For hydraulic pressure control valves used in military industry, Krischnan only found AAK

China [CN]

Krischnan, from Greece, has been engaged in the procurement of hydraulic valves for 6 years. At the beginning of the year, their hydraulic power unit used in military equipment needed to purchase hydraulic pressure control valves. Krischnan selected a supplier who has cooperated for 4 years to sample the hydraulic pressure control valve, which is required to be leak free and free of jamming. 1 month later, the accuracy of the hydraulic pressure control valves produced by the original manufacturer did not meet the equipment requirements, but this has already been the manufacturer's limit. Krischnan can only re select the manufacturer of the hydraulic pressure control valves and specially note with specific accuracy requirements that the cylindricity of the inner hole of the valve cage needs to below 2μm, the surface roughness is Ra0.15. He contacted more than 10 hydraulic valve manufacturers in 1 week, and only 2 manufacturers were willing to sample, but they still did not meet the equipment requirements. More than 2 months of time wasted, Krischnan became very anxious.

Krischnan found AAK at Google and left a message asking whether there were hydraulic valves for military equipment. I was not sure about his purpose, so I gave an irrelevant answer that AAK had supplied hydraulic valves for aerospace 4 years ago. Krischnan sent the drawing of the hydraulic pressure control valve the next day, emphasizing that it was used for military equipment and reminding the machining accuracy and geometric accuracy. He seemed to be afraid of another failure, stressed and reminded again and again.

3 days later, I told him that we are 90% confident to be successful. If AAK also failed on this hydraulic pressure control valve, he would not need to go around in Ningbo again. The next day, Krischnan paid the development fee. After 45 days, AAK sent 30 samples of hydraulic pressure control valves.

At the beginning of last month, Krischnan said in an email that although the time of AAK samples was longer than that of other hydraulic valve manufacturers, the AAK hydraulic pressure control valve was recognized by the engineer and the equipment commissioning was smooth. At the same time, he also sighed: after 3 rounds, only AAK was found to be able to produce the hydraulic pressure control valves that can be used in military industry. 

AAK focuses on 3 points to control the accuracy of the valve hole in the valve cage of the hydraulic pressure control valves:

1. The valve cage inner hole processing process was re optimized in 6 steps: drill the top hole with deep hole drill, vacuum quenching, rough honing, semi fine honing, artificial aging treatment, fine honing, and the process parameters were reset. Most manufacturers of hydraulic pressure control valves can only achieve 3 steps: vacuum quenching, rough honing and fine honing.

2. As for the details of honing, 0.04mm full honing allowance shall be reserved during rough honing of inner hole to lay a good foundation for subsequent fine honing and grasp the stress generated by honing. Here, skill is required, which is also a key step of accuracy.

3. More attention is paid to fine honing. An oilstone made of cubic boron nitride is used for fine honing. After fine honing, the cylindricity of the inner hole of the valve cage is below 1.5μm and the surface roughness is below Ra0.1μm. 

AAK hydraulic pressure control valve, 6-step optimization, 2 detailed points, you can also try a small order!

https://www.aakindustry.com/info-detail/hydraulic-pressure-control-valves-aak355