To work correctly, moulds, especially large ones, often need long ejection strokes. However, standard sleeves have a limited guide length, which means that they are unable to guarantee long strokes. Indeed, if the pin inside the sleeve exceeded the guide limit it would be impossible to withdraw it into the guide hole. This explains why designers often request sleeves with longer guides. But this solution, in addition to being costly, can also affect the mould integrity during operation, due to the high friction generated by an extremely long guide.
The Nostep sleeve ejectors offered by Pedrotti are a perfect and economical solution. They feature an extremely smooth connection between the relief hole and the pin guide hole. The radius is such that any interference or sticking of the pin against the sleeve’s relief hole is avoided. When the pin, during the ejection phase, emerges from the guided section, its withdrawal is ensured thanks to the guide radius, while its extremely smooth surface, free from imperfections, avoids any damage to the profile surfaces.
The advantages of this solution are particularly apparent in the presence of a long thin pin, which is naturally more subject to bending or likely to result in contact between the seats and the sleeve. What is more, there is a further significant advantage of using this sleeve. During mould assembly, it is really easy to insert the pins into the sleeve: all you need to do is press them, and they will easily find room thanks to the self-aligning function guaranteed by the Nostep process, and this all adds up to time savings and user friendliness.
To be efficient, the product must be built with particular attention to quality, starting from the choice of the steel, through to the finishing of the surfaces. For this reason, Pedrotti carries out every step in the production process in house: from turning of raw steel to heat treatments, and from internal surface lapping through to the manual checking of every single piece.