Automated control of razor blade colorization

[0039] A suitable thermal oxide process for forming the colored oxide layer and manufacturing the razor blade is shown diagrammatically in FIG. 1. First, a sheet of blade steel is slit into strips. The strips are then welded together and then perforated for ease of handling during subsequent processing.

[0040] When the desired sequence of pre-hardening steps has been completed, the blade material is subjected to a hardening process, which includes austenization of the stainless steel. A typical temperature profile for the hardening process, which is conducted in a tunnel oven, is shown in FIG. 2. The material is quickly ramped up to a high temperature, e.g., approximately 1160° C., maintained at this temperature for a period of time, during which austenization of the stainless steel occurs, and then allowed to cool. A forming gas (e.g., including hydrogen and nitrogen) flows through the high temperature zone of the oven during austenization. The composition and flow rate of the forming