A forming apparatus is provided for forming a film into a sleeve around a filling tube. The forming apparatus has contact surface geometry that is contacted by the film as it travels thereacross configured to ensure smooth forming of the film into the sleeve. Smooth forming of the film into the sleeve is achieved, in part, by reducing longitudinal tensile forces in the film, by selecting the contact surface geometry to minimize transverse variations in tensile forces in the film, and by having contact edges of the contact surfaces shaped to reduce unnecessary stresses in the film.