The surface roughness of AAK hydraulic directional control valves with mirror grinding is 12 times better than that of its peers

China [CN]

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-detail/hydraulic-directional-control-valves-aak298