The sealing arrangement of a screw conveyor depends on the properties of the material being conveyed, the conveyor's installation angle, and the bearing layout. Two common designs are the flange-mounted bearing housing seal and the inverted bearing housing seal. They differ in structure, sealing method, and suitable operating conditions.
Flange-mounted bearing housing seal
The flange-mounted bearing housing seal relies on controlled shaft clearance and, when required, a skeleton oil seal to limit material leakage and lubricant loss.
The clearance between the screw shaft and the shaft opening in the side plate must be kept within 1 mm. This reduces the gap through which material could escape. The sealing components and bearings are integrated into the same bearing housing, which is installed outside the dry-side end plate.
A skeleton oil seal can also be fitted to this arrangement. Its flexible sealing lip contacts the shaft surface to form a dynamic seal, helping prevent dust ingress and lubricant leakage.
This design is suitable for horizontal or slightly inclined screw conveyors where reliable sealing is required. It is particularly applicable to the conveying of dry, fine-grained materials.
When the equipment requires modifications to the bearing housing or related mating dimensions, we can provide custom machining of the relevant precision components based on customer drawings.
Inverted bearing housing seal
The inverted bearing housing seal places the bearings inside the conveyor trough. Its internal arrangement separates the bearings from the conveyed material and reduces wear caused by direct contact.
The bearing housing is installed inside the trough. One end is welded to the main screw shaft, while the other is welded to a disc. The disc diameter must be smaller than the inner diameter of the trough to allow material to flow through without obstruction.
For the bearing arrangement, a shaft is fixed to the end plate to support two bearings. Both bearings are housed inside the inverted bearing housing. This layout keeps the bearings separated from the conveyed material and prevents direct contact between them.
The sealing effect mainly comes from the pressure exerted by the material inside the trough, which forms a natural seal. The clearance between the bearing housing and the shaft is also controlled through precision machining to reduce the risk of material leakage.
This arrangement is mainly used in vertical or steeply inclined screw conveyors. It is particularly suitable for sticky or lumpy materials and helps prevent material from flowing backward or leaking out.
How to choose between the two sealing arrangements
The flange-mounted bearing housing seal relies on shaft clearance control and the use of a skeleton oil seal. It is suitable for horizontal or slightly inclined conveying conditions. The inverted bearing housing seal uses an internal bearing arrangement to separate the bearings from the conveyed material, with material pressure helping to form a natural seal. It is more suitable for vertical or steeply inclined conveying applications.
The selection should take into account the moisture content, particle characteristics, and stickiness of the material, as well as the conveyor's installation angle. These factors help determine the appropriate bearing housing structure and sealing arrangement. For non-standard equipment, we can also machine custom bearing housings, shafts, and other related components according to customer drawings to meet specific structural and dimensional requirements.
Hansheng Automation also provides drawing-based precision machining for components used in other industries. Our work includes functional parts for tobacco packaging and filling machinery, as well as precision structural components for yachts and RC racing cars. We support single-piece and small-batch production based on customer-supplied engineering drawings.
