  Most industrial machine tools have a serial kinematic architecture, which
means that each axis has to carry the following one, including its actuators
and joints. High Speed Machining highlights some drawbacks of such
architectures: heavy moving parts require from the machine structure high
stiffness to limit bending problems that lower the machine accuracy, and limit
the dynamic performances of the feed axes. That is why PKMs attract more and
more researchers and companies, because they are claimed to offer several
advantages over their serial counterparts, like high structural rigidity and
high dynamic capacities. Indeed, the parallel kinematic arrangement of the
links provides higher stiffness and lower moving masses that reduce inertia
effects. Thus, PKMs have better dynamic performances. However, the design of a
parallel kinematic machine tool (PKMT) is a hard task that requires further
research studies before wide industrial use can be expected. Many criteria need
to be taken into account in the design of a PKMT. We pay special attention to
the description of kinetostatic criteria that rely on the conditioning of the
Jacobian matrix of the mechanism. The organisation of this paper is as follows:
next section introduces general remarks about PKMs, then is explained why PKMs
can be interesting alternative machine tool designs. Then are presented
existing PKMTs. An application to the design of a small-scale machine tool
prototype developed at IRCCyN is presented at the end of this paper.
