Essay question "Evaluate the effective use of an appropriate secondary machining technique". No engineering knowledge needed for this! Each of the techniques has already been described in a lot of detail and the question does not relate to the production of something specific. I think this question is confusingly worded. If it was about something specific, the answer could be framed along the lines of "a grinder would be effective in finishing item ABC because of XYZ reasons but the disadvantage might be CDE reasons". Approach taken has been to say "grinder does ABC as does milling machine but grinder more effective because is also does CDE". Any interpretations gratefully received!