Why Cleaning is a Must in the Flexo Industry

Published: April 29, 2024

By Al Husti, Account Manager, Anderson & Vreeland

The importance of proper care and cleaning cannot be overstated. Proper cleaning translates to defect-free products, which improves a company's bottom line. Putting off cleaning for even a brief time can cause damage as ink dries quickly. The ink can harden, which can make it difficult, or sometimes impossible, to remove later. Be sure to clean printing plates, ink chambers, anilox rolls, sleeves or cylinders immediately after each job.

Ingredients needed for a "picture-perfect" flexographic printing job:

• Clean flexo plates

• Clean ink chambers
• Clean anilox rolls

• Clean cylinders and print sleeves.

The common element is all these ingredients are CLEAN. Hand and machine cleaning are the two methods for plate cleaning, and there are benefits to both. The choice depends on what the specific needs of the machine are. Manual cleaning is a well-known method with a low cost and minimal space requirement. However, this can be a time-consuming process that involves costly labor. If a flexo plate is not cleaned correctly, ink may not stick to the printing area which will affect image quality.

If not cleaned carefully, too much, or inconsistent hand pressure can cause plate damage, especially on fine highlight dots. If hand pressure is too light, plates may still contain dry ink, will not print properly and can become unusable. Do not use anything abrasive when cleaning a plate. A soft sponge or lint-free wipes work well. The biggest concern with hand cleaning is finding plate damage the next time they are used which can cause expensive press down time.

Automated or machine plate cleaning is highly effective for all types of ink. Machine plate cleaning is a gentle, consistent method utilizing temperature-controlled chemistry that is sprayed on the plates as it's automatically transported through the processor.

This systematic method cleans with soft brushes, rinses and dries the plates assuring a high-quality result. It's important to select optimum cleaning chemistry for your ink type to ensure less use of product while maximizing the number of plates cleaned between chemistry changes. This method of cleaning requires a more substantial start-up cost, as well as space and maintenance.

To ensure ink chambers function properly, its crucial they are cleaned regularly before the ink dries and hardens. Dried ink particles can affect doctor blade seating and cause the chamber to be misaligned.

A dirty anilox roll will have a decreased BCM volume and cause inconsistency in overall printed colors. This will increase press downtime, material usage and overall labor costs. Ink costs, an expensive part of ink formulation, will also increase with a dirty anilox roll as the addition of ink pigments will be necessary to hit proper color.

There are many considerations when deciding on the proper anilox cleaning method. The types of inks being cleaned, as well as the difficulty in eliminating those inks from the roll without damage, are key factors. The equipment used should be dependable, easy to operate, efficient and cost effective. Not making the right decision or utilizing the right cleaning method can be expensive from a labor, ink, production and material waste standpoint.

There are four types of effective anilox roll cleaning methods: Liquid/blasting, ultrasonic, laser and, of course, the original method of manual cleaning. Liquid chemical machine cleaning can be highly effective and used daily.

With this method, the anilox roll is first treated with ink-specific solvent to soften the ink. This process is followed by a high-pressure wash which dissolves and cleans the remaining ink from the anilox cells.

The disadvantage of this method is the use of chemicals which can affect the physical properties of the roll or inner anilox sleeve. The blasting method utilizes sodium bicarbonate to penetrate ink inside the anilox cells. The powder residues can be removed with water. This technology, while effective, is not commonly used today.

Ultrasonic cleaning technology is highly effective, economical and has a minimal investment cost. It is also easy to install and operate as the process is fully automated. The combination of ultrasonic waves and a cleaning agent are used to wash the roller.

However, the roller is not immediately available for use after cleaning as it must cool down to room temperature first. In the event of a damaged anilox roller coating, the cleaning agent may penetrate the metal parts, resulting in corrosion or blisters.

Laser is the newest cleaning technology that uses no chemicals, making it environmentally friendly. It's a fast, high-quality, effective method which can reduce cleaning times. The anilox surface is not heated during cleaning, so the roll can be used immediately when the cleaning cycle is complete.

When using a laser cleaning system, one must take care to ensure the right optimum settings are used. This process requires knowledge and experience and the cost to invest in this cleaning technology can be expensive.

Different cleaning solutions work best with distinct types of ink. It is also important to determine what type of ink a machine is printing with before choosing the solution you use. Failure to thoroughly clean print cylinders and flexo sleeves could result in the plate lifting during the production run so they should be cleaned as soon as they are removed to avoid ink drying and hardening.

From the various cleaning methods above, one can see how important it is to clean and maintain their flexographic printing plates and equipment. There are several processes for cleaning that a user can adopt in their organization. Cleaning has become less time consuming thanks to automatic plate processors and anilox cleaning equipment.

It’s imperative to educate and train employees in the importance of cleaning and implement a procedure that is regularly followed to see the overall cost savings. The right flexo specialist can help you determine the best cleaning process for your operation, one with optimum chemistries to maximize productivity. Creating a cleaning process that is consistently adhered to is as important as having the right technology!

About the Author

Al Husti is the Northeast Account Manager for Anderson & Vreeland, Inc. — a total solution provider with over 60 years of flexo experience. With nearly 40 years as an industry expert, Al has a deep understanding in all the cleaning products A&V offers to ensure customers' machines run at peak performance resulting in world-class results on every job.