Metal Laser Cutting: Choosing the Right Materials for Precision and Quality

Metal laser cutting is a highly precise process that allows for the custom cutting of thin, flat, sheet, or roll stock metal. It offers a cost-effective solution for creating parts with exacting tolerances. When it comes to metal laser cutting, choosing the right materials is crucial to ensure the quality and performance of the final product. In this article, we will explore the factors to consider when selecting metal materials for laser cutting and the various options available.

Factors to Consider when Choosing Metal Laser Cutting Materials

When selecting the materials for your metal laser cutting project, several factors should be taken into consideration. These factors include laser wavelength absorption, aspect ratio, material malleability, material stresses, non-homogenous materials, and assist gasses.. Let’s dive deeper into each of these considerations:

Laser Wavelength Absorption

Laser wavelength absorption refers to the process by which a material absorbs laser energy depending on the wavelength of the laser beam. Different materials have different absorption properties, with some being more absorbent at shorter wavelengths and others at longer wavelengths. Photons with shorter wavelengths are generally easier to be absorbed by materials compared to photons with longer wavelengths. Matching less optimal wavelengths for a specific material can cause the material to heat up and produce undesirable cut quality.

Aspect Ratio: Material Thickness to Smallest Part Geometry

In the context of laser metal cutting, aspect ratio refers to the proportional relationship between the width and height of the cut or the kerf. It is commonly expressed as two numbers separated by a colon, such as 1:1 or 2:1. The aspect ratio in laser metal cutting is important because it affects the quality and precision of the cut. A higher aspect ratio means a narrower and deeper cut, while a lower aspect ratio means a wider and shallower cut. The choice of aspect ratio depends on the specific requirements of the cutting application, such as the material thickness and desired cut quality.

Material Malleability

Metal laser cutting is a non-contact machining process that utilizes a high-powered laser beam to cut through various types of metal. Unlike traditional contact machining methods, such as milling or drilling, laser cutting does not rely on physical force to remove material. Instead, it uses the intense heat generated by the laser to melt or vaporize the metal, creating a precise and clean cut.

One of the key advantages of laser cutting is its ability to process materials with different levels of malleability. Malleability refers to a material’s ability to be deformed under compressive stress without fracturing. Laser cutting can effectively cut through both malleable and less malleable metals, including steel, aluminum, copper, brass, and titanium.

Material Stresses

Metal laser cutting is a highly precise and efficient process that utilizes a focused laser beam to cut through various types of metal. However, it is important to consider the material stresses induced by the localized heating during the laser cutting process.

When the laser beam interacts with the metal surface, it generates intense heat in a small area. This localized heating causes the metal to undergo thermal expansion, which can lead to material stresses. The thermal expansion can cause the metal to warp or distort, especially in thin or delicate materials.

The extent of material stresses depends on several factors, including the laser power, cutting speed, material thickness, and the type of metal being cut. It is crucial to carefully optimize these parameters to minimize the impact on the material.

To mitigate material stresses, laser cutting processes often incorporate features such as water cooling or air assist systems. These systems help dissipate the heat and prevent excessive thermal buildup, reducing the risk of material deformation.

Advanced control systems can also minimize material stresses. Controlling laser energy over time that is delivered to the workpiece is managed by the laser power, cutting speed, and beam focus. These laser parameters can result in a cleaner and more accurate cut while minimizing material distortion.

Non-homogenous Materials

Non-homogeneous materials, such as FR4, fiberglass, or glass reinforced phenolic laminates, are often used in various industries, including electronics and PCB manufacturing. These materials pose challenges when it comes to traditional contact machining methods, as they can leave burrs, rough edges, or edge protrusions that may affect the functionality and aesthetics of the final product.

In such cases, laser cutting provides an excellent solution. The non-contact nature of laser cutting eliminates the need for physical contact with the material, reducing the chances of burrs or rough edges. The high-powered laser beam melts or vaporizes the material, leaving behind precise and clean cuts.

For non-homogeneous, laser cutting offers several advantages that enable the creation of complex shapes and designs with close tolerances. This is especially crucial in the electronics industry where small and delicate components require .001” – .002” profile tolerances.

Secondly, laser cutting provides excellent edge quality, with minimal heat-affected zones. This is particularly important for non-homogeneous materials, as any excessive heat can affect their structural integrity or electrical properties. By managing the lasers energy over time, laser cutting minimizes the heat transfer to the surrounding areas, resulting in clean and smooth edges without any edge protrusions.

Assist Gasses

The use of assist gasses such as nitrogen, oxygen, and argon in laser cutting plays a crucial role in controlling the cut quality. These gasses are used to blow away molten material from the cutting area, which helps achieve cleaner and more precise cuts.

Nitrogen is commonly used as an assist gas in metal laser cutting. It helps prevent oxidation and produces clean cuts in materials like stainless steel and aluminum. By displacing the oxygen in the cutting zone, nitrogen minimizes the formation of oxides, resulting in high-quality cuts with minimal discoloration.

Oxygen, on the other hand, is used for cutting materials like mild steel. When mixed with the laser beam, oxygen reacts with the material, creating an exothermic reaction that facilitates the cutting process. The reaction generates additional heat, which increases the cutting speed and enables efficient cutting of thick materials.

Argon is mainly used as an assist gas for laser cutting both metals and non-conductive materials, such as acrylics or wood. It helps to prevent charring and burning by displacing the surrounding air and reducing the risk of ignition. Argon assists in achieving clean and precise cuts in these materials, minimizing post-processing requirements.

The choice of assist gas depends on the material being cut and the desired cut quality. By using the appropriate assist gas, laser cutting machines can optimize the cutting process, resulting in improved edge quality, reduced heat-affected zones, and minimal post-processing requirements.

Conclusion

Metal laser cutting is a versatile process capable of cutting various types of metals and metal alloys like stainless steel, nitinol, titanium, aluminum and molybdenum to name a few. When choosing the materials for laser cutting, it is important to consider factors such as laser wavelength absorption, aspect ratio, material malleability, material stresses, non-homogenous materials, and assist gasses.

An equally important consideration is the selection of a laser metal cutting service provider. Not all service providers are the same. Many laser contract service providers specialize in one or two specific applications or are limited by the types of lasers available to them.

Micron Laser has been providing laser cut metal parts and laser material processing services for more than 20 years with 20 plus lasers optimized for your material selection.

Micron Laser’s application experience combined with all the laser metal cutting advantages will ensure your part design’s quality fabrication. Contact us today to discuss your specific requirements and benefit from their expertise in material selection and laser cutting techniques.