A method and apparatus for welding ends of two separate articles or a single article to form a single welded article. The apparatus comprises first and second molds for supporting and clamping first and second ends of at least one article and an infrared heating element for thermally energizing over a prescribed period of time the first and second ends of the at least one article to a welding condition. The apparatus further comprises a regulator for altering the power supplied for energizing the infrared heater over at least a portion of the prescribed period of time to achieve increased electromagnetic radiation penetration into the body of the at least one article beyond the first and second ends. The apparatus also comprises an actuator for advancing the first and second ends into a contacting position to form a single welded article.