vertical movement by vertical tubes 38 which are fixed in the base plate 2 and slidable in the head plate to avoid thermal stresses these tubes are also hollow and water cooled threaded rods 40 mounted in brackets 42 on the base plate engage nuts 44 in vertical sleeves 46 on the carriage these rods are mounted in bearings 47 in the head plate and are driven by a motor 48 fig1 through a speed reduction arrangement 50 for the purpose of raising or lowering the carriage the particulate material is fed to the container as by a conveyor tube 52 extending through a furnace 54 this tube is withdrawn axially by suitable mechanism not shown so that it will not interfere with the vertical movement of the ram or the carriage 28 with the heating coil thereon the vertical movement of the ram is by a hydraulic actuator 56 on the head plate the piston rod or plunger 58 of the actuator being connected to the upper end of the ram the press is positioned within an enclosure 60 suitable for use as a vacuum chamber and a vacuum tight door 62 permits access to the container and to the cover positioning apparatus obviously before lateral movement of the container with the surrounding support ring toward the door 62 the heating coil 26 will have been moved upward out of operative.