FAQ – Micro abrasive waterjet

 

 

Here we have gathered the most frequent questions we get about micro abrasive waterjet technology and our product. Do you have further questions not answered in the list, please get in contact with us – we are happy to tell you more!

The Finceut WMC500II can cut virtually all materials such as wood, rubber, glass, metal alloys, engineering ceramics, carbides, combined materials etc. It can also cut combined materials with complex structures like sandwich materials like carbon fibre reinforced plastics with honeycomb. Harder materials such as alumina or zirconia generally require harder abrasive material to obtain an efficient cutting process.
- Hardened glass cannot be cut as it has a stress balance where any disturbance will make it crack. - Diamond is difficult to cut due to its extreme hardness. Theoretically, it can be cut but it requires an abrasive material in the cutting process that is extremely hard which will give impractically short life length of the focus tubes currently available.
Soft materials can sometimes be cut with pure water. Drop erosion can actually quite quickly erode through a 1 mm steel sheet. At elevated pressure (6000 bar) trials show possibility of cutting of 3 mm titanium. Anyhow, most dense materials of higher strength will require that you add abrasive material in the jet in order to be cut efficiently. Water itself is not erosive enough to quickly remove material and cut through, the particle erosion from the abrasives makes the cutting process more aggressive. You can use abrasive of different materials and sizes and you need to select the abrasive with respect to how hardness of the material you intend to cut, the size of the focus tube etc.
- The micro abrasive waterjet cutting system is optimized and scaled down which entails the possibility to work with a kerf down to 0.2mm. With the small kerf you are able to cut complex, narrow geometries. - Micro abrasive waterjet cutting requires a very stable and precise machine. Finecut WMC500II has a motion system which is mechanically linked to the workpiece. Hence, the rigidly linked system will be less sensitive to external influence. A traditional setup with the workpiece being clamped on a separate table and the motion system generating the cutting path being part of another structure add a risk of errors generated from relative motion between the structures caused by external disturbances. - Microwaterjet consumes significantly lower flows of water and abrasive material. Although precision powders are more expensive the low consumption makes the total cost lower while the added value to the products can be higher. - Traditional abrasive waterjet is more powerful and can cut thicker materials, but is typically rougher and used in applications which require less precision.
The speed of cutting depends on material properties and thickness of the material you want to cut. The harder and thicker the material is the slower you need to cut. If you want smooth, fine surfaces the cutting speed need to be reduced. The Finecut WMC500II can move the cutting head with a speed of 20 meters/minute but it is very few material that actually can be cut with this speed. As with any abrasive waterjet cutting speed till affect the quality of the cut. To make an example the FAW300 cutting system can make a separating cut in 3 mm thick stainless steel at 300 mm/min. but more typically 60 mm/min or even 30 mm/min are used depending on the application and precision requirements.
Yes, the Finecut WMC500II can be used for milling purposes. In fact milling capability has been one of its design critera. The encapsulated design and powerful direct drive motion system make it suitable for milling. The control system allows dual servo parameter By selecting appropriate nozzle combination, water pressure, abrasive flow and controlling the traverse speed of the jet you can choose if you like to cut through or only remove material to a desired depth. 3D surfaces can be achieved by scanning the over the surface. The highly dynamic motion system allows for variable depth control by speed variation while traversing over the work. There are several different approaches to milling strategies.
The thicker and harder the material is, the slower you can cut. It means that you can cut thick material but the process will be slow. If you increase the waterjet size and the size of the focus tube, the flow of water and abrasive will increase and the cutting will go quicker but it will still be difficult to meet high tolerances for parts cut of thick materials. We generally say that the FInecut WMC500II is suitable for cutting materials up to 30 mm thickness but there are always exceptions depending on material properties and quality requirements. If you need to cut thicker parts you can fit an AWJ cutting system in the machine. The limit for cutting thin materials will depend on how you can solve the fixturing and material handling. The Finecut WMC500II generate very low cutting forces but still thin material might move only by the airflow around the jet and need to be fixtured somehow. The machine itself has no limit in how thin materials that can be cut.
The Finecut machine requires a controlled environment to fully take advantage of its precision capability. The temperature should not vary much and preferably be kept around 20 C. The fine abrasive powders are sensitive for moisture and should be kept in dry air. The machine has adjustable rubber damped feet but the floor should not vary more than ca ±10 mm beneath the machine. The machine has a small footprint and does not affect the near environment. We have customer applications where the Finecut stand side by side with high precision milling centers. The pump can be placed in a separate room. As the consumption of high pressure water is low the effect of distance between pump and machine is not a problem. The machine need a supply of electric power, pneumatic air (6.5 bar, dry and oil free) and water. Good water quality is essential for the operation. We can supply water treatment if it is needed. As the process use water there will be a continuous water flow to the drain. The machine should preferably also be connected to a ventilation system to extract mist from the work area.
Water generally contains both minerals in solution and particles. Particles need to be removed as they can damage pump seals (scratch) as well as the jewel orifice that creates the high supersonic water jet. To obtain an efficient jet the jewel orifice need to have a circular sharp edge. Particles being accelerated towards the jet emanating from the orifice strikes and damages the edges with detrimental effect on the jet performance. Upon pressuring the water some soluble materials will solidify and will then become particles that damages the components in the same manner. Solidified material can also cause build-up on orifice edges that changes the jet geometry.
The focusing tubes wear conically from the top down. This make them stay quite stable in dimension until the wear cone approaches the end of the focusing tube. The life time depends on orifice size and pressure (jet power), diameter ratio, amount and type of abrasives used and the length of the focusing tube. The FAW300 focusing tubes are often used about 100 hours. The limit where our customer stop using them depend on the practices and demand for precision.
No, you do not need experience from waterjet cutting nor experience from CNC programming or others. The Finecut WMC500II has a unique intuitive HMI (human machine interface) which is very easy to learn, use and operate. The interface is modern with apps and symbols you know from your daily life.
As all machines some care must be taken to make sure the machine will run without unintentional stops. It is a precision machine and it will serve you well if you should treat it with care. Most important tasks are: - Make sure you keep the abrasives dry – always close the containers after filling. - Keep the machine clean to make sure any buildup of abrasive will not affect your fixturing or your machines motion. - Check the high pressure connections for leakage. In case drops are forming even a fine leakage create a high velocity stream that can quickly erode the stainless steel couplings. - check that the water treatment (if you needed one) is activated and has not run empty. It is always a good idea to end the day by cleaning and inspecting the equipment.
The micro abrasive waterjet is a non-thermal cutting process. On a micro scale the erosion mechanisms upon contact create momentarily very localized heat but it is continuously cooled by water and will not create heating that change material properties. When the jet cuts through the material a large part of the energy remains and need to be dissipated. A catcher tank below the work table absorbs the kinetic energy from the jet by agitating the water in the catcher tank. This creates some heat and dipping your hand in water of the catcher tank by the end you will feel that it is luke warm. In general this does not have significant influence on the machine performance. An optional water cooler system can be installed to take care of the heat in some cases. However, in general this is not required.
Yes, all our options can be retrofitted. Customers that decide to buy a Finecut WMC500II can be sure that they can add existing options later on and they can also benefit from new future developments.

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