOU pay the penalty of low accuracy.
• Don't get a chassis with rails bolted to the tank - With a dial indicator, you can see that a tank will swell up to 0.015" as the jet cut. Bolting to the tank puts precision rails in a bind. All Romeo Engineering machines have the drive train detached from the tank to prevent distortion.
• Ensure the chassis is ballscrew driven - Romeo Engineering designs include ballscrews which have been certified to be matched sets. Avoid single nut designs or those that use oversize ball bearings or phased tracks. Definately avoid rack & pinion systems are only accurate to around 0.015 inches.
• Get closed loop servo motors only - Do not accept open loop stepper motors. Avoid machines that use servos with so-called "follower rack & pinion" which are just as worse. Try to determine if the vendor knows why they use the motor they use. Their are a lot of brushless and brush motors cog at less than 3 RPM, which is the prime speed for a lot of waterjet cutting. Our power train runs at the speed of light, whereas other brands are limited to conventional clock frequency speed.
• Ensure that the machine is mechanically accurate first and foremost - Do not accept a machine that has been electronic compensated to meet the specification. Electronic compensation is a software trick used to map out position errors. That accuracy will be short lived.
• Witness the accuracy for yourself and get a written report - For quality assurance, all Romeo Engineering machines are checked with one of our high precision laser interferometers capable of measuring sub-micron accuracy.
• Ensure the structure is made of steel - Romeo Engineering's waterjet chassis are built entirely of heavy structural steel and not aluminum extrusion.
• Ensure all guideways are precision machined flat and straight - Romeo Engineering uses the world's largest surface grinder. Our design dictates that the straightness and flatness are permanent features of the rigid structure. Do not accept machines with shims or spacers.

• Ensure that the controller is RS-274 complaint - Our controller follows the United States standard for CNC programming architecture. It is compatible with thousands of CAD/CAM software packages. On the other hand, many competitlve brands use proprietary code that is not supported by any other format. Be aware if a vendor offers you free software upgrades for life. That may be true only until the next operating sytem is released. Then you are stuck with a proprietary machine or forced to buy all new hardware.
• Ensure the controller is right for you - There are "traditional or conventional" type controllers and PC based controllers. Traditional controllers have fast dedicated purpose processors. However, most traditional controllers are adapted from milling machines and do not include special software features desired for waterjet cutting. The vast majority of controllers in the waterjet industry are now PC based because they tend to cost less and are much easier to upgrade as technology changes.
• If the controller is PC based, learn if the controller is a CPU driven or DSP driven - CPU driven controllers are not stable. The Romeo Engineering RE2000NT Waterjet Controller is digital signal processor (DSP) driven using special microchips designed exclusively for servo motion control. Romeo Engineering designed the RE2000NT Waterjet Controller from the ground up dedicated for waterjet cutting. It runs on Windows 2000 platform and includes all sorts of clever software functions exclusively for waterjet cutting.
• Know how large a part program the controller can handle - Romeo Engineering's RE2000NT allows unlimited part program size. Competitive controllers are sometimes limited to less than 5,000 lines; that is simply not enough if you want to scan and cut images.

• Get the specifications about life cutting speeds for abrasive nozzles - KMT Waterjet Systems focusing tubes use a special low binder formula of carbide for long life and wear resistance. KMT Waterjet Systems focusing tubes are also a full 3/8" diameter for durability. Some competitive brands have a small diameter with weak thinner walls, which cause the carbide to fracture easier.
• Get prices up front for technician service and spare parts - Spares include orifices, focusing tubes, valve packing, pump seals, and check valves. Be aware that the bid price may not reflect the long term cost of spare parts.

• Do not accept vacuum orifice feeders - They tend to surge because light particles are drawn first, then heavier particles. The result is more striation and wear on the nozzles.
• Do not accept vibratory feeders - They depend on inconsistent in-coming source electricity voltage and frequency, so they cannot be calibrated accurately. Romeo Engineering uses a special positive displacement abrasive feeder design. It even has a display meter to illustrate the pounds per minute of abrasive delivery. Accurate abrasive delivery is very important because the consumable cost of abrasive is the highest percentage of operation cost. Hence, the more accurate abrasive delivery, the less waste and less cost.

• Determine if the vendor will be able to support you operation over an extended period.
• Does the vendor have a history of rejected machines?
• Does the vendor have used machines available?
• Is emergency service available?

The life of waterjet orifices, seals, and components is directly proportional to the purity of water. The supply water to the intensifier must meet specifications established by KMT Waterjet Systems. A very important parameter is Total Dissolved Solids (TDS), which is an indication of the amount of minerals dissolved in the water. For waterjet cutting, it is desirable to have a TDS around 50 parts per million. Do not reduce TDS below 5 PPM or the water will become too aggressive. The TDS can be measured with a resistivity meter.

At 60,000 psi, water is compressed approximately 14% by volume. Under this immense pressure, dissolved solids are forced out of the solution. Even though water appears "clean", it still contains dissolved minerals. Those minerals act as microscopic abrasive to erode high pressure orifices & seals or to build up grime that plugs up nozzles. This is especially true when using .005 inch or smaller diameter jewels. The following table shows the acceptable level of water quality. Some areas of the United States can use straight tap water. In other areas it may be necessary to condition the water using a simple water softener, reverse osmosis, or de-ionizer. (Note that if de-ionized water is in fact required, then we need know prior to manufacturing the pump because it may require different seals).

To reduce maintenance and increase the life of high pressure orifices, seals, etc, the water supply should comply with the following water quality specifications.

* Do not reduce beyond this amount or the water will become too aggressive.

In many areas of North America, tap water straight from the municipal supply is fine to supply the intensifier pump. Most areas however do have relatively "hard water", which means it contains calcium and magnesium. A water softener is inexpensive and in general will increase the life and performance of the intensifier pump.

When the amount of TDS (total dissolved solids) is too high, then you have two options: De-ionization (DI) or Reverse Osmosis (RO). Do not use a water softener with DI or RO systems. We generally recommended the de-ionizer over reverse osmosis. The benefit of a DI filter is that for every gallon of water input, you get one gallon output. For example, a 25 horsepower intensifier pump requites 0.5 GPM of clean water. That is equivalent to 720 gallons per 24-hour day. A suitable size reverse osmosis unit will have about 35% recovery, so you would expect to loose 1,300 gallons per day down the drain.

The main problem with DI systems is that the resin beads will become depleted and must be regenerated. The regeneration process uses powerful chemicals that you do not want stored on site. Therefore, you typically use an outside company who can regenerate the resin for you.

The majority of impurities in potable water are in the form of disassociated ionized mineral salts such as NaCl and CaCO₃. Because such ions by definition carry an electrical charge, their presence is directly related to the ability of the water to conduct electricity, or resistivity. Hence, resistivity (and its reciprocal conductivity) are the best parameters by which to gauge the purity of water. Resistivity is a measure in ohm-cm and its reciprocal conductivity is measured in mhos-cm or siemens. It is important to realize that resistivity/conductivity is a measure of only ionic impurities and is not affected by particulates, bacteria, or other organic contamination. We usually use a 10k light to indicate when the filter needs to be regenerated.

Proper nozzle size is a function of cutting speed, thickness of material, pump size and cost. In general, larger nozzles will cut faster with a better finish and will cut thicker materials because there is more momentum. However, there is less appreciable gain in speed or quality when cutting thin materials like sheet metal with a larger pump. Also note that 60 and 75 horsepower models are available.

With Romeo Engineering Inc's abrasive feeder (patents pending), you will usually run about 0.50 pound per minute. On thick parts you can choose to flow around 1.00 pound per minute. The meter will flow more, but usually there is no need. If somebody tells you otherwise, then they are either not an experienced user or they want you to wear out the nozzle so they can sell you replacement nozzles! You should see very few grains of "sand" inside the catcher tank. Otherwise all your money is going down the drain. The most common abrasives are garnet and copper slag. Abrasive is typically sold in 60 and 100 pounds sacks. Romeo Engineering Inc deals in bulk volume and can pass those savings along to you. Garnet is a pinkish mineral that is mined all over the world. It is commonly used on sandpaper and it is available in 60 to 120 grit depending on the speed and finish desired. Romeo Engineering Inc does not recommend 50 or 60 grit. It is too coarse to give a good finish and will wear out a nozzle faster. The 80 grit alluvial garnet is very popular. Other types of abrasive are available. Romeo Engineering Inc does not sell or promote silica quartzite.