Right From The Start ... this jet engine bracket was designed


to be an investment casting. Dimensional tolerances were well within industry


standards. Usual practice on hole location would have required drilling of the four holes. By allowing hole locations to vary from their true positions by .010 instead of .005 or less, it was possible to cast the


347 stainless part complete-per-print ready for assembly. The same result could also be obtained by increasing the hole size to compensate for any variation in location of the hole center.


Perseverance Paid Off . ..


in converting this aerospace clamp from a part that was machined from bar stock into a part ready to use as an investment casting. Tolerances were well within industry standards, providing no restriction to conversion. But the diamond knurl


over the entire end radius had to be cast sharp and ~ormal to the contour. The bar stock approach for


making the knurl was to grind it in after hardening to RC 36 min. The foundry was unable to guarantee the same degree of sharpness in the knurl, but provided a sample of another 410 stainless part to indicate degree of sharpness obtainable. The value analyst was then able to present his case visually to the design engineer, who agreed to use the castings if they passed the necessary performance test.


Success of the casting is attested by the thousands of clamps which have since been purchased and placed into operation without a single rejection or failure.


8


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12