Tag: plastic doctor blade

  • New Polymer Doctor Blades with MicroTip Are Best for Applying Special Effects Coating

    New Polymer Doctor Blades with MicroTip Are Best for Applying Special Effects Coating

    Anyone who uses doctor blades for printing knows the range of options available today.  From the thickness of the material to the tip configuration, a doctor blade’s design has a direct impact on the job it will do.  While traditional tip options have ranged from straight to rounded to lamella, the new kid on the block, “MicroTip,” offers printers a smart choice when applying special effects coating.

    Special effects coatings are challenging

    More and more, packaging companies are using specialty coatings to differentiate their brands and create a tactile and visual experience for consumers.  However, special coatings such as glitter, grit, soft-touch, metallics and pearlescents present particular challenges for the printer.  These coatings have high viscosities and contain larger particles which make it difficult to accurately control the amount of coating

     

    being applied. (UV chemistries, common in specialty coating applications, have a viscosity of 5-7 times that of water and solvent-based formulas.)  This higher viscosity applies extra pressure to the metering blade, resulting in hydroplaning or “spitting” (especially at high line speeds), and increases coating consumption and waste.  In these cases, a customized blade solution is often necessary to control the lay-down of coating.

    New Polymer Doctor Blades with MicroTips can help

    Doctor blade manufacturers have found a way to make new polymer doctor blade materials that can overcome the limitations of steel in specialty coating applications.  By engineering a modified lamella tip, known as a “MicroTip”, on these materials, they have introduced a doctor blade product that offers the best of traditional plastic and steel.

    Why do they work?

    When used to apply special effects coating, steel blades are subject to accelerated blade wear from the coarse anilox engravings and corrosion from the harsh coating chemistries.  Today’s new polymer materials are compatible with all coating formulas and do what plastic blades are known to do best: last longer.

    MicroTip profilesThe blades can be engineered to a full range of size and profile combinations to optimize metering performance with the higher viscosity and large particulate formulas.  They range in thickness from .027”/.7mm to .050”/1.25mm to offer varying degrees of stiffness, rigidity and deflection.  These properties combined with the new MicroTip edge allow the blades to achieve a fine contact area with the anilox roll and deliver a fluid transfer of coating to the blanket with no spitting or slinging, even at high press speeds.  Add to this a range of MicroTips, (M10, M15 and M25) and these blades can be customized for a “perfect fit.”

    Doctor blade optimization for special effects coating

    The choice of blade thickness and tip will be determined by the anilox configuration, which is driven by the viscosity and solid load of the coating.  Typically, higher line screens and lower cell volumes will require a smaller MicroTip (an M10 or M15 for dull/satin/gloss coatings for example), but as line screens decline and volumes increase, a MicroTip providing a larger contact area (M15 or M25) will perform better.  By optimizing their next generation polymer doctor blades with the appropriate MicroTip, printers are able to achieve longer blade life in these applications than with steel.

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    If you’re a printer struggling with special effects coating, consider switching to a next generation polymer doctor blade with a MicroTip.  A magical combination of advanced material and tip might be just what you need to achieve a perfect lay-down of coating with longer blade life to boot.

    Request a Free TruPoint Doctor Blade Sample
  • How to Prevent Anilox Roll Scoring

    How to Prevent Anilox Roll Scoring

    blankAnilox roll scoring poses a challenge for many printers, evident when a shiny line encircles the roll, indicating a groove or “scoring” of the anilox roll. If you are a printer this means dark lines in your print – especially when printing solids. If you are applying a coating, it’s even more important to reduce scoring since most coatings are clear, and heavy coating lines are hard to detect.

    Once scored, an anilox roll can often be used selectively, working around the score lines. But at some point, the roll needs to be reengraved and depending on size and finish, comes with a significant cost.

    Scoring often arises from debris trapped between the doctor blade and the anilox roll. Common sources include particles from steel doctor blades, dried ink build-up, or coating particles in the fluid delivery system. To minimize or eliminate anilox scoring, consider the following practblankices:

    1. Maintain Good Housekeeping:  

    • Prevent dried ink or coating from accumulating on the anilox rolls and related components within the ink delivery system
    • Use filtration in the fluid delivery system to remove dried, hard debris during prolonged production runs.

    2. Implement Magnets: 

    • If using metal doctor blades, add high-strength magnets to the fluid delivery system to capture steel particulates.
    • Maintain minimal pressure between the doctor blade & anilox roll when using steel blades to avoid entrapment of dried particulates.

    3. Optimize Mechanical Setup:  

    • Ensure level and parallel alignment of the doctor blade chamber or single blade holder with the anilox roll.
    • Misalignment can lead to excessive pressure needed to engage the doctor blade, this will bend the blade and increase chances for particle entrapment.

    4. Use Plastic Containment Blades:  

    • Consider using a plastic (polyester) doctor blade for the containment blade on enclosed chambers.
    • This change cuts steel doctor blade usage (and particulate) in half, reducing the chances for scoring to occur.

    5. Switch to Polymer Doctor Blades: 

    • Explore transitioning to plastic or polymer doctor blades to eliminate steel from your system.
    • Polymer doctor blades have advanced dramatically in terms of stiffness, edge smoothness, blade life, and durability for long production runs and offer metering quality that meets or exceeds steel.

    In conclusion, anilox scoring is permanent damage commonly caused by debris between the doctor blade and the anilox roll, resulting in a defective product. Minimize anilox scoring and save unnecessary engraving costs by filtering inks or coatings and using magnets with metal doctor blades. Alternatively, you can switch to plastic doctor blades to potentially eliminate the problem altogether.

    Request a Free TruPoint Doctor Blade Sample

  • Polymer Doctor Blades are Safe Substitutes for Steel in Flexible Packaging

    Blade_Safety_Accident_Free_Days_215x275If you are using steel doctor blades, you are probably well aware of the risk of serious cuts from handling the blades. Pressroom injuries can be expensive in terms of morale and accident-related expenses. Today’s next generation polymer blades combine the best of traditional plastic and steel blades and provide safe substitutes for steel in flexible packaging applications.

    As steel doctor blades wear, their tips become honed through contact with the anilox roll, leaving razor-sharp edges. Press operators need to be extremely careful and wear protective gloves when removing the worn blades from the press to avoid injuries.

    Until recently, steel was the only material capable of producing the high quality print required in flexible packaging applications so printers had no choice but to accept these risks. While plastic blades were safer, they were not able to achieve a fine enough contact area with the high line screen rolls.

    blankToday’s next generation polymer blades act as a hybrid between steel and plastic and offer a safe alternative to steel. The combination of an advanced polymer material and an innovative “MicroTip®” design allows these blades to perform in highly demanding applications where previously steel was the only option. Due to their material composition, the new polymer blades are safe to handle even when worn. Converting to these blades will reduce lost-time accidents and can save a printer a lot of money in terms of workman’s compensation insurance rates, medical bills, labor replacement expenses and press downtime.

    When it comes to the pressroom, safety is everyone’s concern. Flexible packaging printers no longer have to accept the danger that comes with using steel blades to get the print quality their customers demand. To greatly reduce the risk of injury and associated costs, try substituting next generation polymer blades for steel.

    Request a Free TruPoint Doctor Blade Sample

  • New Doctor Blade Technology Is Worth a Look

    new doctor blade technology innovationAs a consumables manufacturer introducing new doctor blade technology to a mature industry, we’re constantly hearing, “But I’ve done it this way forever.” Press men are busy and don’t’ have time to waste trying new products when their current ones are working fine. But changing times call for an ongoing evaluation of your print process to find ways to improve. Today’s printers are smart to run controlled tests of new products to make sure they are maximizing efficiency and profitability and “keeping up with the times.”

    Anilox Roll Evolution

    Chrome anilox rolls

    Let’s use anilox rolls as an analogy. When chrome-plated anilox rolls came on the market almost 80 years ago, they were an improvement over the previous (and crude) methods of ink transfer. Steel rolls were covered with a chrome layer and mechanically engraved using a knurling tool. The dimples or “cells” filled with a precise volume of ink and carried them to the plate. This gave the printer more control over the ink application process and better print quality.

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    As the industry continued to evolve, however, the limitations of chrome-plated rolls became apparent. The chrome surfaces wore down quickly from the friction between the roll and the doctor blade. Due to their shape, the cells quickly lost volume capacity and print densities declined. Also, the maximum line screens that could be achieved with the knurling tool were 500 lpi which was only enough for basic and moderate graphics reproduction. As demands for higher quality printing increased, and there were advancements in presses, plates and inks, so did the need for better anilox roll technology.

    Ceramic-coated rolls

    To keep pace with the industry, anilox roll manufacturers began applying a ceramic coating to their rolls using a plasma spray device. These new surfaces had hardness of over 1400 Vickers compared to 850-900 Vickers for the chrome-plated surfaces. As the hardness of the roll determines its strength and durability, the new surfaces had better resistance to wear from the doctor blade. These rolls were too hard to engrave mechanically and lasers started being used to etch the rolls. The lasers produced a consistent engraving with cleaner cells and more distinct cell walls. Higher line screens could be achieved to expand a printer’s graphics capabilities. The ceramic surfaces not only lasted longer but the cells were also less sensitive to volume changes from wear. Printers gained more control over print quality and were now able to achieve target ink densities with thinner ink films.

    New doctor blade technology

    blankLike presses and other press components, doctor blades have evolved to adapt to the market. Blade manufacturers are continually experimenting with new materials and edge designs and introducing new doctor blade technology to keep up with their customers’ needs.

    Steel

    Today’s steel blade users have a choice of carbon, stainless, long life, coated and ceramic blades to fit their precise applications. Until now, steel was considered the only material capable of achieving a fine contact area with the roll and producing an effective wipe on high line screen engravings. Printers had to accept the downside of frequent blade changes, injuries and anilox roll scoring because there were no alternatives.

    Plastics

    Plastics, on the other hand, have always been known for their blade life and safety. The material has to be thicker to provide rigidity and these blades were suitable only for producing low-moderate graphics. The upside is that they don’t have to be changed as often, and the long and steady wear period allows for consistent ink film thickness for the duration of the print job. The material is also safer to handle and won’t score anilox rolls. Plastic doctor blade choices include a variety of acetals, UHMWs, and polyesters.

    Next generation doctor blades

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    Flexo Concepts® recently introduced a new blade that acts as a hybrid between steel and plastic. A combination of an advanced polymer material and an innovative tip design called “MicroTip™” allows the blade to perform in high line screen applications where previous non-metallic materials were not an option. Printers using these advanced polymer products get blades that can produce the graphics quality of steel while remaining safe to operators and anilox rolls. The blade is now successfully being used in a range of narrow web and wide web applications.

    As with anilox rolls and other press components, new doctor blade technology has gone hand in hand with the evolution of the flexo printing industry. The new polymer MicroTip blade is an example of a product that, once again, improves upon “what you were using before.” Why not try it?

    Request a Free TruPoint Doctor Blade Sample
  • Corrugated Ink Delivery Systems: Two-Roll or Doctor Blade?

    Corrugated Ink Delivery Systems: Two-Roll or Doctor Blade?

    blankThe flexographic ink delivery process has come a long way since the days when “Fragile – Do Not Drop” and “This End Up” were the only requirements of box printers.  New press designs are able to achieve the quality of work that has traditionally been done by litho lamination, and corrugated printers have to produce a consistently high level of quality to compete.  The evolution of the ink delivery process from a two-roll ink metering system to the enclosed doctor blade chamber has made this possible.

    There are currently three types of ink metering systems used in corrugated printing applications:  the two-roll system, the single blade system and the enclosed doctor blade chamber system.  All three systems rely on an anilox roll to transfer ink to the plate.  The difference lies in how the ink is applied to the anilox roll.

    corrugated two roll inking system
    Two roll corrugated inking system

    The Two-Roll Ink Delivery System

    In the original two-roll ink metering system, a fountain roll rotates partially submerged in an open ink pan, picking up ink and applying it to the anilox roll.  The anilox roll transfers the ink to the plate cylinder which then lays it down on the sheet.  Though still widely used in the industry, there is a lot of variability in the two-roll system which results in a lack of control over the amount of ink transferred to the plate:

    • Imprecise wipe of the anilox roll leads to inconsistent volume of ink delivered to the sheet.
    • Color strength fluctuation and ink slinging can occur at higher press speeds due to the hydraulic force between the rubber roll and the anilox roll.
    • Transfer characteristics vary according to the hardness or “durometer” of the rubber roll.
    • Ink viscosity is subject to evaporation, dust and surface skimming due to the open tray design.
    corrugated single blade inking system
    Single blade corrugated inking system

    Single Doctor Blade Ink Delivery System

    The addition of a reverse angle doctor blade added precision to the ink metering process.  In the single blade ink metering system, a doctor blade made from steel, plastic or a composite material is used to replace the rubber roll.  The blade is installed just beyond the ink metering nip to shear ink from the anilox roll surface.  Doctor blade ink metering systems give the printer better control over the volume of ink being delivered to the plate.  Where a rubber roll often leaves an additional ink film on the surface, a doctor blade shears ink cleanly from the roll.  The inks perform better on press and a printer can achieve a more consistent ink film thickness.  Ink consumption is reduced, and color application is consistent across the sheet even at higher press speeds.

    corrugated chamber doctor blade inking system
    Chamber doctor blade corrugated ink delivery system

    Enclosed Chamber Doctor Blade System

    The most recent development in the flexographic inking process is the enclosed chamber doctor blade system.  In this system, two doctor blades are used along with an enclosed chamber to dispense the ink to the anilox roll.  The reverse angle blade acts as the metering blade and wipes excess ink from the anilox roll.  The trailing blade acts as a capture or containment blade and holds the ink within the chamber.  Foam, rubber or felt gaskets seal both ends of the chamber and keep ink from leaking out.  The ink is delivered through a closed loop from the ink pump to the doctor blade system and then back to the pump.

    With this method, a printer can maintain ink viscosity because the enclosed design provides protection from evaporation of solvents or amines from the ink, depending on whether the ink is solvent or water-based.  Also, dust, slinging and skimming are minimized.  Better control over ink usage means lower ink consumption by as much as 15% per year.  The system holds less ink than open pans, so there is not as much leftover ink at the end of a press run and ink can be removed and stored for future use.

    blank blankDue to a more efficient cleaning process, a smaller amount of cleaning solution is needed to clean up a chamber so cleaning solution waste and disposal costs are also reduced.  Color changes are quick, speeding up changeover and setup time on a run.  The enclosed chamber system is more eco-friendly because of reduced ink consumption and disposal of waste ink as well as a lower volume of cleaning solution and water required to wash-up the station for a color change.

    After years of being relegated to jobs with low graphics requirements, flexography now rivals other printing methods for quality.  Today’s corrugated printers are able to produce products that are highly attractive and eye-catching to the consumer due to advances in the ink delivery process.  Whether they opt for a single doctor blade system or see the benefits in investing in a dual blade enclosed chamber, printers gain clear advantages by using doctor blades in terms of controlling ink film thickness and maintaining color consistency.

    Request a Free TruPoint Doctor Blade Sample
  • Optimizing Your Doctor Blade Trialing Process

    Optimizing Your Doctor Blade Trialing Process

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    Testing a new doctor blade in your printing operation should be a collaboration with your suppler that boosts performance while avoiding costly guesswork. Instead of randomly ordering samples, follow a systematic, data-driven approach.

    Collaborate
    Start by sharing key details about your press—dimensions, machine model, blade holder type, ink specifics, and any pain points you are experiencing. This information lets your supplier recommend tailored doctor blades rather than generic samples.  There are a lot of options in terms of material type, thickness, and edge configuration.

    Run  Your  Trialman taking careful notes during a doctor blade trial
    Your supplier will likely send you one or more blades based on your provided data. Appreciate what these are and take care when testing them. They’re designed for your specific needs and should be used in a controlled production run.

    Crawl, Walk, Run

    Install and test the blades under normal operating conditions. Consider starting on a single print/coating station if the blade is new to you.  Contact your supplier with any questions related to setup or installation and alignment.  Clean the blade holder or chamber, using minimal blade pressure.

    Provide Feedback

    Complete any surveys your supplier has seeking feedback on the sample performance. Record important details and observations made during the testing related to blade longevity, metering quality, and any anomalies. Feedback is especially important if the blade fails as this can help your supplier make alternative recommendations by changing blade material, thickness, or edge configuration.

    The Takeaway
    An iterative, collaborative testing process is more efficient than random sampling. By working closely with your supplier—starting with detailed information, running controlled trials, carefully documenting results, and refining based on feedback—you achieve optimal performance and a long-term printing solution.  Embrace this method to streamline your doctor blade selection and keep your press running at peak efficiency.

    Trial a TruPoint Doctor Blade
  • Three Reasons Why Sheetfed Offset Printers Should Replace Their Steel Doctor Blades with Plastic

    Three Reasons Why Sheetfed Offset Printers Should Replace Their Steel Doctor Blades with Plastic

    blankThe goal of a sheetfed offset printer, like every printer, is to produce printed pieces efficiently and economically.  In sheetfed offset coating applications, selecting the right doctor blade will help keep presses running and minimize costs while maintaining a safe pressroom environment.  By replacing steel with non-metallic doctor blades, a printer can reduce pressroom injuries, eliminate anilox roller scoring and extend blade life.

    Three reasons to replace your steel blades with non-metallic doctor blades:

    1. Pressroom Safety

    Steel doctor blades are responsible for a large number of pressroom injuries each year.  As the blades wear, their edges become honed through contact with the anilox roller.  This leaves razor-sharp tips that can cause serious cuts.  Press operators need to be extremely careful and wear protective gloves when removing the worn blades from the press to avoid injuries.  Due to their material composition, non-metallic doctor blades are safer to handle even when worn.  Switching to non-metallic doctor blades will reduce lost-time accidents and can save a printer a lot of money in terms of workman’s compensation insurance rates, medical bills, labor replacement expenses and press downtime.

    2. Anilox Roll Scoring

    Steel blades are also to blame for many cases of anilox roll scoring.  Incorrect blade installation or too much blade pressure can cause small fragments of metal to break away, become trapped against the roller and destroy rows of anilox cells as the roller turns.  The score line appears as a thick band which runs around the circumference of the roller and affects the corresponding area of coating coverage.  The printer wastes substrate and coating and has to have the roller resurfaced or replaced at a significant cost.  In addition to scoring, steel blades accelerate wear on the surface of the anilox roller.  The friction between the blade and roller erodes the anilox cell walls.  As a result, the cell volume is reduced and the anilox roller can no longer carry the precise volume of coating that it was designed to deliver.  Non-metallic blades are non-abrasive and will neither score rollers nor cause accelerated wear on the anilox roller.

    3. Blade Life

    Steel blades wear quickly and need to be replaced frequently.  Non-metallic blades, on the other hand, have a long, slow wear period and  deliver a consistent application of coating for the duration of the print job.  They have a low coefficient of friction which means they need to be changed out less often.  By switching from steel blades, a printer can minimize press disruptions and keep presses running longer.

    For sheetfed offset printers using in-line tower coating units, there is a non-metallic blade available for every application. Tresu and Harris & Bruno chamber users can opt for the TruPoint Orange® blade with MicroTip® edge – a blade capable of effective metering with the added advantages of improved safety, reduced anilox roller scoring and longer blade life.

    Request a Free TruPoint Doctor Blade Sample

  • New Polymers Meter Like Steel Doctor Blades

    blankSteel doctor blades used to be a printer’s only option to produce high-end graphics.  It wasn’t because he didn’t want longer blade life and the safety benefits that came with using plastic, steel was simply the only material that could sufficiently meter a high line screen roll.  Not anymore!  Today’s next generation polymers and advanced tip engineering have at last resulted in a non-metallic doctor blade with the metering quality of steel.  This blade can replace steel doctor blades in a full range of flexo printing applications from solids and lines, to reverses and fine print, to screens and process work.  Here’s why.

    Steel Doctor Blades vs. Traditional Plastic

    Due to its thinness and stiffness, steel has been the only blade material that could achieve a fine point of contact sufficient to execute a clean wipe on a high line screen anilox roll.  By comparison, the characteristics of traditional plastic doctor blades require them to be thicker to provide the same rigidity.  While they have other benefits in terms of safety and blade life, their thickness prevents them from maintaining a fine contact area with the anilox.  As they wear and their contact area with the anilox roll grows, plastic blades produce changes in tonal value and dot gain when metering high line screens.  For this reason, they have historically been limited to  jobs with low to modest graphics requirements.

    Next Generation Polymers

    Now, specially formulated polymer doctor blades can compete with steel in the most demanding graphics applications.  Unlike traditional plastic, the stiffness of the next generation material with a precisely engineered MicroTip™ edge allows the TruPoint Orange doctor blade to achieve and maintain a fine contact area with the anilox roll.  Orange can deliver effective metering on line screens up to 2,000 lpi (785 L/cm) and produce graphics of the highest quality.  The following diagrams compare the contact areas of traditional plastic, steel and next generation polymer blades:

    Doctor Blade Contact Area Comparison
    Doctor Blade Contact Area Comparison

    As shown, the contact area of a worn traditional plastic blade grows to .060″ (1.52mm) compared to a contact area of .016″ (.40mm), for a worn steel blade.  The next generation polymer is able to maintain a contact area of .012″ (.305mm), equal to or smaller than that of most steel doctor blades, throughout the life of the blade due to the edge design.  The engineered tip wears slowly and evenly and delivers consistent ink film thickness for the duration of the print job.

    Today’s innovations in polymer doctor blades offer printers a viable alternative to steel.  A combination of advanced materials and new tip technology has yielded a blade that meters as well as steel on the highest line screens yet retains the benefits of traditional plastic.  Printers no longer have to compromise on anilox scoring, blade life, and safety to fulfill the most demanding graphics requirements!

    Request a Free TruPoint Doctor Blade Sample
  • Plastic Doctor Blades – Advanced Polymers Compete with Steel

    Plastic Doctor Blades – Advanced Polymers Compete with Steel

    blankWhile steel doctor blades used to be the only option to produce high-end graphics, a printer had to deal with the shorter blade life and pressroom injuries that came along with using the material. No more! Recent innovations in materials technology and tip engineering have at last resulted in polymer doctor blades that can compete with steel and also resolve a number of common problems in the pressroom.

    Steel doctor blades are thin and rigid which allows them to achieve a fine contact area with the anilox roll. A fine contact area is required for the blade to achieve an effective wipe on high line screen rolls used in more demanding graphics applications. Traditional plastic doctor blades, on the other hand, have long been preferred for their longer life in less demanding graphics applications. Plastic blades had to be engineered thicker in order to provide enough rigidity to maintain good contact with the anilox roll and achieve a sufficient wipe. The thickness and larger contact area prevented these blades from being effective when used to meter mid to high line screen rolls. While they lasted significantly longer and were safer to handle than steel blades, they tended to leave more ink on the surface of the roll; this produced dot gain and poor image quality in the printed piece.

    blankSteel Blade Disadvantages

    Despite its reputation for being the superior metering material, steel has many disadvantages. The blades wear quickly and need to be replaced frequently. Operators are also exposed to cut hazards when removing the worn blades from the press, and the metal fragments can come loose and score anilox rolls.  The environmental impact of using steel can also be significant. There are huge energy costs associated with the manufacture of steel blades as well as anilox resurfacing, and additional station clean-ups generate a lot of contaminated waste. Despite these drawbacks, steel was believed to be the only doctor blade option to execute a clean wipe on a high line screen anilox roll, leaving printers no choice.

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    New polymer doctor blade contact area is smaller than steel

    New Polymer Doctor Blades

    Today, specially formulated polymer doctor blades offer the best of both steel and plastic. Unlike traditional plastic doctor blades, the next generation material allows for a precisely engineered micro-tip which wears slowly and evenly throughout the life of the blade. The micro-tip edge allows the blade to achieve a fine contact area with the anilox roll and deliver effective metering on line screens up to 2000 lpi or 785 L/cm. The long and steady wear period of the next generation polymer doctor blade maximizes press uptime and allows for consistent ink film thickness for the duration of the print job.

    Compared to steel, the polymer material does not develop a dangerous cutting edge after use, and the worn blades are safe to handle. Also, the material will not separate, splinter or crack and produces no metal fragments that can lodge between the doctor blade and the anilox roll. A reduction in anilox scoring means better image quality, less downtime, less waste and lower roll replacement costs.

    Polymer doctor blades have come a long way in recent years. A combination of advanced materials and a micro-tip edge has produced revolutionary new doctor blade option for printers: a blade that can compete with steel in the most demanding graphics applications while retaining the safety and blade life benefits of traditional plastic.

    Request a Free TruPoint Doctor Blade Sample
  • Doctor Blade Installation: Correct Angle and Pressure are Needed for Consistent Performance

    Doctor Blade Installation: Correct Angle and Pressure are Needed for Consistent Performance

    The anilox roll and doctor blades are designed to work together to deliver a precise amount of ink to the plate. It is important to take time during a doctor blade installation in order to ensure print quality.

    A doctor blade that’s installed correctly will have uniform, balanced contact with the anilox roll and remove ink consistently across its surface. Blade positioning, orientation, angle and pressure will affect the delivery of a precise amount of ink to the plate, and proper installation will give the printer control over consistent, repeatable print quality.

    3 Keys To Doctor Blade Installation Success

    1. Handling

    It’s essential to handle the doctor blade with care to prevent damage. Additionally, make sure to clean the surface of the doctor blade holder before inserting the blade.

    2. Orientation

    It is essential that the metering and containment blades be positioned correctly when they are installed. Depending on the rotation of the anilox roll, the metering blade could be positioned on the top or the bottom of the chamber. Keep in mind that the metering blade is always the last blade to contact the roll before the ink transfers to the plate. The containment blade is installed in the opposite location. If the two blades are installed in reverse, the metering blade will not achieve the appropriate point of contact with the roll and remove the correct amount of ink before transfer. It is important to remember that the MicroTip or bevel should point away from the roll or towards the chamber to prevent streaking.

    The angle at which the blade comes into contact with the anilox roll is also crucial to proper doctor blade installation and optimum blade performance. Ideally, the contact angle should be 30° tangent to the anilox roll circumference. In reverse angle and chamber blade applications, the doctor blade angle should be between 28° and 32°. If the blade angle drops below 28°, a larger part of the blade’s edge will come into contact with the roll. When this happens, the contact area is too big to meter effectively and the blade may allow ink to pass underneath or “hydroplane” at high speeds. If the angle exceeds 32°, it will result in faster wear on the blade.

    3. Pressure

    When a doctor blade chamber is properly aligned, light pressure between the anilox roll and doctor blade is all that’s needed to produce a clean wiping action. In fact, applying the lightest possible pressure necessary to maintain sealing and metering will produce the best results. Excess pressure can cause a deterioration in print quality, wasted ink and substrate, and accelerated.

    blade and anilox wear. A good way to tell if you’re using the correct amount of doctor blade pressure is to look at the roll once it’s inked. Before increasing pressure, the anilox roll will appear glossy. This is a sign that too much ink is remaining on the surface. Pressure should be increased gradually until a satin finish appears on the surface of the roll. A satin finish is a good indication that the correct amount of pressure has been achieved and the doctor blade is effectively shearing the excess ink from the roll. If pressure is increased beyond this point, the doctor blade edge will bend and hydroplane. The roll will again begin to look glossy because it is flooded with too much ink.

    The doctor blade plays a key role in the performance of the anilox roll and the printer’s control over print quality. Take the time to double-check blade positioning, orientation, pressure and angle during doctor blade installation to guarantee that the anilox roll delivers the precise volume of ink for which it was designed.

    Download Now: Free 3 Keys to Success Installation Infographic
    Download Our 3 Keys to Success Infographic!