Anilox roll size tolerance (top)
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Dimensional tolerances are a key factor influencing the performance of anilox rolls.
Most articles and technical literature on anilox rolls fall into the following four areas:
1. Engraving (geometry, number of screen lines, ratio of depth to opening angle, etc.);
2. 2 laser (pulse CO2, continuous band CO2 and YAG);
3. Coating of ceramic surfaces;
4. Cleaning, maintenance and maintenance.
These issues are very important and require in-depth research and understanding to develop an ideal anilox roll system to ensure consistent print quality. However, in order for these important components to work properly, printers and anilox suppliers should also pay attention to other aspects. This article is a brief introduction to some basic knowledge of the tolerances of the dimensions of anilox rolls, including: bearings, bearing surfaces, gears, balance.
The dimensional tolerance of the anilox roll is important because if the dimensional stability cannot be maintained, then whatever the geometry of the mesh, the number of screen lines or the depth and opening of the engraving, what kind of use The quality of the engraving of the laser, the quality of the anilox roller or the cleaning, maintenance and maintenance of the anilox roller are not satisfactory.
All components of the anilox roll, such as the diameter of the bearing surface, the diameter of the gears of each stage, the keyway, the balance, the TIR (total deviation of the indication), the characteristics of the cylinder, the characteristics of the ring, the diameter of the surface to be engraved, etc. must all fall on the data. Within the specified tolerance range, otherwise the anilox roller will not operate properly. These problems are often overlooked or cannot fully understand the impact of tolerances on quality. Let's take a look at the issues related to space size and tolerances.
First, the bearing and bearing surface
The diameter of the bearing surface must conform to the tolerances specified by the bearing manufacturer. Different bearing types and installation requirements, the parameters also have corresponding changes. Different bearings have different inner diameters, outer diameters, tolerances, and rated loads. The deviation range of a bearing tolerance refers to the centrifugal condition of the bearing deviating from its absolute central axis. There are various ways to describe this deviation, which we will explain later.
At present, many printers do not have the structural drawings of the printing press, nor do they know the tolerance or allowable deviation of the bearing surface of the anilox roll. Some people may not believe it, but it is a fact. The easiest way to understand these basic parameters is to turn to the printer manufacturer. Another way to understand the size of the bearing surface is to look up the name of the bearing manufacturer. Usually the name is always engraved on the bearing base and written with the bearing number. Once found, call the bearing supplier for specific parameter data. The diameter tolerances for a brand of flange mounted bearings are listed in the table below and can be used as a reference.
Bearing sleeve tolerance
0.5" - 1.937", +0.0000" to -0.0005"
2" - 3", +0.0000" to -0.0010"
3.187 inches or more, +0.0000 inches to -0.0015 inches
Bearing inner diameter tolerance
0.5" - 0.625", +0.0008" to -0.0000"
0.75" - 1.937", +0.0009" to -0.0000"
2" - 3", +0.0010" to -0.0000"
3-3.187 inches or more, +0.0012 inches to -0.0000 inches
Taking the above table as an example, if a bearing with an inner diameter of 0.5 inches has a possible bearing tolerance (ie, bearing sleeve tolerance): a maximum diameter of 0.5 inches and a minimum diameter of 0.4995 inches. The bushings at the ends of the anilox roll are also commonly referred to as "spigots".
Too small a bearing surface size will cause the drum to rattle and cause misalignment problems, which will reduce the service life of the bearing and damage the bearing surface. Poorly maintained bearings will harden during continuous operation, causing severe wear on the surface of the bearing sleeve and, in severe cases, a new bearing sleeve.
Maintenance personnel who unload old bearings or install new bearings must ensure that the bearing surfaces and bearings themselves are not subject to excessive damage. Frequently occurring bushing damage has significant groove marks, notches, grooves, or scratches on the surface of the drum caused by hammers, screwdrivers, rods, and any other tools that may be used during the unloading of the bearings.
A basic principle is that the bearings cannot be tapped on or under the shaft. Failure to properly handle the bearing during the installation of the bearing will result in bending of the bushing, resulting in a TIR (total indicated runout) that is too large, causing multiple printing failures and reducing bearing life. For the anilox roll, TIR refers to the case where the drum body (engraving area) cooperates with the bearing sleeve on the roller shaft. In general, the TIR of a bearing sleeve should not exceed 0.0005 inches.
It is best to invest in a better bearing removal tool (bearing pull-out) to unload the bearings and strictly follow the manufacturer's recommendations during installation. Before the bearing is mounted, the bearing base can be expanded by means of a bearing heater, which is contracted to achieve a perfect match between the bearing and the base. When installing the internal bearing, it is best to cool the bearing in the cooler for one hour, allow the bearing to shrink to fit smoothly into the bore, and then seal the bearing when it returns to ambient temperature. In addition to this, it must be ensured that there are no spots or rough edges on the bearing surface. It is also necessary to ensure that the outer diameter of the bearing used in the inner bore of the bearing or the inner bore assembly used in the outer diameter assembly is clean. A good suggestion is to apply a very thin film of oil on a less smooth surface before installation. A small bearing surface radius or a beveled surface of the bearing bore can also make the installation process simpler. If the bearing is not installed correctly, the bearing will be damaged and the surface of the bearing or the surface of the bore will be offset. The result is that these surfaces are not concentric or of an incorrect size, and these conditions may affect future installations and cause TIR failures. Ultimately affects print quality and increases the extra cost of drum repair.
Typically in printing applications, "standard size" bearings are mounted on a running and sliding machine. Mounting bearings on such machines does not require pressure or other forms of force. Such bearings are commonly used on high precision machines, calipers, high friction machinery and other machine components.