The packaging of food determines the extent of food waste. Mechanical punching, roller needle punching, and laser perforation are used in packaging to extend the shelf life and freshness of products. Different punching methods have varying effects on extending the product's shelf life. Laser perforation is specifically designed for micro-perforated modified atmosphere packaging, which is more effective in extending the product's shelf life. What are the differences between mechanical punching, roller needle punching, and laser perforation? 1. Mechanical Punching These holes are made by mechanically punching through the film. Common hole diameters are 3mm, 6mm, 8mm, or 10mm. Mechanical punching is widely used in packaging fresh fruits and vegetables, including films and bags. It is mainly used for packaged products that do not require an extended shelf life, such as potatoes, carrots, etc. Large holes facilitate product ventilation, ensuring more effective preservation of food during the entire distribution and retail display process. 2. Roller Needle Perforation These holes are made by a series of heated needles. They are usually 1-2 mm in size and can be made in rows. Micro-perforation is most commonly used in the packaging of fresh baked goods and pies. It is also often used for packaging grains, dried pasta, bulk beans, and vegetable products. Micro-perforation allows excess moisture to escape, thereby extending the product's shelf life. If vegetables or grains can stay fresh longer, suppliers can reduce waste, and consumers can store them for a longer time. 3. Laser Perforation Laser perforation is made using a laser. The size and position of the holes on the packaging are customizable. The hole size can range from 80µm to 160µm. Laser perforation can be used when you want to design modified atmosphere packaging to control the gas composition of the package. It is ideal for fresh produce, including but not limited to pre-cut vegetable mixes and salad mixes. It is also suitable for fresh produce with a short shelf life, such as berries. Laser cutting involves irradiating a laser beam onto the material to be cut, heating, melting, and vaporizing the material, and blowing away the molten material with high-pressure gas to form holes. Then the beam moves over the material, and the holes continuously form a slit. For general thermal cutting techniques, except for a few cases where cutting can start from the edge of the plate, most need to drill a small hole in the plate first, and then start cutting from the small hole. Principle of Laser Perforation The basic principle of laser perforation is: when a laser beam with a certain energy irradiates the surface of a metal plate, except for a part being reflected, the energy absorbed by the metal melts the metal to form a metal molten pool. The molten metal has a higher absorption rate relative to the metal surface, that is, it can absorb more energy to accelerate the melting of the metal. At this time, properly controlling the energy and air pressure can remove the molten metal in the molten pool and continuously deepen the molten pool until the metal is penetrated. In practical applications, perforation is usually divided into two methods: pulse perforation and blast perforation. 01. Pulse Perforation The principle of pulse perforation is to use a pulsed laser with high peak power and low duty cycle to irradiate the plate to be cut, so that a small amount of material is melted or vaporized, and is discharged from the perforated hole under the combined action of continuous hitting and auxiliary gas, and continues to proceed step by step until the plate is penetrated. The laser irradiation time is intermittent, and the average energy used is relatively low, so the heat absorbed by the entire processed material is relatively small. The residual heat effect around the perforation is small, and there is little residue left in the perforation area. The holes drilled in this way are relatively regular and small in size, and basically have no impact on the initial cutting. The process is as shown in the figure below: After the laser beam irradiates the workpiece, it first heats the surface of the material, as shown in (A); as the heating gradually deepens, it plays a role in perforation, i.e., (B) ~ (C) ~ (D), until finally penetrating as shown in (E). The entire perforation process is not completed at one time, but is done step by step, gradually deepening until penetration. Therefore, the time for this method of perforation is relatively long; however, the resulting hole is small, and the thermal impact on the surrounding area is also smaller. 02. Blast Perforation The principle of blast perforation: A continuous wave laser beam with a certain energy is irradiated on the workpiece, causing it to absorb a large amount of energy and melt, forming a pit, and then the auxiliary gas removes the molten material to form a hole, achieving the purpose of rapid penetration. Due to the continuous laser irradiation, the hole diameter of blast perforation is larger, and the spatter is more severe, so it is not suitable for cutting with high precision requirements. The entire process is as shown in the above figure: the focus is set above the surface of the material, and the hole diameter is increased to heat quickly. Although this perforation method will produce a large amount of molten metal, which will splash onto the surface of the processed material, it can greatly reduce the perforation time. This test uses the GW Laser 5M series multi-module 12KW high-power laser. The advantages of this product are: adopting 976nm technology, with an electro-optical conversion rate of more than 45%, significantly reducing electricity costs; more advanced single-mode high-power modular design, making the product more compact, with better stability, smaller size, and lighter weight; super ABR anti-reflection capability, easily cutting high-reflective materials such as gold, silver, copper, and aluminum; excellent HBF high-brightness flat-top mode output, with excellent thick plate cutting and welding performance. Source: Laser Manufacturing Network, Laser Intelligent Manufacturing Explorer