The fabrication of the membrane fabrics is work that requires experienced personnel and should only be carried out by specialists. Furthermore, a good knowledge base of the fabric itself should be assured as well as knowledge of the special equipment and adequate production facilities.
Production itself can be subdivided into four phases:
1. Delivery and material inspection 2.Cutting 3.Welding
Experienced manufacturers nominate an employee as quality assurance manager to oversee production. This guarantees a sufficient control of the delivered fabrics and therefore a successful manufacturing process right from the beginning. Apart from the assessment of the final manufactured fabrics, this person should be involved in every intermediate step. During the production process, records are made of all the work steps to guarantee state-of-the-art workmanship.
After quality control, cutting patterns are generated using 3D computer models of the structure. The required compensations for individual production weave batches of membrane material should be considered here as well. Furthermore, edge corrections for welding seams and edge details are alsocalculated throughout this process. These electronic cutting patterns are then transferred by a computer into a controlled cutter/ plotter.
joining or assembly process of the single membrane areas (patterns) for
the PVC-coated fabrics is normally carried out using a high frequency
induction method. Purpose-built welding machines are used to fabricate
powerful seams. The hand-held welding
process by means of hot-gun tools is used to do the detailed work like
corners or other more complicated seams. The process is kept under control by measurements of the external gauges, which deliver periodical data of parameters such as
the output temperature or the executed pressure.
High frequency welding is performed by conducting electrical energy in the form of a radio frequency field to the two surfaces that are to be joined together. The electrical field is conducted to the material through a metal tool, called an electrode.This stimulates the molecules in the material to move at a speed of approx. 25 million times per second. The friction that arises between the molecules generates the heat that is required to fuse the material together. By using this technique, an optimum weld seam can be created, which has a similar strength to the surrounding material. To guarantee the welding result, the performances need to be tested with each machine adjustment, new start or malfunction. The minimum seam resistance should be at least 70% of the material resistance.