I am working with data from a time-based process. The axes of the chart have already been converted to display time but when generating a control chart (IR) the control limits are displayed numerically not as time (h:m:s) which is not helpful. I've tried all options I could find in the menus and online but I cannot get the control limits to display time.
If I am understanding your problem correctly, you might try using seconds, or minutes, or hours as the y-axis rather than the h:m:s format. That way, the y axis calculations for control limits can make sense. Is your y-axis data time between events or time until something happens? If that is the case, then your format for the y axis must be in seconds, or minutes, or hours, etc.
If the time is calendar time, then you must use that data as your x-axis.