Laser Cutting vs. Waterjet Cutting

Laser and waterjet cutting are both processes used in industrial manufacturing. Laser cutting can be used with wood, metal, ceramic, steel, leather, aluminum, and a huge variety of other materials. The process works by focusing a powerful laser beam — a powerful light beam tightly focused onto a small point. The energy from the laser beam that hits this one, small spot will heat it enough to melt it or vaporize it and cut through the material. Laser cutting provides high precision and minimizes the risk of distorting the workpiece. 

Waterjet cutting is a precise type of subtractive manufacturing that is frequently used to cut materials like metal, stone, tile, rubber, foam, and cloth. The cutting action of a water jet is produced by directing a high-pressure, small-diameter stream of water at the material to be cut. The material on the cut line is physically eroded away, not melted or vaporized. A jet of pure water is sufficient for cutting softer materials, but to cut harder materials, such as glass or metal, an abrasive material is added to the water jet. 

The biggest difference between the laser cutting and waterjet cutting processes is the actual method of material removal: a laser melts or vaporizes the material by heating it, while the high-pressure waterjet physically blasts away small particles of solid material with almost no heat. While waterjet and laser cutting are both relatively environmentally friendly technologies, waterjet cutting uses more raw materials (abrasive, water). Laser cutting, on the other hand, may require ventilation to remove toxic fumes created by melting or vaporizing certain feedstocks. Although all methods of cutting accomplish the same tasks, choosing the right one for the task depends on the material to be cut, production volume, and the level of precision needed. 

Laser Cutting and How It Works

Laser cutting is the process of using a very high-powered laser to cut or engrave materials by moving them along a flatbed. Wood, cardboard, acrylic, and other materials are simple laser-cuttable materials. But while it cuts by burning, it is important to be aware of the kind of odors the material releases. The laser machine creates a potent, reliable, and adjustable light. The light is then redirected and focused until a fine point is achieved. It gets extremely hot and slices through the material after a certain amount of concentration is attained. As soon as the laser process is complete, the final workpiece can be removed. The laser cuts the design out by tracing the vector image on CAD software. Two common types of laser cutter are CO2 laser and fiber laser.

Laser Cutting Advantages vs. Waterjet Cutting

Some of the advantages of laser cutting vs. waterjet cutting include:

1. A laser cutter generally cuts more quickly than a waterjet cutter. A laser cutter can cut at speeds of 20-70 inches per minute, while a waterjet is generally restricted to 1-20 inches per minute.
2. If precision is required in the design then laser cutting is the better choice. For a laser cutter, the minimum cutting slit size is 0.15 mm, while for a waterjet cutter is 0.5 mm.
3. The laser cutting process is quieter than water jet cutting. When in use, a laser cutter makes a 75 dB sound. A waterjet cutter, on the other hand, makes a noise that can reach 90 dB.
4. Laser cutting produces less solid and liquid waste than waterjet cutting because the cutting method uses only light as a cutter. Waterjet cutting produces both liquid (used water) and solid (cutting abrasive + feedstock particles) waste that has to be treated for proper recycling or disposal.

Laser Cutting Disadvantages vs. Waterjet Cutting

Some disadvantages of laser cutting vs. waterjet cutting include:

1. Lasers are generally only capable of cutting materials up to about 30 mm thick, although the most powerful lasers may be able to make cuts up to 40 mm deep. However, laser cutting is not the best method for cutting thick materials. Waterjet cutting excels at slicing through parts as thick as 250-300 mm. 
2. Because laser cutting vaporizes a small amount of the work material, laser cutting produces potentially hazardous vapors that require a good ventilation system. In this regard, waterjet cutting is more environmentally beneficial because it generates no fumes.

Waterjet Cutting and How It Works

Waterjet cutting, also known as waterjet machining, is a technique that uses a high-velocity stream of water to remove material from a workpiece's surface or split it into two pieces. Wood, rubber, and plastic are examples of softer materials that can be cut using the waterjet machining method. An abrasive material is combined with water to cut harder materials, such as metals or stones. Water from the reservoir is transferred into the intensifier using a pump. Water pressure is increased by the intensifier from 5 bars to around 4000 bars. The accumulator receives this water at high pressure from the intensifier. The high-pressure water is stored in the accumulator where it is made available whenever needed. The high-pressure water is then directed toward the nozzle, where it is transformed into kinetic energy. 

About 1000 m/s of water is released from the nozzle. Within the nozzle, abrasives like garnet or aluminum oxide are combined with water. The nozzle has a mixing chamber where high-pressure water and abrasives are combined. When this fast-moving water hits a workpiece's surface, it takes materials from it. Pure and abrasive are two different types of waterjet cutting or water jet machining. Here is an example of waterjet cutting (cutting a Xometry logo):

Waterjet Cutting Advantages vs. Laser Cutting

Some advantages of waterjet cutting vs. laser cutting include:

1. Waterjet cutting is useful for processing thick materials. Laser cutting, on the other hand, cannot cut through as much material as waterjets. 
2. Waterjet cutting is a cold-cutting method and does not generate heat input to the part. Laser cutting, on the other hand, emits a high level of heat and radiation.
3. Waterjet does not produce any hazardous byproducts. In contrast, depending on the material being cut with a laser, hazardous vapors may be produced and may require a ventilation system. 
4. Waterjet cutting produces clean and smooth cuts which typically do not need post-processing. On the other hand, laser cutting can leave some burn marks, requiring the part or affected area to be cleaned off.

Waterjet Cutting Disadvantages vs. Laser Cutting

Some disadvantages of waterjet cutting vs. laser cutting include:

1. Waterjet cutting cannot maintain the same precise dimensional tolerances that laser cutters can. Laser cutting is better suited for applications that require high precision.
2. For materials less than one inch thick, a laser cutter is faster than a water jet. However, for materials close to or more than one inch thick, the laser cutter's advantage begins to disappear.
3. While waterjet cutting is considered an environmentally friendly technology, it requires water treatment to separate out the used abrasive before the water can be reused, and depending on the abrasive used and the material being cut, the solid waste may require hazardous waste disposal. Laser cutting, on the other hand, requires only good ventilation and an air filtering system to trap particulates from the metal vaporization process.

Laser Cutting vs. Waterjet Cutting Key Comparisons

Speed comparison: Laser cutters operate at a higher speed than waterjet cutters when cutting materials that are less than an inch thick. Laser cutters can typically cut at a pace of 70 inches per minute. The ideal speed for a waterjet cutter, however, is roughly 20 inches per minute.

Precision comparison: Laser cutting has an advantage over waterjet cutting when it comes to precision. Although both techniques provide good accuracy, laser cutting is significantly more accurate. This can be cut with an accuracy of 0.15 mm. Waterjet cutting, on the other hand, enables a cutting precision of 0.5 mm. 

Materials used comparison: The material to be cut is one of the deciding factors in selecting between the two cutting processes. Laser cutting finds relevance in a wide variety of materials which include, but are not limited to, glass, metal, plastic, and wood. Nonetheless, when it comes to reflective materials it becomes unsuitable. The reason is that laser cutting depends on light energy being delivered to the material to heat and melt or vaporize it. That process is impeded when some of the energy is reflected off the metal instead of being used to heat and cut the material. Also, it is unsuitable for thermolabile materials (materials that respond negatively to heat) because they decompose when heat acts on them. 

Waterjet cutting, on the other hand, can cut a broad range of materials, except for tempered glass or diamonds. The reason is that the technology does not generate heat and instead cuts by the force of pressurized water. 

Mutual Alternatives to Laser Cutting and Waterjet Cutting

Some mutual alternatives for laser cutting and waterjet cutting include:

1. Plasma Cutting: Plasma cutting uses a stream of ionized gas at temperatures above 20,000 C to melt a cutting path in a material. Because the method necessitates the creation of an electric arc between the electrode and the workpiece, the materials it cuts must be electrically conductive. A plasma cutting machine can cut a variety of materials, such as aluminum, nickel, titanium, stainless steel, plain carbon steel, etc.
2. Oxy-Fuel Cutting: In oxygen-fuel cutting, metal is heated to the ignition temperature (minimum temperature required to start combustion) using a mixture of oxygen and fuel gas, such as acetylene. Afterward, a concentrated jet of pure oxygen is directed into the heated region, generating a chemical reaction between the metal and the oxygen that is exothermic. As a result, a material known as iron oxide or slag is created along the warmed region. The oxygen jet finally removes the slag, allowing it to cut through the metal. This technique cannot be used on non-ferrous metals because they form metal oxides that have higher melting temperatures than the base metal. The oxides form a protective scale over the metal instead of falling away to form a cut. 

How Xometry Can Help

Xometry provides a wide range of manufacturing capabilities, including sheet cutting and other value-added services for all of your prototyping and production needs. Visit our website to learn more or to request a free laser cutting or waterjet cutting quote.

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