I've often been asked if the engraved coasters I make are 'laser cut' - they are not - which brings me to today's topic: how to tell if something is cut or engraved with a laser (vs. cut or engraved with a CNC).
Goto Tiper to know more.
Lasers always leaves telltale signs in wood: since a laser does its work with heat, there will be burn marks along the edges of whatever was cut. And similarly, a laser does its engraving into wood items via burning, so that engraving is always burned. This isn't the burning you see of a log in the fireplace, but rather, because of the very controlled power and positioning of a laser, just a potentially modest darkening of the material around the edges. That is, the engraving done by a laser will never be the same color as the natural wood.
Cutting or CNCing the wood uses a rotating cutter head to remove material from a solid piece of wood. The three main advantages of this as compared to a laser are:
No discoloration of the edges or surface from a laser
Great control over depth of cut, allowing you to make true three dimensional objects or cuts
Ability to work with much thicker pieces of wood
However, because the material is removed by a spinning cutter head rather than burning away by the width of the laser beam, a laser generally allows you to get more detail and sharper edges. That is because the cutting or engraving is just the width of the laser beam, and because a spinning bit can sometimes 'tear out' wood fibers around where it is cutting. Also, for interlocking pieces - such as in a puzzle or the pair of coasters above - laser cut pieces would generally fit together more snugly and can be cut via just 'drawing the lines'; trying to do that with a CNC would either leave a much larger border between the pieces, or require cutting individual pieces from much larger stock if a snug fit is desired.
Compare that with these CNC'd objects:
To sum up the properties of the results: laser engraving gives you incredible detail albeit with some discoloration, while CNC engraving gives you depth. And laser cutting gives you very clean vertical lines but also with discoloration, and limited to thin materials, while CNC cutting allows you to work through thick materials and to cut to very specific depths to form truly three dimensional objects.
Do you have some cool laser- or CNC-made products to share? Or does this trigger other questions in how to tell the difference, or when to use one approach vs. the other? I'd love to hear your thoughts on the topic.
The laser cutting process uses a tightly focused high-energy light/radiation laser beam to create rapid, high-temperature-gradient heating of a single, small-diameter spot. This triggers rapid melting/vaporization of the target material, allowing the spot to travel down through the material thickness rapidly and precisely.
The hot spot is blasted with gas, blowing away the melted/vaporized material. This process exposes the cut bottom to allow renewed melting and localized cooling, enabling the cut to proceed. For lighter and more reactive metals, the gas assist uses nitrogen to minimize oxidation. Alternatively, for steel, oxygen assistance accelerates the cut process by locally oxidizing material to assist in slag clearance and reduce the reattachment of melted/cut material.
Laser cutting machines are built in a variety of formats. The most common type keeps the workpiece stationary while laser optics (mirrors) move in both the X and Y axes. Alternatively, a 'fixed optic' format keeps the laser head stationary and the workpiece moves. A third option is a hybrid of the two previous methods. All methods execute 2D and 2.5D G-code patterns using a computer-controlled programming system to deliver fully automated, complex cutting paths. Figure 1 is an example of a laser cutting process:
Laser cutting advantages include: high precision, no material contamination, high speed, unlimited 2D complexity, a wide variety of materials, and a wide variety of applications and industries.
Are you interested in learning more about laser carving machine for wood? Contact us today to secure an expert consultation!
The narrowness of the energy beam and the precision with which the material and/or the laser optics can be moved ensures extremely high cutting quality. Laser cutting allows the execution of intricate designs that can be cut at high feed rates, even in difficult or fragile material substrates.
Traditional rotary cutter processing of materials requires coolants to be applied. The coolant can contaminate the cut parts, which must then be de-greased. Grinding processes may also require coolant/lubricant to be applied. The ablation of the grinding wheel, a natural part of the process, leaves carbide granules that are a hazard in many products. Similarly, water cutting leaves garnet residues. Laser cutting involves only energy and gases and poses no risk of material contamination of the resulting parts.
Few production methods can come close in processing speed to laser cutting. The ability to cut a 40 mm steel sheet using a 12 kW oxygen-assisted laser provides speeds some 10x faster than a bandsaw and 50'100 times faster than wire cutting.
Laser cutting allows intricacy through the nature of the G-code movement control method of positioning and the small size of the applied energy hot spot. Features that are only weakly attached to the main body are cut without any application of force, so the process is essentially limited by material properties, rather than process capabilities.
Laser cutting is a flexible technology that can be adapted to cut widely different materials efficiently, including: acrylic and other polymers, stainless steel, mild steel, titanium, hastelloy, and tungsten. This versatility is increasing as technology develops. For example, dual frequency lasers can be applied to cut carbon fiber reinforced composites'one frequency for the fiber, one for the bonding agent.
Laser cutting finds application in many manufacturing industries because of the combination of versatility, high processing speeds, and precision. Sheet materials are key to production across most manufacturing industries. Applications of laser cutting across industries include: airframes, ships, medical implants, electronics, prototyping, and mass production.
Laser cutting disadvantages include: limitations on material thickness, harmful gases and fumes, high energy consumption, and upfront costs.
Most laser cutting machines sit in the <6 kW range. Their cut depth is limited to ~12 mm in metal thickness'and they accomplish that only slowly (~10 mm/s). It requires the largest and most powerful machines to reach the practical limits of cutting. However, similar limits apply to waterjet and wire erosion cutting. All three processes perform these deeper cuts faster than can otherwise be achieved.
While many materials'particularly metals'do not produce harmful gases in the cutting process, many polymers and some metals do. For example, PTFE and various fluoropolymers produce phosgene gas (which is incompatible with human environments) when heated to high temperatures. These materials require controlled atmosphere processing.
Laser cutting machines have a higher energy consumption rate than other cutting tools. A 3-axis CNC machine cutting out 40 mm steel plate blanks will consume around 1/10th of the power of a laser cutting machine extracting the same part. However, if the processing time is 1 minute on the laser cutter and 20 minutes on the CNC, the net power usage is 2:1 in favor of the laser cutter. Each part will have a different profile in this regard, but the differentials are rarely simple to analyze.
The alternatives to laser cutting are wire cutting, plasma cutting, waterjet cutting, and CNC machining.
Plasma cutting is similar to electrical discharge machining (EDM) in that it erodes material by applying an arc to ablate the substrate. However, the arc is conducted from an electrode on a superheated gas plasma stream that directs the arc and blasts out the molten material from the cut. Plasma cutting and laser cutting are similar in that both are capable of cutting metal parts. Additionally, plasma cutting is suited to heavy materials and relatively coarse processing, for example, preparing heavy steel components for architectural and ship projects. It is a much less clean process and generally requires significant post-cut cleanup to make presentable parts, unlike laser cutting.
Waterjet cutting is typically a small machine process for the precise processing of a wide range of materials. The garnet abrasive employed is considerably harder than the majority of processed materials, but the hardest workpieces do pose a challenge for the process. Waterjet cannot match the processing speeds of laser cutting on thicker, hard substrates. In terms of similarities, both waterjet cutting and laser cutting produce high-quality cut parts, are suitable for working with many materials, and both processes have a small kerf (cut) width.
CNC machining is considered one of the more traditional methods of extracting parts from flat material stock. It is similar to laser cutting in that both produce high-precision parts, are fast, reliable, and provide excellent repeatability. Compared to laser cutting, CNC requires more setup and more processing time. CNC also delivers lower throughput/capacity and requires greater manual intervention. However, results can be of similar quality, albeit at a generally higher cost. Rotating cutting tools apply considerable forces to the cut material and can result in more extensive local heating. The main advantages of CNC processing are the ability to accommodate complex 3D designs and to perform partial depth (rather than through) cuts.
If you are looking for more details, kindly visit decoration laser cutting machine.