convert(datetime, substring(replace(MANUFACTURED_DATE,'/',''),5,2) +
substring(replace(MANUFACTURED_DATE,'/',''),3,2) + substring(replace(MANUFACTURED_DATE,'/',''),1,2),112)
That's just so unnecessary - read the Books online entry for convert. (tip: highlight the word convert in your query in management studio and press F1 key)
just use convert(datetime,MANUFACTURED_DATE,3) to convert 2 digit year UK format (dd/mm/yy) dates or convert(datetime,MANUFACTURED_DATE,103) to convert 4 digit year UK format (dd/mm/yyyy) dates