Chemical Machining

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MENG 439
Dr. L. K. Gaafar
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.

• Can be classified into
• Chemical Milling
• Chemical Blanking

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Chemical Milling

• Shallow cavities on sheets, plates, etc
• Selective attack by chemicals on workpiece
• Used in aerospace industry
• Used to fabricate microelectronic devices

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Chemical Blanking

• Blanking of sheet metals
• Material removed by chemical dissolution
• Used to produce fine screens, flat springs, etc
• Very cheap but efficient

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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)

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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.

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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).

http//web.mit.edu/ndemarco/www/chemmilling/slide6
.html
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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.

http//web.mit.edu/ndemarco/www/chemmilling/slide6
.html
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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.

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Materials

• Aluminum
• Chromium
• Copper (oxygen free, rolled)
• Nickel
• Steel (carbon, stainless)
• Lead
• Zinc

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Applications

• High Precision Parts
• and Decorative Items
• Gaskets
• Washers
• Sensors
• Nameplates
• Jewelry
• Microprocessor Chips

http// www.suron.com