At present, there are many kinds of hydraulic pumps in injection
moulding equipment. Because of the influence of power, speed,
pressure, flow rate, metal material and other factors, the
selection of hydraulic oil is more complicated. Generally speaking,
HL oil can be used for low pressure pump, and HM oil should be used
for medium and high pressure pump.
The order of antiwear effect of lubricity (antiwear) of hydraulic
oil on three kinds of pumps is vane pump > plunger pump >
gear pump. HM oil is the best choice for the hydraulic system of
vane pump, regardless of its pressure. Because the contact and
movement between vane and stator of vane pump is easy to wear, the
steel-to-steel friction pair material is the most suitable for
using high zinc HM antiwear hydraulic oil.
HM oil and HL oil can be used for low-pressure plunger pump,
zinc-containing HM oil for high-pressure plunger pump, but when
there are bronze and silver-plated parts in plunger pump, high-zinc
antiwear agent will cause corrosion and wear. This kind of plunger
pump should choose ashless or low-zinc antiwear hydraulic oil.
For gear pumps, HH, HL and HM oils can be used, but for high
performance gear pumps, HM oils should be used. For combined
systems such as vane pumps and other pump combinations, vane pumps
should be the main choice. When other pumps are plunger pumps, the
selected oil should also be accepted by plunger pumps.
Generally speaking, HL oil is preferred for axial piston pumps, but
not for vane pumps. High zinc HM oil is suitable for all kinds of
vane pumps. Ashless HM oil is suitable for axial piston pumps with
copper and silver components, and also for low and medium pressure
vane pumps, but not for high pressure vane pumps. Low zinc HM oil
has a wide range of applications. It is suitable not only for
medium and high pressure vane pumps, but also for plunger pumps
with copper and copper components.
Reasonable selection of hydraulic oil is only the starting point of
normal operation of hydraulic equipment. In the process of system
operation, the performance changes of hydraulic oil should be
detected in time to ensure proper maintenance in time, so as to
prolong the service life of hydraulic oil, system and components,
and avoid system failures or even accidents caused by working
media.
The service life of hydraulic oil (i.e. oil change period) varies
greatly due to the variety selection of hydraulic oil, working
environment and operating conditions of the system. If the selected
oil is reasonable and the quality of the oil is good, the oil
change period can be greatly extended if the hydraulic system and
the hydraulic oil are well maintained and managed.
