The selection of suitable materials for valve bodies can be as diverse as the use of solenoid valves itself.
In most cases, the medium, pressure and temperature determine the materials used in a solenoid valve. The material selection usually begins with the choice of a suitable sealing material. The body material is usually already specified.
In 90% of applications it will be a choice between brass and stainless steel. These two “classes” dominate the conventional solenoid valve market. However, not all brass is the same – see the current discussion “Lead-free brass” – and stainless steel is not the same as stainless steel – the differences between the individual alloys are essential for the right choice for critical media.
As a plastics expert I would like to point out that, in addition to brass and stainless steel, there is a whole range of other, perhaps more suitable materials that can be more appropriate and more cost-effective for the specific application. I am thinking here in particular of aluminum but also of the whole range of engineering plastics.
In the field of low-cost solenoid valves (washing machines, coffee machines, …), plastic is almost exclusively used as the body material. Here plastic (which offers the injection molding manufacturing process) is ideal for large series and the required properties of the valve body can be tailored with the proper material selection.
However, engineering plastic can also showcase its special properties very well in smaller quantities and unusual requirements on durability. PTFE is the first material to be mentioned here. Apart from the fact that PTFE is almost universally resistant, it can be machined very well and quantities of “only” a few hundred can be produced inexpensively.
In addition to PTFE, there are many other engineering plastics that can be used: PEEK, PVDF, PSU, PPS, POM, PA, …
It is important to use the “right material” – stainless steel 1.4404 is extremely durable and has a very nice and valuable appearance, but processing it on the milling machine is very complex and therefore expensive – perhaps the durability of POM is sufficient? – Costs incomparably cheaper.
A customized valve designed for a specific application can often not only be more efficient but also cheaper than a standard valve.