Additive Manufacture of Hydraulic Components

Additive manufacture gives the opportunity to create complex hydraulic components (e.g. valve bodies) which are of much reduced weight, only adding material where necessary. The geometry can be optimized to meet stringent design requirements, without the normal subtractive manufacturing constraints. For small production runs, for example production numbers typical in aerospace, manufacture can be very cost-effective, with high repeatability and low material waste. A significant reduction in part count and consequent simplification of assembly is also possible. With the dramatically increased speed of prototyping, AM promises a much shorter development cycle.
In this talk, the potential and challenges of AM for hydraulic components are reviewed, focussing on the powder bed fusion laser melting process. A detailed example is given of an aerospace servovalve body additively manufactured from titanium alloy (Ti6Al4V) on a Renishaw AM250. Laser melting is known to be successful with this material, although research is still required to ensure the characteristics and quality are suitable for aerospace applications. In particular, fatigue life is affected by surface finish and microstructure, and the effects of build process parameters and heat treatment are just starting to be understood. Certification questions arise with flight actuators and using additive manufacturing for safety critical parts requires new standards to be developed. Examples of other hydraulic AM components are also reviewed, including manifolds, actuators and other types of valves, for both aerospace and industrial applications.