with the water, while machining the parts which will be coupled to the axle
with their respective key slots.
In order to polish the turbine wheel, a grinder is applied first, if necessary,
or simply a small emery, files and abrasive paper, beginning with a coarse
grain and finishing off with finer grains.
Once the turbine wheel is completely finished, including both machining
and polishing, it requires dynamic balancing. This process will depend on
the rotational speed at which it is to operate. Dynamic balancing is
required since in the casting process the material is not uniformly
distributed, and so this will reduce vibrations and increase the working life
of the bearings and other components.
2.4. Manufacture of the axle
See plan 04
A. Materials.
• Special hardened steel for rotation and flexion uses (DIN: 34
CrNiMo 6, Boehler VCN 150), identifying colour: green
B. Method
A minimum oversize of 4 mm should be allowed for in the diameter of the
axle, for machining. For the turbine discussed here, the axle will have a 60
mm diameter, and so the raw materials should be purchased with a
diameter of 64 mm, in order during machining to remove the black shell
and de-carburised layer which generally contains microfissures.
Machining, both on the lathe and of the key slots, is performed in
accordance with the manufacturing plans.