The objective of this paper/presentation is to examine the subject of case hardening by focusing on lessons learned in the real world; illustrating as many practical examples of problems/solutions as time permits (1 slide/1 problem/1 solution/1 minute). The emphasis is on what went wrong - and how it was corrected. Processes such as boronizing, carbonitriding, carburizing, nitriding, and nitrocarburizing - austenitic and ferritic will be discussed and compared. Atmosphere, induction, plasma and vacuum topics and techniques will be covered. A key aspect of this paper/presentation will be a discussion of current and emerging methods for optimizing cycle times with emphasis on gear applications and metallurgy including the wind energy industry. Discussion topics will include simulation software programs and factors that can cause deviations from the norm - part geometry, material (composition, trace element chemistry, hardenability, grain size), microstructure, fixtures and fixturing, surface condition and cleanliness, equipment induced variability, atmosphere types and stability issues, control schemes, sensors, and pre and post treatments to name a few.