Soft Paper Calender Machine

Application:

The fixed mid-height soft calender (single nip and double nip) is suitable for calendering paper with a deckle less than 1880 mm. The internal multi-zone mid-height controllable roll soft calender (single nip and double nip) is suitable for calendering paper with a deckle more than 1880 mm.

Using a soft calendering machine for paper processing greatly improves the uniformity of sheet density and ensures less dots or imperfections and better printing on paper. Consequently, soft calendering machine has replaced the hard calendering machine in many paper mills.

Applications of the Soft Calender

1. Standard newsprint (DIP)

2. Improved newsprint

3. SC-B rotogravure

4. LWC (Light weight coating paper) offset

5. Coated or uncoated woodfree paper

6. Coated or uncoated board

7. Print and writing paper

Working Principle：

Calendering is a repeating process between a smooth roll surface and a coarse web surface after the paper web comes out of the drying section. The working principle of a paper calendering machine is very similar to ironing, yielding smooth paper through the action of heat and pressure. Both the common calendering machine and the super calendering machine achieve great calendering effects through the repeated pressure of multiple rolls. The soft calendering machine accomplishes the calendering process by rising the surface temperature of rolls and the width of nip. After process is finished, the smoothness of paper can be increased by 30% to 40% while the paper thickness reduces by less than 10%.

Advantages：

When pressurizing, elastic deformation of soft roll leads to surface contact between hard roll and soft roll. The surface contact width of soft calender 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 plastify. The softened fiber is easier to be calendered, thus increasing smoothness.

The rebound resilience of surface material enables the soft roll surface to suit any bad flatnes

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