The Three Following Case Histories By F. Valenta, Cercast, Inc.


Knotter Disc is Produced in Large Ouantities


toughness and resistance to erosion and corrosion in the field, 410 stainless steel was selected for this investment casting.


Originally, seven different components were blanked, machined, and furnace brazed to obtain the part. This method was costly and yielded a disc of unsatisfactory quality. The investment casting


process offered an integrally cast part that required only one boring operation (center hole). Also, with investment casting the most suitable material could be chosen and the surface finish and tolerances


improved. Cost savings were substantial. This casting is made in large quantities, which is proof the investment casting process is not necessarily limited


to small runs. It is competitive in many applications with other mass production methods, especially if steel alloys are involved.


Valve Wedges Converted From Forgings High pressure valve components were previously


considered suitable for forgings only, and considerable money was spent machining forged valve discs. But investment castings have now been used successfully for


some time in valve applications, especially for discs of gate valves varying in sizes up to and including 2 inches.


Consider the variety of sizes and shapes of valve wedges


in the picture. All of these have one thing in common-they were converted from forgings to investment castings. These wedges are cast so precisely that grinding and


lapping of the seat faces is the only finishing required. Furthermore, without changing tooling any of the wedges


can be cast in a variety of alloys, such as 410, 304 and 316, stainless steels, Monel or even Stellite. This flexibility is well appreciated by buyers. The castings are pressure tight and pass Zyglo inspection both before and after heat treatment.


A cost saving of 30 to 45 per cent is realized, and there


is the added benefit of design flexibility when investment castings are used. This commercial application proves


that high quality investment castings can compete against other mass production processes. The users of the castings have only one regret: they wish they had switched earlier.


The heart of a knotting mechanism for a bailer is a cast disc that weighs 1.2 pounds, has a diameter of 3 inches and is 1 Y8 inches high. Because of its


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