Paper Machine Calender Stack

Product Specifications

Technical details and manufacturing context for Paper Machine Calender Stack

Definition

A calender stack is a critical finishing component in paper manufacturing lines, positioned after the dryer section. It consists of multiple vertically stacked rolls that apply controlled pressure and heat to the paper web. This process smooths the paper surface, improves gloss, controls thickness (caliper), and enhances printability. Modern calenders can be configured with various roll types (hard, soft, heated) to achieve specific paper grades from newsprint to high-quality coated papers. The stack typically includes 2 to 12 rolls, with roll diameters ranging from 300 to 1200 mm. Maximum web width capacity is 2.5 to 10 meters, and operating speeds can reach 300 to 1500 m/min. Line pressure at the nips ranges from 50 to 350 kN/m, and operating temperatures can be set between 80 and 250 °C, depending on the heating system (thermal oil, steam, or induction). Roll surface hardness varies from 60 to 95 Shore D, and surface finish ranges from 0.05 to 0.4 μm Ra, influencing gloss and matte effects. Nip width is typically 10 to 50 mm, affecting dwell time and pressure distribution. Total drive power is 75 to 500 kW, and machine weight ranges from 20 to 150 tons, requiring adequate foundation and crane capacity. Materials used include cast iron, forged steel, polyurethane, stainless steel, and thermal oil for heating. The calender stack is selected based on paper grade, desired surface properties, and production speed. Verification of model-specific values and standards with the legal manufacturer or supplier is essential before procurement.

Working Principle

The paper web passes through nips between stacked rolls under controlled pressure, temperature, and speed. Each nip applies a specific line pressure and, if heated, transfers heat to the web, modifying surface smoothness, gloss, and caliper. The combination of roll hardness, surface finish, and nip width determines the final paper characteristics. The process is continuous, with the web moving through the stack at speeds up to 1500 m/min.

Common Materials

cast iron, forged steel, polyurethane, stainless steel, thermal oil

Technical Parameters

Parameter	Typical range	Notes & selection driver
Number of RollsRequired	2–12 units	Total rolls in stack
Maximum Web WidthRequired	2.5–10 mm	Maximum paper width capacity
Maximum Line PressureRequired	50–350 kN/m	Maximum nip pressure per linear meter
Maximum SpeedRequired	300–1500 m/min	Maximum operating speed
Roll DiameterRequired	300–1200 mm	Standard roll diameter
Heating System Type	Thermal oil / Steam / Induction text	Thermal oil, steam, or electric heating
Drive Power	75–500 kW	Total installed motor power
Operating Temperature	80–250 °C	Higher temperatures improve gloss but may affect coating.
Roll Surface Hardness	60–95 Shore D	Harder rolls give higher gloss but less conformability.
Nip Width	10–50 mm	Affects dwell time and pressure distribution.
Roll Surface Finish	0.05–0.4 μm Ra	Lower Ra gives higher gloss; higher Ra improves matte finish.
Machine Weight	20–150 t	Foundation and crane capacity must be considered.

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM

Top Crowned Roll
Primary pressure application with crown compensation

Material: Forged Steel
Intermediate Rolls
Pressure distribution and web guidance

Material: Cast Iron/Steel
Bottom Roll
Foundation roll with drive connection

Material: Forged Steel
Hydraulic Loading System
Precise nip pressure control

Material: Steel/Hydraulic Components
Roll Heating System Optional
Temperature control for thermal calendering

Material: Stainless Steel/Thermal Oil
Deflection Compensation Optional
Maintains uniform nip pressure across width

Material: Steel/Hydraulic
Web Guiding System
Maintains web alignment through stack

Material: Stainless Steel/Sensors
Lubrication System
Automatic bearing lubrication

Material: Steel/Piping

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Paper Machine Calender Stack.

Manufacturers of Paper Machine Calender Stack

Manufacturer profiles associated with Paper Machine Calender Stack.

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Frequently Asked Questions

What is the typical number of rolls in a calender stack?

The number of rolls typically ranges from 2 to 12, depending on the paper grade and desired finish. More rolls allow for multiple nips and greater control over surface properties.

What heating systems are available for calender stacks?

Heating can be provided by thermal oil, steam, or induction systems. The choice affects operating temperature range (80–250 °C) and energy efficiency.

How does roll surface hardness affect paper quality?

Harder rolls (higher Shore D) produce higher gloss but less conformability, while softer rolls provide better embossing and matte finishes. The hardness range is 60–95 Shore D.

What maintenance signals indicate potential issues?

Unusual vibration, uneven paper thickness, or surface defects may indicate roll wear, misalignment, or heating problems. Regular inspection of roll surfaces and nip pressure is recommended.

Data Basis

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Preliminary Technical Classification

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pressure:	50-300 kN/m (linear pressure between rolls)
flow rate:	100-2000 m/min (paper web speed)
temperature:	50-150°C (typical operating range for paper processing)
moisture content:	2-10% (paper moisture entering calender)
slurry concentration:	N/A (dry process, no slurry involved)

Product Specifications

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