In this article, we will be looking at the process involved in CNC Laser cutting and how it benefits from the traditional cutting methods.
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Unlike in the olden days, customers are on the lookout for state-of-the-art technology where they can fulfil their stringent design requirements and advanced machines capable of doing these jobs.
CNC Laser cutting is the machining technology accepted worldwide by all machinists even though CNC plasma cutting, and CNC wire cutting are being used.
Computer Numeric Controlled (CNC) Laser cutting machines work on the principle that a focused high-power laser beam is used to cut, inscribe, or engrave a metal surface to get the desired shapes.
They are specially used to cut intricate shapes and minute holes with a high level of accuracy. This is possible because of their unique design and process of Laser cutting machines.
A CNC cutter works on computer numerical controls and special computer instructions called G-code to execute the required operations accurately. When it comes to CNC laser cutting, the machine design and its working are slightly different from conventional CNC machines. It works on the principle of a non-contact thermal process. CNC laser cutting machines include a laser head consisting of a laser-focusing lens and a nozzle.
The focusing head and lens focus a beam of the laser through the nozzle. A laser beam is a group of extremely high-intensity light pointed at the workpiece, which gets melted and gets cut into the desired shape. Compressed gas is made use of in CNC lasers to cool the lens and eject the vaporized metal from the workpiece.
When a point on the metallic surface is focused with a high-powered laser beam, rapid heating happens at that point due to the high heat concentration. Not only will it result in rapid heating at that point but also vaporization.
The movements of the laser head and laser beam are controlled by the CNC technology which will help to create desired cuts.
Classification of CNC Laser Cutting machines is done based on the state of the laser medium used e.g. – solid, liquid or gas and the component used in the medium e.g.: Carbon dioxide, Nitrogen etc. The most common laser-cutting machines used in the manufacturing industries are:
· CNC CO2 laser cutter
· CNC crystal laser cutter
· CNC fibre laser cutter
Let’s discuss in detail the various models of CNC Laser cutting machines.
In simple words, CNC CO2 laser cutting machines are the ones where carbon dioxide is used as the operating laser medium. The capacity and capability of these machines to produce superpower output make them the most widely used laser cutters in the market.
The output power of 15KW and generally up to 30% efficiency can be expected in these machines. Suitable for cutting small elements and acute angles, these machines are commonly used to work on sheet metals or any other metals which are lower than 10mm thick.
The greater the power of the machines, the better the quality of the cut on thick metal surfaces.
One of the most recent advanced technologies in laser cutting is CNC fibre laser cutting. In this technology, the laser beam is created with the help of a group of diodes and is passed across a fibre optic cable. Fibre laser cutting is comparatively faster as well as a cleaner cutting method when it comes to cutting on materials less than 5mm thick. This cutting process is highly compatible with almost all materials, though extra care must be given when using silver metal.
Silver metal has the capability to hold the heat of the laser beam which can in turn damage the whole metal during the cutting process. This is a great challenge faced while using this technology to cut silver metals. To overcome this challenge, machinists usually make use of a bracket to transfer the heat from the metal surface.
In CNC crystal laser cutting machines, as the name suggests, the laser beam is created with the help of crystals like neodymium-doped yttrium aluminium garnet and neodymium-doped yttrium ortho-vanadate. CNC crystal laser cutting machines are commonly used to cut thick materials because of the high power of the laser beam. These laser-cutting machines are highly compatible with a wide range of materials be it wood, metals or plastics or glass.
Since we have learnt about CNC Laser cutting, the various types of it and how each variant is different, let’s now investigate the advantage of these machines over conventional cutting machines. Unlike conventional cutting machines, CNC Laser cutting machines help you to work on jobs where you need to cut complicated shapes and designs and even holes as small as 2mm with greater precision and accuracy.
Since the CNC laser cutting machines used high power laser beams to cut, the cuts are super clean, and the outcome is highly finished cuts thereby eliminating the need for additional finishing processes.
In conventional cutting technology, various other machines like milling and deburring machines are made use of to complete a cutting job. With the arrival of CNC machines, the need for all these additional machines or tools is eliminated.
Since this laser cutting is a non-contact process, making use of this cutting technology reduces the challenges of metal damage or contamination. For a faster cutting process, you can always opt for CNC laser cutting machines, whereas when it comes to cutting materials of greater thickness and jobs where super finishing is required you can choose CNC wire cutting.
Conclusion Without any further doubt, CNC laser cutting machines are the most sought technology among machinists in today’s world. Even though CNC Laser cutting machines are expensive, the level of detail it offers in cutting over CNC plasma cutting machines makes it the ideal choice.
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Even though CNC laser cutting technology rules out many odds of conventional cutting technology, extreme care must be taken when you use the machine for the first time. Hence, it’s very important to purchase the machine from a top-tier distributor like Hitek group.
Laser cutting machines are a capable and versatile class of numerically controlled machine tools. They are used in virtually all industries for high throughput, precision cutting, engraving, and marking—from home use cutting card/paper through to shipbuilding and heavy engineering. They apply well-collimated and tightly focused laser radiation to pierce or engrave materials, with CNC-controlled precision and high productivity. There are several types of lasers commonly used in laser cutting, each with its specific characteristics and applications making it apt for selected market niches.
Four main types of laser are used in laser cutting equipment, with a huge range of powers, from a few mW to 100+ kW. A variety of emission wavelengths render them suitable for particular material types. There are also operational factors that make some types of lasers particularly well adapted to limited market sectors, with no solution being universal. Figure 1 shows the laser cutting process:
This article will discuss the 4 types of laser cutters, how they work, and their applications.
Fiber lasers are used principally for cutting and engraving metallic parts. They offer several advantages over other types of lasers, making them a logical choice in industrial applications.
Fiber lasers get their name from the chemically doped optical fiber used to induce the lasing and deliver the energy to the cutting point. The laser source starts with a primer laser, usually a diode type, which injects a low-power beam into the fiber. This beam is then amplified within the optical fiber, which is doped with rare earth elements such as ytterbium (Yb) or erbium (Er). The doping process induces the fiber to act as a gain medium, amplifying the laser beam by cascading excitations/emissions.
Fiber lasers emit a wavelength in the near-infrared spectrum, around 1.06 μm. This wavelength is thoroughly absorbed by metals, making fiber lasers particularly well suited to cutting and engraving this class of materials, even the “problem” reflective metals.
One of the particular advantages of fiber lasers is their exceptional beam quality. This beam quality determines the laser's ability to produce a highly focused application of radiation and therefore a smaller and more precise cut path and higher specific energy (energy per unit area). This also entails lower beam divergence, allowing cuts that open less with increased target thickness.
Fiber lasers are renowned for offering higher cutting speeds and productivity. This also contributes to lower power consumption, compared to other types of lasers. Fiber lasers are generally optimized for cutting metals, including stainless steel, carbon steel, aluminum, copper, brass, and various alloys. They are not as effective for cutting non-metallic materials like wood, acrylic, or plastics, which are more effectively cut with CO2 lasers. Fiber lasers with higher power levels can also process thicker metals effectively.
Fiber lasers possess an elegant, simple, and robust construction and a near-solid state characteristic. This results in suppressed maintenance requirements, relative to other laser classifications. The absence of mirrors and some of the more delicate focal components minimizes alignment issues, improves beam quality, and elevates life span. Some models are capable of providing tens of thousands of hours of use, before requiring significant maintenance.
Fiber lasers are, in many regards, the optimal choice for metal cutting/ablation and engraving tasks. Pivotal factors cementing their commercial viability include: delivering high throughput, outstanding precision, operational and power efficiency, and low maintenance. Their capabilities render them a preferred tool in diverse industries, including: automotive, aerospace, electronics, and manufacturing, in which precise and efficient metal processing is crucial.
For more information, see our guide on What is a Fiber Laser.
Despite being the earliest commercially exploited devices, CO2 lasers remain very widely used in the sector. They benefit from lower CAPEX (though higher OPEX) and a high degree of material versatility/applicability. They’re particularly suited to processing non-metallic materials with moderate precision and efficiency. They are also considered viable in many metal-cutting applications. For metal processing, the absorption spectrum is adverse but various, widely used workarounds can facilitate better functionality.
CO2 lasers are gas excitation devices that use a mixture of carbon dioxide (CO2), nitrogen (N2), and helium (He) to produce the laser beam in an energy cascade sequence. The laser source typically consists of a xenon flash tube or similar, which is excited by an electric discharge to initiate the stimulated emission process. This process is characterized by three distinct energy transitions, only the last of which involves a photon emission. N2 molecules are raised to a higher energy state that they then transmit to the CO2 molecules, which emit photons as they lose their excision energy by impacting He atoms.
This class emits at around 10.6 μm, in the far-infrared spectrum. This wavelength is strongly absorbed by organic materials like wood, plastics, leather, various fabrics, paper, and some non-metallic composites, resulting in highly efficient, clean, and precise cutting.
They have a lower beam quality in comparison to fiber lasers, which means the laser beam is less focused. This is a byproduct of the relative optical complexity of the devices and is also intrinsic to the gas emission system. However, advancements in CO2 laser technology have improved beam quality over the long service lifetime of the technology. The beam typically generates a larger spot size and higher divergence than other systems, which can markedly affect the precision of cuts.
CO2 lasers are widely accepted because of their versatility, relatively low purchase cost, and higher power use per watt of cutting. They can be considerably slower in cutting thick metal materials than fiber lasers. For non-metallic materials, they can offer excellent cutting speed, making them suitable for intricate designs and a wide range of applications. CO2 lasers require more maintenance than fiber lasers, due to the presence of mirrors and other optical components in their design. Additionally, the primary laser source degrades with usage time. They need regular optical-system cleaning and delicate realignment to maintain performance.
Nd:YAG (neodymium-doped yttrium aluminum garnet) and Nd:YVO (neodymium-doped yttrium vanadate) lasers are fundamentally similar solid-state devices. Both emit in the near-infrared spectrum, differentiated by the medium within which the stimulated emission occurs. They are most applicable to cutting and marking of metals and a limited range of non-metals.
Nd:YAG and Nd:YVO lasers are closely related solid-state laser devices doped with neodymium ions. In Nd:YAG lasers, the laser medium is yttrium aluminum garnet crystals doped with neodymium ions. In Nd:YVO lasers, the laser medium is yttrium vanadate crystals similarly doped with neodymium ions. When optically pumped (by a laser or discharge source), the neodymium ions become excited. This leads to the emission of laser light, as they lose the excitation energy.
These lasers emit at a wavelength of 1.064 μm, while Nd:YVO lasers emit at either 1.064 μm or 1.34 μm, differentiated by the crystal orientation. These wavelengths are in the near-infrared range and are well-absorbed by many metals, making these lasers suitable for metal cutting, engraving, and marking applications. Neodymium lasers generally possess high beam quality, low divergence, and a small spot size resulting in high specific energy.
Nd:YAG and Nd:YVO lasers are effective for cutting and processing metals, especially thin sheets and high-precision and lower gauge materials. They are best used for metals, including the more “reflective” materials: stainless steel, carbon steel, aluminum, brass, and copper. They are also suited to cutting ceramics, plastics, and certain composites—but they are poorly adapted to cutting other non-metallic materials. These laser types are well appreciated for their durability and relatively low maintenance requirements, improving up-time and commercial performance. They can provide thousands of hours of use before requiring major maintenance.
Direct diode (or simply diode) lasers are a type of laser technology that utilizes single semiconductor junctions to generate laser light. They are increasing in market penetration in industrial applications, including: cutting, welding, and surface treatment. A direct diode laser is based on semiconductor junctions, typically made of gallium arsenide (GaAs). When a forward bias current is applied to the diode, it emits light by electroluminescence, without requiring a light source for initiation. The emitted light is then guided and focused into a laser beam by optical elements that make a stimulated emission resonant cavity with a half mirror at one end, through which the laser energy is emitted.
Diode lasers are available in a range of wavelengths, varied by the selection of the semiconductor material, dopants, and resonant cavity design. The most common wavelengths for direct diode lasers used in cutting applications are in the near-infrared spectrum, around 900 to 1,100 nm (0.9 to 1.1 μm). Alternate diode systems can emit in the blue and green wavelength ranges. The beam quality of direct diode lasers can vary considerably, though in general diode beam quality is improving with each device generation. Beam quality often does not match that of fiber lasers or CO2 lasers.
Diode lasers offer excellent energy efficiency by low loss conversion of electrical energy into laser light, reducing operating costs somewhat. However, their cutting speeds are generally lower than for fiber or CO2 laser-based devices, when material thicknesses are larger. Direct diode lasers are suitable for cutting a variety of materials, including metals, plastics, composites, and certain non-metallic materials. They are considered effective for high-speed cutting or welding of thin metal sheets, making them suitable for industries such as automotive, electronics, and sheet metal manufacture. This family of devices is simpler and more robust in construction than most other laser types, resulting in a longer operational life span and lower maintenance requirements. They are also of smaller physical size and require fewer ancillary devices, further enhancing maintenance and suitability for mobile applications.
Diode lasers are commonly used in Laser Heat Treating services.
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