A system is proposed for encapsulating in plastics material leadframe items comprising an IC wired to a leadframe. Dust of the plastics material is removed from the encapsulation system, and in particular from those items where dust principally accumulates, such as the surfaces of the molds. To reduce the level of dust which enters the molding region, the path along which the leadframe items are conveyed to the molding region is closed at times when the leadframe items are not being transported there. Additionally, the leadframe items are conveyed to the molding region under a cover including a vacuum source, so that the dust is continually sucked away from them.