Plastics are widely used in various industrial fields, and the demand for plastics in industrial production has gradually approached or even exceeded that of steel materials. Especially in the electronics manufacturing, medical, food packaging, automotive and other industries, plastics have become one of the key indispensable materials, the production of various plastic parts of the precise, high-strength connection needs, but also with the large number of plastics used and increasing.
Welding automotive plastic parts.
The choice of connection process for plastic parts has an important impact on the final application of plastic products. Traditional plastic joining processes include threaded, glued, inserted and press-fit joining, as well as fusion joining represented by hot plate welding and ultrasonic welding. The advantages of these combining methods are simple operation, convenient connection, and strong applicability; however, the disadvantages are also more obvious, such as specific shape requirements, relatively low strength of the connection, in the face of three-dimensional geometric shapes, hollow and other complex irregular shapes, as well as large parts and components, and even after the connection of the plastic parts of the airtightness of a certain requirement, the operating space is small, less efficient.
Welding white structural parts.
At the same time, in the pursuit of product innovation and quality improvement of the modern industrial sector, the welding quality requirements are increasingly high. With the development of laser technology, but also promote the gradual application of plastic welding process, laser plastic welding technology has become an important direction of development, is gradually becoming the new favorite connecting materials, commonly used in white household appliances plastic parts, automotive plastic parts and other parts of the welding.
Laser plastic welding principle
Laser plastic welding, also known as laser light transmission welding, requires the upper layer of plastic workpieces with high light transmission rate, the lower layer of workpieces can absorb laser energy, so the current mainstream welding object for "transparent plastic + black plastic", "transparent plastic + transparent plastic" combination of ways. Therefore, the current mainstream welding object is "transparent plastic + black plastic", "transparent plastic + transparent plastic" combination.
Since most of the transparent plastics have high transmittance and low absorption of light in the 800nm~1100nm band, based on this, Nuffield launched a 980nm semiconductor laser, which integrates a high-precision control system in a compact structure and is easy to use. It utilizes advanced semiconductor laser technology to output a near-infrared laser with a center wavelength of 980nm. The laser energy at this wavelength penetrates transparent or semi-transparent plastic surfaces, is absorbed by the lower layers and converted into heat, which can be used to implement precise and efficient plastic welding. The laser has high electro-optical conversion efficiency, provides continuous laser output, and the power level can be selected according to the needs of the welding process, ranging from a few watts to hundreds of watts of adjustable output, making it possible to take into account the welding of large-area, high-speed plastic components.
The actual application of laser plastic welding includes not only the laser itself, but also the welding head and welding fixture. The use of 980nm semiconductor laser plastic welding, the first two parts to be welded with the help of fixtures assembled together, the basic principle of welding is that the welding head output of the laser beam through the upper layer of transparent plastic, under the control of the program accurately projected to the lower layer of plastic parts to be welded area; the lower layer of plastic in the absorption of a high degree of focusing of the laser energy after the melting, and make the upper and lower layers of the two layers of plastic parts of the contact surface of the heat exchange is fully melted and Combined together, in a certain amount of external assistance, after cooling to form a weld, complete the final welding.
Welding of plastic structural parts of circuit boards.
At the same time, with the help of a special control system, it can realize precise heat control and local heating in the process of transmittance welding, consistent welding quality, avoiding adverse effects on the surrounding materials, and is widely used for welding precision plastic parts in the industries of automotive parts, medical equipment, electronic components and so on.
PC+ABS plastic welding test
In practice, in order to ensure the quality of the weld and sufficient melt depth, it is also necessary to consider the relationship between welding speed and laser power to find the optimal process window.
To weld PC, ABS plastic for testing, the first two plastic parts placed in the carrier stacked, and the use of fixtures to apply pressure clamping.
Adjust the laser output power to 300W, the welding speed is set to 20mm / s (up to 10,000mm / s), the two layers of plastic welding success, weld fusion uniformity, weld width moderate, sealing is good, and the strength of the tensile strength test to meet the requirements.
Laser output power to maintain 300W unchanged, when the welding speed is adjusted to 10mm / s, the two layers of plastic welding success, weld fusion uniformity, weld seam width, good sealing; but due to the high temperature of the molten pool, which may lead to some of the material decomposition, resulting in a reduction in the strength of the weld.
When the power is adjusted to 200W and the welding speed is set to 20mm/s, the width of the weld is moderate, the fusion is good, the sealing is good, and the tensile strength is lower than that of the weld at high power.
Advantages of laser welding
Laser welding is similar to the fusion bonding process, but the advantages of the former are more obvious:
First of all, high precision, the laser's small spot and high uniformity, can accurately align the more minute welding parts, can quickly convert the laser energy into the energy required for welding, to achieve precision welding, and can significantly improve the welding efficiency. Combined with the professionally designed welding head, it ensures that the laser energy is fully absorbed in the welding area, guaranteeing the strength of the weld.
Secondly, the small heat-affected zone can avoid thermal damage to the plastic surface during the welding process, which maintains the transparency and finish of the material. This makes the products after translucent welding not only maintain the original appearance characteristics, but also enhance the solidity of the structure.
Thirdly, it solves the contradiction between welding speed and welding quality in traditional welding methods, and can complete large-area welding in a short period of time, which greatly improves production efficiency. A welding operation that originally takes several hours can now be easily completed in just a few minutes or tens of minutes, saving a lot of time and cost.
In addition, the non-contact welding operation avoids the mechanical stress and vibration generated by the traditional connection method, protects the integrity of the plastic surface, and also ensures the precision of the weld seam, with a closer and more reliable connection between the materials, and excellent sealing, which meets the requirements of waterproofing, dust-proofing and other high-standard products.
Welding automotive plastic parts.
Summary
At present, 980nm semiconductor lasers have shown strong market potential and application value, is a plastic welding tool, especially in automotive plastic welding, brought to achieve high efficiency and stability of the welding effect. In the interior welding, can be used for instrument panel, center console, etc. Welding; in the welding of exterior parts, can be easily capable of door handles, lamps, etc. Welding; in the welding of automotive electronic parts, 980nm semiconductor laser is also outstanding, can be used for many electronic components of the plastic welding, significantly improve the strength of the connection and the sealing, to ensure that the stability and reliability of each component. In the future, with the continuous development of functions, 980nm products will usher in a wider range of applications.
