It goes without saying: if you want to slit vinyl films and non-wovens on a roll cleanly, you need a sharp blade. But the right grind involves more than just sharpness. In the second part of our slitter series, we explain what matters – and why regrinding is best carried out by the manufacturer itself.
Sharpness determines the quality of the cut
In any cutting process, the sharpness of the blade is a key factor – and this naturally also applies to the slitting of vinyl films on a roll. In day-to-day practice, this means two things:
- Use the correct blade: Fit a blade with the appropriate sharpness for the specific application. NEPATA offers blades in various sizes, hardnesses and grinds for the ADWS cutting-off system.
- Have the bladeresharpened regularly: The blade must be resharpened in good time – and in such a way that it functions perfectly again afterwards.
Initial sharpness and final sharpness
Every application first requires a certain degree of initial sharpness to ensure a clean cut without excessive effort. For certain applications, a high level of final sharpness is also crucial to ensure that the cut edges are particularly clean. This applies above all to tough, resilient materials.
But be careful: a blade must not be too sharp either, as this will make it very thin and brittle. Our blade overview in the first part of the series shows which blades and which grinds are suitable for which purposes.
The problem with blunt blades
Dull blades require more force and crush the material rather than cutting it cleanly. This causes material to become wedged into the cut edges, so to speak, resulting in increased fraying. In the case of adhesive films consisting of a top layer and silicone paper as the backing material, this can also lead to unwanted dust build-up on the paper.
Regrinding by the manufacturer
To avoid these problems, slitting blades should be resharpened regularly and, above all, in good time. Resharpening is, however, more demanding than it seems: a blade cannot simply be handed over to just any tool sharpening service. It is crucial to know which phases, what degree of sharpness and what hardness are required for the blade in question. In the past, our customers have repeatedly experienced problems with blades that had been resharpened externally.
That is why we offer all NEPATA customers an in-house regrinding service. We know exactly how the blades for NEPATA machines need to be sharpened to achieve a straight, fray-free cut. Through the appropriate heat treatment, we also ensure the cutting edge has the optimum hardness.
The alternative: solid carbide blades
Anyone requiring a high level of cutting sharpness can opt for a solid carbide blade. It makes a significant difference, particularly when working with tough materials: perfect cut edges, no smearing, no fraying. Added to this is a long service life – the blade stays sharp three to five times longer than a standard blade made from HSS steel. This means less frequent blade changes, less grinding work and greater process reliability.
Our video ‘Slitting like a pro’ provides further practical advice on slitting.
Have your blades gone blunt? Send us your enquiry about the NEPATA sharpening service.
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Further articles in our ‘Slitter’ series: