Bearing surfaces are one of the most important factors when it comes to an anilox roller. Not only does this determine the overall life of the roller, but the performance of the roller as well.
If, for some reason, the dimensional integrity of the roller cannot be maintained or held “true” this has a direct impact on your anilox’s ability to produce a nice and consistent screen on whatever the printing application maybe. There are other factors that can impact that this, as mentioned in some of our other blogs. Be sure to use high quality cleaners when caring for your rollers and to care for them frequently.
The overall diameter of the bearing surface must comply to the tolerances provided by the bearing manufacturer. The range of tolerances is in direct reference to the centrifugal integrity of the bearing deviating from its absolute center.
Please contact the OEM/press manufacturer for referrals are technical data needed to maintain your bearings. It is also possible to contact the bearing manufacturer for additional clarification. The bearing manufacture information is always located on the bearing base and includes a bearing identification number or serial key. You can reference this information when contacting your bearing supplier for specifics/necessary information. The following is an example of tolerance data:
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
Too small a bearing surface size will cause the anilox shaft to chatter, which will reduce the lifespan of the bearing and damage the bearing surface. If the bearings are not maintained, they will harden during long runs, causing damages to the surface of the bearing sleeve.
Be sure that the press operator confirms that the bearing surfaces and bearings themselves are overly worn. Signs of bushing damage can include groove marks, notches, grooves, or scratches on the surface of the anilox caused by hammers, screwdrivers, and any other tool that may have been utilized in removal and replacement of the bearings.
A general rule to remember is that the bearings should not be tapped on or under the anilox shaft. Failure to do so during the installation of the bearing will result in a bent bushing, creating a TIR (total indicated runout) that is outside of specs, reducing bearing life. For the anilox roll, TIR refers to the case where the engraving area meets with the bearing on the shaft. For all intended purposes, the TIR of a bearing sleeve should not exceed 0.0005 inches.
We recommend in investing a removal tool to safely remove the bearings and to comply with the OEM's recommendations during installation. When mounting the bearing, the base can be expanded utilizing a bearing heater. Please be sure that the outer diameter of the bearing is in the inner bore of the bearing. A good suggestion is to apply a modest layer of oil on the surface before being installed. If the bearing is not installed correctly, this could cause damage to the surface of the bearing, or the surface of the bore can be impacted. The result is TIR failures. This will also cause an issue in print quality and will result in a replacement anilox.