Advanced machining

1. Photochemical
milling
1

2. Introduction
• Photochemical milling (PCM) is a
variation of chemical milling (CHM).
where the chemically resistant mask
is applied to the work piece by
photographic techniques.
• The two processes are quite similar
because they both use chemicals to
remove metal by the CD action and
some of the steps required in both
cases are similar.
*chemical dissolution (CD)
* Special coatings called mask ants or
mask
2
Fleet Readiness Center Southeast Engineer Technician
Rodney Williamson uses an ultrasonic thickness gauge to
ensure the chemical milling process produces the desired
result of .040 inches. The gauge settled on exactly that
number for this part. (U.S. Navy Photo by Clifford Davis)

3. process
PCM consists of the following steps
1. Preparing and preclearing the work piece
surface.This provides good adhesion of
the masking material.
2. Masking using readily strippable mask.
3. Scribing of the mask, which is guided by
templates to expose the areas that receive
CHM.The type of mask selected depends
on the size of the work piece
4. The work piece is then etched and rinsed,
and the mask is removed before the part is
finished
3
PCM is usually used on three-dimensional parts
originally formed by another manufacturing
process, such as forging and casting of irregular
shapes.
As with photochemical machining, areas not to be
machined are masked from the CD action of the
chemical solution.

4. 4
Process cont.
Important parameters in
(CHM)
(a)MRR= C×A
,(mm³/min) C: penetration
rate(mm/min).
(c) Time of etch (Tm)=d/c , (hr)
(d) Fe(factor etch)=d/u,
d: depth (mm), under cut(mm)

5. Advantages
1-Speed
2-Low cost tools
3-Complex parts can be produced
4-Mass production
5-Possible to conduct
modifications
6-Elimination of burring
7-Ease of fabricating thin metal
parts
8-No deformation
5
Disadvantages
1-Redesigning from scratch
2-Environmental unfriendly
3-Alternatives of photo etching

6. Application
6
• Thin gauge (under 0.050 in (1.3 mm))
parts in a broad range of alloys
are candidates for photo etching.
• Industrial applications include fine screens
and meshes.
• Battery grids
• fuel cell components
• sensors, springs
• pressure membranes
• RF and microwave circuits and
components, semiconductor
• lead frames

7. 7
Electro
polishing

8. 8
introduction
• Electro polishing is an electrochemical
process that removes material from a
metallic part, typically stainless steel or
similar alloys. The part is immersed in a
temperature controlled bath of
electrolyte (typically mixtures of sulfuric
acid and phosphoric acid) and the part
serves as the anode as it is connected to
the positive terminal of a DC power
rectifier DC and the negative terminal of
the rectifier is attached to the cathode
which is typically made from titanium or
other alloys which do not dissolve during
the electro polishing process.

9. 9
Process
• As the rectifier applies current, it passes
from the anode to the cathode by way of
conduction through the part.
Throughout this process, the part surface
area metal is dissolved in the electrolyte.
This process can be tightly controlled to
dissolve extremely small amounts of part
surface area resulting in micron level
thickness of part surface area
• Since the electrical conduction occurs
evenly over the entire part surface area,
the process typically removes the most
surface area per unit volume which is
typically burrs and other scratches.

10. 10
The electro polishing process may
improve a surface finish by up to 50% and
sometimes more. The electro polishing
reaction removes material while it
improves surface roughness, but since it
removes material, electro polishing
process runtimes are minimized to
maintain dimensional tolerances. Since
electro polish systems improve a surface
on the microscopic level, macroscopic
textures or surface scratches will only
result in a smoother texture or smoothed
scratch. Mechanical polishing is utilized to
remove macroscopic surface
imperfections.

11. 11
Advantages
• Simple , it did not need a
huge place or a suitable
machines ‘’Can be done at
home ‘’
• Does not make a
Mechanical Deformation
• Provides clean and
smooth surfaces
• Improve the surface finish
Disadvantages
• EP dose not remove fuels , sludge or
any insulating material.
• handling of components may lead to
additional exposure to workers
• Secondary liquid waste are
generated
• limited by the size of the batch in
immersion process
• The access to contaminate parts and
free space are required when an
electrode is used

12. 12
Application
• For Piping &Tubing
• For MedicalApplications
• For Machined Parts
• For NuclearApplications
• For Food & Beverage
Processing
• For Clean Rooms

13. Names of group
Hamdy hamada01
Assem Hussien
Abdelrahman Abdallah
Shady Heshmet
Usama Alsmsam
Hussien Hamed Alsakary 05
02
06
03
04
This Research
Osama Ahmed Nasr
10
Essam magdy07 08 09
11 12
13 14 15
Sayyed khairy salama Alsayyed Fathy
Mohammed salah
Mohammed Nasr
Abdelrahman saleh
Mohamed Kamel
Yasser Monjed

14. References
• Advanced Machining process (Hassan Elhofy –
Production department of Alexendria univirsty
• Pope & Meads Ltd facto(Established in 1953 by
Eddie Pope and John Meads)