Cristoforo is from an Italian hydraulic equipment company. At the beginning of last year, the hydraulic station they sold to South Africa was complained by the customer in less than half a year. The oil temperature in the hydraulic station was abnormal, as high as 80 ℃, and the efficiency of the whole hydraulic transmission was poor. The after sales service found that the hydraulic relief valve was stuck, which affected the load relief and caused the oil to heat up. The original hydraulic relief valve manufacturer believed that the jamming was caused by unclean hydraulic oil. After detecting the hydraulic oil, there was no abnormality. When disassembling the hydraulic relief valve, it was found that the contact surface between the valve spool and the valve hole was worn, which should be caused by the coaxiality deviation between the valve spool and the valve hole of hydraulic relief valve, resulting in the jamming. The original manufacturer agreed to replace it, but half a year later, the old problem happened again, and Cristoforo was criticized.
Cristoforo had to find manufacturers with long service life of hydraulic relief valves. He contacted many manufacturers and found that most of them were not able guarantee a service life of over 1 year for the hydraulic relief valves with a maximum flow of 240L and a pressure of 450bar, but only 6 months. Finally, only 3 manufacturers were willing to test samples, including AAK. AAK engineers determined that the material selection was a key step according to the parameter requirements of the hydraulic relief valve. After 2 months, 30 samples of hydraulic relief valve were sent out.
Last week, we received the PO of hydraulic relief valves from Cristoforo. He said that although AAK was the latest to deliver the samples, in the service life test, the hydraulic relief valve samples provided by the 3 manufacturers showed that only AAK had no abnormalities after a service life of more than 1 year. For this kind of customized, high demand and non-standard hydraulic relief valve, our 3 advantages are not available in most manufacturers in Ningbo.
1. The durability of hydraulic relief valve mainly depends on the material selection according to the working conditions. For this hydraulic relief valve, AAK selects 20CrNi2MoV high carburized bearing steel from Germany, combined with carburization pretreatment process, through secondary quenching + cryogenic treatment + low temperature tempering process, it is cooled to 650 ~ 700 ℃ and then discharged after being cooled to 450 ~ 500 ℃. The microhardness is 237 ~ 247 HV, and its wear resistance and contact fatigue performance are increased by more than 3 times. The heat treatment of this material is difficult to control, and most manufacturers cannot control it.
2. In terms of material selection of AAK hydraulic relief valve, there are full-time engineers who use Brinell hardness tester to compare and test various materials under the test conditions of 3000kg force and 10mm ball. Many manufacturers cannot do this kind of material selection method.
3. AAK has a precision honing machine, equipped with diamond reamers, to do a good job in finishing. After honing, the dimensional accuracy of the valve hole of the hydraulic relief valve is IT7 ~ 4, and the surface roughness can reach Ra 0.32 ~ 0.04 microns.
AAK hydraulic relief valve, high pressure, large flow, with a service life of more than 1 year, you can also have a small try!