Laser cutting

Laser cutting is a special way to cut materials using a very strong beam of light called a laser. The laser beam is focused on the material, which then melts, burns, or disappears, leaving a clean edge. It is often used in factories to make things, but schools, small businesses, artists, and hobbyists also use it.

The laser beam is guided by special tools called laser optics and a computer system known as CNC (computer numerical control). This helps direct the laser to the right place. The pattern to be cut is programmed in advance using something called G-code, which tells the machine how to move.

Many companies make these machines. Laser cutting is popular because it can make very precise and neat cuts on many different materials.

History

In 1965, the first laser cutting machine was used to make holes in diamond tools. This machine was made by the Western Electric Engineering Research Center. In 1967, Britain started using lasers to cut metals with oxygen. By the early 1970s, this technology cut titanium for airplanes. At the same time, CO₂ lasers cut materials like textiles because they were not strong enough for metals.

Process

Laser cutting uses a strong beam of light to cut materials. The beam is made very small, often thinner than a thread, to make precise cuts. Before cutting, the laser makes a tiny hole to start.

One good thing about laser cutting is that it can cut materials cleanly and precisely. It works well for some metals and can cut without bending or damaging them much. However, it might not cut very thick pieces as easily as other tools.

Types

There are three main types of lasers used in laser cutting. The CO₂ laser is good for cutting, boring, and engraving. The neodymium (Nd) and neodymium yttrium-aluminium-garnet (Nd:YAG) lasers are similar but used for different jobs. Nd is used for boring and when you need strong energy but not too often. The Nd:YAG laser is used when you need a lot of power, and also for boring and engraving. Both CO₂ and Nd/Nd:YAG lasers can also be used for welding.

CO₂ lasers can be powered in two ways: by passing a current through the gas or using radio waves. The radio wave method is newer and more popular because it avoids problems that happen with the older method. CO₂ lasers are used to cut many materials like metals, plastic, wood, and paper. YAG lasers are mainly used for cutting metals and ceramics.

Fiber lasers are another type that is becoming popular. They use a solid material instead of gas and can cut very small details, making them great for cutting reflective metals like copper and brass. Fiber lasers are fast, use less energy, need less upkeep, and can work on many tough materials.

Methods

Laser cutting uses different ways to cut materials, based on what is being cut.

One way is called vaporization cutting. The laser heats the material fast, making a small hole that gets bigger as the material turns to vapor.

Another way is melt and blow, used for metals. The laser heats the metal until it melts, and then a blast of gas pushes the melted metal away, making a clean cut.

Thermal stress cracking is used for brittle materials like glass. The laser focuses on one spot, making the glass crack, and the beam can guide the crack to make a precise cut.

There are also special ways for cutting silicon wafers used in making tiny electronic parts, and reactive cutting, which uses a laser beam to start a flame that cuts through thick steel plates.

Tolerances and surface finish

Laser cutters can be very precise. They can position themselves very accurately, within just 10 micrometers. The smoothness of the cut edge, called roughness, depends on the material's thickness, the laser's power, and how fast it cuts.

For example, when cutting low carbon steel with 800 W of laser power, the roughness is 10 μm for 1 mm thick sheets, 20 μm for 3 mm, and 25 μm for 6 mm.

This process can hold very close tolerances, often within 0.001 inch (0.025 mm). The shape of the part and the machine's strength affect how close the cut can be to the exact size needed. The typical smoothness of a laser cut may range from 125 to 250 micro-inches (0.003 mm to 0.006 mm).

Machine configurations

There are three main types of industrial laser cutting machines: moving material, hybrid, and flying optics systems. These types differ in how the laser beam moves over the material to be cut. In all of these, the axes of motion are usually called the X and Y axis. If the cutting head can move up and down, it is called the Z-axis.

In moving material lasers, the cutting head stays still, and the material is moved under it. This keeps the distance from the laser to the material the same and makes it easier to remove any bits of material that are cut away. However, it usually needs fewer parts to guide the laser but can be slower.

Hybrid lasers have a table that moves in one direction and also move the cutting head along a shorter path. This helps keep the laser's path more steady and can use the laser's power better.

Flying optics lasers keep the material still and move the cutting head with the laser beam over the material in both horizontal directions. These machines are the fastest, which is helpful when cutting thinner pieces. They often do not need the material to be held in place. However, they need special ways to adjust the laser beam when it moves closer to or farther from the machine.

Pulsed lasers can send short, powerful bursts of energy. This is useful for making small holes or when very slow cutting speeds are needed, because it stops the heat from melting the whole piece being cut.

Most industrial lasers can pulse or cut continuously under control by a computer program. Double pulse lasers use pairs of pulses to improve how much material is removed and the quality of the holes or cuts. The first pulse removes material from the surface, and the second pulse stops bits of material from sticking to the sides of the hole or cut.

Five and six-axis machines can also cut shaped pieces of material. There are also different ways to aim the laser beam to keep the right distance from the material for cutting.

Power consumption

Laser cutting uses a lot of power, which is important to remember. Different lasers work better for different tasks. For example, CO₂ lasers are about 5 – 10% efficient, fiber lasers are 20 – 30% efficient, and direct diode lasers are 30 – 40% efficient when cutting sheet metal.

The power a laser needs changes based on how strong it is and how it’s set up. The amount of power, called heat input, depends on what you’re cutting, how thick it is, and how fast you want to cut it.

Production and cutting rates

The speed of a laser cutter depends on a few things. These include the laser's power, the material's thickness, and the type of material. Strong industrial lasers can cut carbon steel that is about half an inch thick. Lasers can often cut materials much faster than a regular saw—up to thirty times faster.