Stepless ejector sleeves

Increased productivity and minimized risk of breakage

KNARR plays a pioneering role in the production of stepless ejector sleeves. More than 20 years have passed since the first patented ejector sleeves conquered the market. Solid experience and continuously advanced know-how undoubtedly make KNARR the right partner for this type of product. After a further expansion of the production line in 2012, also large-scale mould making can be served with stepless sleeves up to a length of 1000 mm. However, what is the sleeve’s recipe for success?


In contrast to the classic sleeve shape with a stepped guiding length, the inner diameter is tapered. Any damage to the ejector pin – which runs inside the sleeve – is almost impossible thanks to the stepless design of the clearance. The stability gained is another positive side effect. The same also applies to the combination sleeve and core pin: for the application in which the sleeve makes the stroke, which in turn exceeds the guiding length, the core pin slides out of the guide in each cycle. Complications caused by this can be avoided using a tapered guide: The results are significantly less wear and a minimized risk of breakage.


The use of stepless sleeves not only increases maintenance intervals, but also reduces service and spare part costs. Fewer downtimes and longer tool life have a positive effect on the amount of output. Even assembly and disassembly is much more relaxed thanks to the easier threading of the ejector package.


ArticleTreatmentØL max.
38188hardened2 – 16 mm250 mm
38781hardened4 – 12 mm1000 mm
38488nitrided3 – 16 mm250 mm
38882nitrided5 – 12 mm1000 mm

The use of stepless ejector sleeves holds enormous optimization potential.

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