Page 9 - SKF-Food-Line-ball-bearing-units

Insert bearings and sealing system

At the heart of each unit is a high-quality corrosion resistant insert
bearing with AISI grade 420 stainless steel inner ring, outer ring and

balls The Blue Range bearing units also incorporate a patented,
bearing sealing system that adopts a radically different approach to
preventing damage caused by detergent ingress into the bearing

The bearing is designed as a single row deep with the highest hygienic design and food Due to this innovative design, the sealing
groove ball bearing with a sphered (convex) safety requirements (e g open food process- performance is not limited by the lip contact
outside surface to the outer ring The ing zones) The sealing system consists of a force against the shaft This means that the
sphered surface matches a correspondingly non-contacting seal and a flinger, located at seal can achieve high levels of protection
sphered, but concave, housing bore The the outer circumference (fig. 1) The flinger coupled with low energy consumption The
design minimises internal loads on the bear- provides the first barrier against the ingress internal gutters are designed to guide deter-
ing that would exist if initial misalignment of both solid and liquid contaminants This gent away from the bearing Whereas the
went uncorrected closes against the bearing outer ring when aim of a detergent is to penetrate and clean,
pressure washed this novel approach aims to work with rather
The bearing inner ring is extended on the than against the detergent
outboard/locking side It is locked on the Next, the design provides a series of internal
shaft with two stainless steel grub screws concentric “gutters” (fig. 2) which contain
that are positioned at 120°, minimising inner and collect any drops of detergent that pen-
ring distortion while maintaining good grip- etrate and then guide them, circumferen-
ping strength tially, around and away from the bearing
(fig. 3)
The inner ring of the bearing is dimensioned
to accommodate the fitting of the back seal,
letting the units be deployed in applications

Fig. 1 Fig. 2 Fig. 3

The bearing seals are patented.

Sealing system effectiveness The post-test analyses confirmed that detergent ingress is typically
Accelerated testing has shown that this design provides better contained within and channelled away by the first or second of the
sealing performance by actively dealing with detergent ingress multiple gutters
rather than seeking to passively exclude it In testing, detergent
In addition, both the friction torque and the temperature mea ured
droplets were allowed to enter the seal at a rate of 5 drops per
from trials of the 206 size are considerably reduced, considering
minute over a period of 500 hours, after which the internals of the that there is only one contacting lip instead of two
seal were examined

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