Letter-Perfect Results . ..


were achieved on this investment cast silicon brass imprinter for postal equipment. Operation


of the part required that the lettering be perfect in detail, square to the drum radius, and


accurately located from the center of rotation to insure a clear imprint. At first glance, the tolerances shown on the drawings appeared to be too close to be maintained on a casting.


The designer and manufacturing engineer met with the casting producer for consultation.


They decided that the tolerances shown were necessary for producing the part as a fabricated assembly but were not required


for a one-piece casting. It developed that the radius to the top of the printing surface was the most critical dimension and had to be


held to close tolerance. This tolerance, which originally was plus .001, minus zero, was set at ± .003 and was guaranteed by the foundry's 100% inspection with a checking fixture. The result of this cooperation was a


money-saving successful investment casting.


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