Laser cutting has revolutionised the manufacturing world, offering precision and speed across a vast array of materials. Whether you’re a seasoned engineer or a newbie in the field, one thing remains clear: material thickness plays a pivotal role in the cutting process.
The challenge isn’t just about selecting the right type of laser – it’s about understanding how different thicknesses interact with the beam to either optimise or hinder the process. Having spent countless hours in workshops and manufacturing floors, I can tell you from experience that getting these variables right is crucial for achieving the best results.
How Laser Cutting Works: The Fundamental Process
Laser cutting isn’t just about pointing a laser at a material and cutting through it. There’s a lot of science involved. Essentially, the laser beam directs high-energy light onto the material, heating it up to the point of melting and vaporisation. Once the material is molten, a stream of high-pressure gas – often nitrogen or oxygen – blows the molten metal away, leaving behind a clean cut.
I remember my first encounter with laser cutting; it was in a local engineering shop in Victoria. The first time I watched the beam slice through thick metal, it was like seeing a hot knife through butter – except with a lot more precision. That precision, though, is a result of understanding the material’s thickness and its response to the heat generated by the laser. Materials react differently to the laser based on their thickness, and getting that right requires careful calculation and testing.
The Different Types of Lasers Used in Cutting
The laser cutting world isn’t just one size fits all – there are different types of lasers for different jobs. Here’s a rundown of the most common types you’ll encounter:
| Laser Type | Best Suited For | Advantages | Disadvantages |
| CO2 Lasers | Non-metals (wood, plastics, etc.) and metals | High power output, beam quality | Limited to 2D or 3D cuts, not suitable for reflective materials |
| Fiber Lasers | Reflective metals (aluminium, copper, brass), thin metals | Fast, energy-efficient, precise, and low operating cost | Limited cutting thickness for non-metals |
| Nd: YAG Lasers | Fine cutting of thin metals, highly detailed work | High peak power, fine details | Slower cutting speed compared to fibre lasers |
Key Factors Affecting Laser Cutting Performance Across Different Material Thicknesses
1. Laser Power: Balancing Energy for Optimal Cutting
Laser power is the main factor that determines the thickness a laser can handle. More power means faster cutting speeds and the ability to cut through thicker materials. A 500W fibre laser, for instance, can easily cut through 6mm carbon steel, while a 40,000W laser can slice through materials as thick as 100mm.
I once worked on a project where we had to cut through 30 mm-thick stainless steel. The power had to be precisely calibrated; too much power, and we risked causing heat damage or wider kerf, which would ruin the precision. It was a balancing act, and getting it right saved us hours of rework.
2. Material Properties and Their Influence on Cutting
The type of material you’re cutting can significantly affect your laser’s performance. The thermal conductivity, reflectivity, and strength of materials all impact how the laser cuts through them.
| Material | Thermal Conductivity | Reflectivity | Strength/Density | Cutting Difficulty |
| Steel Alloys | Moderate | Low | High | Easy to cut with CO2 or fibre lasers |
| Aluminum | High | High | Low | Challenging with CO2, easier with fibre lasers |
| Copper | High | Very High | Moderate | Challenging, fibre lasers with specific settings required |
| Titanium | Low | Low | Very High | Difficult, requires high-power lasers |
| Wood | Low | Low | Low | Easy to cut, requires attention to flammable materials |
3. Cutting Speed: Finding the Right Balance
Cutting speed is directly related to material thickness. Generally, thinner materials require faster speeds, while thicker materials need slower speeds for effective cutting.
I’ve seen the impact of cutting speed on material quality; when cutting thin metal, increasing the speed can result in cleaner cuts. However, with thicker materials, a slower speed is necessary to allow the laser to penetrate fully. If you go too fast on thick materials, you risk leaving the cut incomplete, while going too slow can lead to unwanted burning or distortion.
4. Assist Gases: Choosing the Right Gas for Material Type and Thickness
Assist gases play a key role in laser cutting, and the choice of gas affects the quality of the cut.
| Gas Type | Best Suited For | Benefits | Challenges |
| Oxygen | Ferrous metals (steel) | Speeds up cutting for thick materials | Can cause oxidation, leaving rough edges |
| Nitrogen | Stainless steel, aluminium | Produces clean, oxide-free edges | Requires higher laser power for thicker cuts |
| Air | Non-ferrous materials (plastic, wood) | Cost-effective, works well for thin materials | Limited use for thick metals |
Thickness Capabilities: How Different Laser Types Handle Varying Material Thicknesses
1. CO2 Lasers: Cutting Through Mild and Stainless Steel
CO2 lasers are renowned for their ability to cut through thick materials like mild steel and stainless steel. They typically handle materials up to 25mm thick, and when using high-power versions, they can even cut up to 70mm. I’ve seen them perform especially well in industries where thick metal cuts are necessary, like automotive manufacturing.
2. Fibre Lasers: Precision and Efficiency for Thinner and Reflective Materials
Fibre lasers can cut through a wide range of materials with high efficiency, especially thinner materials and reflective metals like brass and aluminium. A fibre laser with 4000W of power can handle 12 mm-thick stainless steel with precision, making it ideal for intricate cuts. I’ve used fibre lasers for complex parts in electronics manufacturing, where speed and precision are paramount.
3. Nd: YAG Lasers: A Versatile Option for Fine and Versatile Cuts
Nd: YAG lasers are particularly good at both fine and thick cuts. With their high peak power and shorter pulse duration, they can be used for cutting both thin and thick materials, particularly when detailed, high-quality work is required. I’ve found them invaluable when dealing with materials that require both precision and power.
Optimising Laser Settings for Different Material Thicknesses
1. Adjusting Power and Speed: Key Settings for Thickness Variability
For thicker materials, you’ll need to adjust your laser settings accordingly. Higher power and slower speeds are essential to penetrate through the material, while thinner materials require lower power and faster speeds to avoid overheating.
2. Fine-Tuning Focus Position and Beam Quality
Ensuring your focus is spot-on can make or break the quality of the cut. For thinner materials, the laser focus is typically placed right at the surface, while for thicker materials, you may need to adjust the focus slightly deeper into the material.
Laser cutting is a powerful tool in modern manufacturing, offering unmatched precision and speed across a range of materials. By understanding how material thickness influences the cutting process and adjusting your laser settings accordingly, you can achieve optimal results every time. From selecting the right type of laser to fine-tuning power, speed, and focus, mastering these variables is the key to successful laser cutting. Whether you’re working with thin sheets of aluminium or thick steel plates, understanding these principles will allow you to cut with confidence and efficiency.
