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<br />H. As the FIVfL sheet materials pass through the machine, they must come in <br />contact with the wedge in order to heat the material properly. ILPI hot <br />wedge welding machines aze equipped with pressure shoes which assure <br />contact between the FIVfL sheet and the wedge as the material passes <br />through the machine. Once the welding machine has been set up for a <br />particular FiVIL thickness, further field adjustments are not required. The <br />wedge has an adjustment that is actually a stopping device to keep the "hot <br />shoe", or anvil from being pulled into the nip/drive rollers. Caution must <br />be taken ensure that the wedge is not adjusted too closely to the nip/drive <br />rollers, especially when material is not going through the machine. The <br />drive, or wedge units, must be disengaged before the material runs <br />completely out of the machine. Serious damage will occur to the FvfL <br />sheets if the wedge gets pulled through the nip/drive rollers. <br />The front part of the seaming device should be inspected for sharp comers <br />and irregular details which may damage the FMLs. <br />J. Temperature controllers on the wedge device should be checked <br />periodically. <br />III. Actual Seaming Process <br />A. The hot wedge system is properly positioned for the making of a dual <br />(split) seam. <br />B. The principle of the hot wedge is that both surfaces to be fused come into <br />intimate contact with the hot wedge, or anvil. The wedge lifts up both <br />layers of FML off the subgrade and fusion is brought about by <br />compressing the two melted surfaces together, causing an intermingling of <br />the polymers at a pressure of approximately one hundred pounds per <br />squaze inch. The hot anvil itself reduces the surface tension of the viscous <br />polymer sheets and acts as a scraper/mixer, followed closely by the nip <br />roller which squeezes the two FMLs together. <br />47 <br />