Keeping cranes in motion: igutex more wear-resistant than steel

igus presents lubrication-free and corrosion-resistant polymer bearings for STS, RTG and RMG cranes.

Handling containers around the clock, often in extreme conditions, is the everyday life of STS, RMG and RTG cranes in ports worldwide. Failure of the wheel and axle units, the bogies, caused by premature wear, puts an enormous strain on crane operators and ports. igus revealed a solution at the port exhibition TOC Europe last month in Rotterdam: wound, lubrication-free and corrosion-resistant polymer igutex bearings for heavy duty use.

Ship-to-Shore (STS) cranes, as well as Rubber Tyred Gantry (RTG) and Rail-Mounted Gantry (RMG) cranes, operate all year round in the harshest conditions, exposed to dirt, dust, sea salt, heat and cold. Some components respond to these extreme conditions and loads with premature wear, such as the bearings of the crane bogies – the wheel and axle units – which, for example, move an STS crane weighing several tonnes along rails.
Excessive wear often causes system failures, as Rob Dumayne, director of dry-tech products at igus UK, knows. “Every failure costs time and money, a burden that ports can afford less and less as they face higher handling capacities and increasing competitive pressure.”

To relieve the burden on crane operators and ports, igus presented an alternative to classic steel bearings at TOC Europe 2024: igutex polymer bearings. Steel bearings present an ongoing potential problem due to corrosion, rapid wear and lack of lubrication. The plain igutex bearings made of high-performance plastic are extremely robust and wear-resistant, and at the same time corrosion-free and dirt-resistant. In addition, they do not require any lubrication. There is a huge cost advantage: £188 billion annually is spent on lubrication in all industries worldwide¹. In addition, there are associated maintenance costs of at least £156bn per year². And yet there are always failures due to insufficient lubrication, costing up to £590 billion globally³ . The use of lubrication-free plain bearing technology therefore reduces maintenance costs, conserves personnel resources in a time of skilled worker shortages and increases the service life of cranes. This all combines to increase the productivity of the port.

Surface pressure of up to 200 MPa is possible
igus manufactures most lubrication-free plain bearings using plastic injection moulding. However, for heavy-duty applications such as chassis mounts of cranes with surface pressures of more than 80 MPa, the material structure does not always offer sufficient mechanical stability. igutex composite plain bearings are therefore manufactured in a two-stage winding process. Firstly, the winding machine first produces an inner layer of filament fabric with integrated solid lubricants. The microscopically small lubricant particles are released during the operation and enables dry running with low friction coefficients. The second winding then creates a protective outer shell made of a resin-impregnated, hard-wearing glass fibre fabric. “Due to this two-stage winding, the igutex polymer bearings achieve a maximum permissible surface pressure of up to 200 MPa,” says Dumayne. “This makes the polymer bearings strong enough to work with low wear and yet are fail-safe in STS cranes. These igutex bearings have been described as the toughest plain bearings in the world.”

Polymer bearings beat steel and bronze bearings in tests
The fact that the wound polymer bearings are more wear-resistant than steel bearings has been proven by igus in the in-house 4,000m² test laboratory. On a test rig, bearings with both diameter and length of 40mm were loaded with 80 MPa. These were oscillated 50,000 times by 50 degrees at a speed of 30 cycles per minute. The result: The steel bearing (15MnCr5) suffered such massive shaft wear that engineers had to stop the test after 10,000 cycles. After the same time, the bronze bearing failed due to wear on the bearing itself. “However, the igutex bearing survived 50,000 cycles with only minimal signs of wear,” says Dumayne. “These benefits are being recognized by more and more crane manufacturers and operators around the world. For example, the company Tan Cang Gantry Joint Stock Company (TCGT) from Vietnam is equipping RTG cranes with completely lubrication- and maintenance-free high-load plastic bearings as part of a cooperation with igus. Not only for new crane systems, but also for existing ones, and switching from metal bearings to polymer variants is a simple process.”

That is because igus can manufacture the bearings, which usually have a diameter of 100mm or more, with the same dimensions. Application consultants are available on-site to assist with changeovers.