Ejector plate

Ejector plate drive with hydraulic cylinders

Hydraulic cylinders are often required to drive the ejector plate in cases where using the machine's ejector motion is not desired or not possible. Multiple cylinders are always used for this purpose. These cylinders are fitted either on the outer side of the mold or they are integrated into the mold. The required strokes can also vary greatly depending on the plastic component's characteristics. Therefore, very different cylinders are commonly used to support the same function.

Our ejector plate solutions

In cylinders fitted to the outside of the mold, block cylinders are almost always the best choice. Their rectangular shape makes them perfect for fitting them to the side of the mold. Hydraulic oil can be supplied externally via regular hoses or via bores through the mold. Our BZ 250 block cylinder features a variable system connection intended for cases where the oil required for long strokes is to be fed through bores in the mold. Here, the bores lead into the side of the cylinder, making them independent of the stroke.

If the cylinders are to be integrated into the mold, screw-in cylinders or built-in cylinders are popular choices. They are very small and compact. Since the strokes in such applications are usually quite short, venting is a particular concern here. This often requires creativity or expert advice since venting on the cylinder is usually not an option. Our Technical Sales department will be happy to help in such cases.

Our double barrel cylinder is often used in applications where the ejector stroke is very long and the cylinder is to be integrated into the mold. Bottle crates are an example of this. The great advantage of double barrel cylinders is that the hydraulic ports are located on just one side of the cylinder, despite the long strokes.

Tips and tricks:

  • Cylinders with short strokes and small piston diameters often lack a vent. If this air remains in the cylinders during operation, failures are bound to occur in many cases. 

  • A rigid connection between cylinder and core is not recommended as it may cause lateral loads and, thus, cylinder failure. We would like to refer to our couplings and the matching counter pieces from our accessories at this point.
  • Long strokes may take too much time, leading to fast operational cylinder speeds. Please consider that ejector plates often move great masses that need to be decelerated again. Our linear cushioning enables us to specifically calculate the braking characteristics required for your application.

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