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FLEXO Magazine : June 2013
Plants & Processes Blade Audits & Their Impact Match Performance to Potential By Bill Warner Unlike the dreaded income tax audit performed by the government, the blade audit is a desirable and infor- mative process that flexographic printers may actually want to request. A blade audit can help improve printing quality, lower doctor blade usage and cut costs associated with printed waste and press down time. For those who haven’t heard of a blade audit, otherwise known as a blade analysis, it is a process of studying one or more worn doctor blades to gather data regarding how they were used. Your blade vendor can usually provide this service for you. This article will describe the blade analysis process, what the investigation uncovers, and how to apply the audit results to your process to ensure high quality, consistent results. BLADE ANAYSIS The analysis process is usually initiated by some concern with the blade performance or a print issue that is attributed to the doctor blade. After contacting your blade vendor, you can request—and the supplier might even suggest—a blade analysis be performed to help diagnose the issue you are having. Of course, a blade analysis can also be requested if you are not experiencing any difficulty, but simply want to know more about the setup parameters of the blade. We will begin by asking for some data regarding your ap- plication, so that we have as much information as possible to help put the pieces of the puzzle together as the analysis progresses. The worn blades, preferably matched doctor and containment blades if running a chambered inker, are sent to the blade vendor and your work is done until the blade analysis is completed. In general, Allison Systems analyzes the blades in three places unless there are special circumstances that will dictate that more or different sample sections be analyzed. The three sections are located near either end and in the center of the blade. The analysis begins by logging the blades into the system, measuring the blade’s overall dimensions, and measuring the amount of wear on the blades at each of the sample sections. After the blades are measured, samples are cut from the working edge of the blade in the sections that are to be analyzed. These samples are prepared for view- ing in the digital microscope by polishing the cross sectional edge of the sample. A sample is then mounted in the microscope, so that the angle worn on the blade by the anilox roll can be measured as well as the blade “footprint.” The angle that is measured is defined as the contact angle and the “footprint” is the measurement of the amount of doctor blade material that is in contact with the anilox roll (Figure 1). Sometimes, when we look at a sample in the microscope, we will see more than one wear angle. Two or more angles worn in the blade is the result of changing the position of the doctor blade during the ASPECTS OF AUDIT • Blade dimensions are measured • Wear is documented • Samples are cut for viewing under microscope • Angle and blade footprint are acquired • Data is compiled in report format • Recommendations are offered to help improve doctoring efficiency Figure 1: the angle that is measured is defined as the contact angle and the “footprint” is the measurement of the amount of doctor blade material that is in contact with the anilox roll. 220 Adams St. Riverside, NJ 08075 856-461-9111 email@example.com www.allisonblades.com Call, email, or visit our website to put the Allison Advantage to work for you! Dual Head Peristalitic Pump to Control both Supply and Return Flow from the Chamber OEM or Custom End Seals for most Flexo Chambers Composite Chambered Inker Systems to Replace OEM Equipment or for New Applications Extensive line of Metal, Plastic, and Composite Doctor Blades for any Flexo Over 45 Years of Quality and Service! Quality products and quick deliveries direct from Allison Systems, the manufacturer you can count on for all your doctor blade related needs. Systems Corporation 74 FLEXO June 2013 www.flexography.org