Plastic Laser Cutting

Can you laser cut plastic? Of course! It is widely known that you can laser cut metal, whereas laser cutting of plastic is a lesser known phenomenon in the manufacturing industry. DLF Plastics is the manufacturer of laser-cut plastic parts, semi-finished products and finished products. Laser cutting is a widely used and well-known production technique in the metal industry. Like metal, many types of (technical) plastics are perfect for laser cutting. We use industrial CO2 laser cutting machines, with which we cut hundreds of parts for various sectors in the manufacturing industry every day.

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How does laser cutting of plastic work?

In theory, laser cutting of plastics works in the same way as laser cutting of metal. In the case of plastics, generally less laser power is used than for metal. Otherwise, the technology in a laser cutting machine is virtually the same. By focusing a laser beam on an extremely small surface, the laser “burns” through the material, as it were. In fact, the plastic evaporates immediately when the laser beam strikes the surface. To prevent the plastic from burning during cutting, we blow cutting gas over the material to be cut. This cutting gas also ensures that no fusion of the plastic takes place. The "saw cut” depends on the machine adjustment and material thickness between 0.05 and 0.15 mm. This is also one of the greatest advantages of plastic laser cutting compared to plastic milling. When milling plastics, you quickly lose between 5 and 15 mm per saw cut, purely because of the thickness of the cutter! Of course, milling also has advantages compared to laser cutting, so we cannot produce 3D shapes as well with a laser. For this reason, milling is chosen from an economic point of view when producing 3D parts, such as depressions and slots.

The laser cutting process

Generating the laser beam consists of stimulating the source that creates electrical discharges, which is in fact comparable to a fluorescent tube. During the stimulation of this source, the created beam is reflected by means of a mirror until the beam has reached sufficient energy to escape from the laser source. The laser beam then leaves the laser source in the form of a very focused light beam.
The light beam created is then guided via a number of mirrors towards the surface to be cut. In order to obtain an even stronger and more focused laser beam, the beam is focused by a lens before it hits the material. This lens actually functions as a magnifying glass and focuses the laser beam on a surface of approximately 0.1×0.1 millimetres. With this heavily focused laser, the materials can then be cut very precisely. The "cutting” actually takes place because the material hit by the laser beam evaporates.

The 6 biggest advantages of plastic laser cutting

Compared to other cutting techniques, laser cutting has various advantages. As a result of these advantages, plastic parts are increasingly being manufactured with a laser cutting machine. The production speed is higher than with milling, and, as a result, the production price decreases.

1. High cutting speed

Of course, the advantage you can achieve with laser cutting depends on each specific part. The cutting speed is different for every type of plastic. For example, we can cut Acrylics (PMMA) faster than POM-C with the same thickness. Even the colour and composition of the material affects the cutting speed. We can thus cut black HDPE faster than the white version. For Acrylics, the difference between various colours is minimal. On average, laser cutting is about 20 to 50% faster than milling.

2. Complex designs easy to cut

Where you have to take into account the thickness of the cutter when milling, this is not a factor when laser cutting. A laser cutting machine can cut out shapes, and thus products, that simply cannot be produced with a milling machine. These are in particular small parts with sharp corners, for example. The very narrow cutting width contributes to the ability to cut complex shapes.

3. Very narrow cutting width

The cutting width for laser cutting, depending on the material and the adjustment of the machine, is between 0.05 and 0.15 mm. Very small! We work with various types of focus lenses. Some lenses have a long and relatively wide focus; these lenses are used to cut plastics between approximately 5 and 25mm. For thinner plastic sheets, we use other lenses with a shorter focal point. The advantage of these lenses is that we can cut in even more detail; the disadvantage is that this lens offers too little power to cut through thicker materials. These smaller lenses are extremely suitable for super detailed laser engraving!

4. Tight, clean cutting edge

Because the plastic evaporates during laser cutting, no chips are released. There is also no mechanical contact visible on the cutting edge, purely because there is no contact between the cutting tool and the plastic. We are regularly asked whether the plastic burns when you cut it with a laser. In response to this question, we often show a number of laser-cut plastics. The cutting edges are often stunningly beautiful! Some plastics require extra attention when adjusting the machine. Polycarbonate in particular is a plastic that has a less attractive cutting edge at thicknesses of more than 5 mm. The reason for this is that this material absorbs the laser light less well, causing the cutting edge to turn brown.

5. Contactless high-speed cutting

We mentioned it before: contactless cutting. For both milling plastic sheet material and cutting (with a plotter) thinner plastic foils, contact takes place between the cutting tool and the workpiece. In principle, this does not have to pose any problems. Nevertheless, we often see thinner foils tearing during cutting. The thicker plastic sheet material often shifts during milling. Because laser cutting takes place contactless, the plastic cannot tear and/or move during the cutting process. This reduces the margin of error and results in higher productivity and lower cost!

6. Radius-free corners

Sounds very complicated, but it isn't. Because a milling cutter is round, and rotates very fast, no right angle can be made with it. A corner always contains at least the radius of the cutter. For an 8mm milling cutter, this means that a corner always has an inner radius of 4mm. An outer corner can be made radius-free with a milling cutter. The advantage of laser cutting is that both inner and outer corners can be produced without any problems. The cutting surface of 0.1×0.1 mm does not matter how sharp the corners should be. The laser cutter makes all corners radius-free.

The 4 disadvantages of plastic laser cutting

In addition to the advantages you have been able to read above, laser cutting of plastics also has a number of disadvantages.

1. Only 2D shapes are possible

As soon as pockets, depressions and/or, for example, slots must be made in a material, it becomes less attractive in terms of cost to manufacture with a laser cutting machine. Because a laser cuts from top to bottom, it is only possible to cut straight down. Making an depression in the material is possible, but due to the small surface area of the laser beam, this is usually not interesting in terms of cost. The laser always removes layers of 0.1×0.1 mm. In order to “engrave" away 1mm of material, a laser must therefore go back and forth 10x. For pockets/depressions larger than a milling cutter, working with a milling cutter is a more efficient method. If depressions have to be made that are smaller than the milling cutter diameter, laser cutting does offer a solution! Due to the very small laser beam, it is possible to realize those smaller depressions precisely.

2. Limited thickness possible

Depending on the type of material, we can laser cut to a certain thickness. The maximum thickness we can laser cut depends on the type of plastic. Acrylics is a plastic that can be laser cut to thicknesses of 15 to 20 mm; thicker is possible, but the cutting edge becomes less beautiful. Polycarbonate looks similar in terms of material, but this material can be neatly laser cut to a thickness of about 5 mm with the right cutting gas. So how thick we can cut depends on the type of plastic. For example, we cut many HDPE parts, the maximum thickness of which is between 10 and 12mm. Thicker parts are usually produced with a milling cutter.

3. Heat input

Laser cutting is a thermal process. This means that we can cut plastic by heating it. There is a downside to that. The material around the cut is exposed to heat. Because the laser moves at a high power and a high speed over the material, hardly any heat is introduced into the material. The cut does become very warm, causing it to evaporate. The “Heat-Affected Zone” is relatively small. The Heat Affected Zone is the piece of plastic (around the cutting edge) that is exposed to higher temperatures. By applying the right type of cutting gas in combination with the right amount of cutting gas, we can minimize this area. This reduces the chance of warping the workpiece. Nevertheless, the heat input can cause adverse effects in some situations. Of course, a workpiece also gets hot during milling. The great advantage of milling is that the milling cutter and the workpiece can be cooled with liquid, for example. As a result, very little heat is introduced into the workpiece. If we cooled the laser beam with liquid, the power of the beam would be lost. With laser cutting, we are limited by the cooling capacity of the cutting gas. Contact us if you have any specific questions about heat input.

4. Not suitable for all materials

Despite the versatility in the number of types of plastics we can laser cut, there are also a number of plastics that we absolutely cannot (and do not) cut. You will have to have these materials milled because these plastics emit harmful substances during laser cutting. Examples include:

- PTFE (Teflon)
- PVB
- PVC
-Carbon

In principle, PTFE laser cutting, for example, is possible, but because we put the health of our personnel first, we do not cut this material.

Would you like to have the above materials processed? Then you will have to choose from a different processing technique. Of course, we are happy to help you. Feel free to contact us if you have any questions or comments.

Laser cutting applications

Laser cutting is, as mentioned earlier, a widely used type of processing technique that offers a solution for many types of markets. In addition to finished products, DLF Plastics also supplies many types of parts and semi-finished products to our customers. In addition to private individuals, we help customers who work in very diverse markets to realize their ideas.

Several examples of these markets are:

- Yacht construction
- Mechanical engineering
- Automotive industry
- Electrical engineering
- Food industry