Pumps, valves and fittings

Pumps, valves and fittings often work in media that are anything but forgiving: oil, drinking water, wastewater, chemicals or district heating water at high temperatures. The component must function correctly throughout its entire operating life without changing shape under pressure and temperature loading. We take this into account when selecting fixturing and cutting data, so that residual stresses in the material are minimised, and the workpiece keeps its geometry once it is put into service, not only when it lies on the measuring table.

A pump housing or a valve intended for a district heating plant or a chemical process often experiences temperature cycles several times a day. This places demands on how mating surfaces and threads are executed, so that thermal expansion does not destroy the seal over time. We work closely with the customer's designers on where there should be clearance and where there should be a tight fit, so that the component can expand without losing its function.

Cavitation, erosion and corrosion are among the mechanisms that degrade pump components over time, and they often begin exactly where the surface has a rough edge or a sharp transition. We place emphasis on surface finish in flow paths and deburring of edges that meet the medium directly, so that the component lasts longer than it otherwise would with the same choice of material.

In a rotating machine such as a pump, it is not the individual dimension but the relationship between several dimensions that determines whether the component functions. Concentricity between bearing seats, squareness between shaft and flange, and an even gap all the way round an impeller are examples of requirements that cannot be read from a single tolerance field on the drawing, but which we factor into the machining strategy itself.

We machine critical surfaces in as few setups as possible, often in one, to avoid shifting references along the way. This gives better relative precision between mating surfaces, seal grooves and bearing seats than if the workpiece had to be turned several times between different machines, and it is precisely this relative precision that the customer experiences as lower noise and longer service life in the finished pump.

Roundness, cylindricity and flatness are documented on 3D measuring equipment, because these form requirements are often more important for function than any single diameter measurement. A shaft can lie within the diameter tolerance and still cause problems if it is not sufficiently round. We therefore measure form errors as a standard part of the inspection on critical pump components, not only on a sample basis.

Pumps and valves for critical processes, energy plants or food production often require documentation that follows the component for the rest of its service life. We issue measurement reports on the critical dimensions the customer defines in advance, and we can link material certificates, process history and measurement reports at component or batch level, so that documentation can be retrieved again if a question about a particular delivery arises later.

For large series, we use statistical process control to track how critical dimensions develop from workpiece to workpiece. This allows us to intervene if a bore or diameter begins to drift towards a tolerance limit, long before it becomes a deviation the customer discovers at incoming inspection. Data from SPC can be made available to the customer as part of the delivery, if agreed.

For components that must be approved by the end customer or an authority, we adapt the scope of documentation to the requirement, from a simple delivery note to a full measurement report with traceability back to the material certificate. The scope is agreed before the series begins, so that we do not have to recreate documentation retrospectively if the need changes during a project.

Designs for pumps and valves often contain the customer's own knowledge of performance curves, material choices and geometries developed over years. We treat that knowledge confidentially, store drawings and models with role-based access, and readily enter into a confidentiality agreement before a dialogue about a new component begins.

We are happy to get involved in the design early, while the cheapest changes are still possible. A different placement of a seal groove, a changed radius, or a tolerance that is relaxed in one place and tightened in another can make a component significantly cheaper to produce without changing the pump's performance.

Once the design is locked, we hold it firm throughout the delivery. Programs, fixtures and measurement plans are archived under the customer's order number, and we do not change a process without agreement, even if we could see a technical advantage in doing so. Stability in the process is part of what the customer pays for.