Bulletin 2/2010 - Siempelkamp NIS

Mechanical machining – mill head on a vertical boring and turning mill
Mill head and trunnion ready-packaged for the transport to the end customer
Wooden pattern of a 180° mill head segment
SIEMPELKAMP | FOUNDRY
transport. The mechanical machining of large mill heads requires
experience, know-how and up-to-date machinery.
The sight of a rotating mill head with a 14 m (46 ft) diameter and
a weight of 280 t (307 US tons) on a vertical boring and turning
mill is spectacular. Customers and mine operators from all over
the world such as Xtrata, Rio Tinto, BHP from Australia, Chile,
and Peru come to Krefeld to experience this unique sight.
The art of this machining process is the stress-free clamping of
these segments onto the machine. A drilled bolt pattern of
13,500 mm, consisting of 76 mm diameter holes and accuracy
H7 in excess of a maximum tolerance of 0.1 mm at bolt circle
diameter are the technical standard. When machining the
segments they tend to fl ex. “We treat them like raw eggs,” is the
statement of a production supervisor.
After successful acceptance and careful packaging, our order
processing department comes into play one more time. Now the