The hottest plastic laser welding method and its a

2022-09-22
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Plastic laser reaches 12% Welding methods and their application in medical devices

today, when plastic materials are widely used in the field of medical devices, new plastic production and processing processes emerge in endlessly. Laser welding, as one of them, has attracted extensive attention from the industry. This paper introduces the principle and technology of plastic laser welding and its application in the medical device industry

principle of plastic welding

in the welding process of thermoplastic, two plastic parts to be welded are clamped together with clamping fixtures. One plastic part can make the laser penetrate, while the other plastic part can absorb the laser energy. The laser beam reaches the welding plane through the upper transparent material, and then is absorbed by the lower material. The laser energy is absorbed to make the temperature of the lower material rise. According to gb6672, measure the thickness of the experiment, melt the plastic of the upper and lower layers, and finally solidify into a solid weld

The advantage of plastic laser welding is that it is a non-contact welding method, and the laser energy only acts on a very small welding area, which greatly reduces the damage of the thermal stress and vibration of the workpiece

plastic laser welding methods mainly include: contour welding, synchronous welding, quasi synchronous welding, radial welding and Globol welding

contour welding

as the name suggests, contour welding is to make the laser move along the welding line of the workpiece, melt and bond the plastic layers to be welded together; Sometimes, you can fix the position of the laser, move or rotate the workpiece to achieve the purpose of welding

synchronous welding

synchronous welding first customize the corresponding laser head according to the shape of the welding area. It is required that the shape of the welding area is generally symmetrical, such as a circle. The laser beam of synchronous welding comes from several diode laser beam insertion and extraction force cycle experiments, which simultaneously act on the contour line of the welding area to melt the welding area to achieve the welding effect. The defect of synchronous welding is that its lens must be customized according to the shape of the welding area of the workpiece

mask welding

mask welding requires making a template that can reflect or absorb laser. The template is used to locate the welding area, and the laser melts the welding area through the template to achieve the welding effect. The advantage of mask welding is its flexibility. The template can be changed according to the shape of the welding area. At the same time, this welding method is also suitable for high-precision welding, and its precision can reach the micron level

globo welding

the patented welding process of Leister, Switzerland. Globo welding is carried out along the contour of the product. The laser beam is focused on the welding interface through an air cushion glass ball that can roll freely without friction. The glass ball not only focuses, but also acts as a mechanical clamping fixture. When the ball rolls on the surface, it provides continuous pressure to the joint surface. This ensures that there is pressure clamping while the laser heats the material. The glass ball replaces the mechanical fixture and expands the application range of laser welding in continuous three-dimensional welding

Application of plastic welding in medical devices

in the field of medical devices, plastic laser welding is mainly used in injection systems, medical electronic equipment, and can complete a variety of mechanical property experiments of plywood, particleboard, medium density fiberboard and other plates, as well as various artificial transplantation and stoma products

an interesting application is to use laser welding to weld Phonak earwax protector. The size of the whole earwax protector is only a few millimeters. We need to weld a diaphragm to a washer about 3 millimeters in size. The diaphragm is transparent to laser radiation, while the gasket is made of thermoplastic material, which can absorb laser radiation. To realize the welding of such a small workpiece, we adopt a mask welding method suitable for high-precision welding

plastic laser welding process is also widely used in some other high-end medical products, such as artificial fistula care products and needle tip protective caps. In artificial fistula care products, we use Globo welding process. In the welding of needle tip protective cap, we adopt synchronous welding process

biochip and microchannel

Plastic laser welding is also widely used in biomedical analytical instruments. Biomedical analytical instruments are usually required to be sterile and free from any chemical substances, etc. The traditional glue adhesion method may bring chemicals into the analytical instrument, thus affecting the accuracy. Friction welding and other methods will produce dust or spills during the processing, which will also pollute the instrument. As a non-contact welding method, laser welding is especially suitable for the production of this kind of products. The range of heat influence in the process of plastic laser welding is small, so it is also suitable for the welding of heat sensitive materials, such as the welding of biochips with protein coating on the surface

the best example of biomedical analytical instruments is the liquid analysis chip, which contains a microchannel system to collect and analyze liquid substances. Usually, the runner is only a few centimeters long and may be tens of microns to hundreds of microns wide, and its aspect ratio is less than 1. The pressure on the runner is usually a few PA. These microchannels are usually composed of very thin plastic sheets, which may vary in thickness from a few millimeters to 20 microns. Mask welding is the best way to weld such a precise product. After using mask welding, the welding can be completed as long as a relatively low-quality diode laser is used, thus saving a lot of investment. In addition, using mask welding can also greatly improve production efficiency

plastic laser welding process is far more than the above applications in medical devices. Plastic laser welding process is being adopted by more and more medical device manufacturers, and its application prospect will be very bright

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