1. Chemical Machining Ooi Chik Liang Winnie Wong Yien Yien Lim Zhen Wen Goh Kok Rong Tan Weng Giap Chuah Khang Chuan Chuah Guan Li Tan Chuang Ki Copyright © 2011. All Rights Reserved.

2. Do you know? Chemical machining is a well known nontraditional machining process is the controlled chemical dissolution of the machined work piece material by contact with a strong acidic or alkaline chemical reagent. Chemical machining method may be the oldest nontraditional machining method which is used to shape copper with citric acid in the Ancient Egypt in 2300 BC. Interesting Facts

3. Chemical Machining  Was developed based on the observation that chemicals attack metals and etch them by using chemical dissolutions. Classified into: Chemical Milling Chemical Blanking

4. Chemical Milling  Shallow cavities on sheets, plates, etc…  Selective attack by chemicals on work piece  Used in aerospace industry  Used to fabricate microelectronic devices

5. Chemical Blanking  Blanking of sheet metals  Material removed by chemical dissolution  Used to produce fine screens, flat springs, etc…  Very cheap but efficient

6. 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)

7. Steps of chemical machining Work piece Preparation Coating with masking material Scribing of the mask Etching Cleaning masking material

8. Maskants Tough enough to withstand handling Well adhering to the workpiece surface Easy scribing Inert to the chemical reagent used Able to withstand the heat used during chemical machining Easy and inexpencive removal after chemical machining etching

10. Etchants High etch rate Good surface finish Minimum undercut Compatibility with commonly used maskants, High dissolved-material capacity Economic regeneration Etched material recovery Easy control of process. Personal safety maintenance “Etchants are the most influential factor in the chemical machining of any material.”

12. Advantages Easy weight reduction No effect of work piece material properties Simultaneous material removal operation No burr formation No stress introduction to the work piece Low capital cost of equipment Easy and quick design changes Requirement of less skilled worker Low tooling costs The good surface quality Using decorative part production Low scrap rates (3%)

13. Disadvantages Difficult to get sharp corner Difficult to chemically machine thick material Scribing accuracy is very limited, causes less dimensional accuracy Etchants are very dangerous for workers Etchant disposals are very expensive

14. Green Concern Environmental issues in chemical machining operations may be the most important factor affects the machining process should be used or not. Most of the chemicals such as cleaning solutions, etchants, strippers etc. are very hazardous liquids. Therefore handling and disposal of them are very costly.

15. References O http://www.archivesmse.org/vol28_8/28810.pdf