It is known that China is a country with rich natural resources and vast territory. Even though, the resource stock is declining in the growing process of every industry. Focusing on current resource lackage situation, recycling on resources attracts more attention from the public. Reproducing is one of the recycling measures demanding highly in techniques. This needs to be mentioned especially in machinery production industry because of the benefits it can bring upon the original productions

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... d less damage to the original machines. This paper focuses on the remanufacturing of construction machinery hydraulic valves and its benefit. Remanufacturing construction machinery is an indispensable in the manufacture way of engineering machinery manufacturing, the remanufacturing of hydraulic valve is one of the important. In general, the working environment is very bad, such as soil dust, cold heat, various difficulties and hardships which caused serious influence on the engineering machinery service life, leading a large number of hydraulic valve failure every year. The related enterprises remanufacture batch of useful spares by recycling of waste hydraulic valves. By satisfying the demand, remanufacturing greatly reduces the cost of production, saving resources, and gains huge economic benefits. Failure Mode of Hydraulic Valves First, abrasion. The failure caused by the wear of the hydraulic parts is more common. Parts in the working process produce mutual friction forces leading the surface changes and the quality of the parts diminishes not enough to perform. There are many reasons explaining the friction existing such as rubbish and oxidized materials from oil in the hydraulic valves resulting corruption and abrasion on the surface then producing impurities intensify the friction force between the hydraulic valves. Fig 1 shows the inner abrasion situation of a hydraulic valve. Fig 1 abrasion situation inside a hydraulic valve Second, deformation of a hydraulic valve. When the hydraulic valve suffers an excessive force outside, it will deform and lower the flexibility of its spares which produces unstable inner pressure finally affects the mutual transform inside hydraulic valves. Third, overwork of a hydraulic valve. Under a long-term, high load working condition, the hydraulic spool, valve seat, spring will have to suffer from the overwork and crack, makes the spring elasticity decreased, length changes, the valve seat damaged, which will directly affect the normal work of the hydraulic valve.