From your morning cup of coffee to the millions of packages delivered daily, flexographic printing has found its place all around us. Flexographic printing is a versatile and widely used production process that caters to many industries. Also known as “flexo printing,” this technique combines letterpress and rotogravure elements to create high-quality prints on a wide variety of substrates.

Zeller+Gmelin has been a leading producer of UV and LED flexographic printing inks for decades. This blog will discuss how flexographic printing works, its typical applications, and its advantages and disadvantages. For any questions or to discuss your unique flexo operations, please get in touch with Zeller+Gmelin. We’re here to serve you!

Understanding Flexographic Printing

“Flexo printing” refers to a relief printing process that uses flexible plates made from rubber or polymer materials. These plates are wrapped around rotating cylinders on the printing press. The image areas on the plate are raised, while the non-image areas are recessed. The ink is transferred to the printing plates via an anilox roll or sleeve and transfers the image onto the substrate as it passes through the rolls, creating a printed impression. Flexographic printing presses are manufactured in 4 main formats, according to the size of the printing web: narrow-web, mid-web, wide-web, and corrugated. All in all, flexographic printing is a prevalent print method used for various applications and produced worldwide.

Equipment Involved in Flexographic Printing

Printing Plate

Printing plates serve as the image carrier in the flexo printing process. They are typically made of rubber or polymer material and engraved with the raised image areas used to transfer the ink to the substrate. Printing plates are wrapped around a printing cylinder to create a continuous surface. Each color or element of the design usually requires a separate printing plate.

Anilox Roll

The anilox roll is a crucial part of the flexo printing process. Its primary function is to uniformly distribute solvent-based, water-based, or UV/LED inks onto the printing plate in a consistent even layer. Anilox rolls are engraved with thousands of microscopic cells, and as they rotate in the ink reservoir or ink chamber, the engraved cells become filled with ink while a doctor blade removes the excess ink. The anilox then comes in contact with the raised image on the printing plate and transfers a uniform layer of ink to be printed on the substrate.

Anilox cells can be laser, mechanically, or electromechanically engraved and come in various geometries. The most popular cell geometry is the 60˚ Hexagonal, but anilox engravings also come in 45˚ Quad, Longcell, Channel, Trihelical, Positive, and many more!

Substrates

Flexography can print on various substrates, making it a suitable printing method for multiple products. The choice of substrate depends on the specific requirements of the product being printed. Common substrates include:

Paper: This common substrate comes in various forms, from coated papers for labels to packaging.

Paperboard: A thicker, sturdy material, paperboard is used for food and consumer packaging, such as cereal boxes, cosmetic cartons, and beverage packaging.

Plastic Films: Flexo printing is well suited for printing on flexible packaging materials such as plastic bags, shrink sleeves, and pouches.

Foils: To add an embellished finish or a decorative shine, flexo printing can utilize metallic substrates.

Corrugated board: From simple brown boxes with black text to eye-catching point-of-purchase, corrugated board is a typical substrate in flexo printing.

Printing Cylinder

Printing Cylinders carry the printing plates and transfer the inked image onto the substrate using precise pressure. Multiple cylinders can be used for multi-color printing processes.

Dryer

After printing, the substrate passes through a dryer section that evaporates the solvents from the ink, leaving a dry and finished print. If you’re using UV or LED inks, this section will consist of high-powered UV/LED lamps that quickly convert the ink into a solid before the next print station.

Common Applications of Flexographic Printing

Packaging

With the capability to inside print and produce packaging at a high volume, flexo printing is extensively used for packaging such as food packaging, cosmetics, pharmaceuticals, protective folding cartons, product labels, flexible packaging, and much more!

Corrugated Packaging

In the production of corrugated boxes, flexographic printing is used to add block letter print and icons or more detailed branded designs to the corrugated board’s outside and/or inside surface. Examples of corrugated flexo print are packaging for electronics, furniture, shoes, eCommerce, logistics, and other consumer goods.

Labels

Flexo printing is preferred for producing labels for food and beverage, wines & spirits, cosmetics, pharmaceuticals, and logistics. The ability to print vibrant, high-quality labels efficiently and achieve specialty print effects in narrow web flexo makes this printing method a popular option for label applications.

Flexible Packaging

The flexibility of flexographic printing makes it a go-to choice for producing flexible packaging materials like stand-up pouches, bags, sachets, shrink sleeves, and more. It can handle the unique requirements of these materials, such as heat resistance, full branding wraps, tamper resistance, and product security.

Advantages & Disadvantages of Flexographic Printing

Flexographic printing offers several advantages:

Quality: When all processes and print components are controlled, flexo can achieve an impressive level of print quality for its customers. With optional units for cold foil, specialty coatings, and varnishes, flexo printing can achieve an incredibly stunning print at a more cost-effective price.

Versatility: Flexography can print on a wide range of substrates, making it a flexible printing option suitable for various industries and applications. Many flexo presses are modular, capable of adding specialty units for full, one pass, in-line production.

High Speed: Flexo presses can achieve high production speeds, over 500m/min, making it an efficient option for medium to large print runs.

Cost-effective: Flexo printing is more cost-effective than offset printing and can achieve quality for medium to large print jobs more economically. Cleaning and maintenance costs are also more economical than other printing methods.

Alternatively, flexo printing also has some disadvantages:

Image Resolution: Compared to offset printing, flexo has some limitations in achieving high-resolution images though, this difference is becoming smaller daily.

Setup Time: The job changeover and setup process for flexo printing can be time-consuming. However, many OEMs have created quick changeover systems, improving set-up times tremendously.

Not ideal for Short Runs: While it is efficient for medium to large print runs, flexo printing is less cost-effective for short runs due to the investment in plates, ink, and anilox rolls, along with the setup times involved.

Here for the Long Run

Flexographic printing has carved its niche in printing technologies for decades. Its wide range of applications, efficient production capabilities, high-quality end products, and cost-effectiveness make it a popular printer choice. However, its limitations in image resolution and suitability for short runs should be considered when selecting the printing method for the job. As technology evolves, Zeller+Gmelin will continue to be at the cutting edge of flexographic printing, offering high-performance UV and LED printing inks for your most challenging applications. As you begin or continue your journey into flexographic printing, consider the ink specialists at Zeller+Gmelin for any questions or opportunities. To learn more about Z+G flexographic inks, click here or contact our team to discuss your unique print goals.

The post What is Flexographic Printing? first appeared on Zeller + Gmelin.

As LED curing systems gain wider acceptance in the Flexographic industry, the benefits of the systems create many compelling reasons to switch. Extended lamp life beyond 30,000 hours, instant on, “cool curing” with minimal heating and distortion of the substrate, reduced energy consumption, consistent depth of cure, no toxic mercury from the lamps and no ozone generation (and therefore no necessity for ventilation), are just a few significant benefits with LED flexo curing technology.

As more and more flexographic LED systems are installed, Zeller+Gmelin has formulated high quality LED flexo inks to help converters take advantage of the many benefits of this exciting new technology. Before “flipping the switch” on either ordering a new press configured with an LED curing system, or retrofitting an existing press with an LED system, it’s important to ask the right questions to ensure you’re purchasing the best system for your future.

Here are some common questions we receive from customers getting started with LED Flexo inks and answers from Zeller + Gmelin Ink Specialists to assist you in your journey into LED technology.

Frequently Asked Questions

Will an LED system really save money?

The short answer is yes. Though each manufacturer has unique cost saving benefits innovated into their LED curing systems, all LED systems are known for achieving big savings in energy consumption. LED curing systems are incredibly more energy efficient and can help converters save money on energy bills and other soft benefits throughout the plant. Also the cost savings attributed to less maintenance, consistent curing, and instant on-off technology keeps your equipment up and running, reducing downtime and increasing profitability.

What is the curing quality of LED compared to UV?

From our perspective, one of the biggest benefits of LED is the consistency of cure, compared to a conventional mercury UV system. With conventional UV curing systems, curing consistency can decline over the life of the bulbs and regular maintenance is required: including cleaning the reflectors, bulb replacement after around 1000 hours (considering the bulb output will continuously decline over the life of the bulb), and maintenance of the other mechanical components of the system.

Alternatively, an LED system offers steady, consistent curing power output for the life of the system, without the steady decline in curing power. With LED curing technology, your ink curing stays consistent – especially important if you’re running low migration work!

Can I run LED Flexo inks on my conventional UV presses too?

Maybe you’re still using UV curing systems throughout your operations and you’re hesitant to make the switch to LED only to end up with two inventories of inks: LED-curable and UV-curable.  At Zeller + Gmelin, we adapt our inks to the needs of the market and formulated the 17 Series LED Flexo Inks for “dual cure”, meaning they will cure under both LED and conventional mercury curing systems.

If you’re running operations with both LED and UV curing systems, you only need one inventory of Zeller + Gmelin LED Flexo inks to use throughout your operations.  Just be aware that the reverse is not true – UV flexo inks designed for mercury systems will not cure under an LED system.

What are the benefits of LED curing systems, not available on UV systems?

Though LED and UV curing technologies ultimately both cure ink effectively, LED systems have multiple benefits unique to its low heat and energy-efficient characteristics. To begin, UV curing systems have short-wavelength lamps that convert oxygen into ozone, which can irritate your operators and will need to be ventilated – while LED systems create no ozone to vent. LED is also known for its much cooler operations – while LED systems will create some heat in the web, it’s nothing like the heat generated by a conventional mercury system, since those bulbs also emit infrared wavelengths. This also translates into quieter operations.

Additionally, LED systems are instant on and off, with no warm up or cool down time necessary. These benefits make LED systems an excellent option for curing many colors, especially heavy opaque whites, at higher run speeds.

What are the limitations of LED systems?

LED curing has limitations for surface printed clears, like coatings and varnishes. LED is great for “buried” clears, like lamination and cold foil adhesives, but clear surface coatings don’t develop a good level of surface cure with LED. Many of our customers install LED on all but the last unit, where they keep a mercury bulb to cure coatings.

Why are LED inks more expensive than UV inks?

LED Flexo inks, at least right now, cost a little more than comparable conventional UV flexo inks. This is primarily due to the relative “newness” of LED inks in general, which limits available raw materials for formulation. Just like cell phones, computers, and any other new technology, the costs start out higher until that technology becomes more widespread. We expect the cost of LED inks to continue to come down as the technology is adopted into the industry on a wider basis.

Making the Switch to LED Flexo

LED curing systems for narrow web printing are still evolving. Like any other new technology, your decision needs to balance your current need with where the technology has advanced to today and where it is expected to be in the next 6 months. Now that you better understand the benefits and limitations of an LED curing system, you may be ready to take the next step.

At Zeller + Gmelin we are here to assist you through every important ink-related decision. We can put you in touch with our LED curing system partners, and even introduce you to customers who have embraced LED curing, so you can speak firsthand with them to inform your decision.

Talk to your Zeller + Gmelin Account Manager today to discuss your operations and see if it makes sense to step into the world of LED curing systems and inks.

The post Getting Started with LED Flexo Inks: Frequently Asked Questions first appeared on Zeller + Gmelin.