Rubber Pulley

Cold Bonding vs. Hot Vulcanising: What’s the Difference?

Rubber pulley lagging is the process of bonding a layer of rubber to the conveyor pulley’s shell. Currently, there are two main rubber lagging techniques used today and these are cold bonding and hot vulcanising.

Each method has its pros and cons which we’ll discuss in this article. We’ll go over what’s involved in each process to help you determine the best rubber lagging method for your applications.

Cold bonding

Cold bonding is the process of gluing strips of rubber lagging straight onto the steel pulley. This technique has been used for many years due to its convenience and cost-efficiency. Cold bonding is less involved compared to hot vulcanising and can be performed on-site when sudden lagging problems arise.

If done properly, cold bonding can provide satisfactory results for light to medium pulley applications. However, cold bonding doesn’t offer 100% rubber tear adhesion which means service life is somewhat reduced.

Advantages of cold bonding

One of the main benefits of cold bonding is low application cost. Thanks to a simplified gluing process, cold bonding is easier to perform which helps keep the costs down and ensures shorter lead times compared to hot vulcanising.

Another key benefit of cold bonding is that you can perform emergency lagging repairs without having to remove the pulley from the conveyor. Convenience and affordability are what makes cold bonding ideal for simple rubber pulley lagging.

Disadvantages of cold bonding

The downside to cold bonding is that there are many different modes of failure that can potentially occur. One example is the gaps between the rubber strips. Over time, the glue and filler used to bond the rubber strips can wear away, thus creating gaps where water can penetrate the lagging. This can result in pulley shell corrosion which significantly affects the pulley’s performance.

When they pulley shell corrodes, the rubber lagging can potentially lift off from the pulley shell. The shell itself will need to be machined to remove the corrosion which will result in a thinner pulley shell.

It’s for these reasons that cold bonding is best reserved for light to medium applications since the average service life is much shorter compared to hot vulcanising.


Pros of cold bonding:

  • Low application costs
  • Convenient and straightforward
  • Great for emergency repairs
  • Shorter lead times

Cons of cold bonding:

  • Short service life
  • More potential for failure
  • Potential for pulley shell corrosion

Hot vulcanising

Hot vulcanising is generally considered to be the superior rubber lagging technique and for good reason. Because the process eliminates any gaps in the lagging, hot vulcanising offers fewer modes of failure. This provides better overall performance and service life compared to the conventional cold bonding method.

Advantages of hot vulcanising

One advantage of hot vulcanising is that the bond strength between the rubber and pulley shell is stronger compared to cold bonding. In addition to that, hot vulcanising does not create joins in the lagging which eliminates the risks of shell corrosion and prevents the rubber from separating from the pulley.

A process for installing ceramic lagging using hot vulcanising has been developed. This addresses any issues with lagging to shell bonding, resulting in a stronger and more reliable adhesion not only between the lagging and the pulley but also between the individual lagging strips. Hot vulcanising ensures a 100% rubber tear bond between the lagging and the pulley shell.

Disadvantages of hot vulcanising

While hot vulcanising is the preferred method for rubber lagging, it does come with its disadvantages. One is that the process takes longer to finish. Hot vulcanising is done by applying a continuous rubber layer around the pulley shell which is then cured and melted to create a seamless rubber lagging. This can take hours to finish which leads to longer lead times.

Hot vulcanising also requires special equipment and cannot be performed on-site, thus making it unsuitable for emergency repairs. It’s also more expensive to perform compared to cold bonding.


Pros of hot vulcanising:

  • Better for performance and service life
  • Prevents rubber from separating from the pulley
  • Stronger bond adhesion
  • Eliminates gaps in the rubber lagging

Cons of hot vulcanising:

  • Longer lead times
  • More expensive to perform
  • Requires special equipment

Choosing the right rubber lagging method

There’s a time and place for both rubber lagging methods. Cold vulcanising is still very much used today especially for those who want a quick solution that’s easy and affordable. Hot vulcanising, on the other hand, is ideal for maximising conveyor pulley performance while ensuring a repair-free application.

Make sure to consider the pros and cons of each rubber lagging method to determine the best technique to use for your conveyor pulley.