Kiln Bogeys carry up to 25 tons spread over 8 or 12 wheels and are subjected to temperatures of about 80oC (176oF) for periods of up to five days. Conventionally, roller bearing with the rollers running directly on the wheel are used. If the bearing fails the wheel may sustain damage and may have to be changed. Because of the high temperature and corrosive conditions in the kiln, the bearings do not have a long working life.
To increase bearing life and reduce replacement costs, a number of saw mills have used Vesconite as the bearing material. The best results have been obtained by replacing the roller bearing with a steel bush lined with a ready to fit Vesconite bush (OD 38 mm x ID 28 mm - 70 mm long)(OD 1.5" x ID 1.1" - 2.8" long). The use of a ready-to-fit thin wall Vesconite bush minimises material and machining costs.
At some saw mills heavy wall bushing stock was machined to take up the bearing space previously occupied by the roller bearing. This approach is not as successful. The heavy wall bush that results is prone to damage if the kiln rails are not well aligned.
Where the kiln rails are in poor condition, it is essential to use thin wall bushes. Initially test only a sample number of bogey wheels in case the poor repair of the rails damages the Vesconite bushes.
The change to Vesconite bushes results in the following improvements:
- Substantial savings on bearings and bogey wheels
- Vesconite gave over four times the life of roller bearings
- No lubrication
- Lower friction - the loaded bogeys move more easily
- Simplified replacement process, reducing downtime
- No wear of kiln wheels by Vesconite bushes, whereas worn roller bearings damaged wheels.