Water jet cutting is a revolutionary process that can cut through various materials with high precision and minimal heat damage. One key factor determining the performance of water jet cutting is its speed.

In this article, we will examine how speed affects water jet cutting and the relationship between speed, cut quality, and surface finish. We will also compare water jet cutting speed with other cutting methods. So, let’s begin.

What Is The Cutting Speed Of A Water Jet?

The pump’s power primarily determines a water jet’s cutting speed. The greater the power, the higher the speed of the waterjet cutting machine. Our typical waterjet cutter operates within a pressure range of 40,000 to 60,000 psi (psi is the measurement of pressure). 

At a pressure of 40,000, water is jetted out of the nozzle at a speed of approximately Mach 3 (760 m/s). To effectively cut through materials, the water is discharged at a speed exceeding Mach 3 (1020 m/s) when the pressure is increased to 60,000 psi.

What Factors Affect Water Jet Cutting Speed?

Water jet cutting is a highly efficient method used in various industries for precision cutting. The water jet machine’s speed depends on several factors that are crucial in determining the cutting speed. Here are the important elements that influence the speed of water jet cutting:

Pressure

The pressure of the water jet machine is a critical factor influencing the cutting speed. The higher the pressure, the faster the water velocity, which directly increases the cutting force.

The speed of the water is primarily determined by the high-pressure pump used to accelerate its flow. Increased pressure can also improve the quality of the kerf section, resulting in better cutting results.

Used Abrasives

The abrasive size, quality, and quantity in water jet cutting also affect the cutting speed. Abrasives with higher hardness offer faster cutting speed. The industry standard abrasive is garnet with an 80 mesh size.

However, garnet itself comes in various grades and variations. For optimal cutting results, it is wise to use garnet with a fine grain and good homogeneity.

Nozzle Diameter

The diameter of the nozzle used in water jet cutting plays a significant role in determining the cutting speed. A larger nozzle diameter allows more water to flow through, increasing the water’s eroding power. However, using a large nozzle may make it harder to maintain the very high pressure of the water jet stream.

For instance, cutting a 5 mm sheet of aluminum with a 0.007″ diameter nozzle can be done at around 15 inches per minute, while using a 0.014″ diameter nozzle can increase the cutting speed to approximately 40 inches per minute.

It is important to note that a larger nozzle diameter results in more water and abrasives flowing per minute, which can increase the overall cost of the process.

Material Thickness

The thickness of the material being cut is an important factor affecting the water jet cutting speed. In general, the cutting speed decreases as the material thickness increases. For instance, a water jet cutter can cut a 6 mm thick stainless steel sheet at a speed of 6 inches per minute.

However, cutting a 20 mm thick stainless steel sheet with the same cutter and nozzle diameter may reduce the cutting speed to around 2 inches per second. Thicker materials require more cutting force, ultimately resulting in a slower cutting speed.

Malzeme Türü

Different materials have varying physical characteristics, affecting a water jet’s cutting speed. Soft and porous materials are easier to cut, while tougher materials take longer.

For example, a typical water jet cutter can cut a half-inch thick glass at a speed of 12 inches per minute. On the other hand, cutting a half-inch thick titanium sheet with the same cutter may reduce the speed to 6 inches per minute.

Water Flow Rate and Water Quality

The water quality used in a water jet system significantly impacts the cutting speed. Impurities in low-quality water can clog the nozzles and tubes of the machine, leading to a slowdown in the cutting process and equipment failure. Using treated water ensures faster cutting and increases the lifespan of the equipment.

Additionally, adjusting the flow rate of the water can affect the cutting speed. A higher flow rate results in a faster cutting process due to increased eroding force.

However, a higher flow rate may also lead to faster component deterioration and increased operating costs. Finding the optimal flow rate requires testing different rates on various use cases.

Angle of Taper

The taper angle has a minor effect on the cutting speed in water jet machining. Sharp angles can accelerate the cutting process, while low taper angles may slow it down.

However, it is important to note that steep angles can compromise the precision of the cutting. Therefore, balancing speed and accuracy is crucial when considering the taper angle.

Length of Focusing Tube

The length of the focusing tube has an adverse relationship with cutting speed. The water jet stream’s velocity decreases as the tube lengthens.

In turn, this causes the accuracy and cutting speed to decrease. Both precision and cutting speed are maintained with a shorter tube.

Cutting Style

The quickest cuts are those that are straight. The cutting speed is reduced as the water jet cutting head must stop and then move once again to accomplish a 90-degree rotation.

Using rounded edges rather than sharp ones is the greatest technique to increase cutting speed. By doing this, the machine can continue cutting around the bend without pausing.

Operator Experience

Skilled operators may set up the machine for optimum cutting quality and speed. It sometimes takes time for inexperienced operators who are new to the procedure to set up and understand the results along the way.

Unskilled workers may need some time and plenty of trial-and-error to optimize the process for speed. As a result, if high-speed cutting is your priority, ensure a qualified person is using the machinery.

Electrical Grid Stability

Even when the water jet equipment is operating flawlessly, manufacturers often notice a decrease in cutting speed. The equipment’s power supply fluctuates, which causes this to happen.

The equipment itself may also be harmed by these variations, which further reduce the cutting speed. Make sure your power grid is steady for a quicker and more efficient functioning of the water jet.

The Relationship Between Waterjet Cutting Speed, Cut Quality And Surface Finish

The relationship between waterjet cutting speed cut quality, and surface finish is crucial. Two notable characteristics of waterjet technology that directly affect the outcome are stream lag and taper.

As cutting speeds increase, stream lag, which refers to the delay between the initial contact of the waterjet stream and the material being cut, becomes more pronounced. Cutting too quickly can result in a stream lag that negatively impacts the overall cut quality.

Moreover, the speed at which the cut is performed can also influence taper, which is the variation in the width of the cut from top to bottom or vice versa. When the cut speed is too slow, a taper can occur. This affects the surface smoothness by creating a cut that is wider at one end compared to the other.

How Waterjet Cutting Speed Compares To Other Cutting Processes?

When comparing the cutting speed of waterjet cutting with other methods, it’s crucial to consider the type of material being cut, its thickness, and the required quality. Here’s a general comparison:

Waterjet vs. Laser Cutting

Laser cutting is typically faster than waterjet cutting. However, laser cutting generates heat, which may cause thermal damage or deformation in certain materials.

Waterjet cutting, which is a cold-cutting process, avoids this issue, making it a better choice for heat-sensitive materials.

Waterjet vs. Plasma Cutting

Plasma cutting is generally faster than waterjet cutting for materials that it can handle effectively, including metals like steel.

However, like laser cutting, plasma cutting can cause thermal damage. Furthermore, plasma cutters may struggle with precision cuts on thinner and non-conductive materials, unlike waterjet cutters.

Waterjet vs Wire EDM

Wire EDM (Electrical Discharge Machining) is a method that uses electrical discharges to cut through materials. While precise, it’s generally 10 times slower than waterjet cutting, especially for thicker materials.

Additionally, EDM can typically cut conductive materials, while waterjet cutting can handle a broader range of materials.

Sonuç

Water jet cutting speed is a critical factor that can make or break your cutting operations. As you now understand the factors that affect cutting speed and you can optimize it accordingly. Ultimately, you can achieve higher productivity, improved cut quality, and cost savings. 

However, you need to select the right type of machine and train your staff on how to use it safely and efficiently. Why not Bize ulaşın to handle it for you? We will help you find the best waterjet cutting solution for your needs.