Waterjet Machining with CMS' Tecnocut Waterjet Solutions
"Machining" is the name which is used to describe a number of various "subtractive" processes in which raw—or semi-processed—material is reduced to a desired final shape and size. As such, a wide range of materials require machining as part of their industrial manufacturing process. Traditionally most "substractive" processes have used a metal cutting tool used by hand, mounted on a machine, or placed in the spindle of a machine to carry out the material removal process.
The first practical demonstration that water pressurized to a very high level, with and without an abrasive, could be an important cutting methodology came about in 1962 by Philip Rice of Union Carbide with the introduction of a waterjet capable of generating a 50,000 psi pressure stream to cut metals, stone and other materials. Following which there has been constant improvement in the technology; until today waterjet cutting technology can be seen at use in almost all the major industries and in cutting almost all manner of metals and materials conceivable.
What is a waterjet?A water jet cutter, also known as a water jet or waterjet, is an industrial tool capable of cutting a wide variety of materials using a very high‐pressure jet of water, or a mixture of water with an abrasive substance.
The term abrasive jet refers specifically to the use of a mixture of water and abrasive to cut hard materials, such as metal or granite, while the terms pure waterjet and water‐only cutting refer to waterjet cutting without any use of added abrasives, often used for softer materials, such as food or rubber.
Waterjet cutting is often used while manufacturing machine parts. It is the preferred method when the materials being cut are sensitive to the high temperatures generated by other methods. Waterjet cutting is used in various industries, including mining and aerospace, for cutting, shaping, and reaming operations.
Why use a waterjet?
A waterjet cutting machine offers many unique advantages over other CNC cutting systems, such as EDM, laser, or plasma. These include the ability to cut virtually any material to thicknesses over 12" and the absence of heat hardening in the cut materials.
- Waterjet cutting doesn't affect a material's basic makeup, it creates no heat along its cut path to affect the material's original integrity
- Waterjet cutting doesn't have the material limitations of other methods, both in variety of material and thickness
- Waterjet cutting can produce remarkably complex cuts with up to 5 axis axes of motion
- Waterjet cutting has a small cut kerf so material loss is greatly minimized
- Waterjet cutting can produce high depth-to-diameter ratio through holes that won't damage threading taps
- Waterjet cutting can achieve high accuracy parts while being able to obtain almost square inside corners when needed
- Waterjet cutting can cut a wide range of materials such as steel, titanium, aluminum, and fiberglass up to 12" thick
Why a Tecnocut waterjet by CMS?
CMS Industries/CMS North America is a manufacturer of complete CNC machining center solutions, including waterjet cutting machine integration.
CMS Tecnocut is the CMS Industries division specializing in manufacturing waterjet cutting machines for the cutting of hard materials and soft goods. Within CMS Industries, CMS Tecnocut is supported by CMS Tecnocut SpA's production and engineering staff. The Tecnocut company was established in 1992 and specializes in the design and construction of leading edge technology for waterjet cutting systems. CMS Tecnocut is among the charter members of AIW (Italian Waterjet Association) and a member of WJTA (Water Jet Technology Association – USA).
CMS Tecnocut's technology advantages include:
- Technologically advanced high pressure intensifier pumps in a range of sizes for waterjet cutting
- High performance 3-axis and 5-axis cutting robots in a broad range of cutting envelopes
- CNC control software and CAD/CAM software packages developed in-house for complete control of the waterjet cutting machine
- CMS Tecnocut's Intelligent Kerf Compensation system (IKC) intelligently manages the cone shape of the waterjet stream and adjusts for this phenomena with CNC control of the cutting wall angle to obtain a precision square cut edge over the full range of material thicknesses, both from the outside and inside of the cut path
CMS Tecnocut's main strengths are:
- Design and manufacture of all major components (including high pressure pumps) at CMS owned facilities in Italy
- Innovative, industry leading high performance intensifier pumps
- In-house design of high performance multi axis cutting robots
- Custom systems to provide solutions for any technological or production issue
- Full in-house support for all system components (including pumps and software)
- Customer service optimized to provide fast and thorough support for our customers
A CMS Tecnocut waterjet cutting machine is ideal for:
- Companies seeking in-house waterjet cutting capabilities from an industrial partner that can supply complete systems with cost effective cutting performance, thorough training, applications advice and 100% 24/7 technical support
- Companies engaged in job shop cutting services that require maximum cutting performance and application capabilities, both in materials and cutting envelope
- Companies requiring a highly productive cutting solution for the manufacture of goods made from soft materials such as rubber, vinyl, foam, and insulation that does not require the use of blades or stamping operations
How a waterjet works
The diagram to the left shows the part of the system related to "pure" waterjet cutting and that added on to create "abrasive" waterjet cutting.
#1 - High‐pressure Water Inlet
High pressure is produced by a pressure intensifier.
#2 - Primary Nozzle (“Orifice”, “Jewel”)
The primary nozzle transforms the water pressure energy into kinetic energy and is made of synthetic sapphire or diamond, with a diameter from 0.2 to 0.5 mm; the water is transformed into a stream with a speed of up to 900 m/s—one traveling over 2,000 mph—depending on the pressure.
#3 - Abrasive
Only used for cutting hard materials.
#4 - Mixing Chamber and Focusing Tube
The mixing chamber and focuting tube is the place where the abrasive particles are mixed with water, accelerated and their path aligned in order to achieve a coherent jet.
#5 - Focusing Nozzle
#6 - Cutting Water Jet
#7 - Cut Material
So then, a waterjet cutting machine operates by supplying up to 90,000+ psi water through a plumbing system to the cutting head. Inside the cutting head, a sapphire, ruby or diamond orifice restricts the high pressure water flow to a diameter ranging from 0.004" to 0.020". This focused stream of supersonic water is capable of cutting rubber, soft plastics, food, insulation, synthetic turf, carpet, and countless other soft materials. As most of these materials are so easily cut, a large number of waterjet systems purchased for cutting soft materials are configured with two or more cutting heads, thereby greatly increasing the production capability of the machine.
Harder materials can be cut when an abrasive powder, such as garnet, is mixed into the stream of water. To aid in this process, the abrasive cutting head incorporates a mixing chamber below the orifice. The flow of high pressure water through this chamber creates a venturi vacuum effect, which in turn draws the garnet powder into the stream. This abrasive-enriched waterjet stream is then re-focused by a mixing tube, which typically has an internal diameter between 0.020" to 0.050". The exiting abrasive stream produces a kerf width that is roughly the same size as the mixing tube ID and is ideal for cutting aluminum, steel, titanium, granite, composites, wood, glass, and many other materials.
Abrasive usage is typically between 0.5 to 2.0 pounds per minute, depending on the orifice/mixing tube combination, garnet mesh size, and the application's requirements.
Cutting Technology Comparison
With the number of CNC cutting methods available to today's fabricator, including EDM, laser, plasma and waterjet based systems, making the correct choice between these technologies can sometimes be daunting. However, when application requirements such as part accuracy, process speeds, and material demands are compared against the abilities of these sometimes competing methods, a careful evaluation will often lead to selecting the best cutting method.
The laser cutting process uses a focused beam of high energy infrared laser light to cut material by selectively vaporizing and melting a highly localized area, while the use of an assisting using an assist gas is used takes place to remove the molten material from the resulting cut. Laser cutting is one of the fastest and most accurate methods for cutting a variety of metals and non-metals. Laser cutters can process 16 gauge stainless steel at speeds up to 400 IPM, while at the same time attaining part accuracies approaching 0.001". Outside of acrylics and wood, laser cutting is mostly limited to non-reflective metals <1" thick.
Plasma cutting uses a controlled electrical arc to create a superheated gas plasma jet. This electrically conductive, ionized gas plasma is hot enough to easily cut through a variety of metals, with part accuracies better than 0.010", which are attainable with the high density torch designs. Plasma cutting systems are most often used when the tight tolerances of a laser cutter (and its higher capital costs) are not required. Plasma cutting is limited to metals and applications not requiring high accuracy cutting.
Waterjet cutting uses a low volume, very thin stream of ultra-high-pressure water for cutting high precision parts. This thin stream of water leaves the cutting head at over twice the speed of sound, and when a small amount of abrasive is added to the stream, it is capable of cutting virtually any material. Waterjet cutters are able to cut soft materials such as rubber gaskets at very fast rates, and with a quick change in cutting heads, thicker materials such as 4" stainless steel can also be cut to part accuracies < 0.002". While waterjet cutting is typically a slower cutting process than laser or plasma it has the advantage of being able to cut virtually any material, it does not heat harden the cut edge (important for tapping holes), and can produce smaller hole diameters in thicker materials.
|Materials Range||Mostly Metallic
|Only Metallic||Any Material|
|Material Thickness||To 3/4"||To 1 1/2"||To 12"|
|Part Accuracy||< 0.002"||> 0.010"||< 0.002"|
|Kerf||=> 0.008"||=> 0.060"||=> 0.020"|
|Cut Edge Micro-Fracturing||Yes||Yes||No|
|Cutting Head Standoff (2D Cutting)||+/- 0.005"||+/- 0.020"||+/- 0.030"|
|Additional Cutting Heads||High Cost / Complex||Med. Cost / Simple||Low Cost / Simple|
|Post-Processing||Slight Hardened Slag||Hardened Slag||Minimal To No Burr|
The triplex crankshaft pump uses technology that is similar in operation to an old style flywheel press brake. Much like in a combustion engine, it uses alternating pistons to compress water in pistons that are coupled to a crankshaft, which is in turn connected an electric motor, usually through a belt. In short, the design operates in a similar fashion to the standard pressure washer, albeit at a much higher pressure level.
While this design is inexpensive to build, it has a major shortcoming: it does not deadhead—that is, it requires a continuous flow of high pressure water from the pump while running to prevent catastrophic failure. This makes the high pressure plumbing more complicated; it requires an additional high pressure valve to shunt high pressure water flow into the cutting tank when the cutting head valve is closed. These designs also typically require maintenance at a much higher rate than hydraulic intensifiers.
Inline Hydraulic Intensifier Pumps
Inline Hydraulic Intensifier pumps work at levels of up to 60,000 psi. This hydraulic ram is caused to oscillate from side to side through the use of a switching mechanism, which can be either mechanical or electrical.
A holding tank, called an attenuator, is required on the output to reduce pressure variations in the water being supplied to the cutting head. Electric motors in the range of 15 hp to 150 hp are most often used to power the hydraulic pump that drives the intensifier section. While this design is not as mechanically efficient as a crankshaft pump, it tends to be more reliable and require less maintenance.
Parallel Hydraulic Intensifier Pumps
CMS Tecnocut pioneered parallel pump technology. The parallel intensifier pump operates in a similar fashion to the inline pump, but offers a key advantage: the hydraulic cylinders operate in a parallel fashion, which means one cylinder is always in compression mode. This parallel operation minimizes pressure fluctuations and eliminates the need for the attenuator vessel while also improving pump efficiency and reliability.
When evaluating the purchase of a waterjet cutting machine, it's important to consider the following:
Waterjet systems require 3 phase electricity (typically 480VAC) with enough amperage to power the high pressure pump.
Cutting Water Supply:
The high pressure pump will require a high quality water source to ensure the longest lifetimes for its internal components.
The cutting head will require a clean source of 80 PSI air up to 6 SCFM for its operation.
Cutting Room Environment:
A waterjet cutting machine will produce a fine abrasive dust that will coat the surrounding area. Care must be taken to ensure that any surrounding equipment is not negatively affected by this dust.
The waterjet cutting process can generate a fair amount of mud/debris, which requires that the cutting tank be emptied from time to time. EPA and local disposal regulations may need to be addressed if the waterjet system will be cutting materials that may appear on an environmental watch list.
Overflow Water Drainage:
Depending on the size of the pump, a waterjet cutting machine can generate over 2 GPM of overflow water from the cutting tank. Local regulations may require this overflow water to be processed before being released into the drainage system. The buyer should check the local water regulations in regards to the anticipated materials being cut. One option to address this issue is the addition of a closed loop water system for the waterjet installation.
Cutting Water Requirements:
In a waterjet cutting machine, the high pressure pump represents a large capital investment. Considering this cost, it is in the system owner's best interest to extend the life of the pump's internal components for as long as possible. Even under the best of circumstances, the pump will require routine maintenance which includes the replacement of seals, check valves, valve points, filters, and other components. As parts for this routine maintenance can cost several hundred dollars, it is desirable to maximize the time between servicing in order to minimize the operating costs associated with routine maintenance. The quality of the water being supplied to the pump is the single most important factor for extending the life of the pump and in maximizing the time between servicing.
Desired Levels For Water Purity:
|PH Value||From 6.5 to 8.5|
|Suspended Particles||Filtration To 0.5 Microns|
|Total Dissolved Solids (TDS) *||< 50 PPM (Maximum 150 PPM)|
|Iron||< 0.2 Mg/L|
|Calcium||< 25 Mg/L|
|Chloride||< 100 Mg/L|
|Sodium||< 50 Mg/L|
|Sulfate||< 25 Mg/L|
|Silica Content||< 15 Mg/L|
|Hardness (CaCO3)||< 25Mg/L|
Methods Of Water Treatment:
- Ion Exchange (softening)
- Reverse Osmosis (RO)
- De-Ionization (DI)
- Particle Filtration
* Water treatment producing TDS (Total Dissolved Solids) content of less than 0.5 ppm is NOT recommended since the aggressiveness of the purified water may damage pump components.
1 PPM = 1 Mg/L (milligrams per liter) = 1000ug/L (micrograms per liter)
Waterjet cutting quality
Waterjet cutting quality is defined by numbers between 1 and 5, where the higher number (5) defines the best quality and the lower (1) defines the lowest quality.
The quality of waterjet cutting is directly influenced by the cutting speed. The higher the cutting speed, the lower the cutting quality, both in terms of surface finish (roughness) and in terms of the kerf of the cutting groove.
In the figure below, the differing legs of the piece have been cut using the same length of cutting time, but with different cutting speeds, resulting in a different cutting quality.
Cut quality is conventionally defined through a variable value from Q1 to Q5.
Mechanics / Workshop / Job shops / Sub‐contractors
The workshop can take advantage from the use of waterjet cutting for its ability to cut a wide range of ferrous materials and non‐ferrous, with significant thickness, yielding a cut surfaces which is easy to reprocess, in some cases already finished as well as for possibility of using cutting optimizers which can "nest" parts within other parts and thus improve overall part yield.
Production of semi‐finished and finished products of stainless steel and aluminum for the architectural sector (interior and outdoor). Production of steel furniture for professional kitchens.
In the pictures below, the 3,000 m² screen with forest motive design, over 70 different door types, 1,400 m glass parapet, of the Dolder Hotel in Zurich, manufactured by CSTLL for the fitter FRENEL & REIFEL, by using the Tecnocut cutting robot.
The production of technical items can take advantage from the use of waterjet cutting for its high flexibility—the ability to cut very complex shapes, materials with significant thickness, bevel cuts using 5 axes.
A waterjet makes it possibile to achieve high productivity at reasonable cost, while allowing for optimization of "nested" parts cutting.
Waterjet cutting in this sector covers the production of:
- gaskets, sealing strips, insulation material and specific packaging made of foam
- articles made of foam for: home, sports, car, leisure, construction, industry and trade
- insulating parts for building and industry
- industrial seals, made of various materials: rubber, foam, metal, graphite, insulation materials.
In the aerospace sector waterjet cutting is particularly suited for the cutting of metal parts in aluminum, titanium, stainless and hardened steel, zirconium, inconel, copper, brass, alloys (especially alloys with high heat resistance), of parts made of glass, and parts made of plastic or composite materials: all of this due to its versatility, the absence of thermal alteration, the ease of rework of the surfaces obtained and the possibility of cutting optimization.
The Tecnocut waterjet 5‐axis solution makes possible optimal cutting of some metal parts – such as inconel disks – and of parts made of foam – for example, for insulation.
Tecnocut waterjet cutting with 5 axis control is also important for machined parts made up of various mechanisms: supports, brackets, control panels, turbine blades (blanks), skin, struts, seats, brakes, and landing gears.
Automotive, Agricultural Tractors, Heavy‐Moving Machines, Railway
In the fields of transport vehicles and work waterjet is used to cut flexible parts made of plastic material, parts of copper, aluminum, titanium. The advantages it provides are: the ability to perform complex forms, difficult to work with other technologies (for examploe, inner corners and holes with very small radii), cut edges finished well, allowing easy rework of the pieces, a good balance between cost and productivity. In the pictures to the side, a motor‐stator flange made by copper and an aluminum net for silencers.
In the railway sector waterjet is used to cut structural parts, engine parts, control panels, various mechanical parts. The cut materials are laminates, rubber, plastics, stainless and hardened steel, heat sensitive materials, zirconium, titanium, inconel.
The main advantages of waterjet technology in the medical field are its high flexibility combined with a modest investment, the ability to cut special metals, without thermal alteration, obtaining a cut surfaces which is easy to reprocess, in some cases already finished, and the time savings for subsequent processing by machine tool, together with the possibility of using "nested" part cutting optimization.
In the field of defense waterjet is used to cut structural parts, control panels, mechanical parts made of laminates, rubber, stainless and hardened steel, heat sensitive materials, titanium, copper, brass, alloys.
Waterjet's cutting advantages here are its ability to cut a wide range of materials, even with significant thickness, obtaining cut surfaces which are easy to reprocess, and in some cases already finished and as well the possibility of using "nested" part cutting optimization.
In the marine industry waterjet is used to cut structural parts, control panels, mechanical parts, interior furnishing. The materials treated are plastic and composite materials, rubber, glass, stainless steel, aluminum, copper, brass.
The advantages of waterjet cutting in this sector are its versatility, its ability to cut a wide range of materials, its ability to cut material with a significant thickness and the possibility of using cutting optimizers.
Tecnocut Technology Overview
Cutting with a water jet or waterjet cutting is a technology that uses a very high-pressure jet of water (up to 7,000 bar) to cut many types of materials.
The energy necessary for cutting is obtained by concentrating through a suitably calibrated hole, a flow of water up to a pressure of 413.7 MPa (60,000 psi) that produces a coherent jet of water projected at twice the speed of sound. The jet, to which can be added abrasive material if needed for cutting materials which "pure" water cannot cut, is directed against the surface of the workpiece and determines the separation of the parts through a dual action—combined erosion and abrasion.
Pressurizing water is achieved by a special volumetric pump hydraulically driven called an "ultra high pressure intensifier", the true heart of waterjet technology, which produces high-quality cutting as well as a fast and precise processing of all materials, even long complex shapes, bringing about the creation of the cut surface as well as its good surface finish, free from any processing residue.
Waterjet technology reduces the waste of material removed for the separation of parts and facilitates the optimization operation of the slabs (nesting).
The advantages resulting from waterjet technology are several: short time to immediate production, advantageous in the processing of all materials in which any thermal or mechanical stress may affect the physical-chemical characteristics, non-polluting: the absence of fumes or powders ensures a comfortable working environment—risk-free.
Tecnocut Overview - The force of water shapes idea
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