CONTENTS
      •   Introduction (Chemical machining)
      •   About Chemical machining process
      •   Elements of process (i.e..process parameters)
      •   Influence of etchant medium
      •   Chemical blanking
      •   Applications, advantages, disadvantages (Chemical machining)
      •   Selection of Maskants, Etchants
      •   Chemical milling 
      •   Chemical engraving
      •   Photochemical blanking
                                    INTRODUCTION
       •   A chemical machining process is actually an etching process in which the 
           metal is removed by the chemical conversion of metal into metallic salt.
       •   Chemical machining is the stock removal process for the production of 
           desired shapes and dimensions through selectively or overall removal of 
           material by means of controlled chemical attack with acids or alkalis.
       •   In chemical machining material is removed from the workpiece by 
           controlled dissolution using strong chemical reagent known as “etchant”.
       •   Two methods of metal removal by chemical means…
       •   1) Non-selective metal removal
            – Metal is removed from the entire exposed surface of a part. 
            – Removing burr/metal from casting, forging, extrusions
            2) Selective metal removal
            – Work is covered with a chemically resistant layer and thereby preventing chemical action 
               on those areas.
            – Area where metal removal is required is left unprotected. The work is placed in the 
               etchant solution and metal is removed from the unprotected area.
          CHEMICAL MACHINING PROCESS
       •   Chemical machining process the 
           desired metal is removed using 
           etchant solution. Etchant can be 
           sprayed on the workpiece or the 
           workpiece can be dipped in the 
           etchant solution.
       •   The metal is gradually 
           transformed into metallic salt by 
           chemical reaction. The MRR can 
           be controlled by controlling 
           concentration, composition and 
           operating conditions of the 
           etchant solution.
                                                         Fig 1. Chemical process
  Cont..
   STEPS OF CHEMICAL MACHINING PROCESS
    – Work piece preparation
    – Coating with masking material
    – Scribing of the mask
    – Etching
    – Cleaning of the masking material
            Fig 2. Steps of chemical machining process