Sunday 22nd Sep, 2019

Elastotec proves pulley lagging’s longevity

Elastotec aims to change how the mining industry sees pulley lagging by proving it isn’t a consumable item, and that if correctly designed, applied and specified, it can last as long as the mechanical components of the pulley.

Elastotec aims to change how the mining industry sees pulley lagging by proving it isn’t a consumable item, and that if correctly designed, applied and specified, it can last as long as the mechanical components of the pulley.

Conveyors often play a major role in mining operations, transporting tens of thousands of tonnes of ore per hour.

Because of this, when something causes a conveyor to breakdown, the unplanned downtime can cause millions of dollars in lost productivity each day.

Specialist pulley lagging company Elastotec has spent more than a decade focusing on increasing the service life of pulley lagging to substantially improve conveyor availability.

David Molesworth, Sales Director at Elastotec, says the company believes a conveyor should never stop because of pulley lagging failure.

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“Lagging does not work individually. It is part of a system that needs to work together with the pulley and the belt,” he says.

“Pulley lagging is a vital part of a conveyor, providing wear resistance, grip and protecting both the pulley and the belt from damage and build-up.

“However, in many situations there is still an attitude that views pulley lagging as a consumable item and is replaced multiple times during a pulley’s service life. We believe this doesn’t need to be the case and that pulley lagging can be engineered to last as long as the other mechanical components on the pulley.”

Elastotec has spent more than a decade designing, understanding and installing pulley lagging and collecting data from each site to build a database of common lagging failure modes.

It found that one of the most common failure modes for pulley lagging systems was debonding from the pulley shell. Ceramic lagging is traditionally applied using a two-part neoprene contact cement in a process known as cold bonding. This method is convenient, but Elastotec found a number of limitations that impacted the reliability and service life of the bonding.

Cold bonding’s adhesion between the rubber backing on the lagging and the steel pulley shell often doesn’t achieve a full rubber tear bond, which is where the bond strength is greater than the rubber strength. In applications with high belt tensions, the shear forces applied by the belt can exceed the bond strength between lagging and the pulley shell, leading to lagging separating from the pulley.

For pulleys operating in wet environments, corrosion can occur at the lagging/pulley interface, lifting the edge of the lagging and allowing water in. In addition, cold bonding joins can be weak points for water ingress, which can corrode the pulley shell and debond the lagging.

To eliminate these issues, Elastotec developed a method of bonding pulley lagging it calls Hot Vulcanised Ceramic Lagging. The pulley is put into a pressure vessel, where the lagging is attached with hot steam at high pressure.

Mr Molesworth says this creates a product with no joins, eliminating the issues of water ingress, and ensures a 100 per cent rubber tear bond.

“Because of that bond, the pulley lagging can’t be delaminated. You would have to tear the rubber itself in order to get it off,” he says.

Elastotec believes that the application of the lagging is just as important as the engineering and provides training for its approved applicators to install its lagging. Training covers both application techniques and understanding of lagging failure modes so that the correct type of lagging is selected for each application.

The company has found it gets the best results when its approved applicators work closely with a mine’s engineering and maintenance staff. Approved applicators listen to mine engineer’s expertise to help guide them in the application process.

Mr Molesworth says the application process has been improved and updated over time as new techniques were developed.

“We have the benefit of working with international companies in Europe, Asia, and North and South America, and have seen different methods of applying pulley lagging. Over the past ten years we’ve taken what we have developed in-house plus what we have learned from our international partners and incorporated it into our own applications methods,” he explains.

“We have also undertaken significant in-house testing at temperatures between -50°C to 75C, as our product is also sold in regions with vastly different climatic conditions, like Russia and India.”

“Our outdoor ageing station has a range of lagging samples, which we test every six months. After seven years we are still obtaining 100 per cent rubber tear bonds, showing that the lagging is able to handle some of the roughest conditions,” Mr Molesworth says.

This extensive testing has made Elastotec confident in its pulley lagging solutions to the point where the company offers a warranty with its lagging. Elastotec says its hot vulcanised lagging won’t debond from the pulley, the edges will not lift, and water will not get through the joins. Additionally, the Elastotec warranty covers tile debonding – which is another reason why conveyors have to stop for lagging or pulley replacement.

“We introduced the warranty a couple of years ago to show that we were serious about providing pulley lagging that would last,” Mr Molesworth adds.

“Since 2012, more than 800 hot-vulcanised Elastotec pulley lagging systems have been installed internationally with zero failures.”