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Cut Costs - Obtain Greater Design Freedom By F. Valenta


Cercast Inc.


Investment casting has reduced production costs of this transmitter housing by 40 % .


The housing, figure ( 1) , was originally designed as a dip-brazed part and a subsequent design called for plaster mould casting. Finally, it was designed for investment casting and many new design features were able to be added, such as cast-in threaded bushings, cut-outs, recesses and holes.


Besides saving 40% on production costs, the investment cast housing out-performed the dip-brazed housing in vibration tests. Improved quality over plaster casting was apparent on pressure testing. Machining was reduced to a minimum.


The 1lb., 6 oz., housing is cast of 356T51 alumi- num and a surface finish of 63 RMS is obtained. Complex design configuration is revealed by the tooling illustrated in figure (2). All undercuts are produced by the split core technique. The core for the main cavity alone is split 16 times. Is Design Freedom expensive? Not with in- vestment casting!


Redesigning in Investment Casting Economies By C. Warner Smith


Gray-Syracuse, Inc.


A "hook fitting," used to retain an external storage pylon to rotary wing aircraft, was previously constructed from four different pieces; two machined parts, a machined elbow and a piece of tubing. The pieces were assembled in a brazing operation and individually cleaned. An additional machin- ing operation was required to obtain the proper hook con- figuration.


An investment casting replaced this four-part assembly. Cast of 4130 steel, the part was usable after two minor machine operations.


The use of an investment casting resulted in a saving of 50 % over the previous construction method, including amortization of the tooling over just the first run. In addi- tion to this cost savings, the cast hook offers the benefits of a high strength, single unit part for safer operating use and longer wear.


How strong is the hook? The pylon assembly itself weighs 29 pounds and is capable of carrying loads up to 1,100 pounds. Here is another example of how investment casting does the job better, for less.


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