(1964-65) Blank Pattern - RB-6120, INCO

Coin Details

Description

Experimental blank planchet RB-6120, continuing the intensive study within the RB-61xx composition family. This blank represents a composition that differs from RB-6115 and RB-6125 by increments small enough to suggest precision optimization of a near-final alloy formulation. The INCO experimental program's structure reveals a clear experimental methodology: broad survey testing identified promising alloy families, intermediate testing explored the major variations within each family, and intensive testing like that documented in the RB-6110-6130 range refined the most promising compositions to production-ready specifications. RB-6120 occupies the intensive refinement phase, where the goal was not to discover fundamentally new compositions but to determine the exact formulation that would perform optimally when produced at the scale of hundreds of millions of planchets per year. Manufacturing consistency at this scale demanded alloy specifications with tolerances wide enough to be practically achievable yet narrow enough to ensure uniform coin quality — a balance that could only be established through the kind of detailed compositional study documented in these closely spaced entries.

Rarity Notes

R-7 to R-8. Very rare experimental blank from the precision optimization phase of the RB-61xx study.

Cross References

RB-6120 (Robinson-Breen catalog). INCO experimental blank planchet series, RB-61xx group, 1964-65.