An interesting little picture this week illustrates how small gravity rollers can be used alongside powered rollers to create smooth movement of smaller parts on a roller conveyor.
Powered roller conveyors are an economical way to transfer parts. They are often used where an application requires a long run such as packing lines or warehouses.
Gravity roller conveyor systems and their powered counterparts however rely on the bottom of the product being conveyed to be quite flat and also that the product is not too short.
Rule of thumb dictates that it's best to get 3 rollers under the product on a roller conveyor whether powered or gravity, assuming uniform weight distribution on the product of course.
If that can not be achieved because the product is too short, then a belt conveyor is often the solution. In some cases however that's not a rational choice and bends would be a good example.
Roller bends are cheaper generally than belt bends. In the application in the photo, gravity rollers are used in the gaps between the powered rollers to create a smooth transition.
This can also be used on straight conveyors too, but keep an eye on the cost, as a belt conveyor may be cheaper on the straights.
For more information on gravity conveyors go to http://www.asconveyorsystems.co.uk/Gravity-Conveyors.html