Customer case

Abrasive aggregates no match for Dynapac’s asphalt roller drums in Hardox®

March 09, 2022 6 min read

A section of abrasive aggregates during road paving

Case details

Product Hardox® 450
Country Sweden
Company Dynapac Compaction Equipment AB
Industry Yellow goods and construction
Brand program Hardox® In My Body

When the going gets tough, Hardox® steel in oscillating drum rollers keeps them rolling. Discover how Dynapac’s asphalt rollers can turn for 10,000 hours yet require little maintenance.

The roller drum of an asphalt paver, made in strong and tough Hardox® steel.
Dynapac CO 4200 Oscillating roller

Case details

Product Hardox® 450
Country Sweden
Company Dynapac Compaction Equipment AB
Industry Yellow goods and construction
Brand program Hardox® In My Body

Road rollers counteract tougher wear with tougher steel

The trend towards thinner asphalt layers and harder aggregates favors the use of oscillating rollers. Oscillating drum rollers compact asphalt through a horizontal massaging motion that makes the aggregates move and realign in a denser formation. But this movement creates a grinding effect on the drum’s surface.

The active life of a roller is often more than 10,000 hours. To avoid the need for a drum replacement because of excessive wear during this time, the usual solution is to use a thick drum made of mild steel like S355 steel. But roller and paver manufacturer Dynapac decided to take their design in a different direction.

A big and strong yet lightweight roller paving a road. The drum is made in Hardox® 450 abrasion-resistant steel.

Roller drums get thinner and lighter yet stay hard to fight wear

Dynapac wanted to use a relatively thin steel to make the drum light. There is no advantage having a thick and heavy drum. On the contrary: with a lighter roller drum you can reduce the size of the mechanical components that rotate the drum and create the oscillations. This in turn reduces the fuel consumption of the asphalt roller, to the benefit of the operator.

When Dynapac’s design and production team looked for a working solution, they targeted a 16 mm (0.63”) thick wear plate for the roller drum. To ensure the service life was long enough, they also needed a hard steel that could cope with the particular wear challenge seen on an oscillating drum. Plus, they needed to be sure it could be bent into a perfectly round shape without having to invest in new rolling equipment. And finally, as if that wasn’t a hard-enough specification, it had to be as easy to weld as conventional steel.

A road roller by Dynapac, with roller drum made in Hardox® steel.

Ideal combo of hardness to fight abrasion and ductility for workability

Abrasion-resistant Hardox® steel promised to deliver on all accounts. After consulting with material and production specialists at SSAB’s Knowledge Service Center and testing different grades of Hardox® wear plate, Dynapac concluded that Hardox® 450 had the optimum mix of hardness for wear resistance and ductility for workshop performance.

Dynapac first built a vibrating drum made of Hardox® 450 to make sure that production equipment could work with the tough steel. That drum was sold to a customer in Poland. After 1,000 hours hard operation the grooves from the turning of the drums were still clearly visible on the drum surface. “At that point we really felt that we found the right steel, and partner, to work with,” says Andreas Lager, structural analysis and design manager at Dynapac.

“In this project we worked very closely with SSAB‘s wear and manufacturing experts. We used their knowledge to establish the best way to bend and weld the drums. This cooperation has been very valuable when developing our new oscillating rollers,” says Andreas Lager at Dynapac.

When the production techniques were in place, a couple of full-scale prototypes were constructed and put into action in regular field tests.

“Our prototype rollers were monitored for up to 1,000 hours of tough operation and the belt drive on the oscillating drums showed hardly any wear at all. It will be really interesting to see how the rollers perform in the field,” Lager says.

Manager Andreas Lager of Dynapac Compaction Equipment in front of an asphalt roller drum that is certified Hardox® In My Body.

Andreas Lager, Dynapac

Built for high productivity and low maintenance

“A Dynapac roller normally requires extremely little maintenance. But the timing belts inside the oscillating drum are something that might need to be replaced during the machine’s lifetime. This is the case on all oscillating drums due to how they’re constructed. That’s why we put a lot of effort into making the change as simple and fast as possible. A belt swap on both sides in a Dynapac CO roller can be done in as little as two hours, thanks to a smart design and easy access through large manholes on each side of the drum. I think this must be some kind of record!” Lager says.

Close-up of the Hardox® 450 steel branding on a wear plate.

Hardox® helps roll the racetrack at Formula 1

Many of Dynapac’s oscillating rollers in its CO series are now in full operation around the world. Some of the rollers were involved in a prestigious project in Asia, ensuring a perfect surface on the new Formula 1 racetrack in Hanoi which will be ready for racing in 2020.

Bright red Formula One racecar with oscillating rollers that use Hardox® wear steel.
The Hardox® In My Body decal on an oscillating drum roller. This is a sign of the highest quality standards.


Dynapac is an international company with a heritage that goes back to 1934, when the company was founded in Sweden. Its main business is high-tech asphalt and soil compacting rollers between 1 and 21 tons, pavers and light equipment. Dynapac is now headquartered in Karlskrona, Sweden, and has production facilities in Europe, South America, and Asia. Dynapac is part of the FAYAT Group.

Since 2017, Dynapac has been a member of Hardox® In My Body, SSAB’s quality program for companies that use Hardox® wear plate in products that are designed and manufactured according to the strictest quality requirements.

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