Borborema quarry gets four times longer life from Metso truck bed lining

For five years, Metso Outotec has been serving Borborema quarry with the highest-quality rubber lining. The Metso rubber lining was installed five years ago on two trucks in its fleet and those same linings are still in use. According to a specialist at Borborema, the linings should last for an additional two years, which means the Metso rubber lining is at least four times more durable than the traditional steel linings.

Premature wear of the truck's components when lined with steel

Located 400 kilometers from the state capital of São Paulo, the quarry produces approximately 70 thousand tons of aggregates per month, with the average production varying depending on market demand. The site’s haul trucks have a capacity of 16 m³ and are filled by a 36-ton excavator equipped with a 2.1 m³ bucket.

During the daily operations, drivers don't have to worry about damaging the box and the truck because the Metso rubber lining helps absorb the repeated impact and stress of unloading the heavy abrasive material.

Oswaldo Nogueira Sigolo Filho, Manager of the Borborema quarry, sums up his thoughts on the Metso rubber lining:

“Without the Metso rubber lining, typically the body is first filled with thinner material to form a protective layer for the dump body. Then the truck is loaded with gross rock material. The Metso rubber lining absorbs impact and prevents premature wear of the truck’s components, such as the leaf springs,” he notes.

Sigolo Filho is responsible for monitoring the performance of the equipment and maintaining the centralized data for the entire fleet. According to him, the trucks lined with Metso rubber lining are the smallest trucks in the fleet that are operating in combination with the 36-ton excavators. This makes the shock absorption an essential factor in terms of the work and safety during the loading process.

50% reduction in noise levels and vibrations

Tests run by the Metso Outotec experts showed a 10 dB noise reduction during loading and unloading of the dump body, which is equivalent to a 50% reduction of perceived noise. This improves the noise levels during operation to under 87 dB, which is within the range indicated by international standards.

“When driving the trucks equipped with Metso rubber lining, the drivers benefit from greater comfort due to reduced noise levels and vibrations during loading cycles,” confirms Sigolo Filho.

Metso Outotec studies demonstrate that the Metso rubber lining absorbs 50% to 90% of the impact energy during the loading process. This reduces vibrations transmitted to the truck frame and other suspension elements, such as the shock absorbers, bushings and bearings. The strain on the motor, where the most sensitive components of the equipment are located, is also significantly reduced.

A cost-effective option to extend service life

Sigolo Filho points out that the longer wear life and increased impact absorption advantages will also be verified by analyzing the vibration tests he and his team are performing and compiling.

Metso Outotec technical teams also carried out scan tests to measure the wear rate of the linings used at the Borborema quarry. The results revealed an average wear of 60% during the five years of operation. Considering the lining thickness of 100 mm, the thickness of the dump bed registered 60 mm (due to the discount of the bolts with 40 mm thickness). This results in an estimated 20% wear margin for the lining.

“This is sufficient for another two years of operation, considering the current volume of the quarry,” says a Borborema specialist.

Unlike the steel linings, the Metso rubber linings are modular, so the areas with the highest wear can be replaced without having to change out the entire lining. This represents a cost-effective option to extend the material service life and reduce future investments.

The scan tests performed by Metso Outotec established that the area in the back of the rubber lining showing higher wear should be the first to be replaced. This was predictable, since this is the area where the most of the abrasive material goes through.

“At this point, the measured wear was 36.6 mm,” observes Douglas Andrade from Metso Outotec technical sales support. He adds that the central plate in the front region of the truck showed the least average wear, 8 mm, which is 80% better than the results from the discharge zone.

Modularity saves time, labor and costs

Sigolo Filho notes that focusing on the areas with higher wear and replacing just those areas reduced the overall maintenance load for the entire dump body.

“The modular replacement is not as simple as replacing a Metso Outotec mesh screen, but it is infinitely faster than changing the lining of the entire dump bed. It saves time and labor, and also reduces material costs,” he adds.

Even before the installation, the experts at Metso Outotec prepared a pre-planning engineering study in order to optimize the whole process – from the initial order to the acquisition, delivery and installation itself. Replacing the lining on a complete dump body normally takes between 32 and 72 hours and should be performed by a Metso Outotec expert using special equipment to weld the 150 material pins. Then again, the modular exchange can be performed by the customer themself in just a few hours, representing significant time saving.

Metso rubber lining exceeded initial expectations

With an installed production capacity of up to 100 thousand tons per month, Sigolo Filho and his crew are already preparing for another dump truck with the same capacity of 16 m³ to complete the fleet. This new vehicle will receive the Metso rubber lining, the durability of which is expected to be the same or even higher. Sigolo Filho explains that they will take one of their existing trucks without lining and compare the data with the two vehicles that are equipped with Metso rubber lining. The intention, he says, is to identify the minutes or even seconds gained in each loading cycle when Metso rubber lining is used.

 “I believe there’s a difference, mainly due to the confidence of the drivers; they feel more comfortable to unload onto the dump body when it is lined with the Metso rubber lining,” he explains.

In terms of technical disadvantages, Sigolo Filho couldn’t identify anything significant and emphasized that the type of the material sliding on the lining did not seem to make any difference.

“These trucks are used for loading of gross rock material, pre-crushed, so there is no concern with regard to the material sedimentation that occurs on trucks transporting thinner material,” he adds.

“Nevertheless, we noted none of the losses that can occur in the presence of fine material during the process or when we use trucks occasionally to transport the crushed stone used for some ground repair,” he concludes.