Kraft Paper Making Machine Line Two/Four Roll Soft Calender

Product Description

Paper Machine Soft / Hard Nip Calender Machine

The calender is a device used to improve the glossiness of paper surface, and is a type of calendering and glazing process. After the printed surface is coated, wait for the glazing layer to dry. If the smoothness and glossiness of the glazing layer need to be improved again, it can be calendered by the calender. Generally, the glossiness of glazing is about 65-85%, and after calendering, it can reach a glossiness of more than 90-95%.
 

Soft Calender

The fixed crown soft calender (single nip and double nip) is suitable for calendering paper with a deckle less than 1800 mm. The internal multi-zone crown controllable roll soft calender (single nip and double nip) is suitable for calendering paper with a deckle more than 1800 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.

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 processed by this hard calendering machine, the paper sheet has its smoothness improved greatly and the coating weight is reduced as well.

Technical Parameter
 

Trim width	1575-4200mm
Paper grade	Two-side offset paper and high-grade writingprinting  paper 300m/min
Basic weight	50-80g/m2
Temperature range of the paper web	45-65ºC
Moisture content of paper web	4-8%
Max design linear pressure	160-200KN/m
Working speed	80-350m/min
Design speed	400m/min
Dynamic balance speed	500m/min
Driving roll(heating) hardness	HSD74±2°(shore hardness)
Surface temp of heating roll	110-220ºC
Diameter of the soft roll	600mm

Working Principle of the calender
 

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%.

Suitable Calender for Different Paper Kind

Soft Calender
1. Newsprint paper 2. Light weight coating paper 3. Coated or uncoated woodfree paper 4. Coated or uncoated board 5. Print and writing paper

Hard Calender
1. Coating base paper 2. Standard newsprint 3. Linerboard