Hardness of all parts in the AAK hydraulic check valve reaches above HRC65

In the Spring Festival, I received a confirmed price for a large quantity of
hydraulic check valves from Stephen. The contact between Stephen and I is only
2-3 times in the whole last year. It was noted at the end of the email that he
needs me to contact him as soon as possible to discuss this hydraulic check
valve. Stephen comes from American CASE company. We met the year before last.
After communication, it was learned that at the beginning of last year, a
bulldozer of their company needed to use hydraulic check valve, the one that
AAK had made samples at the beginning. Because the price of AAK hydraulic check
valve was 20% higher than that of his original supplier, Stephen did not choose
to purchase hydraulic check valve from AAK. Some time ago, the customer
complained that the hydraulic pump was damaged due to the sudden increase of
hydraulic system pressure.

Stephen communicated with the original hydraulic check valve manufacturer and
the manufacturer replaced the hydraulic check valve with a new one, but 3
months later, the same problem came again. The customer was very dissatisfied
that this delayed the construction and needed the problem solved at one time.
Stephen went back to AAK and asked about the price of the hydraulic check
valve. He needed us to maintain the quotation offered last year. I asked
Stephen why he went back to AAK to purchase the hydraulic check valve. He told
that since the first complaint from the customer, their engineers retested the
original hydraulic check valve samples. The hardness of AAK sample was the
highest, and the material hardness of each part of the hydraulic check valve
was no less than HRC65.

I know why their hydraulic check valve went on strike in 3 months. When we made
the sample, we knew that the working pressure was more than 450bar, which was a
challenge for the hydraulic check valve. The material hardness of each part of
the hydraulic check valve is required to reach more than HRC65. There may be no
more than 5 hydraulic valve manufacturers that can reach this level in Ningbo.

Stephen wondered why the material hardness of each part of AAK hydraulic check
valve can be over HRC65?

1.Material selection is the core. AAK adopts 20CrNi2MoV high carburizing
bearing steel imported from Germany for this hydraulic check valve.

2.Heat treatment is the key. Through secondary quenching + cryogenic treatment
+ low-temperature tempering process, it is cooled to 650 ~ 700 ℃ and put into
the furnace. After cooling to 450 ~ 500 ℃, it is discharged from the furnace.
The micro hardness is 237 ~ 247 HV.

3.In the later stage, point-to-point testing is the key. SonoDur3, a Rockwell
hardness tester imported from Germany, adopts the UCI hardness test method, and
the test program is fast and mobile to carry out nondestructive testing on the
hardness of each component of the hydraulic check valve efficiently and
accurately.

Stephen may understand that AAK has extreme pursuit for the hardness of
hydraulic check valve to meet the working pressure above 450bar. Two days
later, after the order of the hydraulic check valve was confirmed, he said that
the complaint about the hydraulic check valve that had plagued him for half a
year was finally solved at one time. We told him that he only needs to wait
patiently for the delivery in 40 days, and the rest will be left to AAK.

AAK hydraulic check valve is exquisite in every detail. Welcome to give it a
try!

https://www.aakindustry.com/info-d , etail/hydraulic-check-valves-aak152

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