Complicated Design Freedom Possible in · stment Cast Part


By C.H. Porter Casting Engineers


Even in the smallest investment castings ... com- plex designs are possible. And here's proof!


A coin-operating machine component, figure (1), was formerly a series of stampings and fabrications staked together and plated. Redesigned for invest- ment castings, it is now cast in 303 stainless steel eliminating plating and previous production and assembly problems. Unit cost was increased but a savings was still possible by lower line assembly and adjustment time. The total assembly of 13 stamp- ings was reduced to six castings ... substantially reducing overall tolerance accumulations. Also of signficant importance to the customer was a drastic reduction in maintenance and service calls.


The complicated casting shown in figure (2) is a spool with 11 intercepting cored holes. Previously machined, there was a problem with burrs from the hole drilling. Investment casting the part in 8620 steel completely eliminated this burr problem.


Three socket wrench components are shown in figure (3) including a stud, pawl, and cap. These components are delivered as-cast after gate-grind- ing. The parts are all 1" or smaller and weigh from Y2 - 1 Y2 ounces. They are cast in nickel-chrome- moly-steel, 8650 with a surface finish of 50-90 RMS.


Gyroscope Design Requires High Strength, low Weight By G. Demeter


Rex Precision Products


This particular part is a high production item ... and a number of manufacturing methods were evaluated ... but the design flexibility of investment castings indicated the maximum economy.


The requirement is for a part designed with high strength and low weight. In addition, it has to be made of a material which could be non-galling in contact with mating parts.


The alloy chosen was aluminum 356. To ob- tain maximum stability, which is a requirement due to a very close tolerance machining, the castings are heat treated in five cycles, includ- ing deep freezing.


It is a significant application and investment casting proved the most economical way to achieve optimum results.


5


5


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10