There are many cutting techniques in manufacturing with CNC waterjet cutting and CNC plasma cutting being one of the most common. These processes play an important role in many industries from medical and construction to automotive and aerospace. Though they may appear similar, they have unique benefits and produce different results.
Using the right CNC cutting metal operation makes all the difference. The process you use will determine the cut quality and result. Are you looking to use CNC waterjet cutting or plasma cutting for your project? Then, you are in the right place. This article will break down how each technique works for you to determine the most appropriate one.
What is CNC Waterjet Cutting
CNC waterjet cutting is a computer-controlled process that uses highly pressurized water to cut through materials. Based on the type of material and the thickness level, you can also add abrasives such as garnet or aluminum oxide to enhance cutting efficiency and accuracy. The process of CNC waterjet cutting begins by creating the design and programming the cutting path. You then select the appropriate nozzle and cutting pressure. As the water and abrasive material leave the nozzle, they result in a cutting action using erosion and external forces.
Pros and Cons of CNC Waterjet Cutting
CNC waterjet cutting is an important process in manufacturing because of its many benefits. You stand to gain the following when you use a CNC waterjet cutter.
Accuracy and Precision
CNC waterjet cutting produces accurate and uniform cuts without flaws. This technique can achieve tolerances as low as +/- 0.005 inches because of the precise movement of the nozzle. CNC waterjet cutting can create complex designs that would have been difficult with conventional methods.
No Heat Affected Zone
The cutting tools in CNC waterjet cutting are water and abrasives. It does not cause heat-affected zones because it is a cold-cutting process. The absence of heat prevents potential damage and thermal distortion. The base metal retains its shape and original properties even after the cutting action.
Material Compatibility
CNC waterjet cutting is suitable for many engineering materials. All you need to do is adjust appropriate parameters based on the material you are working with. CNC waterjet cutting can cut through metals, plastics, rubber, and foam. You can also use it for glass, ceramics, granite, and cloth.
CNC waterjet cutting also has some disadvantages. The following are some limitations of this process
Costs
CNC waterjet cutting comes with a high initial investment. Small and medium-scale businesses may not be able to afford it. Furthermore, the cost of operating and maintaining the machine is on the high side. You need to properly maintain the machine and replace the abrasive material frequently to prevent downtime.
Material Thickness
You may find it challenging to cut thick materials with this technology. It is easier when working with 9 inches or less. Note that the thicker the material, the more time and energy you spend cutting. Additionally, the quality of the cut decreases as the material thickness increases.
What is CNC Plasma Cutting
CNC plasma cutting is a thermal process that uses a high-energy ionized gas known as plasma to cut through electrically conductive material. You carry out plasma cutting by passing an inert gas, usually nitrogen, through a nozzle. When the power source is on, an electric arc forms between the workpiece and the nozzle. The arc ionizes the gas creating an accelerated jet of hot plasma. The plasma arc melts and evaporates the material resulting in a cutting action. Simultaneously, you use an inert shield gas to blow off the molten metal and protect the workpiece. CNC plasma cutting is fast and you can use it for complex projects.
Pros and Cons of CNC Plasma Cutting
The following are some advantages you get from using the CNC plasma-cutting process
High Cutting Quality
CNC plasma cutting produces high-quality and clean cuts. You have precise control over the torch and can concentrate the plasma arc accurately. This process requires low heat input and results in a small heat-affected zone.
Speed
The speed of CNC plasma cutting is second to none. It is faster than other cutting techniques as you can cut at a very fast rate. This feature makes CNC plasma cutting suitable for the mass production of parts.
Repeatability
CNC plasma cutting is repeatable and you would get the same result over and over. The final cuts are consistent as long as the parameters such as amplitude, speed, and gas coverage remain the same. This ensures that the parts within a batch closely resemble each other.
Some shortcomings of CNC plasma cutting include
Conductive Materials Only
You can only use CNC plasma cutting for conductive materials. Conductive metals like aluminum and steel readily ionize to create and maintain the plasma arc. They readily transfer heat and electricity to result in a smooth and clean cut.
Noise and Fumes
CNC plasma cutting operation can be noisy as the arc generates a loud hissing sound. Furthermore, the vaporized metal during the process is a potential source of dust and fumes. This is why it is important to ensure proper ventilation and use noise-reducing enclosures when working with a plasma cutter.
Comparison of CNC Waterjet Cutting and CNC Plasma Cutting
There is no straightforward approach to choosing the best between CNC waterjet cutting and plasma cutting. Knowing the major differences between the two techniques can serve as a starting point. Waterjet and plasma cutting differ in the following ways.
Material Thickness
The thickness of the material in question is a major determining factor. You should go for CNC waterjet cutting when working with thick materials. This technique can cut through 9-inch thick metals and plastics. On the other hand, CNC plasma cutting may be the most appropriate for metals that are 1-2 inches thick.
Part Tolerance and Accuracy
You can also differentiate between waterjet cutting and plasma cutting based on the tolerance level each process achieves. Waterjet cutting produces accurate parts with a tolerance level as tight as 0.001 inches. However, the tolerance level of a plasma cut part is loose and is usually 0.015 inches.
The effect of heat is another significant difference between CNC waterjet cutting and plasma cutting operations. Waterjet cutting lessens the incidence of heat-related effects. There is a reduced risk of heat-affected zones or thermal distortion. With plasma cutting, the high heat input may affect the areas near the melted part.
Productivity and Cutting Speed
The cutting speed and productivity rate of CNC waterjet cutting and plasma cutting differ. With a plasma cutter, you can go as high as 200 inches per minute. However, waterjet cutting comes with a speed of 12 inches per minute or less. This feature makes plasma cutting suitable for high-volume production.
Material Compatibility
The type of material you want to cut will also play a role. Plasma cutting works only with electrically conductive materials such as copper, stainless steel, brass, aluminum, and iron. On the other hand, waterjet cutting comes with more material flexibility. You can cut plastics, metals, wood, granite, and wood.
Environmental Friendliness
When it comes to environmental friendliness, CNC waterjet cutting has an advantage. This process does not need heat input which reduces energy consumption. Furthermore, CNC waterjet cutting is a closed-loop system. This means that all the consumables and waste products such as excess metal and water get recycled.
Edge Quality
The quality of the cut edge is another significant difference between CNC waterjet cutting and plasma cutting. Waterjet cuts are smooth, burr free and do not need further grinding or secondary finishing. On the other hand, plasma cutting produces rougher edges that require deburring.
Operating Costs
The cost of operating a CNC waterjet cutter is different from that of a plasma cutter. waterjet cutting comes with higher operating costs. The reasons for this are not far-fetched. The cost of the abrasives is high and they are not easily recyclable. Additionally, it has more maintenance requirements.
Safety Considerations
Waterjet cutting has an edge from the safety point of view. It is a safer process when compared with CNC plasma cutting. Plasma cutting uses a high-temperature arc that leads to burns if you are not careful. It generates a high level of noise and sparks. This process also increases the risk of electrical shock.
Applications
Their numerous differences influence where you use both techniques. Its high tolerance and material versatility make waterjet cutting useful when fabricating components in the medical, food, and aerospace industries. However, plasma jet cutting may be the most appropriate for shipbuilding, heavy equipment manufacturing, and industrial applications.
Conclusion
There is no standard way to determine the best between CNC waterjet cutting and CNC plasma cutting. A lot of factors will influence your decision. Go for plasma cutting when working with thick metals that easily conduct electricity and if the tolerance level does not have to be very tight. CNC waterjet cutting may be the most appropriate for thin materials and when accuracy is required. Are you new to CNC cutting or are you exploring your options? We hope this article has answered all your questions. Do you still have questions or clarifications? Reach out and get expert advice from Zintilon to aid your selection process.
