Notes on belt designing - Chukoh Beslt, the company designing and manufacturing PTFE Belts.

Shape of pulley

Use a flat pulley. Especially if you are anticipating running loss, we recommend that you apply rubber lining to the pulley which drives the belt. Thickness of the lining should be about 5 to 10 mm and hardness of 50 Durometers (SHORE'S Durometer A).

Length of the pulley and width of the belt

Use a pulley slightly longer than the width of the belt. See the following, for the relation between the width of the belt and the length of the pulley: For the Tru Trac pulley, however, this is not the only equation to be used.
P=1.13 (B+5)
P: length of the pulley (mm)　B: Width of the belt (mm)

Thickness of the belt and the diameter of the pulley

The relationship between thickness of the belt and the diameter of the pulley is important for proper conduction and long life of the belt. When designing a driver pulley, refer to the following table.

Criteria for tension to be applied

In designs, generally the belt tension is 1/10th of the tensile strength of the used material (at the joints); however, tension below 10N/cm is considered appropriate.
Especially in the G type belts, exceeding this value not only results in a reduced belt life, but also causes wrinkles and folds which might lead to damage.
Please discuss with us about the width of the belt as width may vary according to the specifications for material used for joints.

Driving system

Generally, single driving system is widely used, as shown in the following diagram.

Belt supporting device

The supporting device has two types, carrier roller support and plate support; however, when choosing your device, consider about the weight, shape and possibility of displacement of the movables. (Generally, the plate support system is used in carrying the light weight products. While using the plate system, we recommend you use the G type adhesive tape lining.)

Tension device

For a steady running of the belt, the belt must function at a uniform tension. The take-up pulleys are also a very important device. The take-up pulleys work as shown in the following diagram. The design, however, should be according to the requirements.

Belt meander

It depends on the use and the size of the belt that how much a belt can meander; however, flouroplastic belts with lesser stretch ability are prone to meandering. The relation between movement of the pulley and behavior of the belt is as follows.

Difference in the behavior of the belt depending on the stretching

When an end of a pulley is subjected to tension, the fluoroplastic belt with characteristically lesser stretchability moves to the opposite direction (the direction that releases the tension) vis-à-vis the end subjected to tension

Behavior of the belt when the pulley is adjusted

(1) Behavior of flat belts

See the above diagram.

(2) Behavior of belts with snub pulley

a) Belt movement adjusted as per the parallelism between the pulleys
If you rearrange the parallel snub pulley as per the below diagram, the belt shifts in the direction of the arrow. Diagram

b) Belt movement adjusted as per the parallelism between each roller and the ground
If you rearrange the parallel rollers as per the below diagram, the belt shifts in the direction of the arrow.

(3) How the belt shifts according to the position of the snub pulley:

The belt shifts according to the position at which the snub pulley is mounted. If you reposition the snub pulleys A, B in the direction of the arrow (when seen from the front side of the following figure), the belt shifts in the direction of A', B'.