Extended lifetime coater blades feature carbide coating

Overall, the challenges in blade coating include paper quality variations and short blade lifetime - with corresponding issues of edge wear, decreasing smoothness, worsening of coat weight profiles and defects - leading to production losses. The result is blades needing to be replaced often, leading to high total blade costs.

Extended lifetime blades

The need for longer blade life has driven the development of extended lifetime blades. These blades are made from blue steel, but the tips of them are made of a hardened substance. The most common blade tip currently in use is made with carbide coating, one of the hardest known compounds. A minority of blades used feature ceramic coating, typically chromium oxide. A very small percentage of coaters continue to use steel blades.

A high quality carbide blade will leave a uniform layer of coating color on the paper or board surface for the desired coat weight. This improves efficiency and has a major positive impact on product quality.

These coated blades provide excellent paper quality and longer blade lifetime - leading to more production, less broke and overall lower total blade costs. The extended lifetime blades are high quality and cost efficient.

Valmet's carbide coated blades

Valmet has the widest know-how of carbide coatings for use in paper and board machines. The Valmet Coater Blade family (earlier known as the PermaCote family) comprises the xC, nC, eNC and eC blades. All are designed for optimized process performance.

The Valmet Coater Blade family are the highest performing coater blades currently available for paper and board making.

Valmet Coater Blade xC for superior paper quality

The xC blade is composed of high quality special nanocarbide, providing excellent paper smoothness and short run-in time with a low wear rate and low streaking tendency. Its dense structure and carbide surface smoothness are optimized for demanding top coating.

Valmet Coater Blade nC for demanding top coating and high paper quality

The nC blade features a blade life that is up to 25% longer than traditional carbide materials. Made of high quality nanocarbide, it also has a dense structure which results in excellent smoothness. Expect increased production and less downtime with the nC blade.

Valmet Coater Blade enC for maximized lifetime in top coating

The enC blade, also made of high quality carbide, is optimized for top coating especially before heavy final calendering. Its lifetime is similar to that of the nC blade, at up to 25% longer than traditional carbide blades.

Valmet Coater Blade eC is the cost efficient solution for coating

The eC blade, of high quality carbide, is optimized for pre-, back- and middle-coating and is also suitable for top coating before multinip calendering. Valmet Coater Blade eC provides excellent edge wear resistance, good paper smoothness and a long lifetime. These combine for substantial savings in paper and board production costs.

Angles and thicknesses

All of these extended lifetime blade materials can be ground into multiple bevel angles and on several blade thickness stocks to match an individual coater’s needs. Compound angles are common as they provide more of an operating window to work with. All Valmet's carbide coater blades are available for bent and stiff blade applications in all geometries.

Trials available

If extended blade lifetime is the goal, some trial work is required to determine the best balance between blade geometry, coater setup angles, machine direction coat weight control and cross machine direction coat weight control. Since these blades are harder, they will not wear in to the coater non-uniformities rapidly – hence the trial work is needed to optimize blade and beam geometry.

Applications for extended lifetime blades

Extended lifetime blade use is common on coated board machines, especially those that run in bent blade mode or low angle rigid blade mode. These blades exhibit far superior running life as well as good coating surface qualities.

Light weight coated machines also use extended lifetime coater blades, but justification for using them is more related to machine uptime. If the coater has frequent sheet breaks, mills find it harder to justify the extended lifetime blade’s higher cost

Each mill has to determine what the cost/benefit alternative is for each blade type.

Valmet has the know-how

Valmet has a thorough understanding of the papermaking process, including all types of coating methods. The use of proven production concepts, carefully selected raw materials and internally developed special manufacturing methods ensure the consistently high quality of all Valmet consumables. In addition, Valmet’s service center network offers you local maintenance and expert services and access to global process know-how and technology through over 70 service centers on 5 continents.

For more information regarding Valmet's line of extended wear coater blades, please contact your Valmet representative.