US Patent 7316292 Spun extrusion side entry muffler

By using a spun extrusion method to form a side entry exhaust inlet, a muffler can be completely stuffed and end caps can be spun onto opposing ends of the muffler on a high speed production line without interruptions. The side entry exhaust inlet is formed within a muffler shell at a position between the opposing ends. A spinning tool engages an internal peripheral area of the side entry exhaust inlet to form a spun extruded surface that extends outwardly from the muffler shell.