Seals cull oil leaks

Innovative use of bearings helped stop troublesome oil leaks at Kodak’s Harrow paper manufacturing line.

Steadily exuding oil around four rotating shafts on motor couplings was a cause of concern for Kodak’s management. As well as the oil spills, the company was also concerned about the disastrous consequences of the gearbox oil level falling so low that it might run dry and seize.

The chief offender was the labyrinth seal on a 12cm diameter motor coupling input shaft, spinning at 1700rpm and losing oil at a rate of up to 2 litres a day. This was closely followed by the tacho output shaft which was dripping about 2 litres per week.

Oil forced past the labyrinth seals by an internal pressure approaching 2bar was supposed to feed back into the gearbox housing, but due to wear this was no longer the case.The two remaining output shafts, both geared down to about 240rpm were less problematic but still required some treatment.

Resin Coating Technologist Paul Bishop went straight to Mike Doel of Blue Diamond. Blue Diamond decided that its AJY Exclusion seal range was ideal for the task. This seal range, with its sophisticated lip arrangement and integral wear sleeve for perfect mating on the shaft, effectively provided a virgin shaft in a controlled environment for the lips of the seal to run against. This solution was effective because it separated the two media; the wear sleeve fitted over the previously scored shaft with no further machining required.

However, installing an effective modern oil seal on the motor coupling shaft would involve removing and refitting the heavy electric motor and modifying the flange to match the improved seal housing dimensions: the best estimate for this was at least 8 hours, perilously close to the 12 hours upper limit set for planned maintenance downtime.

It was easier, as well as a valid trial of a supposedly more efficient sealing technique, to tackle first the shafts on the tacho and extrusion screw drives. Once a Blue Diamond type TA seal was fitted on the extrusion screw shaft, it did not allow a single drop of oil to pass. Oil leaks from the motor coupling shaft were stopped by installing a Blue Diamond type TC seal. In all cases it was necessary to modify the flange area to suit seal dimensions, but it was never more difficult than simply turning out a ring that was too small, or packing up one originally too large.

Blue Diamond Bearings Tel: 023 8062 9944; Fax: 023 8062 9771

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