24
SMALL AND MEDIUM-
SIZED ENTERPRISES
Micrometer
precision work
Mechanical machining
of the central ring
CLP Srl,
Borgo San Dalmazzo, Italy
Working on the Wendelstein
7-X central
ring has opened completely
new areas of
work for the company,
as well as additional
fields for contracts.
The pre-machining
of coil components
for the international
experimental reactor
ITER and the final
machining of coils for
the Japanese-European
fusion device JT-
60SA, for which CLP
also designed and
manufactured the coil
transport kits – these
are all activities that
have resulted from the
cooperation with IPP.
Wendelstein 7-X central ring
Photo: IPP, Beate Kemnitz
The superconducting magnetic coils for Wendelstein 7-X are bolted to a massive central
ring. This steel ring is subject to forces of roughly 100 tons. For that reason, the ten
individual ring segments had to be positioned with high precision. The steel segments
weighing several tons and standing several meters high were transported to CLP in northern Italy
for the mechanical finishing of the metal surfaces with a precision of roughly 100 micrometers
(100 millionths of a meter) using a milling machine. During the process, they each had to be rechucked
several times. Special techniques had to be developed, which could guarantee precise,
reproducible positioning despite the size and weight. Additionally, the workshops had to be
equipped with thermostats to achieve the required operational precision. IPP and CLP designed
and successfully implemented computer-controlled measurement procedures to check the
precision. Special deep drilling techniques were developed for connecting the segments to each
other using long screws made of special steel.