DESIGN DATA ON PRODUCTION METHODS 



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CASTING DATA 

 Centrifugal Casting 



Materials Suitable. — Alumininn, bronze, Monel, beryllium copper, iron, steels of 

 various grades, stainless steel, copper, and other nonferrous materials. 



Shapes. — Any combinations of cylindrical shapes such as wheels, gears, screw- 

 down nuts, bushings with tapers, and parts with varying diameters. 



Maximum Size. — Screw-down nuts, weighing approximately 3,600 lb. each, for a 

 new continuous-type steel mill, have been centrifugally cast. 



Finish Allowances. 



Outside diameter, in. 



4K. 



2 or less 

 2 



4K-6. 

 6 -10. 



Over 10 



Outside diameter 

 allowance, in. 



Inside diameter 

 allowance, in. 



Ford casting of both bevel and cluster gear blanks allows only .I32 to He in. stock 

 for machining. 



Wall Thickness, — Practical minimum about H in. 



Relative Cost. — More costly in smaU quantities than sand castings in small 

 quantities. However, as quantity increases to 20 or more, the cost is little if any more 

 because of the material required for extra gates and risers in sand castings. Centrif- 

 ugal mold cost is only about 15 per cent that of a comparable forging die. Generally 

 the cost of a permanent metal die for centrifugal casting can be justified by as few as 

 10 or 12 pieces, although customarily such a die is not made for fewer than 25 or. 

 30 pieces. 



Typical Examples. — The bushings for Hamilton Standard propellers were for- 

 merly sand cast of beryllium copper with scrap running as high as 30 per cent. Perma- 

 nent mold castings did not prove feasible. Scrap has been almost eliminated by use 

 of aluminum bronze centrifugal castings of tapered hollow bushings. 



In another case, several hundred bronze rings, about 45 in. outside diameter, and 

 20 in. inside diameter and 3 in. thick, originally specified as forgings were found to 

 have satisfactory physical properties when centrifugally cast. Die costs would have 

 been high for the comparatively few forgings required. Another gain was less time 

 required to get delivery. 



Permanent Mold Casting 



Size limitations: 



Largest permanent mold casting produced, 20 X 16 X 34 in., weighing more than 

 100 lb. 



Smallest permanent mold casting produced weighed less than 1 oz. 

 Minimum tolerance, all dimensions: 



Up to 5 in +0.010 in. 



Over 5 in Add 0.001 in. per in. of length 



