This type of power transmission allows you to cover long distances without adding lubrication. They operate with minimal noise and produce hardly any vibration. Most materials for these belts are rubber and plastic.
What is a timing belt?A timing belt gear is a synchronous drive system. Here, power is transmitted between two parallel shafts on which toothed pulleys are mounted. These pulleys are connected by a toothed belt. This is a belt that connects exactly to the toothed belt pulleys.
Timing belts are primarily made of rubber such as Neoprene and Polyurethane and often have cord layers in them for reinforcement. The serrations on the belts allow them to transmit large forces. But how do you determine which belt is right for your timing belt pulley?
3 steps for choosing the right timing belt:
- Based on the tooth shape and dimensions, determine the type of timing belt.
- Count how many teeth are on the gear train.
- Measure the width of the timing belt.
Benefits of timing beltsTiming belts are wear-resistant, have good chemical resistance and are suitable for high-speed timing belt pulleys. In addition, they have a high degree of flexibility and a low noise level. By connecting the belt to the timing belt pulleys, there is precise positioning. The use of a timing belt ensures that lubrication is not necessary, and due to the correct positioning, no slippage takes place between the belt and the pulley.
Types of timing beltsThe timing belts can be divided into 2 main groups. Metric dimensions and Inch dimensions.
1. Metric dimensions
These are process belts made of Polyurethane (also called PU). PU is made of a high-quality thermoplastic polyurethane. This gives them very good running properties and high wear resistance. The timing belts have a steel pull cord. The teeth are trapezoidal with a metric tooth pitch. The belts are suitable for a T-profile and an AT-profile. A T-profile is suitable for standard process belt applications. An AT profile has a different tooth profile. Partly because of the large tooth volume, these belts have a high load capacity. The dimensions of these belts are indicated in mm. If you have a timing belt with the dimensions: 60-T10-800 then this is a belt with a width of 60 mm, tooth pitch 10 mm and a length of 800 mm (80 teeth).
Within the metric timing belts are also the high power belts. These are made of rubber and you recognize them by the round tooth shape.
2. Inch dimensions
These are timing belts made of black neoprene with a trapezoidal profile. Neoprene is a synthetic rubber produced through the polymerization of chloroprene. The tensile cords of these timing belts are made of fiberglass. The tooth pitch of this type is indicated in letters and is derived from inches. 1 inch = 25.4 mm. The most common tooth profiles are:
- H (½” - 12,7 mm)
- L (⅜” - 9,525 mm)
- XL (⅕” - 5,08 mm)
Toothed belts with both metric and inch dimensions can have coverings or overlays applied to them. In addition, they can be machined and ground to size in various ways.
Friction belts versus vacuum beltsThe commonly used belt-drawing principle works with conveyor belts running on either side of the forming pipe. These belts push the film web down along the pipe. Three types of belts are used: friction belts, vacuum belts and a combination of these two types.
- Friction belts: friction belts take advantage of the fact that the friction between the conveyor belts and the packaging material is greater than the friction between packaging material and forming pipe. Especially with packaging material with a smooth outer surface and (providing additional friction) polyethylene on the inside, this friction difference is so small that it can cause problems.
- Vacuum belts: with vacuum belts, the film is sucked against the bands. This eliminates friction between film and forming pipe and makes the process considerably smoother.
- Vacuum-assisted friction belts: in a combination of these two techniques, the friction between film and forming pipe is reduced, but not completely eliminated.
For better film web running, some machines have, in addition to the friction belts, a driven roller that sits just in front of the forming shoulder: after all, friction on the forming shoulder is greatest. The additional pushing force provided by this rubber roller also allows a steeper run-in angle and thus enables better track behavior.