A Comprehensive Guide to the Different Types of Flexo Presses

What is a Flexographic Printing Machine?

Flexographic printing, commonly known as flexo printing, is one of the most widely used analog printing techniques. It is preferred across the world for its flexibility and suitability for long, static print runs. In its simplest form, a flexographic printing machine uses a flexible printing plate, which is made from rubber or photopolymer, to print ink on a substrate. Unlike lithography or gravure printing, flexographic printing features a raised image on the printing plate.

How Does it Work?

The flexographic printing process can be described as follows. This makes it possible for flexographic printing machines to print large quantities of printed products on various materials.

Plate Preparation: The first step involves the preparation of a flexible printing plate. These are the areas that will be imaged, while the other areas are sunken on this plate, which is usually made of a photopolymer material.

Ink Application: The prepared plate is then placed on a plate cylinder of the printing press. Ink is delivered from the ink fountain to an anilox roller, which is a cylinder that has a surface with thousands of small cells engraved on it. These cells dispense and deliver a specific volume of ink to the printing plate. A doctor blade wipes off the excess ink on the surface of the anilox roller so that only the ink in the cells is used.

Ink Transfer to Plate: The ink from the anilox roller is then directly applied to the raised image areas of the mounted flexographic printing plate.

Transfer to Substrate: The substrate, which can range from very thin plastic films to thick corrugated cardboard, is fed through the press and passes between the plate cylinder (which carries the inked plate) and an impression cylinder. Pressure is applied, and the ink from the raised image on the plate is transferred to the substrate.

Multi-Color Printing: In cases where the design to be printed is of many colors, the substrate goes through several printing units. Each unit has its own plate cylinder and uses a different color of ink. Accurate registration means that each color layer overlays properly on top of the other to produce the final image.

Drying: In most cases, the printed substrate is taken through a drying unit after the ink has been applied. The type of drying method used depends on the type of ink used in the particular process. Some of the common techniques include hot air drying for water based inks, solvent based inks and UV curing for UV curable inks.

Different Types of Flexo Printing Presses

The flexographic printing presses are available in different forms and sizes and are meant to suit the various printing requirements and the type of substrate to be printed. These presses can be classified according to the mechanical construction, the size of the substrate, and the driving mechanism.

Based on Mechanical Structure

Central Impression (CI) Flexo Presses

Central Impression (CI) flexo presses are those in which the impression cylinder is large and is surrounded by the printing units. The substrate is clamped onto this central cylinder throughout the entire printing process to achieve very high register accuracy especially when printing on flexible and stretchable materials such as plastic films.

In a CI press, the printing unit comprises of an anilox roller, a doctor blade, a plate cylinder, and the central impression cylinder. The substrate moves around the central drum and each of the printing units deposits a different color of ink. This reduces the likelihood of web movement between color stations, which results in improved print quality with accurate register. CI presses are ideal for high quality printing on flexible packaging for food, pharmaceuticals and other consumable products that require accurate register.

Stack Type Flexo Presses

Stack type flexo presses have printing units that are arranged in a vertical manner where one printing unit is positioned above the other. The substrate is then transferred through each of the printing units in a continuous manner with individual impression rollers for each color station. This design is quite basic and has the benefit of being able to print on both sides of the substrate in one run, which is useful for paperboard printing, multi-ply labels, and some forms of flexible packaging.

Stack presses are very universal and can work with a wide range of substrates, but their registration might not be as precise as CI presses, particularly with flexible materials. However, they are useful in many other printing applications where very high accuracy in registration is not a critical factor. Stack presses are usually equipped with several printing decks for multi-color printing and can be equipped with other working units for further operations such as die cutting or varnishing.

In-Line (Unit Type) Flexo Presses

In-Line, or Unit Type, flexo presses have the printing units placed in a line in one plane. The substrate is fed in a linear fashion through the press and through each of the printing units. Every printing unit has an impression cylinder of its own. This configuration also provides easy access to individual printing units for configuration, calibration, and service.

In-line presses are very flexible and can be equipped with a number of printing stations ranging from one to another depending on the need of the application. They are suitable for printing on paper, paperboard and some flexible films. In-line presses are usually combined with other converting operations such as die cutting, slitting, and folding, which makes them suitable for creating finished goods such as labels, folding cartons, and envelopes in one run.

Based on Web Width

Narrow Web Flexo Presses

Narrow web flexo presses are those that are used for printing substrates that are not more than 20 inches wide and in most cases, they are as small as a few inches. These presses are suitable for small format jobs such as labels, tickets, tags and other narrow web applications. Narrow web presses are characterized by their compact size and are used for short to medium runs at high speeds. They are usually designed with inline finishing capabilities like die cutting, laminating, and slitting to enable production of finished products in one run. This feature is particularly beneficial to label manufacturers who need to produce labels in large quantities within a short time and with little wastage. These presses are commonly applied in retail packaging, food and beverage, and pharmaceutical industries where fast, efficient, and flexible solutions are required for small format production.

Mid Web Flexo Presses

Mid web flexo presses are those machines that are in between the narrow and the wide web presses and are used for handling substrates that are between 20 inches and 40 inches in width. They provide a good combination of speed and versatility that can be used in various types of printing such as flexible packaging, folding cartons, and large labels. These presses are suitable for applications that need moderate to high levels of production. They are more automated and have better control systems than the narrow web presses, making them more efficient in their operation. Mid web presses also accept a range of inks and substrates, which makes it easier for the printers to meet the product requirements.

Wide Web Flexo Presses

Wide web flexo presses are used for large format printing, where the substrate size is over 40 inches and some of the presses can handle up to 100 inches or more. These presses are mainly used in production printing where large format printing is needed. Some of the uses of polyethylene are in flexible packaging of food, beverages and consumer goods, and in the production of corrugated cardboard used in packaging boxes. Wide web flexo presses are designed for high speed and are suitable for handling thick materials such as corrugated papers. Due to their capability to print large areas at a very fast rate, they are very useful in industries that require large scale packaging. These presses are usually fitted with additional features such as high speed drying systems and inline finishing to enhance productivity and quality. Wide web presses are essential for organizations that require high volume production and at the same time need to achieve high quality printing.

Based on Driving System

Geared Flexo Presses

Geared flexo presses are the conventional method of controlling the motion of the various cylinders in the printing units. In this system, a number of mechanical gears mesh the main drive shaft with the plate cylinders, anilox rollers and impression cylinders. This mechanical linkage ensures that all the components rotate in a proper sequence and in the right position to ensure registration for printing.

Geared presses are very sturdy and have been used in the industry for many years as they are very reliable. Although geared systems may cost less initially and are more compact, they may have slight registration problems at high printing speeds because of mechanical factors such as gear backlash and wear. However, they are still useful in many printing applications where the need for very close registration is not critical.

Gearless Flexo Presses

Flexo printing machines without gears are a new innovation in the printing industry, which has improved the precision of the printing process. In this design, the plate cylinder, the anilox roller, and the impression cylinder are each driven by their own servo motor. These individual motors are electronically controlled and synchronized, thus there are no mechanical gears involved.

This direct drive approach has several benefits: higher registration accuracy at higher speeds, faster tool changes because gears do not need to be shifted, less noise, and less maintenance because there are fewer parts that wear out. Although the cost of a gearless flexo press is higher than that of a conventional one, the advantages in terms of quality, productivity, and time-saving make it a worthwhile investment for applications that require high performance and accuracy.

Advantages and Disadvantages of Flexo Printing

Flexographic printing offers a compelling set of advantages, making it a preferred choice for numerous printing applications. However, like any printing process, it also has its limitations.

Key Advantages of Using Flexo

One of the major strength of flexo is its ability to accommodate various substrates. It can print on thin plastic films and flexible packaging materials, paper, paperboard, corrugated cardboard, non-woven fabrics and other materials with rough surface.

Flexo is also characterized by high print speed, which makes it suitable for high volume production especially in the packaging sector. This makes it cost effective for long runs since it is possible to produce a large number of printed copies within a short span of time.

Another advantage of flexo printing is the flexibility of the inks that can be used in the process. Flexo presses can use water-based inks, solvent-based inks, and UV-curable inks, which gives the printers the freedom to select the most suitable ink type for their job and substrate. The advancement in the use of water based inks has also added to the benefits of flexo especially in food packaging where issues to do with safety and the environment are of great importance.

In addition, flexo presses can be equipped with inline finishing operations like die cutting, laminating, varnishing, and slitting, which means that the final product can be produced in one run, which saves time and money. The fact that flexo presses are less complex in their mechanical construction compared to some other printing technologies can also mean that they are easier to maintain and therefore cheaper to run.

Common Limitations of Flexo Printing

However, it is important to note that flexo printing has its own drawbacks as well.

It is difficult to obtain the same level of detail and image sharpness as in lithography or gravure printing, but flexo is gradually overcoming this problem due to the development of new plates and press designs.

Another one of the main disadvantages of plate making is the cost and the time it takes to produce the plates especially for small production runs. Although flexo plates are very strong and can be used for many runs, the cost of making the plates may be relatively high as compared to other printing techniques for short runs.

Dot gain, the situation where printed dots are larger than the dots on the printing plate, can also be more significant in flexo printing and may impact the quality of the image. To reduce dot gain, it is important to control the ink viscosity, pressure and the characteristics of the plate.

Last but not the least, color management in flexo printing can be slightly challenging than in other forms of printing and it is usually dependent on the operator to make slight adjustments to ensure that the color quality of the prints is consistent throughout the production process.

How to Choose the Right Flexo Printing Press for Your Needs

Selecting the appropriate flexo printing press is a critical decision that can significantly impact a printing business’s productivity, efficiency, and profitability. Several key factors need to be carefully considered during the selection process.

Defining Your Printing Requirements and Applications

The first step that one has to take when choosing a flexo press is to identify the specific printing requirements and applications. First of all, it is necessary to decide what kind of products you are going to print: flexible packaging, labels, corrugated boxes, folding cartons or other specialty products such as film wraps and non-woven fabrics. Understanding your product range will help you determine whether you need a narrow web press, mid web press or a wide web press. It is also necessary to determine your print volume whether you are going to print small volumes with high turnover of jobs or large volumes of high turnover items. There are also features such as multi-sided printing, inline finishing processes such as lamination or die cutting, or the ability to handle different substrates. It will help you to make the right decision if you consider your current production rate and the possible future growth.

Industry/Product Type	Key Characteristics	Recommended Flexo Press Type(s)
บรรจุภัณฑ์แบบยืดหยุ่น	High print quality, tight registration, often on flexible and stretchable materials	Central Impression (CI) Flexo Presses, Wide Web Flexo Presses
Labels, Tags, Tickets	Small format, often short to medium runs, may require inline finishing	Narrow Web Flexo Presses, In-Line (Unit Type) Flexo Presses
กล่องลูกฟูก	Thick substrate, large format, high volume	Wide Web Flexo Presses, Stack Type Flexo Presses
Folding Cartons	Paperboard substrate, may require die-cutting and other converting	In-Line (Unit Type) Flexo Presses, Mid Web Flexo Presses
Paperboard Printing (general)	Various widths and thicknesses, may need double-sided printing	Stack Type Flexo Presses, In-Line (Unit Type) Flexo Presses, Mid Web Flexo Presses
Film Wraps, Non-woven Fabrics	Flexible materials, can be large format	Central Impression (CI) Flexo Presses, Wide Web Flexo Presses

Evaluating Print Quality, Speed, and Substrate Compatibility

It is necessary to compare the print quality, the print speed and the compatibility of the flexo press models with the various substrates. Some of the important aspects of print quality include the resolution, color quality, registration quality and the ability of the press to handle fine details. Some of the factors that help in enhancing the print quality and reducing the defects include high quality anilox rollers, better plate mounting systems, and automated registration controls.

An aspect that should not be overlooked is the speed of the printer especially for those business people who need their work done as soon as possible. However, this should not be done at the cost of the quality of the prints; the speed and the quality of the prints should go hand in hand.

Another factor that is taken into consideration is the compatibility of the substrate. Ensure that the press you choose is capable of handling all the substrates that you wish to print on in terms of material, thickness and surface finish. This means that compatibility defines the quality and productivity of the press based on the model of the press that is appropriate for a given substrate. Selecting a press that is compatible with a wide range of substrates means that you can print on different types of media without having to slow down or compromise on quality.

Considering Your Budget, Space, and Future Growth

When selecting a flexo press, the cost is a crucial factor to consider, but one should consider the cost of buying the flexo press and the cost of operating the flexo press in the future. Besides the first cost, other costs such as the ink, plates, maintenance, and energy costs may be expensive in the long run. These costs should be estimated to have a clear picture of the financial cost implication of the project.

Also, the amount of floor space that is available in your facility is one of the considerations that define the size and configuration of the press that you can install. Larger presses also occupy more space, which can limit your options or require costly changes to the equipment.

The last but not the least, the future development strategy should also be taken into consideration. At some point in the business, there may be a need to increase the production capacity of the business. It is advisable to choose a press with a modular design or with the possibility of increasing its productivity and versatility. This foresight enables you to be able to grow your business without having to frequently replace equipment or invest more capital.

Key Trends in Flexographic Printing Technology

Flexographic printing technology is gradually shifting towards automation and digitalization. Contemporary plates have registration control, automatic impression setting, and automatic cleaning systems, which enhance productivity and minimize the use of plates. It also increases efficiency and quality of the prints through the integration of digital workflows. In addition, there is a growing trend towards sustainability and environmentally friendly practices, such as water-based and other eco-inks, as well as recyclable substrates. Ink and substrate developments are also contributing to the growth of flexo, with new inks providing better color strength and adhesion and new substrates opening up new uses for the process.

Why Choose KETE for Your Flexo Press Needs?

We KETE is a reliable supplier of flexographic printing equipment, which provides different types of flexo presses. We have over a decade of experience in delivering high-speed presses with production speeds up to 250 meters per minute, which increases the efficiency by 50%. Our presses are suitable for use with water-based inks that are non-toxic and environmentally friendly, thus suitable for use on food packaging. Our machines are designed to be flexible and can print on plastic films, paper, non-woven fabrics and other materials. We are ISO 9001 certified and come with a 2-year warranty, and the company also provides professional overseas installation and training services. KETE is your ideal partner for flexible, efficient and high quality presses with over 200 presses exported to more than 80 countries per year.

Contact us:

• Address: 20th Floor, Xinchao Building, Anyang Street, Ruian City, Wenzhou City, Zhejiang Province, China 325200
• Phone: +86-577-66873227 / 66689036 / 66689037
• WhatsApp / WeChat: +86-18806770163
• E-mail: ติดต่อฝ่ายขาย@ketegroup.com

บทสรุป

Flexographic printing is still widely used in the contemporary world of printing as it is a universal solution for a wide range of products, especially in the field of packaging. The various types of flexo presses that are available in the market, with their respective features and capabilities, enable the business to choose the right equipment that will suit their production line and quality standards. The trends in flexo printing are towards more automation, environmental friendly and better print quality which makes flexo printing to remain relevant in the market. Selecting the right flexo press is a major capital investment and working with a competent and experienced supplier like KETE will help you meet your business goals and succeed in the current market.