(4)Chemical milling applications

1）Outer skin of aircraft fuselage

The aircraft fuselage skin in [Fig.1] is first tension formed into curvature, and chemically milled.

The web portion which constitutes an 80% of the surface area on one side is chemically milled down to the thickness of 0.625mm from 6.25mm, and the weight is reduced from 24kg to 6kg. There was no method to produce such a part in a single piece, previously. They were previously produced by welding or riveting the stiffeners on 0.625mm plates. Dramatic reduction in part count and assembly time were realized and production cost savings were attained.

2) Example of entire perimeter milling

It is difficult to make a certain portion of forged part extremely thin. In the example of the forged part [Fig.2] (a), it is easy to form the thick portion by forging but difficult to make the thin central portion. For such case, the part can be made by forging with the central portion as thin as possible with some margin material left on the entire part, then the overall dimension can be reduced down afterwards to that of the desired by chemical milling.
This technique is also applicable for mechanically milled parts and extruded parts, as shown in [Fig.2] (b).

3) Thickness reduction of cast parts

It is very difficult to produce cast parts with thin features. Here, it is possible to produce cast parts with enough safety margin added to prevent cast failures, then remove the excess material by chemical milling.

4) Tapered milling applications

The tapered milling is performed by gradually immersing and raising in and out of the etchant.