How To Avoid Cracks And Scorching When Laser Cutting Acrylic?

Laser cutting technology is widely used in many industries due to its high precision, high efficiency and flexibility. Especially in the fields of advertising, construction, home decoration and industrial manufacturing, laser cutting of acrylic materials has become a popular choice. Acrylic materials are not only lightweight and transparent, but also have good weather resistance and plasticity, so they are widely used as raw materials for signs, display racks, light boxes and various decorative and functional products.

However, during the laser cutting process, cracks and scorching often have a negative impact on the cutting quality and appearance. Cracks may not only affect the structural strength of acrylic products, but also cause appearance defects of the products, thereby reducing market competitiveness. The scorching phenomenon is manifested as black scorch marks on the cutting edge, which seriously affects the visual effect and makes the product look inferior. Therefore, how to effectively avoid these problems in the process of laser cutting acrylic and ensure the perfection of cutting quality and appearance is the key to improving product competitiveness and customer satisfaction.

1. Material properties

● Thermal sensitivity and brittleness of acrylic

Acrylic is a heat-sensitive material that is easily deformed or cracked by heat. During the laser cutting process, the local high temperature generated by the laser may cause the acrylic material to overheat locally, causing the material to melt or burn. At the same time, due to the brittleness of acrylic, it is easy to crack when subjected to stress, especially at the edge of the cut.

● The impact of cutting thickness and quality on the results

Acrylics of different thicknesses will have different thermal diffusion properties and cutting effects during laser cutting. Thicker acrylic materials are prone to uneven cutting and increase the risk of cracks due to the difficulty in evenly distributing laser energy during cutting. In addition, differences in material quality (such as impurities, bubbles, and internal stress, etc.) will also seriously affect the cutting results. Inferior materials are more prone to cracks and scorching.

2. Laser parameter settings

● Laser power is too high or too low

Improper laser power setting is an important factor leading to cracks and scorching. If the laser power is too high, the high temperature generated during the cutting process will cause the acrylic surface to burn and cause scorching; on the contrary, if the power is too low, it may cause incomplete cutting, increase the stress of the material during the cutting process, and eventually form cracks.

● Cutting speed is too fast or too slow

The cutting speed affects the time the laser contacts the material. If the cutting speed is too fast, the laser does not have enough time to melt the material, which may cause incomplete cutting or cracks; while if the cutting speed is too slow, the material will be heated for too long, which may easily cause local overheating and scorching.

3. Environmental factors

● Changes in temperature and humidity

The ambient temperature and humidity directly affect the physical properties of acrylic and the effect of laser cutting. Too high or too low temperature may cause thermal expansion or contraction of the material, thereby increasing the probability of cracks; and high humidity environment may cause the material to absorb water, affecting the heat conduction in the cutting, resulting in a decrease in cutting quality.

● Dust effects on equipment and environment

The cleanliness of the laser cutting equipment and the accumulation of dust in the working environment may affect the propagation quality of the laser beam. Dirt on the lens or lens will cause the beam to diverge, weaken the laser intensity, and thus affect the cutting effect. In addition, dust in the working environment may react with the laser during the cutting process, causing other adverse reactions and leading to cracks and burning.

Laser cutting is an efficient and precise processing method, but when cutting materials such as acrylic, cracks and scorching may occur. To ensure cutting quality, the following are some detailed effective measures.

1. Optimize laser cutting parameters

● Properly adjust laser power and cutting speed

Laser power: Select a laser power that matches the material type and thickness. Too high power will cause the material to melt quickly, which may cause scorching; too low power may cause incomplete cutting and cracks. It is usually recommended to experiment to determine the most suitable power setting.

Cutting speed: It is also important to adjust the cutting speed. Too slow speed will increase the accumulation of heat in the material, causing scorching, and too fast speed may not be able to cut effectively. A balance should be found according to the thickness and characteristics of the material.

● Correctly select the focal length to ensure laser focus

The focal length of the laser system determines the focusing quality of the laser beam, which can directly affect the cutting accuracy and edge quality. For acrylic materials of different thicknesses, the focal length of the laser needs to be adjusted to ensure that the laser beam is optimally focused on the surface of the material, thereby enhancing the cutting effect and reducing the heat-affected zone.

2. Cooling and gas-assisted cutting

● Use gas (such as nitrogen or air) to reduce the temperature of the cutting area

During the laser cutting process, appropriate auxiliary gas injection can effectively reduce the temperature of the cutting area and reduce thermal damage. Nitrogen, as an inert gas, can not only prevent oxidation reactions, but also form a good cutting effect. Air is also a commonly used auxiliary gas, but it may cause oxidation and is suitable for different applications.

● Apply ventilation or cooling systems to reduce heat accumulation

Equipping the cutting equipment with ventilation or cooling systems can help to continuously remove the heat generated during the cutting process and maintain a stable operating temperature. For example, fans or water cooling systems can be used to ensure the cooling effect when the equipment is running, thereby ensuring the stable performance of acrylic materials during the cutting process.

3. Choose the right acrylic material

● Choose high-quality acrylic to ensure uniform thickness

Select high-quality acrylic materials that have been strictly inspected to ensure uniform thickness and good internal structure. Uniform materials can better withstand thermal stress during cutting and avoid cracks or irregular cutting due to material defects.

● Avoid using aged or inferior materials

Aged materials may have reduced physical properties due to long-term placement, UV exposure and other factors, and are more prone to cracks and brittleness during use. Therefore, it is extremely important to use fresh and qualified acrylic materials to ensure good cutting performance and durability.

4. Design a reasonable cutting path

● Avoid sharp corners and unnecessary complex structures

When designing cutting patterns, try to avoid designing sharp corners and complex shapes. This is because sharp corners will cause stress concentration during laser cutting, which is prone to cracks. At the same time, complex structures may prolong the cutting time and increase thermal effects, thereby affecting the cutting effect.

● Plan the cutting sequence to reduce stress concentration areas

The planning of the cutting sequence can significantly affect the final cutting results. A reasonable cutting sequence should minimize the number of times the laser is applied in the same area to avoid excessive stress concentration. If necessary, an "escape line" can be preset in the design to release stress.

5. Post-processing methods

● Grind or polish the cutting edge

After cutting, grinding or polishing the cutting edge can remove burrs and defects on the edge. This not only improves the appearance of the product, but also reduces cracks caused by physical stress caused by rough edges.

● Use appropriate coatings to improve appearance and protect the surface

Applying a protective coating on the surface of the cut product, such as a transparent acrylic varnish or a special UV-resistant coating, can effectively improve the wear resistance and oxidation resistance of the surface, protect the cut product from the external environment, and thus extend the service life of the product.

Through the implementation of the above measures, the problems of terjadi cracks and scorching during laser cutting of acrylic can be effectively reduced, the cutting quality can be improved, and the use effect and beauty of the product can be ensured. Click here for more information