Finishing Equipment

Paper Machine Calender Machine

DESCRIPTION

Paper Machine Calender Machine Introduction:
Based on the roll structure, paper calender machine can be divided into internal fixed crown roll type and multi-zone crown controllable roll type. It can also be divided into soft nip type and hard nip type as well as single nip Calender and double nip calender. The multi-zone crown controllable roll (CCR) type paper calendering machine is developed to meet specific paper quality requirements, widely used in the papermaking industry.

We offer fixed crown or multi-zone crown controllable roll types of paper calendering machines with soft roll or hard roll. To compensate for the deflection of hot heating rolls, the CCR type of soft nip or hard nip roll can be installed in the top or bottom position.

Soft Calender
When pressurizing, elastic deformation of soft roll leads to surface contact between hard roll and soft roll. The surface contact width of a soft calendar is 10-25 mm, which is 15 times wider than that of a hard calendering machine. The unit pressure of the soft calendering machine is generally 20-40 N/mm2, which is just 1/2-1/4 of that of the hard calendering machine. Owing to the wide nip, the sheet stays longer in the nip, and the energy consumption converts into heat which passes to the paper and makes the paper fiber classify. The softened fiber is easier to calendered, thus increasing smoothness.

The rebound resilience of surface material enables the soft roll surface to suit any bad flatness of sheet, so the soft calendering machine can achieve better softness than common hard calendering machines. Color spots can be eliminated and printability is greatly improved.

Another advantage of the soft calendering machine is paper sheets can be in motion with high moisture under the condition of elimination of paper blackening and color spots. The temperature, nip pressure, width, and a number of the soft calender all have an impact on the calendering effect.

Hard Calender
With high surface hardness, the hard roller acts on the paper through high temperature and pressure, thereby uniformizing the thickness of the paper. Generally, the thickness can be controlled below 0.01mm per nip. After being processed by this hard calendering machine, the paper sheet has its smoothness improved greatly and the coating weight is reduced as well.