Thermal spraying of Yankee cylinder in tissue machines
The Yankee cylinder is the heart of a tissue machine – its surface is critical to production output and creping quality. The Yankee is constantly exposed to chemicals, wet tissue, internal steam pressure and high surface temperatures which means a risk for wear and corrosion. High performance thermal spray coating increases Yankee cylinder efficiency and lifetime by providing a hard, homogenous protective coating.
Valmet Infinikote Yankee Metallizing is the most successful thermal sprayed coating for Yankee cylinders in existence with mote than 500 references globally on both cast iron and steel Yankee cylinders. Valmet Infinikote Yankee Metallizing is a unique patented material and application process resulting in a superior tissue creping surface that maintains the profile and prolongs the life of the Yankee cylinder surface.
Thermal spraying is the ultimate treatment to protect a new Steel Yankee dryer with a hard and durable surface. Also old cylinders are often metallized to improve performance, particularly if there is insufficient remaining cylinder shell thickness and/or if further grinding may affect production capabilities, for instance steam pressure or roll loadings.
A recognized risk of metallizing has been that during the process potentially harmful hexavalent chromium is created. Chromium is a fundamental component of almost every ferrous based hard-facing alloy.
Valmet Infinikote®-2 Yankee Metallizing – Chrome free Yankee thermal spray coating for safety and unparalleled reliability
Having recognized the potential risks associated with the thermal-spraying of ferrous based materials, Valmet embarked on a program of developing new alloyed materials to beat chrome in Yankee metallizing. The new Valmet Infinikote-2 Yankee Metallizing contains no chrome and generates no hexavalent chrome during application. It is the most environmentally safe and durable Yankee metallizing coating available.
The primary performance objectives of the development were to remove the environmental and safety concerns associated with thermally sprayed products containing chrome and to apply the thermal coating with a similar process to current whilst creating a suitable surface for tissue production. Valmet Infinikote-2 Yankee Metallizing achieves this as whilst being 100% chrome free it equals or surpasses all current measured criteria for thermal spray coating performance.
- 100% chrome free
- Tailormade for tissue making
- Long service life expectation through improved wear resistance
- Provides uniform surface for best sheet adhesion during tissue production
- Better paper quality – ideal for running ceramic doctor blades
Improvements in comparison to previous Valmet Yankee thermal coatings:
- 100% Chrome free - safe and environmentally friendly application
- Tougher and more wear resistant – improved material structure and strengths
- Corrosion resistance - better than Valmet Infinikote-1 Yankee Metallizing chrome based thermal coating
- Improved heat transfer properties
Customer success stories and technical articles
Infinikote-2 Yankee Metallizing applied at Metsä Tissue Katrinefors
PM35 Yankee was close to derating, and to keep up the thickness of the Yankee shell and the steam pressure, Metsä Tissue Katrinefors decided to thermal spray it. As Infinikote-1 on PM36 had run successfully, it was natural to choose Valmet as a supplier again.
SCA Ortmann's problems resolved by Infinikote
As SCA Ortmann had applied thermal spraying on their PM 9 earlier, with good results, they decided to spray the PM 4 Yankee dryer too, with Infinikote from Valmet.