Metal Laser Cutting Basics and How Does It Work

What is metal laser cutting? In the machining industry, metal laser cutting is an important subtractive manufacturing process that involves using a high-powered laser beam to cut through different types of metals with precision and accuracy. The laser beam is focused on the material, melting or vaporizing it and creating a clean and precise cut. Because laser cutting is a precise and accurate process, it can easily create parts with intricate details. 

In short, metal laser cutting is highly efficient and precise and can be used in various industries like automotive, electronics manufacturing, etc. This article is a basic guide to metal laser cutting, including its definition, working principles, types, pros and cons, applications, etc. We will provide useful tips for successful cutting. Read on and get more useful information you want. 

What is Metal Laser Cutting?

Metal laser cutting is a process that vaporizes materials using a laser, which creates a cut edge. This process is accomplished by directing the output of a high-power laser. Generally, laser optics and CNC (computer numerical control) guide the laser beam to the material. A laser uses a motion control system to follow a CNC or G-code of the pattern to be cut onto the material. The focused laser is then guided to the material, and the material melts, burns, vaporizes, or is driven away by a gas jet. This leaves an edge with a high-quality surface finish.

Metals are often denser than nonmetals, necessitating a higher-powered laser to vaporize the material off the surface. Laser cutting is a prevalent manufacturing technology in energy storage, computer electronics, robotics, and aerospace. Common parts created by laser cutting comprise flat patterns, face plates, washers, mounting plates, and panels. Although this technology is typically used for industrial manufacturing applications, it is now used by schools, small businesses, architecture, and hobbyists.

Brief History of Metal Laser Cutting 

In 1965, the Western Electric Engineering Research Center began using laser cutting technology for drilling in diamond dies. Shortly after that, scientists created the laser cutting method with carbon dioxide. This advancement increased the versatility of laser cutting. The development of lasers that can cut through metals like mild steel was critical to the mass adoption of the technology.

In 1969, Boeing was the first business to employ gas laser cutting commercially. The employees of this company wrote a paper mainly discussing the concept of using a carbon dioxide laser to cut titanium, Hastelloy, and ceramic. This paper resulted in the development of multi-beam laser cutting, and Boeing began employing laser beams as an efficient cutting method on its production lines. 

During the 1970s, Western Electric began mass-producing cutting machines widely employed in the aerospace sector.

During the 1980s, the usage of gas laser cutting became common. During this time, it is estimated that 20,000 industrial laser cutters were in service. Laser cutting changed manufacturing industries to an extent, and their development heralded the start of a new industrial revolution.

In 1979, Prima Industrie of Collegno, Italy, developed a 3D laser cutting process that vastly enlarged the possible uses of laser cutting technology. Laser power is now widely employed in several sectors, notably vehicle manufacturing. 

How does Metal Laser Cutting Work?

How does laser cutting work? The following covers the process of metal laser cutting and its pre-work. Let’s take a closer look at them.

Prep Work before Metal Laser Cutting

When planning for laser cutting sheet metal, remember a few considerations.

Slots: Slots can be used to align workpieces to each other. However, they must have a kerf allowance for the breadth of the cut.

Holes: Holes should not be smaller in diameter than the material’s thickness. This is referred to as a 1:1 minimum hole size. However, it can vary depending on the material and method.

Size: Knowing the maximum sheet and bed sizes can help you save costs by reducing waste. 

Unsupported areas: This is especially critical for stencils and signs, where letters that leave ‘islands’ of material should have ‘bridges’ of sufficient thickness to keep each part in place. 

How to Laser Cut Metal

Metal laser cutting produces the required cut by burning, melting, and vaporizing the metal with a high-energy laser beam. The laser passes through a focusing lens, concentrating it into a narrow beam and boosting energy density. This focused laser heats the metal’s surface, raising the temperature to an extent enough to generate the cut.

Metal laser cutting offers high-quality parts with clean edges that do not require further finishing processes. However, metals are one of the most challenging materials to cut with a laser due to their reflective nature and high density. Therefore, it is necessary to use a suitable laser with optimal settings for metal cutting to overcome these obstacles.

In addition, due to the reflective quality of the metals, stray laser radiation could get into the operator’s eye and inflict significant harm. To make a safe and successful cut in metal, it is strongly advised to wear appropriate laser safety glasses, follow the laser safety procedure, and maintain good process control.

What Metal Material Can Be Laser Cut?

One of the major advantages of laser cutting is that it can cut almost any material, from thin to thick metals, wood, and some types of plastic. Here we mainly discuss the typical metal that can be cut, including mild steel / low carbon steel, stainless steel, aluminum, titanium, brass, copper, and tool steel. 

Stainless Steel

Stainless steel, especially Austenitic grades 304 and 316, is one of the most popular choices for the laser cutting process. Stainless steel contains large amounts of chromium, which makes the material highly corrosion-resistant, durable, solid, weather resistant, and even suitable for outside use. Moreover, the nickel content makes the steel easier to cut than mild carbon steel. It can achieve very smooth edges and small radius cutouts. Stainless steel is commonly used in industries requiring high-quality finishes. 

Mild Steel/ Low Carbon Steel

Low-carbon steel, known as mild steel, is now the most common steel with approximately 0.05–0.25% carbon content. It is the standard choice for laser cutting structural shapes, brackets, and general fabrication when high strength is not required. Mild steel is a cost-effective material with good machinability, weldability, ductility, and relatively low tensile strength. Although mild steel is cheap and easy to form, it tends to increase the difficulties of laser cutting.

Aluminum 

Aluminum is a lightweight metal and can be efficiently performed laser cutting process. Some non-heat treatable grades, such as 5052 and 6061, are widely laser cut. Its highly reflective nature allows faster cuts but is prone to oxidation cut edges. This metal is used for electronic enclosures, aerospace structures, automotive, and consumer electronics. 

As for all metal laser cutting, scratches are unavoidable in aluminum. In this case, avoiding sharp edges and hard friction on the material surface would be a solution. And using a clear lacquer or light oil on the surface can preserve the surface. Although scratches on the backside of the sheets are common, they are readily removed with a light abrasive. 

Titanium

Although titanium is challenging to cut, laser cutting can be used for precise and intricate cuts. Due to its high strength and lightweight properties, titanium is commonly used in aerospace, medical, marine, and automotive applications.

Copper

Copper is known for its excellent electrical conductivity and is used in electrical and plumbing applications. It can be laser cut effectively, but higher-powered lasers may be required due to their thermal conductivity. Generally, problems with copper discoloration can be mitigated using fiber lasers. When this metal adopts laser cutting, it is common in applications like electrical contacts and heat exchangers.

Brass 

Brass is a copper-zinc alloy, and increased amounts of zinc offer improved strength and ductility. It can be laser cut with good results. Some common uses of brass include costume jewelry, locks, hinges, gears, bearings, hose couplings, ammunition casings, automotive radiators, musical instruments, electronic packaging, and coins.

Tool Steel

Air-hardening grades like D2 and A2 can be laser cut, but their extreme hardness requires high-power density CO2 lasers. Tool Steel can be used for cutting tools, punches, and dies. However, cutting parameters must be carefully controlled to prevent cracking.

Types of Lasers Used in Metal Laser Cutting

Generally, types of lasers used in metal laser cutting covers CO2 lasers, Nd and Nd:YAG lasers, and fiber lasers.

CO2 Lasers

CO2 lasers are among the most commonly used types for cutting sheet metal. They utilize a gas mixture, primarily carbon dioxide, to generate the laser beam. An electrical current is run through a chamber of CO2 gas, which excites the particles in the tube and generates an intense beam of light when focussed using mirrors and lenses. CO2 lasers operate with an efficiency of roughly 20%, which means that much of the power consumed by the laser tube gets turned to waste heat and light rather than laser power.

CO2 lasers are ideal for cutting, boring, and engraving various materials, including most metals and nonmetals. Therefore, CO2 lasers are often used for the industrial cutting of many materials, including titanium, stainless steel, mild steel, aluminum, plastic, wood, engineered wood, wax, fabrics, and paper. They offer excellent cutting quality and are suitable for thin and thick sheets.

Fiber Lasers

Fiber lasers are a form of solid-state laser that is increasingly used in the metal cutting business. Unlike CO2, fiber technology uses a solid gain medium rather than a gas or liquid. The “seed laser” generates the laser beam and is amplified within a glass fiber. Fiber lasers, with a wavelength of only 1064 nanometers, create an incredibly tiny spot size (up to 100 times smaller than CO2), making them perfect for cutting reflective metal. This is one of the primary advantages of fiber over CO2. And fiber lasers can convert almost 80% of their input energy into cutting power. This implies that parts can be created cheaper, and machines can be installed with fewer infrastructural changes.

The following are some of the advantages of using a fiber laser cutter:

• Processing times are short.
• It has reduced energy consumption and expenses as a result of increased efficiency.
• Greater dependability and performance since there are no optics to tune or align and no lamps to replace.
• Minimal upkeep is required.
• The capacity to process highly reflective materials like copper and brass.
• Higher productivity and reduced operating expenses provide a higher return on investment.

Nd and Nd:YAG Lasers

The neodymium (Nd) and neodymium yttrium-aluminum-garnet (Nd:YAG) lasers are similar in style but differ in their uses. Nd laser is employed for boring operations and tasks requiring high energy but little repetition. However, the Nd:YAG laser is utilized for high-power applications and operations like boring and engraving. 

In general, CO2, Nd, Nd:YAG lasers can be used for welding. However, Nd and Nd:YAG lasers operate at a lower wavelength compared to CO2 lasers, which makes them more efficient at cutting thinner materials. In addition, they are solid-state lasers, meaning the lasing medium they use is a solid material, not a gas or a liquid.

Methods Used in Laser Cutting Processes

There are various methods to cut different materials in the laser cutting process. The following introduces several common methods in laser cutting, including vaporization, melt and blow, thermal stress cracking, stealth dicing, and burning stabilized laser cutting.

Vaporization Cutting 

In vaporization cutting, the focused beam heats the material’s surface to a flashpoint, creating a keyhole. The keyhole causes an abrupt rise in absorptivity, rapidly deepening the hole. As the hole deepens and the material boils, the produced vapor erodes the molten walls, blowing ejection out and growing the hole even further. This process commonly cuts non-melting materials like wood, carbon, and thermoset plastics.

Reactive Cutting/ Flame Cutting

Reactive cutting is known as “flame cutting” and “burning stabilized laser gas cutting.” Reactive cutting is similar to oxygen torch cutting, except the laser beam is the ignition source. This process is often intended for cutting carbon steel in thicknesses that exceed 1 mm. Moreover, it may be employed for cutting very thick steel plates using relatively little laser power.

Melt and Blow Cutting/ Fusion Cutting

Melt and blow cutting, also called fusion cutting, employs high-pressure gas to blow molten material away from the cutting region, lowering the power need significantly. The material is first heated to its melting point. A gas jet blows the molten material out of the kerf, eliminating the need to raise the temperature of the material anymore. Metals are often cut with this method.

Thermal Stress Cracking Cutting

Thermal stress cracking cutting exploits the feature that brittle materials are particularly susceptible to thermal fracture. A concentrated beam is directed toward the surface, resulting in localized heating and thermal expansion. This causes a crack, which may be directed by moving the beam. The crack may be moved in m/s. Thermal stress cracking is commonly used in glass cutting.

Stealth Dicing Cutting of Silicon Wafers

Stealth dicing process separates microelectronic chips in semiconductor device fabrication from silicon wafers. It employs a pulsed Nd:YAG laser whose wavelength is perfectly adapted to the electronic band gap of silicon.

Advantages and Disadvantages of Metal Laser Cutting

Metal laser cutting has revolutionized the manufacturing industry, offering precise and efficient solutions for various applications. Below are the critical advantages and disadvantages of this manufacturing technique.

Advantages of Metal Laser Cutting:

High Precision and Accuracy

Metal laser cutting is renowned for its exceptional precision and accuracy. Laser beams can achieve intricate cuts and shapes with minimal deviation, ensuring high-quality end parts. Generally, the parts can be laser cut to within a tolerance of 0.2mm. The high precision of laser cutting is particularly valuable in industries such as aerospace, electronics, and medical devices, where tolerances are critical.

Material Versatility 

Laser cutting can handle various metal materials, including stainless steel, aluminum, mild steel, alloys, and exotic metals. This versatility allows manufacturers to address diverse project requirements without needing tool changes, reducing setup time and costs. It is also suitable for various thicknesses, making it a versatile option for different applications.

Cutting Flexibility

The laser cutting processes are extremely versatile and flexible. A single laser cutter can perform various cutting tasks, including simple cuts, sophisticated ones with complex details, markings, drilling, and even engravings. As a result, producers do not need to replace tooling time by time during the process.

Speed and Efficiency

Once programmed, parts may be cut in seconds, far quicker than plasma or waterjet cutting processes. High cutting speeds, rapid piercing, and kerf widths lead to shorter production cycles and increased throughput.

Low Power Consumption

Unlike other cutting devices, laser cutters don’t need to move distinct parts of the device. This enables them to cut material while spending minimal power. While laser cutters may require up to 10kW of energy, most other operations can take up to five times that amount. Meantime, the low power consumption also makes them easier on the wallet.

Contactless Process

Unlike mechanical cutting methods, laser cutting is a non-contact process. This reduces the risk of material contamination and eliminates the need for tool wear, minimizing maintenance and replacement costs.

Disadvantages of Metal Laser Cutting:

High Initial Capital Investment

Acquiring and setting up top-quality laser cutters involves a significant initial capital investment. The cost of a typical laser cutter may be twice as high as the cost of waterjet or plasma cutters. Small businesses or startups might find the upfront costs prohibitive, although the long-term benefits can outweigh the initial expenditure.

Operating Costs

While laser cutting is efficient, operational costs can accrue over time due to electricity consumption, gas supply, and maintenance requirements. Regular maintenance and servicing are essential to ensure consistent performance.

Reflective Material Limitations

While laser cutting suits a wide range of metals, certain materials, such as reflective metals like brass or polished stainless steel, can be more challenging due to their high reflectivity. Additional measures, such as using specialized gases or coatings, may be required to overcome these limitations.

Heat-Affected Zone (HAZ)

Laser cutting generates heat, creating a heat-affected zone along the cut edges. This can result in material distortion, especially in thinner materials, potentially affecting the final product’s integrity. Therefore, it can require secondary processing in some use cases.

Require Professional Operator

You may need a professional and skilled operator to run the machine during part manufacturing to get the most out of your laser cutters. This way, the operator will rapidly identify a fault or incorrect setup that could hinder manufacturing operations or the machine’s integrity.

Metal Thickness Limitations

Although laser cutting works well with a wide range of materials, it is recommended that thick metals be cut using alternative methods. Typical laser cutters are excellent for cutting aluminum sheets up to 15 mm thick and steel up to 6 mm thick.

Applications of Laser Cutting

Laser cutting is seen in nearly every industry, such as:

Industrial Uses: Laser cutting is widely found in industrial sectors, including manufacturing, aerospace, medical, automotive, engineering, construction, etc. This process is suitable for cutting parts that require high precision and quality, such as metal sheets, pipes, tubes, gears, brackets, flanges, fittings, valves, implants, instruments, tools, molds, and dies. 

Artistic Applications: Laser cutting is also popular in artistic fields, such as design, architecture, fashion, jewelry, crafts, decorations, and more. This is because it can be used to create or enhance various artistic works needing creativity and aesthetics, such as sculptures, paintings, accessories, jewelry, and more.

Personal Uses: Laser cutting is also accessible to hobbyists, enthusiasts, students, teachers, etc. They can use this technology to create or enjoy various personal projects that require fun and learning, such as toys, models, games, educational kits, science experiments, etc. 

Design Tips for the Perfect Laser Cut Metal

Here are some design tips to help you achieve the best laser cut:

• Close the Edges of Your Design. Everywhere you intend to have open or free from metal must be surrounded by a complete, closed contour. If you wish to have a circle laser cut out of a sheet of metal, for example, ensure the arc in your file is a fully connected circle.
• Mind your Metal Tabs and Notches. Getting tabs and notches right maintains the metal sheet’s or plate’s structural integrity while the product is being produced.
• Identify Line Thicknesses and Depths. Clarify and identify what each line style implies when submitting your file.
• Plan for Precise Holes and Laser Accordingly. When aiming to get holes with tight tolerances, it is recommended to employ a laser cutter to pierce and etch the designated locations for said holes. Subsequently, proceed to drill the holes straight, utilizing a drill bit. 
• Decide on Rounded Metal Corner Fillets or Sharp Angles. Sharp corners are frequently observed in sheet metal parts. To enhance safety, fillets can be added to sharp corners.
• Correctly Lay out Your File for Multiple Parts or Thin Features. When cutting many parts on the same metal sheet, it’s frequently desirable to leave a distance at least the thickness of the material between them. 
• Choose the Right Material. Different metals have varying levels of reflectivity and thermal conductivity, which can affect the cutting process.
• Your Details Can’t Be Smaller Than Metal Thickness. The higher the thickness, the less the laser can penetrate and cut the material.
• Remember the Kerf. Kerf refers to the material that evaporates when the laser beam hits the laser cutting material.

Waterjet Cutting VS. Laser Cutting: What are the Differences?

When you choose between waterjet cutting and laser cutting, there are several differences you should consider:

1. Accuracy. Laser cutters can cut as precisely as +/- 0.005 inches. Waterjet cutters make cuts within +/- 0.02 inches.
2. Versatility. Laser cutters are limited in the material and the thickness they can cut. Waterjet cutters are more flexible and can cut just about any material. 
3. Component Costs. Waterjet cutting tends to be pricier due to component wear and consumables. 
4. Operating Costs. Laser cutters cost anywhere from $13-$20 per hour to run. Waterjet cutters are generally $15-$30 per hour.
5. Machine Costs. One benefit that water cutters have over laser cutters is a lower up-front machine cost.
6. Speed. Some laser cutters can cut up to 70″ of material per minute. Waterjet cutters can’t cut more than 20″ per minute.
7. Waste. The laser cutters leave no mess besides a little bit of dust. However, waterjet cutters involve a more extensive cleanup.
8. Safe. Waterjet cutting generally is perceived as more dangerous. Laser cutting is relatively quiet and safe.

Summary

Metal laser cutting is an effective process of producing high-precision and intricate cuts in metals. And it is suitable for a vast array of materials. However, it should be noted that the laser cutter still is a high initial investment, so outsourcing your metal cutting services would be a wise choice. Of course, the alternatives to laser cutting for sheet cutting include EDM, CNC milling, punching, waterjet, and plasma cutting services. You can choose for your manufacturing needs.

Are you looking for a trusted laser cutting service to provide your part with high quality and precision? Then LEADRP is exactly what you need. We are proficient with laser cutting and can ensure that the final part meets your demand. In addition, we offer various prototyping services, including CNC machining, 3D printing, injection molding, and urethane casting. So why wait? Contact us today!

References

Laser cutting – From Wikipedia

A History of Laser Cutting – From Thunder Laser USA

Laser Cutting Metals: Things to Know – From Metal Supermarkets