AAK hydraulic directional control valves with mirror grinding, no jamming

Fabian from the Netherlands left a message on AAK website last month: what is
the reason for the hydraulic direction control valves stuck? In general, the
processing roughness of valve spool and valve hole is poor, or it is caused by
radial unbalanced hydraulic pressure caused by inconsistent coaxiality. AAK
adopts mirror grinding for the finishing of valve spool and valve hole, and the
surface roughness can reach AO=Ra0.08μm, which is more than 10 times that of
its peers.

According to Fabian, in the second half of last year, the hydraulic directional
control valves of the trial order got stuck, which made them very anxious. Thia
hydraulic directional control valve is used on the hydraulic power unit. After
the equipment is commissioned and operated continuously for 48 hours, the
pressure supply of the equipment is abnormal. The engineer disassembled and
found that the contact surface between the valve spool and the valve hole of
the hydraulic directional control valve is too rough, so the hydraulic
directional control valve needs to be replaced, and the surface roughness is
required to reach AO=Ra0.5μm or below. The original manufacturer fed back that
the roughness of valve spool and valve hole Ra1.0μm was their limit. Fabian
was very depressed and had to find a new manufacturer of hydraulic directional
control valve. Fabian contacted more than 10 factories, and none of them
confirmed that the RA of the contact surface between the spool and the valve
hole of the hydraulic direction control valve can be controlled at 0.5μm. They
also told that it was not necessary to control the Ra value when it was stuck,
and Fabian would have no direction. He found AAK Hydraulic Valves and left a
message to ask the reason why the hydraulic directional control valve was
stuck.

According to Fabian's description and the drawing of this hydraulic directional
control valve, I think their engineers' new requirements for Ra value are
reasonable. AAK is able to control Ra value well. We recommended that Fabian
directly test the order. If our Ra value does not meet the standard or the
hydraulic directional control valve is stuck, we can refund it in full.

After 35 days, AAK sent 10 samples of hydraulic directional control valves. Two
weeks later, Fabian informed by email that no abnormality was found during the
commissioning of the AAK hydraulic directional control valves. Their engineers
specially detected the Ra value of the contact surface between the valve spool
and the valve hole, and were surprised that it is Ra0.08μm, which is more than
10 times more accurate than that of peers, and more than 6 times what they
require.

The surface finish of the valve spool and valve hole directly determines the
flexibility of the hydraulic direction control valve, and most hydraulic valve
manufacturers tend to ignore this small detail in the processing process. AAK
hydraulic direction control valve spool and valve hole are precision machined
with the NP520X-F full-automatic universal grinder of Japan's Long Island
Precision grinding machine, which can achieve μ level feed mirror grinding,
the surface of the machined valve spool is like a mirror.

AAK hydraulic directional control valves, no jamming, you can also have a small
try!

https://www.aakindustry.com/info-d , etail/hydraulic-directional-control-valves-
aak , 298

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