Time stamp on X and Y axis in Dashboard Chart


I am using chart in node red dashboard, In default, the X-Axis is the time series, and Y-axis is for other values.

In my task, I have to show the start time and also the finishing time of a series works, I am thinking to plot the start time in X-Axis and finishing time in Y-Axis.

The time is a string variable like, 2020-10-20 12:22:30

I separated and changed to time stamp using

    ts = new Date(year_var, parseInt(month_var, 10)-1, date_var, hour, minutes, seconds).getTime();
    return ts;

The X-Axis is worked well, shows the times correctly, But, the Y-Axis label shows as timestamp in the chart, I need to change the Y-axis labels from timestamp to normal time format(HH:MM:SS) as like in X-axis. How to do that, thanks

Here is the chart plotted in the dashboard,