Automobile manufacturers are increasing their use of high strength steel that can achieve weight reduction of steel while maintaining equal strength to conventional steel as this allows them to achieve compatibility between reduced fuel consumption by lighter body weight and improvement in collision safety. Topy has been working on the use of high strength hot-rolled special sections for truck and bus wheel application.A challenging issue for raw material was how uniform strength is attained. We have succeeded in commercial production thanks to our inherent hot-rolling technologies in controlling material thickness and temperature.
Topy has developed ISO-compliant wheels that are
about 15% lighter compared to the corresponding conventional
wheels by combining a corrugated rim that uses
Topy’s inherent weight reduction technology with an
ECOD-processed disc. The corrugated rims are produced
from rim sections with uneven thickness in a corrugated
shape on their tire-mounting side, allowing the sections
to achieve an optimal thickness distribution when
The rim material is produced by the Steel Division and shipped to the Wheel Division to undergo process forming into rims, capitalizing on the advantages of our integrated production system that enables us to combine our unique hot-rolling steelmaking technologies with superior analysis and design wheelmaking technologies.
The ECOD discs are formed through cold spinning (rocking die forming) of a tube made of steel plate, enabling thinner and lighter discs without compromising the required strength.
Surface treatment of aluminum alloy wheel has long been designed with a focus on long-term corrosion resistance and anti-discoloring, and treatment with chromium has been thought vital for anti-corrosion. However, in view of the environmental regulations in Europe, Japanese automobile manufacturers have started to pay attention to a surface treatment without using heavy metal like chromium.
Topy has spent substantial time to study alternative materials to replace chromium technological development, and has succeeded in chromium-free process for the first time in the world.
SGOR® (Super Giant Off-the-road Rim) wheels are ultra-large
diameter wheels that Topy has developed for
dump trucks used at large-scale mining sites across the
world. Currently, the largest wheels available have dimensions
of 63 inches (about 1.6 m) in inner diameter, 44 inches
(about 1.1 m) in width and weigh as much as 2.83 tons
each, being about
five times the diameter
of ordinary passenger
SGOR® wheels can meet the demanding requirements of mining applications in terms of functionality and hauling capacity, contributing to the reduction of environmental burden.