Cover Story

he would describe a doctor blade, he would say it was a consumable or just a piece of blade that scraped the cylinder or anilox from ink. Today things have changed. Through development of the printing

The Doctor Blade T

he look on doctor blades have changed through the years. +20 years ago, when you asked an operator how

process, especially in flexo, the need for special doctor blades have increased. Printing quality, finer anilox screens, higher machine speeds and machine costs have made it necessary to develop doctor blades and edges that can cope with this. Today a blade must last longer, wipe cleaner and reduce friction more to work with the new demands. Doctor blade manufacturers must continuously find new innovations to keep up with the printers needs to produce well and in an effective way. In more and more cases the simple, low

quality and low-priced doctor blade are less used and giving way for the new high-tech blades. But, on the other hand, a higher priced quality blade is not necessary more expensive to use than a “cheap” blade, often the opposite. If the blade can be used longer, prints better, reduces waste and avoid extra machine stops during run for blade changes, the higher priced quality blade is “cheaper” to use. Important to remember is: there is a difference between a price and a cost! From PrimeBlade Sweden AB’s side, we

have always continued to look for new inventions to simplify and keep up with the printers needs. The philosophy has always been to continue to develop new blades and treatments to make the printers day as easy and effective as possible. One example of this are the treated blades from PrimeBlade Sweden AB known

By Jonas Andersson, Technical Sales Manager at PrimeBlade Sweden AB

as the 900 Nano series. Three Nano treated blade type for the client’s different needs. They have been on the market for several years now and are still extremely popular, especially for the flexo printers, for the long lasting and low friction characteristics. The blades also become more ridged from the process and don’t flex as much as untreated steel blades do. Another blade type is the 700 series, a special ceramic coated blade, especially for the gravure printers. The improved coating of the blade keeps the friction down to a minimum and improves print quality. Often used as a troubleshooter for especially difficult, long and problematic jobs. PrimeBlade Sweden AB also introduces the LF (Low Friction) edge treatment. This treatment smoothens the tip and eliminates any kind of burr or impurities that can be found on untreated blades after edge grinding. By doing so the friction between blade edge and anilox/cylinder is brought down to a minimum and wear is reduced, both on anilox/cylinder surface and blade. The treatment is mainly used on carbon

steel blades but can be made on all edges and types of steel. Other developments are the Dual edge

and Hybrid edge lamella blades. In flexo a common problem is ink spitting. The issue is normally not caused by the doctor blade but often thought so. Main cause is normally originated from the anilox, ink or chamber setup. But in many cases the blade can help minimizing the problem. The spitting cause is often a resonance vibration from the blade or at the blade tip. But unfortunately, there isn’t a universal blade change solution to the problem. In some cases, a change in base blade thickness helps, in other an edge type change helps. With the Dual step lamella edge the

resonance vibration is brought down to a minimum and the ink spitting reduced or eliminated. The Dual edge can be produced on any type of steel blades, on base blade thicknesses from 0,25mm (.010”) and up. The Hybrid edge is for printers that wants a stable and non-growing contact zone edge, but also need room for some blade edge flexibility. This Hybrid edge type is something in between a long lamella and a bevel edge. It can be used both as a working and containment blade in a chambered inking system. More developments of new doctor blade

products are on its way from PrimeBlade Sweden AB. So, keep an eye out to for what’s new next from our side… 8 November 2020

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