Labyrinth seal sets for conveyor idler rollers
Moulded polyamide seal sets for conveyor belt idler rollers. Four-piece sets for bearings 6204, 6205, 6206 and 6305, in PA6 and PA66. In continuous production since 2013.
Why idler bearings fail
Most idler bearing failures are caused by contamination. Fine dust gets past the seal and mixes with the grease into an abrasive paste; water brings corrosion; coarse particles dent the raceway.
On a conveyor with several hundred idlers, poor sealing becomes a continuous replacement programme. A labyrinth seal set keeps grease in and contamination out, with no added drag.
What the seal set has to do
Close the gap between the rotating roller shell and the stationary spindle. Retain grease on the inboard side and prevent the ingress of dust, grit and water on the outboard side — and add no drag doing either.
Sizes
Seal sets are sized to the bearing fitted in the roller. The seal's outside diameter and spindle bore match the bearing's outside diameter and bore.
| Set | Bearing | Bore | OD | Width | Typical duty |
|---|---|---|---|---|---|
| 204 | 6204 | 20 mm | 47 mm | 14 mm | Return rollers, light-duty idlers |
| 205 | 6205 | 25 mm | 52 mm | 15 mm | General material handling |
| 206 | 6206 | 30 mm | 62 mm | 16 mm | Medium to heavy duty |
| 305 | 6305 | 25 mm | 62 mm | 17 mm | Heavy duty, long-centre conveyors, mining and bulk handling |
Roller shell diameter and spindle size vary between manufacturers. Send a roller drawing or a sample end assembly with your enquiry and we will confirm the correct set.
Material grades: PA6 and PA66
| Grade | Properties | Specify for |
|---|---|---|
| PA6 | High impact strength, good toughness, excellent wear resistance | General material handling, standard ambient duty, impact and stone-strike positions |
| PA66 | Higher stiffness, higher heat-deflection temperature, better dimensional stability | Hot conveyed material, higher roller speeds, heavy abrasive duty, sustained high ambient temperature |
Where the application is uncertain, PA6 is the safe default. PA66 is chosen when temperature or long-term dimensional stability governs.
How a labyrinth seal works
Most idler bearing failures come from contamination, which destroys a bearing long before it wears out. Fine dust that gets past the seal mixes with the grease into an abrasive paste that laps the raceway on every revolution. Water brings corrosion products that do the same. Coarser particles dent the raceway outright. In each case the damage comes from material that should never have reached the bearing.
A labyrinth seal works by geometry, without contact. The path between the rotating and stationary members is long and folded, and rotation flings incoming particles outward before they can travel inward, and no surfaces rub. That gives 4 advantages over a contact lip seal:
No wear surface
A lip seal loses contact as it wears, and from that point permits the ingress it was fitted to prevent. A labyrinth has no contact to lose.
No added drag
Lip friction is a real share of motor load once it is multiplied by several hundred rollers.
No heat at the bearing
Heat is what breaks lubricant down. A non-contact seal generates none.
No speed limit
Lip sliding speed caps roller RPM. A labyrinth does not.
Seal set components
The set assembles into the roller end in this order, working inward from the outside face:
| Order | Component | Function |
|---|---|---|
| 1 | Rain cap | Outermost closure. Sheds water and falling material before either reaches the labyrinth. Takes the direct strike from lump and stone. |
| — | Metal cap | Metal retaining cap. Not part of the seal set — shown only to place the plastic components correctly. |
| 2 | Fix seal | Stationary on the spindle. Forms the outer half of the labyrinth. |
| 3 | Rotary seal | Rotates with the shell. Forms the inner half of the labyrinth, and flings incoming particles outward. |
| — | Bearing | Not supplied by us. 6204, 6205, 6206 or 6305 to suit. |
| 4 | Back seal | Innermost. Provides the seating face that sets the bearing squarely in the shell, and closes the inboard side against grease loss. |
A set is four moulded pieces: rain cap, fix seal, rotary seal and back seal. The metal cap and the bearing are not included.
Assembly drawing
Ordering information
Priced per set. A set is the four moulded pieces for one roller end — rain cap, fix seal, rotary seal and back seal. A complete roller takes two sets, one at each end. Metal caps and bearings are not supplied.
What to send us
- Bearing size — 6204, 6205, 6206 or 6305
- Material grade — PA6 or PA66
- Quantity, in sets
- Roller manufacturer, or a drawing reference
Questions buyers ask
Which bearings do the seal sets fit?
Four-piece sets for bearings 6204, 6205, 6206 and 6305. The seal outside diameter and spindle bore match the bearing.
What is the difference between PA6 and PA66?
PA6 has high impact strength, good toughness and excellent wear resistance, for general material handling and ambient duty. PA66 has higher stiffness, a higher heat-deflection temperature and better dimensional stability, for hot material, higher roller speeds and heavy abrasive duty. Where the application is uncertain, PA6 is the safe default.
What does a labyrinth seal do?
It closes the gap between the rotating roller shell and the stationary spindle, retains grease on the inboard side and keeps dust, grit and water out on the outboard side, with no added drag.
How do I confirm the right set?
Roller shell diameter and spindle size vary between manufacturers. Send a roller drawing or a sample end assembly with your enquiry and we will confirm the correct set.
How do I get a quote?
Call or WhatsApp +91 94160 55854, or send the quote request on the Contact page. Tell us the material, how much per hour and when you need it. We read every complete enquiry ourselves.
Request a quote for labyrinth seal sets
Bearing size, material grade, quantity in sets, and the roller manufacturer or a drawing reference. We will confirm the correct set and quote.
A.B. Plastech · Modern Industrial Estate, Bahadurgarh, Haryana
pawar@abplastech.co.in
abautomech@hotmail.com