APPLICATIONS For hydraulic engineers, some of the most convincing arguments for additive manufacturing can be found inside the component rather than on its surface. A conventional manifold may require intersecting drilled galleries, plugged drillings and compromises imposed by the need to get a cutting tool into the material. Additive manufacture can remove some of those restrictions, allowing internal passages to follow more direct routes and potentially reducing weight, part count and the number of potential leakage points. What is considerably more difficult is establishing the evidence that a pressurebearing component made this way can be manufactured repeatedly and safely. This is becoming an important distinction as additive manufacturing moves from development work towards series and replacement production. Demonstrating that a prototype can withstand pressure is useful, but it is not the same as establishing a qualified production route capable of delivering components with consistent properties over successive builds. The regulatory position also needs to be understood accurately. In Great Britain, the Pressure Equipment (Safety) Regulations 2016, usually referred to as PE(S)R, regulate the design, manufacture and conformity assessment of pressure equipment and assemblies with a maximum allowable pressure, PS, greater than 0.5 bar, subject to specified exclusions. Pressure equipment is defined to include vessels, piping, safety accessories and pressure accessories, the latter being devices with an operational function and a pressure-bearing housing. That does not mean every hydraulic component operating above 0.5 bar should simply be labelled as pressure equipment of a particular category. The manufacturer first has to determine whether the particular product falls within scope and how it is classified. Equipment type, the intended fluid and its group, maximum allowable pressure and, depending on the equipment, volume or nominal size can all be relevant to classification and the resulting conformity assessment requirements. Additive manufacturing does not create a separate exemption from that process, nor does it automatically create an additional regulatory category. Where the regulations apply, the manufacturer still has to demonstrate that the relevant requirements have been met. What AM changes is the nature of the manufacturing process and, consequently, some of the evidence required to support that demonstration. This matters because a metal additively manufactured component is not defined by its geometry alone. With processes such as 24 HYDRAULICS & PNEUMATICS September 2026 www.hpmag.co.uk Additive manufacturing is opening up new ways to design and produce hydraulic and pneumatic components. For pressure-bearing parts, however, moving from a proven design to repeatable production brings questions around process control, inspection, qualification and regulatory compliance. H&P reports. Qualifying additive manufacturing for fluid power laser powder bed fusion, feedstock condition, machine performance, process parameters, build orientation, position within the build and subsequent thermal processing can influence the properties of the finished part. ISO/ASTM 52909:2024 specifically addresses the evaluation and reporting of orientation and location dependence in the mechanical properties of additively manufactured metals. For fluid power manufacturers, that should change the qualification conversation. A drawing and material designation remain important, but they cannot by themselves describe everything that determines the characteristics of the finished AM component. The manufacturing route becomes an important part of the product definition. Pressure testing illustrates the problem particularly well. A proof or burst test can provide valuable evidence about the component tested, but many fluid power components spend their working lives experiencing repeated pressure changes. A component surviving its initial test does not, on its own, demonstrate how an internal defect, adverse surface condition or other manufacturing discontinuity might behave after a large number of cycles. ISO/ASTM 52908:2023 is relevant here because it addresses qualification, quality assurance, post-processing, inspection and testing of metallic parts produced by powder bed fusion. The wider standards framework increasingly recognises that AM quality cannot be established solely by inspecting dimensions at the end of production. A more defensible approach is to establish control over the complete manufacturing route. That begins with feedstock and continues through machine condition, the qualified build parameters, component orientation, support strategy, removal from the build platform, heat treatment and any subsequent machining. For a hydraulic component it can also include the finishing of sealing faces and threaded ports, removal of residual powder from internal galleries, cleanliness requirements, Additive manufacturing allows complex internal flow paths to be incorporated into fluid-power components, but qualification extends beyond the geometry to the material, manufacturing process, post-processing and inspection.
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