Choosing the right Cylinder for Mold Core: Aluminium vs Steel Body

We would like to introduce a new factor in choosing the best cylinder for your application, that is, the differences between Aluminum Alloy and Steel block cylinders.

In fact, each of them has its own pros and cons, so we feel that a comparison table referring to Vega products may be useful.

Aluminum Alloy






Light to medium



Max. 100° C without sensors

Max 160° C


Medium (220 to 250) bars

High (450 bars)


Low to medium


Fatigue resistance




Short (V250), up to long (V220)

Short to medium (V450)

Rod end

Female (V250), any (V220)

Female / male (V450)


Magnetic only

Mechanical only

Corrosion resistance

Good for body, fair for other parts

Good for rod, fair for other parts


  • Although the rod is always steel, most of the weight lies in the body, so Aluminum Alloy cylinders are a little more than 1/3 as heavy as the steel ones.
  • Elongation of Aluminum Alloy with a T6 (or equivalent) treatment, is fairly small. Tensile stress is high but impact resistance is not so good as steel.
  • Mechanical properties of an Aluminum Alloy with a T6 (or equivalent) treatment, fall sharply above 110 ÷120° C, so max safe working temperature is 100° C. For steel body cylinders, the limit comes from seals and wear rings. Special versions (much more expensive) are however available.
  • The overall design of the steel-made block cylinders, allow for both a higher static and working pressure.
  • Due to its relatively light construction, V250 id designed for low speed operation, while V220 and V450 can work at double its speed. Actual speed for all is likely to be higher, due to the pump and circuit adopted.
  • Fatigue resistance. Typically a T6 treated Aluminum Alloy has an excellent static resistance but a fatigue behavior fair to good. Non treated steel has a very good fatigue behavior and is recommended for parts operating over many million cycles.
  • Stroke. V250 is only short stroke, while V450 is short to medium. For long strokes our only option is V220.
  • Rod end for V250 is female only. We are developing the male rod end for V450, because it is sturdier and the capabilities of the cylinders can be fully used with it. V220 is the most versatile, having the option for a floating joint too.
  • Sensors. Magnetic only for V220 and V250. Mechanical only (due to the steel body) for V450.
  • Corrosion resistance. Anodizing gives the Aluminum Alloy bodies excellent corrosion properties. Anyway, the machined parts of the rod are subject to corrosion. On the contrary, V450 rod treatment allows for good corrosion resistance, but the body is less resistant (steel with surface coating).

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