02-05-2012, 11:39 AM
Chemical Machining
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Chemical Machining
Was developed based on the observation that chemicals attack metals and etch them by using chemical dissolutions.
Is the oldest of nontraditional machining processes, and has been used to engrave metals and hard stones.
Chemical Milling
Shallow cavities on sheets, plates, etc…
Selective attack by chemicals on workpiece
Used in aerospace industry
Used to fabricate microelectronic devices
Chemical Blanking
Blanking of sheet metals
Material removed by chemical dissolution
Used to produce fine screens, flat springs, etc…
Very cheap but efficient
Characteristics of Chemical Machining
Shallow removal of material(up to 12mm)
Blanking of thin sheets
Low tooling & equipment cost
Suitable for low production runs
Material removal rate(0.1mm/min)
Photo Chemical Machining (PCM)
PCM is a material removal process using chemicals (etchants) to produce high precision parts.
This process is also known as Photo Etching, Chemical Blanking and Photo Chemical Milling.
PCM Process
Artwork- generate design using CAD systems, then plot it using a high precision laser plotter to produce photo-tool.
Chemically clean the metal surface.
Coat both sides of the plate with photoresist. (photoresist is a polymer that adheres to the metal when exposed to UV light).
PCM Process Cont.
Expose plate and photo-tool to ensure image transfer.
Spray metal with etchant or dip it in hot acidic solution to etch all material other than part covered with photoresist (1-15 min.).
Rinse the plate to ensure photoresist and etchant removal.
Advantages
Low Tooling Cost- all tooling is produced by CAD systems at a low cost with a short creation time.
Low Modification Cost- short runs are possible at a low cost, thus, design can be easily modified.
Burr and Stress Free.
Complex Designs.
Thin Plates as thin as 0.005”.
Materials
Aluminum
Chromium
Copper (oxygen free, rolled…)
Nickel
Steel (carbon, stainless…)
Lead
Zinc
Applications
High Precision Parts
and Decorative Items
Gaskets
Washers
Sensors
Nameplates
Jewelry
Microprocessor Chips