Air cushion inflation machine

A machine for converting a web of preformed pouches into inflated dunnage units, the pouches defined by transverse seals extending from a remote edge to within a predetermined distance from an inflation edge, the machine comprising:

• a guide pin for insertion between the transverse seals and the inflation edge to define a path of travel of the web;
• a tensioning device for frictional engagement with the web, wherein the tensioning device holds the web taught during downstream travel;
• an inflation arrangement for inflation of the preformed pouches;
• a sealing arrangement positioned to provide a longitudinal seal that intersects the transverse seals to close the preformed pouches and form a dunnage unit, the sealing arrangement having at least two sealing belts, each belt powered by a drive roller and positioned so that respective first sides engage a surface of the web and pull the web through sealing elements positioned on either side of the web;
• a heating element on one of the at least two sealing belts, wherein the heating element is a substantially flat wire comprising at least one relatively higher resistance portion and at least one relatively lower resistance portion;
• a clamping arrangement positioned to pinch the two layers of the web during travel through the sealing elements, the clamping arrangement having at least two pinching belts, each belt powered by a drive roller and positioned to engage a surface of the web and pull the web and pinch the web through the sealing elements;
• an encoder receiving speeds of the respective belts;
• wherein if the relative speeds of the respective belts is not within a predetermined tolerance, the encoder determines that an error has occurred.