Synthetic fabrics and welding

At present, synthetic fabrics are increasingly used in women's clothing. They have a beautiful appearance, are well erased, have increased strength and resistance to sunlight. According to forecasts, the share of textiles containing synthetic fibers will continue to grow. However, the use of new synthetic materials in the garment industry is associated with a number of problems. When sewing products at high speed, the needle of sewing machines heats up to 300-400 ° C. Since synthetic fabrics have a melting point of up to 250 ° C, when they come into contact with the heated needle, the yarns are melted, which leads to a break in the needle thread and increases the stiffness and brittleness of the seam. As a result, the speed of the piercing decreases, the quality of the finished product deteriorates. Sewing synthetic materials requires the use of sewing threads of the same chemical composition as the material, otherwise wrinkles appear during sewing or after washing or cleaning.

There are two principles of welding - discrete and continuous.

The first principle: this connection of two small parts under the press. The size of the seam is determined by the dimensions of the working surface of the press.

The second principle: is a continuous process like sewing. Begin with one edge of the seam and sequentially weld to the other edge. When working with large-sized products, the cut lies on the table, and the welding machine moves along it. When working with conventional products in clothes - all the way around. The seamstress sits behind the welding machine and directs the product through the machine. The process resembles work on a conventional sewing machine. When welding with a hot wedge, "ironing" is located between two layers of welded materials. The main parameter of this method is the heating temperature of the hot wedge. When welding with hot air, there is a nozzle between the layers of material, from which hot air is supplied under pressure. When welding with hot air, direct welding of two layers of material is distinguished, and sealing of the fillet welds with the help of special tapes. In the literal sense, welding the tape is an adhesive process. In this case, the adhesive layer of the sealing tape is plasticized under the influence of hot air, and the tape is glued to the seam. With the ultrasonic welding method, material heating takes place due to the vibrational energy. It should be noted that the heating pulses pass through the material layer from the outside. In other welding options, the temperature acts directly on the welded surfaces (from the inside). Ultrasound has great advantages in comparison with other welding methods, because in the process, neither the nozzle nor the wedge interfere. But nevertheless for ultrasonic welding there is a limit of a thickness of a material. At a large thickness, the outer layer burns out before the inner layer has time to plasticize.

The use of technologies such as gluing and welding has several advantages over the traditional way of making clothes. A feature of welding seams is their absolute strength. In terms of its physicomechanical parameters, the weld seams are similar to the parameters of the materials being processed. Welding seams are resistant to ultraviolet radiation, like the textile itself. The destruction of the seam, as a result of the breaking of the threads under the influence of sunlight and abrasion, is almost impossible. The strength of the seam is evenly distributed over the entire length, and not applied pointwise as in the fillet welds. On the seam made on the sewing machine the threads are visible. The quality of this seam can be assessed optically. Welding seam is usually internal, and it is not so easy to evaluate from the outside. Quality assurance is provided in most cases by means of a trial weld and further maintaining a constant value of once found optimal welding parameters.