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TECHNICAL
Hydraulic block material: aluminium or steel?
The material sets the balance between pressure, weight and cost.
In most projects the hydraulic block material is chosen not by looking at a price list but by looking at the working pressure and the weight limit of the application. There are three main options: ductile iron, carbon steel and aluminium alloys.
Working pressure
As pressure rises, the yield strength of the material becomes decisive. In circuits that run at high pressure and under shock loads, steel blocks are preferred. Aluminium alloys are used safely in the medium pressure range; however, for the same pressure the wall thicknesses grow, which means the block grows physically.
Weight
In mobile applications, particularly in construction machinery and lift control groups, every kilogram comes off the load carried. The density of aluminium is about one third that of steel; on large blocks this difference also comes back as easier assembly.
Machinability and cost
Aluminium is machined faster, extends tool life and is generally delivered in a shorter time. Ductile iron is more forgiving than steel in terms of machinability and, thanks to its vibration damping, is often used in industrial power units.
Corrosion and surface treatment
If steel and ductile iron blocks are going to work in the open air, surface protection is needed; the common solutions are zinc and nickel plating. On aluminium, anodising provides both corrosion resistance and surface hardness.
Hydraulic block material comparison
| Material | Outstanding property | Typical use | Watch out for |
|---|---|---|---|
| Ductile iron · EN-GJS-400 / 500 | Vibration damping, good machinability | Industrial power units, fixed installations | Surface protection is required |
| Carbon steel · C45 | High strength | High pressure, shock loads | Heavy; plated against corrosion |
| Aluminium · 6061 | Light weight, corrosion resistance | Mobile hydraulics, medium pressure | Wall allowances are larger |
| Aluminium · 7075 | High strength for an aluminium | Light but highly stressed blocks | Costs more than 6061 |
Choosing the hydraulic block material
- Determine the working and peak pressure
- Ask whether there is a weight limit
- Assess the operating environment (open air, humidity, chemicals)
- Take quantity and lead time into account
We choose the hydraulic block material together with you according to the project; the details are on our precision machining page.
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