The filter assembly includes a filter element having an end surface and an end cap connected to the end surface by spin welding. The end cap has an outer diameter that need be no larger than the outer diameter of the end surface of the filter element. Prior to spin welding, the end cap may have a surface with a sacrificial ridge extending from the surface. The end cap is spin welded to the end surface of the filter element by rotating the filter element and the end cap with respect to one another while contacting the sacrificial ridge with the end surface of the filter element, melting the sacrificial ridge by the contact with the filter element to form a molten plastic, and joining the surface of the end cap to the end surface of the filter element with the molten plastic. Also disclosed is a method of spin welding a filter pack to an end cap without a sacrificial ridge.