Model for surface topography prediction in mirror-milling of aircraft
Received: 22 June 2017 / Accepted: 10 November 2017 /Published online: 22 November 2017
Springer-Verlag London Ltd., part of Springer Nature 2017
As a new technology of aircraft skin processing, mirror-milling is an efficient and green processing technology, which is a
gradually developmental substitute for chemical milling. The purpose of this research aims to study surface topography forming
mechanism and the effect of support location on the surface topography forming in mirror-milling of aircraft skin parts. A new
iterative workpiece deformation prediction model is proposed for mirror-milling error prediction of low-rigidity parts. In addi-
tion, the workpiece surface topographies are predicted and verified at different support locations. The results of the study are
summarized: under the same processing parameters, the machined surface topographies with different characteristics are obtained
only by changing the relative position between the support head and the milling head. The support location is the key parameter
of reducing the workpiece deformation error.
Aircraft skin parts are important parts which constitute the
aerodynamic configurations of aircrafts . There are single
curvature parts, double curvature parts, and even more com-
plex shape parts among skin parts . Sometimes the surface
curvature is extremely variable over a whole part .
Lightweight design means less fuel consumption, which
drives the aircraft technologist to focus on lightweight inno-
vation . So the skin parts need to be as thin as possible.
Aircraft skin parts are characterized with large size, complex
shape, thin-floor structure, and low rigidity [5–7].
Currently, the thinning tasks are accomplished by creating
pockets in the skin panel by chemical machining .
Unfortunately, this chemical machining process ends with
chemical pollutants to the environment. Most of the chemicals
such as cleaning solutions, etchants, and strippers are very haz-
ardous liquids. Specially, etchants are very harmful for workers
safety . Furthermore, due to the previous stage of stretching,
most of the panel gets high variation of initial thickness.
Besides, the material removal rate of chemical machining pro-
cess is a constant. The above two reasons determine the fact that
pocket floor thickness is irregular and imprecise [9, 10]. In
addition, there is a long process cycle of aircraft thinning oper-
ation composed of several steps for different cutting depths,
because chemical milling process is not capable of attaining
different cutting depths in a single operation . Also, a large
amount of energy consumption is a bottleneck . So, replac-
ing this industrial chemical milling process with a lower emis-
sion and more environmentally friendly process is sought.
In order to address the above issues, mirror-milling system
(MMS) is proposed to machine aircraft skins and now used in
Airbus Company [13, 14]. This system contains two indepen-
dent five axis machines on opposite sides of the same skin part
moving in a coordinated manner. The first one performs the
pocket machining, while the other provides the support on the
opposite side. The support which must withstand the thrust
force from the milling operation also needs to move smoothly
with low frictional force, which is usually a metallic sphere [4,
10, 15, 16].Compared its superiorities with chemical milling,
MMS has a potential to become the next-generation process-
ing technology of aircraft skin .
As a new technology of reducing the thickness of thin and
large aircraft skin parts, MMS have been widely emerging in
* Zhigang Dong
Key Laboratory for Precision and Non-traditional Machining
Technology of Ministry of Education, Dalian University of
Technology, Dalian 116024, People’s Republic of China
Institute of Advanced Manufacturing Technology, Dalian University
of Technology, Dalian 116024, People’sRepublicofChina
The International Journal of Advanced Manufacturing Technology (2018) 95:2259–2268