A
skill in motion
Ashok
Kumar Gupta takes us through the steps involved in ensuring the optimisation
of a machine tool by improving hydraulic efficiency
The
main power transmission and controls in machine tools are through the
fluid power system. A hydraulic system is used when the most reliable
and repeatable forms of power and motion control is desired. For the
proper operation and getting the best out of the machine tools and plant,
all that is required, is improvement in the design, operation and maintenance
of the power and motion control system of the machine tool. The design
of the system plays a very important part in the performance and maintenance
of the hydraulic system of a machine tool or plant. For efficient operation,
energy conservation and long service life without causing any major
break-down, it is essential to consider the following points during
designing and operation of the hydraulic system.
Cavitations and aeration
Cavitations and aeration are localised gaseous conditions
within a liquid stream, which occurs when the pressure is reduced to
the vapour pressure. Put more simply, cavitations occur when the fluid
doesn’t entirely fill the existing space. Cavitations can be caused
by over speeding of the pump, a restricted or excessively long intake
line, dirty or insufficient capacity suction strainer in the inlet line
of the pump or too high fluid viscosity of oil. The presence of dispersed
bubbles of air in a system’s hydraulic fluid results in an implosion
effect, which occurs when the compressed air bubbles are subjected to
system pressure at the pump outlet. This implosion can cause metals
to be removed from the pressure plates, and the wear plates, near the
implosion point and result in extremely high local temperatures. Pump
aeration makes a loud, crackling noise like marbles being pumped. The
noise is higher pitched at higher pressures. Excessive aeration makes
the fluid look milky. It also causes components to operate erratically
because of the compressibility of the air ...
....CONTD
