I don't know how it happens with all lenders ... but apparently how ours worked ...
MB submitted our file to the lender after getting automated approval
UW reviewed, requetsed appraisals, placed conditions, ect ...
Once UW cleared all conditions they sent the file to be Quality Checked (basically I was told it was not looking at us really - it was justa QC to be sure all was in order on the file)
Once the file passed QC (Quality Check) then it goes back to the UW for it to be marked "Clear to Close"
Once marked "Clear to Close" then the file goes to the doc prep area to have everything drawn up for title company, blah blah blah (HA!)