The cutting speed of a process is a good way to measure its efficiency. Many professionals often ask about the waterjet cutting speed since it is one of the most popular commercial cutting processes.
An idea of waterjet cutting speed can better show how it fares against other cutting alternatives. Additionally, manufacturers can estimate their productivity output based on the speed parameter.
Therefore, this article will go into detail about waterjet cutting speed. You will also learn about the various parameters that affect this value.
How Fast Can a Water Jet Cut?
Waterjet cutters can cut at a speed of 15 cm per minute on average. The speed of cutting is variable and dependent on many different factors. For a better perspective, an alternative cutting technology, such as Electric Discharge Machining (EDM), cuts at around 1 cm per minute.
How many inches per minute can a water jet cut?
The average cutting speed of a water jet cutter is 12 inches per minute. The common range falls between 12 to 15 inches per minute. However, that is not the maximum speed of these cutters. For softer materials like marble and glass, water jet cutters can cut at a speed of astonishing 90 inches per minute.
What are the Factors That Influence Water Jet Machine Cutting Speed?
Many factors play a crucial role in determining waterjet cutting speed. These factors are:
Material thickness is the primary factor that determines the waterjet cutting speed. Cutting speed is inversely proportional to the material thickness. Therefore, when the material thickness increases, the cutting speed decreases. For instance, consider a waterjet cutter cutting stainless steel sheet of 6mm thickness at 6 inches per minute. The same cutter with the same orifice diameter will cut a stainless steel sheet of 20 mm thickness at around 2 inches per second.
Type of Material
The type of material also dictates the cutting speed of the waterjet. Different materials have different physical properties. Some materials are soft and porous. Other materials are extremely hard. Materials with poor machinability lead to slower cutting speeds of the water jet.
To take the variation of the type of material on cutting speed, let us compare stainless steel and marble. A common waterjet cutter can cut half an inch thick glass at 12 inches per minute. At the same time, the cutter will cut half an inch thick titanium sheet at the rate of 6 inches per minute.
The abrasive’s quality, amount, and size influence the cutting speed. Abrasives with a high hardness provide a faster cutting speed. The standard abrasive is garnet with a mesh size of 80. There are many different varieties within garnet itself. Fine-size garnet with high uniformity provides the best cutting results.
There is a wide range of water pressure used in industrial waterjet machines. A lower pressure does not mean you cannot cut harder materials. However, a lower pressure makes cutting slower. High-pressure machines speed up the cutting process for harder materials.
An important thing to keep in mind is that beyond a certain point, the cost of the equipment will increase exponentially with an increase in pressure. This is why 90,000 psi pumps are available in the market but not as common as 60,000 psi. Higher pressure also leads to faster wear and tear of the waterjet equipment.
Higher nozzle diameter leads to a faster cutting speed. A larger nozzle diameter allows for more water volume to pass. This leads to a greater eroding force of the water. The nozzle diameter can be increased within certain limits. This is because the ultra-high pressure of the waterjet stream will be difficult to maintain with a wide nozzle.
To compare the effect of nozzle diameter on cutting speed, let us take the example of aluminium cutting. A 0.007″ diameter nozzle will cut a 5 mm sheet of aluminium at around 15 inches per minute. A 0.014″ diameter nozzle can provide a cutting speed of around 40 inches per minute.
A wider nozzle will also mean more water and abrasives flowing per minute. This will pile up the cost of the entire operation.
Water quality also affects the cutting speed of a dynamic waterjet system. This fact is unknown even to many professionals. Poor quality water contains impurities which can get clogged in the waterjet tubes and nozzles. This reduces the speed of the waterjet system and increases the equipment breakdown rate. Therefore, using treated water is a good way to ensure faster cutting and longer equipment life.
Water Flow Rate
Modern waterjet machines come with a flow rate adjustment system. A higher flow rate leads to a faster cutting operation. This is because more water passes out of the nozzle every minute, leading to a higher eroding force. However, a higher flow rate also means that there will be accelerated wear and tear of the components. It can also increase the operational cost of the cutting process. Using various flow rates on different use cases to find the sweet spot is the best way.
Straight cuts are the fastest to make. 90-degree sharp corners decrease the cutting speed because the waterjet cutting head needs to stop and then move again to make the turn. The best way to optimize cutting speed is to use rounded corners instead of sharp corners. This ensures that the machine can keep cutting through the corner without stopping.
Focusing Tube Length
The cutting speed is inversely proportional to the focusing tube length. A longer tube reduces the speed of the waterjet stream. This, in turn, lowers the accuracy and the cutting speed. A shorter tube maintains both the accuracy and the cutting speed.
The taper angle plays a slight role in the cutting speed. Steep angles increase the cutting speed. Meanwhile, low taper angles reduce the speed. It is important to note that steep angles reduce the accuracy of waterjet machining. Therefore, you will have to find a sweet spot between speed and accuracy regarding the taper angle.
Spending a little time ensuring proper workpiece fixtures can improve the cutting speed and quality. Proper fixtures eliminate any chances of movement of the workpiece and secure it firmly. Besides a faster cutting speed, this also increases the safety of the cutting equipment.
Cutting perpendicular to the material’s grain can lead to a faster cutting speed. This is due to the internal geometry of the materials.
Nozzle wear is a common phenomenon in waterjet cutting. This is due to the extremely high pressure handled by the nozzle. A worn-out nozzle reduces the waterjet operation’s accuracy and cutting speed. This is due to the poor focusing ability of the worn-out nozzle. This can be easily eliminated by following proper maintenance measures for your waterjet equipment.
Abrasive Flow Rate
A higher abrasive flow rate leads to a significantly faster cutting operation. This is because, in abrasive waterjet cutting, the cuts are done by abrasive instead of water. Therefore, increasing the abrasive flow rate leads to a higher cutting rate. However, this also increases the cost of the operation due to higher abrasive consumption.
Waterjet nozzles are designed with advanced engineering to suit different manufacturing goals. For instance, there are specific nozzles for faster cutting operation and nozzles for high-precision cutting. If the cutting speed is your primary concern, using a nozzle designed for faster cutting could be better.
Cutting Head Wear
Cutting head wear and tear has a similar effect as nozzle wear. A worn-out cutting head will reduce the accuracy and speed of the waterjet operation. Therefore, following proper maintenance measures can be a great way to ensure the fastest possible cutting speed.
Workpiece Material Variability
Every material has a degree of internal imperfection. This could be little voids or major internal cracks. These imperfections can affect the cutting speed. Calculating the exact speed varies based on internal geometries can be hard and unpredictable. Using better quality material is a good idea to ensure consistent cutting speed and quality.
Power Grid Stability
It is common for manufacturers to see a drop in cutting speed even though the waterjet equipment is working perfectly. This occurs due to fluctuations in the power supply to the equipment. These fluctuations not only drop the cutting speed but can also damage the equipment itself. Make sure you have a stable power grid for a faster and smoother waterjet operation.
Experienced operators know how to set up the machine for optimized cutting speed and quality. Inexperienced operators unfamiliar with the process often take time to set up and learn the outcomes along the way. It can take some time and a lot of hit and trial for unskilled operators to optimize the operation for speed. Therefore, if high-speed cutting is your priority, ensure that you have a skilled operator working the equipment.
How Does Water Jet Cutting Speed Impact Cut Quality and Surface Finish?
A slower cutting speed usually leads to better cutting accuracy. The relationship between waterjet cutting speed and surface quality is also the same. A slower cutting process can provide a better surface finish. Therefore, while faster waterjet cutting can lead to higher productivity, the outcome might not be as accurate as you desire. Try the machine at different settings and use a speed-accuracy parameter that perfectly meets your requirements.
High-speed cutting is one of the characteristics of waterjet technology that makes it preferred by manufacturers. An important end note regarding cutting speed in waterjet applications is using stacking. You can stack multiple workpieces and cut them together, exponentially increasing speed. Additionally, a high-quality waterjet cutter ensures you get a good and consistent speed throughout the operation.
Techni Waterjet machines are the best in this regard. Multiple models are available, so you can choose one that meets your requirements. All Techni Waterjet machines come with complimentary software to provide cutting processes at the click of a button.