chemical machining
TRANSCRIPT
Dr. Lotfi K. Gaafar 2002
Dr. L. K. GaafarMENG 439
Chemical Machining
Dr. Lotfi K. Gaafar 2002
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
MillingChemical
Blanking
Dr. Lotfi K. Gaafar 2002
Chemical Milling
Shallow cavities on sheets, plates, etc… Selective attack by chemicals on workpiece Used in aerospace industry Used to fabricate microelectronic devices
Dr. Lotfi K. Gaafar 2002
Chemical Blanking
Blanking of sheet metals Material removed by chemical dissolution Used to produce fine screens, flat springs,
etc… Very cheap but efficient
Dr. Lotfi K. Gaafar 2002
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)
Dr. Lotfi K. Gaafar 2002
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.
Dr. Lotfi K. Gaafar 2002
PCM Process
1. Artwork- generate design using CAD systems, then plot it using a high precision laser plotter to produce photo-tool.
2. Chemically clean the metal surface.
3. 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
Dr. Lotfi K. Gaafar 2002
PCM Process Cont.
4. Expose plate and photo-tool to ensure image transfer.
5. Spray metal with etchant or dip it in hot acidic solution to etch all material other than part covered with photoresist (1-15 min.).
6. Rinse the plate to ensure photoresist and etchant removal.
http://web.mit.edu/ndemarco/www/chemmilling/slide6.html
Dr. Lotfi K. Gaafar 2002
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”.
Dr. Lotfi K. Gaafar 2002
Materials
Aluminum Chromium Copper (oxygen free, rolled…) Nickel Steel (carbon, stainless…) Lead Zinc
Dr. Lotfi K. Gaafar 2002
Applications
High Precision Partsand Decorative Items Gaskets Washers Sensors Nameplates Jewelry Microprocessor Chips
http:// www.suron.com