Sellu ja paperi

This slewing screw reclaimer is involved in the biomass process inside a paper mill. The screw sits at the bottom of a silo and moves barks towards the center. The barks will then fall inside a chute and burned in a furnace to produce energy for the paper mill. The slewing screw reclaimer is subject to abrasion. Castolin Eutectic Services refurbished sections of the shaft and the screw flights with chromium carbide hardfacing wire. The screw was then top coated with MeCaWear.

Log debarking is necessary to ensure that the woodroom chips are free of bark and dirt. Several types of mechanical debarkers are used as well as hydraulic debarkers. The ring debarker is used on individual trees, usually in the woodyard, as it is portable. The drum debarker or debarking drum is the most common type of mechanical debarker and is available in a number of design variations. Both short-wood tumble drums and long-wood parallel drums are used. In all designs, bark is removed from the logs by friction created from the rotating drum action as the logs rub against each other. Iron or rubber lifters inside the drum shell agitate the logs and help protect the drum shell from wear.

The arms of the debarker suffer a severe abrasive wear under high pressure. One possible solution consists of an under-layer made using electrode Xuper 680S, then the final hard coating is deposited using  EutecTrode 6 electrode, which presents high resistance to cutting under pressure. The previous solution, using carbide brazed segment, was unreliable with lifetimes from 3 to 150 days. The service life with our solution is reliable and lasts more than 3 months.

In this cyclone the air is separated from the wood and sawdust. Considerable erosion wear results. The complete cyclone was manufactured from CDP 4601 wearplate with parts plasma-cut and formed to the given diameter. The joint welding was with CastoMag 45554 and the weld seam protected with EnDOtec DO*13 wire. An increase of the service life of 5 times compared with the original steel-hardened plate was recorded.

Many pulp and paper mills use recycled paper and cardboard as another source for papermaking pulp. Some mills operate with only recycled materials. The scrap materials are fed into a hydrapulper, which is a vertical tub with a revolving rotor at the bottom. Paper and cardboard with water are shredded by the rotor into pulp and a perforated extraction plate under the rotor pulls the fibres out of the tub. Further cleaning and de-flaking of the pulp prepares it for papermaking. The rotor in the hydrapulper is subjected to high wear from the wastepaper as well as foreign materials.

The rotor of the pulper dissolves waste paper into water to produce usable pulp. The pulp and impurities cause severe abrasive/erosion wear loss at the edges and the blades of the rotor. The lost material can be built up with EnDOtec DO*05 wire and areas of severe wear protected with EnDOtec DO*04 wire. DO*04 is especially recommended for waste paper pulping, because of its work-hardening, crack and corrosion resistance. The repair gives high safety and elongated service life.