Abstract: An improved method is utilized to make an improved mold for forming a plurality of small objects, such as piston rings. The mold is made by stacking a plurality of mold sections formed of gas permeable material, such as CO.sub.2 sand, resin bonded sand or green sand. The stacked mold sections are then clamped together to hold them against movement relative to each other. A wet coating of liquid ceramic material is then applied over the stack of mold sections. This liquid ceramic mold material is dried to form a rigid gas permeable ceramic casing which encloses the stack of mold sections. The rigid casing of ceramic material holds the mold sections against movement relative to each other to prevent break-out of metal from between the mold sections when a flow of molten metal is directed into the mold cavities. Due to the gas permeable construction of both the rigid ceramic casing and the mold sections, gas can readily escape from the mold as the molten metal enters the mold cavities.

Abstract: An improved apparatus for electrolytically removing material from a workpiece includes a plurality of electrodes which are movable relative to each other through working strokes. In order to coordinate the movement of the electrodes, they are stopped at one or more predetermined intermediate positions during their working strokes. When all of the electrodes have arrived at intermediate positions, the electrodes are simultaneously moved away from their intermediate positions toward their end of stroke positions. In order to accommodate variations in the rate at which material is electrolytically removed from a workpiece, the speed of movement of the electrodes and/or the electrical potential established between the electrodes and the workpiece can be varied. Relatively large diameter rams connected with the electrodes are supplied with fluid from relatively small diameter piston and cylinder type pumps.

Abstract: An improved method of forming articles, such as airfoils, includes forming the major side surfaces of a plurality of airfoils in two groups or series along opposite edge portions of a workpiece by utilizing a plurality of pairs of electrodes to effect the electrolytic removal of material from opposite sides of the workpiece. Leading and trailing edge portions of the airfoils are formed by utilizing a plurality of relatively long narrow electrodes to effect the electrolytic removal of material to form slots between the major side surfaces of the airfoils and the remaining portion of the workpiece. During the electrolytic removal of material to form both the major side surfaces and the slots at the leading and trailing edge portions of the airfoils, an electrical potential is established beteen the electrodes and the workpiece and a flow of electrolyte is maintained between the electrodes and the workpiece. After the workpiece has been inspected, a base is formed in association with each of the airfoils.

Abstract: An improved apparatus for forming a plurality of airfoils or other articles includes a plurality of pairs of electrodes which are utilized in the electrolytic removal of material from opposite sides of a workpiece at a plurality of spaced apart locations to form side surfaces of a plurality of airfoils. The electrodes are constructed so that a group of airfoils is formed along each of a pair of opposite minor sides of a workpiece. In one specific instance, a plate having the configuration of a rectangle is utilized. This plate may have a size such that only one end portion of the plate will fit in a working chamber at a time. After a plurality of airfoils have been formed in one end portion of the plate, the plate is withdrawn from the working chamber and the opposite end portion of the plate inserted into the working chamber. In another specific instance, the workpiece included a support frame in which a plurality of partially formed airfoils are mounted.