Traditionally carburising is carried out against a timed setpoint profile where the time periods for the different temperature/carbon stages are selected against empirical post-process material results.
This method provides a steel/alloy dependent recipe, which gives good repeatable performance but heat treaters tend to process at the high end of the case depth tolerance to ensure good repeatable results.
Since the purpose of the process is to provide components with a defined effective case depth, usually with a minimum tolerance, other methods, which allow effective case depth to be selected as the controlling setpoint, have become more widely available.
The case depth diffusion solution is available as a function block within the EyconTM Visual Supervisor and E+PLC400. This uses an algorithm based on carbon potential, temperature, material specification and process factors to determine the carbon setpoint profile.
In this case the traditional recipe hands control to the dynamic on-line diffusion calculation, which completes the carburising cycle to the required effective case depth.