Does this correlation make sense?
I see you have done encoding of feature line using the below code:

line_dict = {'INSPECTION':'0', 'REPAIR':'1' }


if we see the type of the value as below:

   &gt;&gt;&gt; line_dict['INSPECTION']
       '0'
   &gt;&gt;&gt; type(line_dict['INSPECTION'])
   &lt;class 'str'&gt;


it seems it is of object type. This could be the problem. Suggest you do to one hot encoding technique for this feature

Also it is good to an info on your dataset to identify the object columns

&lt;class 'pandas.core.frame.DataFrame'&gt;
RangeIndex: 153381 entries, 0 to 153380
Data columns (total 12 columns):
bodyId        153381 non-null int64
bodyTypeId    153381 non-null int64
color         153381 non-null int64
line          153381 non-null object
shiftNo       153381 non-null int64
Inspection    153381 non-null object
mYear         153381 non-null int64
mMonth        153381 non-null int64
mDay          153381 non-null int64
mHour         153380 non-null float64
mMinute       153380 non-null float64
mSecond       153380 non-null float64
dtypes: float64(3), int64(7), object(2)
memory usage: 14.0+ MB


if you check the data type line  it says object which means the line feature is String