Doctor blades perform the seemingly simple task of removing excess ink from an anilox roll so that a precise amount of ink gets transferred to the printing plate. The number of variables involved with this small, essential tool are significant: they are available in plastic or steel – each with varying degrees of sensitivity and cost – and there are several different options for the edge, or tip, of the blade.
Several label industry suppliers are available to meet the specific needs of converters in this market.
Riverside, NJ, USA-based Allison Systems has been manufacturing cutting blades for a variety of industries for more than 46 years. Today, the company is a manufacturer and global provider of doctor blades and other related products for gravure, flexo and other printing applications.
Allison Systems has the capability to produce a variety of edge configurations on metal, composite, and plastic materials. The metal materials Allison uses to manufacture flexo blades range from high quality carbon and stainless steel to very-long-life tool steel. According to the company, the carbon steel materials are available in white or blue colored varieties with excellent metallurgical properties to precisely and economically meter ink in many flexo applications. Stainless steel is available for certain applications that require additional corrosion resistance.
Allison Gold series of tool steel materials aim to provide very long life when compared to carbon steel blades in abrasive ink and/or rough anilox roll applications. The material used for the Gold series blades is designed to be anilox-friendly and to help reduce anilox
roll scoring problems. For even more abrasive applications, or when experiencing UV ink spitting issues, the Gold series blade is available with a laser hardened working tip. The harder edge provides a working blade tip that can last five to ten times longer than carbon steel materials.
A low friction metallic coating can be applied to the carbon or tool steel materials that will increase lubrication properties between the anilox roll and the doctor blade, increase corrosion resistance, help reduce streaking issues, and extend the life of the doctor blade. Allison’s metal blades can be provided with various edge shapes including its trademarked Superhoned 4.5° bevel, standard 15° bevel, and rounded edges. Superhoned blades offer minimal tip growth as the blade wears with controlled tip deflection under applied loading. The standard blade offers a more rigid tip for maximum anilox clean-up. Rounded blades are for applications that need a strong, rigid working edge that is not easily damaged and where maximum anilox clean-up is not required.
Allison’s offering of plastic and composite blades is extensive. When used in doctoring applications, plastic and composite blades can provide longer life than carbon steel doctor blades and are safer to handle than metal blades. The company’s fine weave fiberglass composite material can be used for flexo doctor and containment blades on ceramic anilox rolls and with abrasive inks. The Graphite composite material has true graphite lubricant added to extend blade life and is generally used for large anilox rolls, long runs and with abrasive water inks. All of Allison Systems’ composite blades are made from cryogenic grade materials with tighter tolerances, no internal voids, and are more heat-resistant than non-cryogenic grades.
Delrin and Delrin with added lubricant can be used for flexo doctor and containment blade applications and will provide moderate print quality while being safer to handle than steel or composite blades. Mylar and Celanex polyester-based materials are often used as flexo containment blades in chambered ink applications to help prevent back doctoring and debris trapping behind the blade. Other plastic materials are available for specialty gravure and flexo applications. Plastic and composite materials can be provided with a standard bevel, a longer seal relief bevel, or unhoned.
In addition to doctor blades, Allison Systems offers chamber end seals and complete chambered blade systems that can be either custom-designed or OEM replacements. Allison also manufactures a heavy-duty dual-head peristaltic pump that is designed specifically for narrow web applications. This pump can be configured to provide precise control of ink flow through the chamber on both the supply and return sides.
All Printing Resources (APR)
All Printing Resources (APR), with corporate headquarters in Glendale Heights, IL, USA, is a distributor of several printing products, including end seals, doctor blades, stickyback and tapes, PVC mounting material and more.
The company’s Technical Solutions Group works with customers to determine specific needs in order to find the best blade for each application. APR’s focus is on reducing risk and saving time, and the many diagnostic tools available in APR’s portfolio allow them to assist in the selection process through blade analysis and audits.
APR says it has carefully chosen the doctor blade manufacturers it represents: Esterlam International, Benton Graphics, Max Daetwyler, and Allison Systems. “All are global leaders that give them the most comprehensive set of blade products to meet specific needs,” the company says.
According to APR, Esterlam International Limited is a leading specialist company focused on developing and manufacturing synthetic doctor blades for the flexographic, gravure, and rotary screen printing and coating industries. Since developing the concept of synthetic doctor blades and introducing the first prototypes in the early 1970s, Esterlam has developed “an unparalleled range of synthetic doctor blades that places them at the forefront of synthetic doctor blade technology,” the company says.
All Esterlam blades are supplied in both imperial and metric standards to meet OEM specifications. Esterlam blades are available in both a high-performance polyester range and the high-quality, long-life UHMW range. They are available in widths ranging from 12-70mm; profiles: 13°, 30°, 45°, stepped and square; thickness from 0.2mm to 2.0mm; and reel length from 30 to 100 m.
Benton Graphics offers the longer-life Ultimeter doctor blade, made from Microloy steel, which was developed to deliver high performance without the high price. Testing has shown that conventional doctor blade steels wear out as much as 57% faster than Ultimeter.
Microloy steel, used in all Ultimeter blades, is custom engineered specifically for higher wear resistance and better performance. This is achieved by using raw material with carefully controlled micro-alloying, ultraclean chemistry and ultrafine grain size. The increased wear resistance provides for longer press runs and less ink contamination. From precision rolling to heat-treating, Microloy steel is exclusive to Ultimeter doctor blades.
Printco Industries LLC is a Pulaski, WI, USA-based manufacturer of enclosed doctor blade systems, flexographic presses, coaters (including wax), laminators and tinters.
Enclosed doctor blade systems are available from Printco for the flexographic, gravure and offset industries in narrow and wide widths. Retrofits are available for all varieties of press designs on the market. Several models are available for low and high volume applications, and to reduce ambient volatile organic compound (VOC) emissions. The Printco Enclosed Doctor Blade Chamber is designed to reduce ink usage, provide for quicker color change and faster press clean up.
Printco features include toolless chamber removal as standard, and toolless blade clamp removal as on option. End seals and blade material of many different varieties are available and in stock for quick delivery. Chambers are available in coated aluminum, composite, carbon fiber and stainless steel.
“One feature Printco has introduced in recent years to the corrugated industry is a new loading and locking mechanism,” says Dave DeMille, sales manager at Printco. “This allows the wide web chamber to fit down inside the press where little room is available. This works very well with the Printco carbon fiber and aluminum chambers.”
Max Daetwyler Corporation (MDC), based in Switzerland with a US plant in Huntersville, NC, manufactures a variety of doctor blades designed for maximum life.
The MDC Longlife doctor blade, says the company, “is the best choice for fighting print defects, such as streaking.” It is commonly used for higher line screens where cleaner doctoring is required. Its hardened coating lengthens blade life, reducing the amount of steel contamination in the ink. Fewer blade changes are needed, resulting in reduced downtime and waste.
The MDC Soft doctor blade is coated with a soft, corrosion-resistant nickel coating. The soft coating provides a more gentle contact point, therefore reducing or eliminating the chance of roll scoring. This coating also heals small nicks in the blade edge, reducing lines and streaking as well as steel contamination of the ink.
Ibostar Plus coated doctor blades have long been used in gravure printing to protect the contact point to insure the doctor blade maintains a clean wiping edge on the most challenging of surfaces. The Ibostar Plus is a coated doctor blade made specifically for laser engraved ceramic to protect the anilox surface by lowering friction values. In addition, this new doctor blade is designed to withstand wear so the sharp wipe it creates at the beginning of the run is maintained throughout long runs or multiple short runs.
The blade tip of the Multiblade for UV inks is manufactured using a specialized process designed to promote stability and reduce wear at the contact point. This thick 100-micron tip increases slowly and proportionally to the 1° angle, therefore increasing stability and reducing tip deflection which can reduce UV ink spitting. This design provides lower blade pressure and wear, longer blade life, stiff blade edge to reduce UV ink problems, as well as less waste and reduced downtime.
The tip of the MDC One-Step doctor blade maintains the same quality and characteristics of the MDC lamella edge (a stepped edge), but the design allows thicker ink to meter normally. The strengthened base decreases blade flex, creating consistent ink film metering without an ink hydroplaning effect behind the blade and eliminating or substantially lessening UV spitting. According to the company, this design provides reduced UV ink spitting, easier and faster setup time, straight mounting without deviations, and perfect ink metering with high viscous inks.
The MDC Standard blade offers a consistent tip thickness. The contact area remains unchanged throughout the life of the blade, therefore no changes in tonal value or gradation occur due to wear.
Flexo Concepts, based in Plymouth, MA, USA, has sold doctor blades across multiple market segments for over 25 years, though, until recently, its focus was in the corrugated market.
“We have a renewed focus on our doctor blades,” says Ken Theriot, marketing manager. In 2012, Theriot says, Flexo Concepts had a big material and machining breakthrough that allowed it to put their trademarked ‘MicroTip’ on a doctor blade.
“There have been a lot of limitations over the past 20 years, a lot of demanding graphic requirements in narrow web that we haven’t had a product for,” Theriot says. “Our TruPoint doctor blades have allowed us to machine a smaller tip on the blade which, in turn, allowed us to meet or exceed the capabilities of steel.”
According to the company, TruPoint blades have outperformed their steel counterparts in high-speed, high-temperature and high-abrasion applications, as well as the highest quality graphic applications. “TruPoint doctor blades outlast steel by up to four times,” Theriot says. “Longer doctor blade life means fewer blade changes, less downtime and increased productivity. Reduced anilox scoring and workplace injury add up to substantial cost savings.”
“Our non-metallic blades have always lasted longer and are safer,” Theriot says, “but we never really had the quality of a steel blade until TruPoint Orange.”
Flexo Concepts did a soft launch of TruPoint Orange and had what Theriot calls “a tremendous response.”
“We released it last year at Labelexpo. We were on ten presses at that show,” he says.
The response has been so favorable, Theriot says, that Mark Andy and Nilpeter have started shipping new presses with TruPoint Orange doctor blades. The company’s relationship with Nilpeter is relatively new, but Theriot says that Flexo Concepts has had many repeat customers as a result of its relationships with OEMs “These relationship are in their early stages but the response has been great,” he says. “We’re having a lot of success with both companies, so we’re very excited.”
Mark Andy Print Products maintains strategic relationships with doctor blade manufacturers and distributes them nationwide. Tina Robertson, technical sales specialist at Mark Andy Print Products, the supplies and consumables division of Mark Andy, shares pointers on choosing the right doctor blade for specific applications:
“Doctor blades are the small dollar, big impact flexo consumable. Few small priced items have as much of an impact on print quality as does the doctor blade. With this single thin piece of metal or plastic, a printer can either make money or lose money. Selecting the correct blade for an application given the variety of materials, metals and plastics, as well as various types of steel offered by doctor blade manufacturers can be a bit overwhelming.
“Before the selection process takes place, have the current blade inspected after it has been used. Capturing and providing specific detailed information relating to the used doctor blade is very important in evaluating the used blade,” says Robertson. “This information includes anilox manufacturer, anilox cell count, volume and engraving configuration, length of run, ink color and type of ink as well as print faults or problems experienced and will assist us with making doctor blade recommendations.
“Comparing the new blade to a used blade will not only show how the blade tip is wearing, but also if the blade was installed level, if there are chips of metal missing, and how much of the blade has been worn away. To the trained eye, a worn blade will tell as much about the printing conditions as a pressman can, but in some cases the blade will tell more,” Robertson says.
Mark Andy Print Products delivers consultative support to maximize pressroom efficiency with the proper tools needed for optimum results. There are a wide variety of blade options available to meet the ever-changing demands of today’s printers. Various blade materials, tip types, and configurations provide a seemingly endless list of options. The team of Flexo Consumables Specialists at Mark Andy Print Products can help optimize your doctor blade selection.