Call Us:0086-15638252792
0%

Table of Contents

A cylinder mould kraft paper machine makes paper on a rotating cylinder covered with wire. That cylinder spins through a vat of diluted kraft pulp, and fibres gradually build up into a wet web on the surface. From there, a felt picks up the web and carries it to the pressing and drying sections. It's a different setup from a standard Fourdrinier machine, which forms paper on a moving table instead.

According to the Food and Agriculture Organization of the United Nations, global paper and paperboard production is now over 400 million tonnes a year. That kind of scale puts real pressure on mills to find equipment that's efficient, flexible, and careful about fibre use. Smithers' research on sustainable packaging also points to ongoing pressure to move away from plastic-heavy formats and toward recyclable paper solutions. So it's no surprise that cylinder mould technology is getting fresh attention.

This type of machine is particularly handy for kraft paper, cover stock, board, and specialty grades. It can create a distinctive formation and a visible surface character — qualities that matter in premium packaging and smaller production runs. Operators can tweak pulp consistency, cylinder speed, forming pressure, and drying temperature. Every one of those settings affects basis weight, moisture, tensile strength, and sheet uniformity.

Small details matter.

A well-maintained cylinder mould can help reduce breaks and keep production stable. That said, it isn't automatically the right answer for every mill. You still have to look at energy costs, vat capacity, furnish preparation, and finishing requirements together. And the term “cylinder mould” gets used pretty loosely in some supplier literature. Before investing, buyers should check technical drawings, trial data, and actual measured output. This guide looks at how the machine works, where it performs well, and which limitations deserve a closer look.

What Is a Cylinder Mould Kraft Paper Machine?
Table of Contents [Hide]
1 Definition and Purpose of a Cylinder Mould Kraft Paper Machine
2 Main Components and Their Functions
3 How the Cylinder Mould Forming Process Works
4 Raw Materials Used in Kraft Paper Production
5 Key Operating Stages from Pulp to Paper
6 Paper Grades and Common Industrial Applications

Definition and Purpose of a Cylinder Mould Kraft Paper Machine

A cylinder mould kraft paper machine forms paper on a rotating wire-covered cylinder. The cylinder turns through a vat of diluted kraft pulp. Fibers settle on its surface, then transfer onto a felt for pressing and drying. This process builds a dense, stable sheet with strong bonding between fibers.

Its main purpose is producing kraft paper, linerboard, wrapping grades, and heavy specialty sheets. Several cylinders can operate in sequence. Each one adds a separate layer. This makes the machine useful for multi-ply structures, especially when stiffness matters more than extreme smoothness. FAO’s 2022 forestry statistics reported global paper and paperboard production above 400 million tonnes. Packaging remains a major demand driver. CEPI’s 2023 industry statistics also showed European paper and board production exceeding 80 million tonnes. These figures explain the continued interest in efficient forming equipment.

Tips: Check formation, moisture balance, and layer bonding during trials. A stable vat level matters. Small changes can create visible streaks or weak edges. Operators should compare laboratory strength results with reel performance. The machine is not a perfect fit for every grade. Its slower drainage can limit high-speed production, and that limitation deserves honest evaluation. A practical review should measure energy use, reject rates, drying capacity, and maintenance time before investment.

Main Components and Their Functions

A cylinder mould kraft paper machine forms paper on a rotating wire-covered cylinder. Its stock preparation system mixes kraft pulp, water, and process chemicals. Refiners adjust fibre development and drainage behavior. Clean, stable pulp matters. Small consistency changes can create visible basis-weight variation.

The machine vat holds the diluted pulp around the cylinder mould. As the cylinder rotates, water passes through its wire surface while fibres form a wet sheet. A breast roll supports smooth stock flow into the vat. The couch roll removes more water and transfers the sheet to the forming fabric. Operators monitor vat level, pulp consistency, and cylinder speed closely. These details affect formation, strength, and surface uniformity.

The press section uses loading rolls and felts to squeeze water from the sheet. Better dewatering reduces dryer energy demand. Steam-heated dryer cylinders then remove remaining moisture under controlled tension. A size press may add starch when improved surface strength is required. The calender smooths the paper and adjusts thickness. Finally, the reel winds the finished web into a parent roll. Sensors and control systems track moisture, tension, temperature, and speed. They help operators respond quickly, but they cannot replace practical judgment. Paper machines still behave imperfectly. A worn felt, blocked spray, or small air leak can disturb production. Experienced crews inspect the sheet visually, not only through screen readings.

How the Cylinder Mould Forming Process Works

What Is a Cylinder Mould Kraft Paper Machine?

How the Cylinder Mould Forming Process Works

A cylinder mould machine forms paper by rotating a perforated cylinder through a vat of diluted kraft pulp. Water drains through the screen, while fibers remain on its outer surface. The forming speed, pulp consistency, and vat level control sheet thickness. Small changes matter.

As the mould rotates, a couch roll transfers the wet fiber layer onto a felt. Several moulds can build a multi-ply sheet, which improves bulk, stiffness, and surface character. Operators often adjust vacuum pressure and forming speed after checking moisture profiles across the reel. Uneven drainage can create weak edges or visible formation marks.

The process remains relevant as global paper demand grows. FAO forestry production statistics reported more than 400 million tonnes of paper and paperboard production worldwide in 2022. CEPI’s 2023 key statistics placed European paper and board production near 79 million tonnes. These figures show the scale, but they do not guarantee efficient forming. Energy use, water circulation, fiber quality, and press-section loading still require close control.

A practical warning: higher speed is not always better. Excessive speed may shorten drainage time and reduce formation uniformity. Cylinder mould systems can produce distinctive kraft sheets, yet their performance depends heavily on disciplined setup and continuous measurement. That part is often underestimated.

What Is a Cylinder Mould Kraft Paper Machine?

The cylinder mould forming process creates a paper web by rotating a wire-covered cylinder through a dilute fiber suspension. Water drains through the wire while fibers form a layer that is transferred to a felt, pressed, dried, and reeled.

The chart shows representative solids-content levels through the main stages of a cylinder mould kraft paper machine. Actual values vary with furnish, basis weight, drainage conditions, pressing, and dryer operation.

Raw Materials Used in Kraft Paper Production

What Is a Cylinder Mould Kraft Paper Machine?

Raw materials strongly influence the performance of kraft paper made on a cylinder mould machine. The main ingredient is kraft pulp from wood chips, usually containing long fibers for tear resistance and shorter fibers for a smoother surface. Softwood pulp often improves strength, while hardwood pulp supports formation and printability.

Recycled fiber can reduce fresh material use, but it requires careful preparation. Collection quality varies widely. Recovered paper is sorted, screened, and cleaned before entering the stock system. Excessive ink, plastic fragments, ash, or fine particles can weaken the sheet and affect drainage. Moisture content also matters because inconsistent moisture changes refining behavior and final paper strength. Small details matter.

Manufacturers may add starch to improve surface strength, sizing agents to control water absorption, and retention aids to keep fine fibers in the sheet. Clean process water is essential because salts and suspended solids can disturb chemical performance. On a cylinder mould machine, operators monitor pulp consistency, refining degree, basis weight, tensile strength, burst strength, and Cobb value. There is no perfect recipe. A higher recycled-fiber ratio may lower strength, while excessive refining can reduce drainage and increase energy use. In practice, the best material blend depends on the required thickness, stiffness, moisture resistance, and end use. Even experienced teams should review test data instead of trusting a fixed formula.

What Is a Cylinder Mould Kraft Paper Machine? - Raw Materials Used in Kraft Paper Production

Material or Parameter Typical Share or Value Primary Function Preparation or Use in Production Key Quality Considerations
Unbleached kraft wood pulp Primary fiber source; often 50–100% of the furnish Provides long, strong cellulose fibers for tear and tensile strength Produced by alkaline kraft cooking, washing, screening, and refining before sheet formation Fiber length, cleanliness, brightness, moisture, and degree of refining affect paper strength and drainage
Recycled kraft paper fiber Commonly 10–80%, depending on the required grade Reduces virgin-fiber consumption and supports recycled-content products Sorted, repulped, screened, cleaned, and sometimes deinked before blending with virgin pulp Repeated recycling shortens and stiffens fibers, which can reduce tensile strength and drainage performance
Unbleached softwood pulp Approximately 20–70% of a strength-oriented furnish Adds long fibers that improve tensile, burst, and tear resistance Refined to develop bonding while maintaining adequate drainage on the cylinder mould Excessive refining may slow drainage and increase energy consumption
Unbleached hardwood pulp Approximately 10–60% of the furnish Improves formation, surface smoothness, and opacity through shorter fibers Blended with longer-fiber pulp and refined according to the target basis weight Too much short fiber can lower tear strength and reduce sheet permeability
Bagasse or agricultural fiber pulp Typically 5–30% when alternative fibers are specified Provides a non-wood fiber option and can contribute to bulk and formation Requires cleaning, depithing where applicable, alkaline pulping, washing, and screening Fiber impurities, silica, variable fiber length, and drainage must be carefully controlled
Process water Pulp slurry commonly enters forming at about 0.5–1.5% consistency Disperses fibers and transports the furnish to the cylinder mould Recirculated white water is clarified and reused where process design allows pH, temperature, hardness, dissolved solids, and microbial control influence runnability
Starch About 0.5–3% of dry fiber mass, depending on application Improves dry strength, surface strength, stiffness, and printability Added internally to the stock or applied at the size press after drying Overuse may increase viscosity, reduce drainage, and cause deposits or surface defects
Alkaline sizing agent Commonly around 0.1–1.0% active material on dry fiber Improves resistance to water penetration and liquid absorption Usually added to the stock system or applied through surface treatment Dosage, retention, pH, and compatibility with starch affect sizing efficiency
Retention and drainage aid Usually measured in low dosage, often below 0.1% active polymer Improves fines and additive retention while supporting faster water removal Added under controlled mixing conditions before the stock reaches the vat Incorrect dosage can create flocculation, poor formation, or unstable machine operation
Defoamer Low dosage; commonly controlled in parts per million Controls foam caused by surfactants, recycled fiber, and process turbulence Metered into the white-water or stock system when foam is detected Excessive use may interfere with sizing, coating, bonding, or surface appearance
Calcium carbonate or mineral filler Often 0–10% in selected kraft grades; lower levels are common for high-strength paper Improves opacity, smoothness, and print surface while reducing fiber cost Dispersed in water and added with a retention system when compatible with the furnish High filler content can reduce tensile, tear, and wet strength; alkaline pH is generally required
Cylinder mould forming system Vat-based sheet-forming unit; typical machine speed varies by grade and design Forms a wet web as a rotating wire-covered cylinder collects fibers from the vat The partially formed web transfers to a felt or carrier and proceeds through pressing and drying Vat consistency, cylinder speed, vacuum, felt condition, and basis-weight control determine formation
Typical kraft paper basis weight Approximately 40–200 g/m² for many packaging and wrapping grades Defines sheet mass, thickness, strength potential, and end-use suitability Controlled through stock consistency, flow rate, machine speed, and vacuum conditions Uniform cross-direction and machine-direction profiles are essential for converting performance

Key Operating Stages from Pulp to Paper

What Is a Cylinder Mould Kraft Paper Machine?

Key Operating Stages from Pulp to Paper

A cylinder mould kraft paper machine begins with cleaned kraft pulp. Bales or recycled fiber are mixed with water in a pulper. Operators then remove plastic, sand, and oversized contaminants through screening. The accepted pulp enters stock preparation, where refining improves fiber bonding. Refining must be controlled carefully. Excessive treatment can slow drainage and weaken the sheet.

The prepared stock flows into a mould vat. Inside, a rotating cylinder covered with forming wire collects a thin fiber layer. Water drains through the wire as the cylinder turns. The wet web transfers onto a felt or carrier surface. Its thickness depends on pulp consistency, cylinder speed, and vat level. Small changes matter here. A few seconds of unstable flow can create uneven basis weight.

The web passes through press rolls to remove more water. It then travels through steam-heated drying cylinders. Temperature, felt tension, and moisture are checked continuously. Over-drying may make kraft paper brittle. Under-drying can cause winding problems. After drying, calendering can smooth the surface, although too much pressure may reduce bulk.

The finished sheet is inspected for strength, moisture, edge quality, and visible spots before rewinding. Experienced operators still face variations in fiber quality and machine response. Perfect uniformity is difficult. Continuous adjustment remains part of responsible production.

Paper Grades and Common Industrial Applications

What Is a Cylinder Mould Kraft Paper Machine?

A cylinder mould machine forms paper or board on a rotating cylindrical wire. It can build several wet layers into one strong sheet. This structure improves bonding, stiffness, and thickness control. Unlike a conventional fourdrinier line, it accepts different fibre furnishes with practical flexibility. The term “kraft” needs care. This machine may produce kraft-based grades, but it is not limited to virgin kraft pulp.

The FAO Forestry Production and Trade database reported global paper and paperboard output at about 420 million tonnes in 2023. Packaging grades represented a major share of this volume. CEPI’s Preliminary Statistics 2023 recorded 79.5 million tonnes of paper and board production among its members. Packaging papers and boards formed the largest product group. Regional product mixes still vary.

Common grades include sack kraft, wrapping kraft, liner, testliner, coreboard, and solid board. Typical basis weights range from roughly 200 to 800 g/m², depending on machine design and furnish. Sack kraft requires high tensile strength and controlled porosity for agricultural, food, and industrial bags. Liner and testliner support corrugated cases. Coreboard serves tubes, edge protectors, and reels. Solid board appears in pallets, partitions, and heavy-duty packaging. Moisture, recycled fibre quality, and drying capacity can change results. I would not treat every kraft grade as interchangeable. The boundary is less tidy than many specifications suggest.

FAQS

What is a cylinder mould kraft paper machine?

It forms paper on a rotating, wire-covered cylinder inside diluted kraft pulp. Fibers remain on the cylinder surface.

What paper grades can it produce?

It can produce kraft paper, linerboard, wrapping grades, and heavy specialty sheets. Multi-ply sheets are a common strength.

How does the forming process work?

The cylinder drains water through its screen while fibers build a wet layer. A couch roll transfers this layer onto felt.

Why are several cylinders used together?

Each cylinder adds another layer. This can improve bulk, stiffness, and bonding in the finished sheet.

Which operating settings affect paper quality?

Pulp consistency, vat level, cylinder speed, vacuum pressure, and moisture balance affect formation and thickness. Small changes matter.

What happens after the wet sheet forms?

Press rolls and felts remove water. Heated dryer cylinders remove more moisture, while controlled tension protects the web.

Can the machine always run at high speed?

No. Faster operation can shorten drainage time and create uneven formation or weak edges. Higher speed is not always better.

What should operators inspect during production?

They should check sheet appearance, moisture profiles, vat level, tension, and reel performance. Screen readings are not enough.

What maintenance problems can disturb production?

A worn felt, blocked spray, small air leak, or unstable pulp flow can create streaks and uneven basis weight.

What should be reviewed before investing?

Measure energy use, reject rates, drying capacity, maintenance time, and laboratory strength results. The machine may not suit every grade.

Conclusion

A Cylinder Mould Kraft Paper Machine is designed to produce strong, durable kraft paper by forming a uniform web of pulp on a rotating cylinder mould. It is commonly used when reliable strength, controlled thickness, and flexible sheet formation are required. The main components typically include the pulp preparation system, stock chest, cylinder mould, forming vat, press section, drying cylinders, sizing or coating unit, calender, and reel. Each part contributes to fiber preparation, sheet formation, water removal, surface improvement, or final paper winding.

The process begins with kraft pulp, recycled fibers, or a carefully controlled blend of both. After cleaning, refining, and dilution, the pulp enters the forming vat, where fibers collect on the partially immersed cylinder mould. The wet sheet is transferred, pressed, dried, and finished to achieve the required properties. Depending on the operating conditions, the machine can produce wrapping paper, bag paper, liner materials, packaging sheets, and other industrial grades. Paper strength, basis weight, moisture, smoothness, and appearance are adjusted throughout the production stages to meet specific application requirements.

Blog Tags:

Liam
Updated:
Liam

Liam

Liam is a seasoned marketing professional at Zhengzhou Dingchen Machinery Co., Ltd, a leading paper machine manufacturer known for its comprehensive approach combining scientific research, design, manufacturing, installation, and commissioning. With over 30 years of industry experience, Liam......
Previous How to Choose a Craft Paper Recycling Machine?