Localized Property Design and Gradient Processing of a Hydraulic Valve Body Using Selective Laser Melting

Selective laser melting is able to produce complicated functional components. However, it may not simultaneously fulfill the diverse requirements of different parts of a component using uniform process parameters. Gradient processing based on the process parameters is proposed to realize the localized property design. An industrial valve body in a typical hydraulic valve was presented as a case study to demonstrate this concept. Lightweight design was first executed. Then, an experimental study was performed to investigate the influence of the laser power and exposure time on several properties, including the density, hardness, tensile strength, and tribological performance. Based on the specific property requirements of the shell, the fluid passages, and the contact surfaces of the valve body and electrical energy savings of the SLM process, three sets of process parameters were then selected to correspondingly fabricate different parts of the valve body. Results showed that the optimized valve body satisfied the relative density requirement of the shell as well as the yield strength and hardness requirements of the fluid passage. Moreover, compared with a solid valve body fabricated using a single set of default process parameters, the gradient processing leads to reductions from 3.5% to 51.8% in coefficients of friction in different working conditions, and a 4.8% reduction in the electric energy consumption. The lightweight design also contributes to a 21.8% reduction in the weight and a 22.9% reduction in the electric energy consumption. The optimized hydraulic valve also had functional characteristics that were comparable with those for the corresponding conventionally processed valve. This gradient processing was supported by design for property, a valuable technique for integrated design and manufacturing of functional gradient components.