Safe, trouble-free overhead conveying with individual polymer ball bearings

Offering high load capacity, and assuring smooth operation, xiros plastic ball bearings from Igus make a big difference in a range of applications in overhead conveyor technology.

As digital transformation increases manufacturing throughput, and with booming online trade, the demands on material handling are constantly increasing. Customers expect faster and more reliable deliveries, meaning order structures and throughput times have changed drastically. Efficient material handling is becoming more and more important.

Companies are therefore increasingly relying on high-tech and automated conveyor systems. Overhead conveyor technology is a popular solution, and overhead travel is suitable for goods in space-optimised places and for fragile goods. However, modern conveyor technology also places high demands on the machine components, especially the bearings, essential elements of the drive technology. For safe and reliable overhead transport, motion plastic specialist Igus offers customer-specific and wear resistant ball bearings made of high-performance plastic.

There are two main types of bearings in conveyor technology: plain bearings and ball bearings. The latter has the advantage that they benefit from low rolling friction and therefore have less torque regardless of weight. Due to their hardness, metallic ball bearings in principle have a high load capacity, but they are susceptible to rust and contamination – even specially coated ones – and are fundamentally unsuitable for use in corrosive or damp environments. In addition, metal bearings require lubricant, as any metallic friction causes wear and loss of performance. If the lubricant is lost or absorbed by dust and lint, the bearing must be replaced.

To fix this issue, Igus offers lubrication-free and maintenance-free ball bearings made of tribologically optimised (friction and wear optimised) high-performance plastics that are ideal for the specific requirements of the application.

Cost-effective, durable and safe

The xiros series includes deep groove, axial, flange and pillow block ball bearings. The inner and outer races are made of the high-performance plastic ‘xirodur’, the cage consists of xirodur or iglidur (another igus polymer), and the balls are made of glass or stainless steel. The product range also includes other types, including guide rollers and self-aligning ball bearings. What makes them special is that Igus’s materials researchers adapt the basic polymers to a wide variety of industrial requirements, including overhead conveyors.

“The xiros ball bearings are also perfect for efficient material handling in overhead conveyor technology. They are not only lubrication-free, maintenance-free and light, but also withstand corrosion, take up little installation space and are a cost-effective alternative to metal solutions,” emphasises Rob Dumayne, drytech product director at Igus UK.

Because of these friction-optimised and wear-resistant polymers, xiros ball bearings are also exceptionally durable. The service life of all the individual products can be calculated easily by using an online tool, that is powered by the data that Igus collects through numerous tests in its own 3,800m² laboratory. Both the xiros material itself and the different material combinations for bearing races, balls and cages are put through their paces regarding wear, load capacity and material behaviour at different speeds, accelerations and temperatures. This rigorous testing is the only way to ensure trouble-free operation.

A wide range of applications

Overhead conveyors are a perfect application. :Our ball bearings are used in various overhead conveyor systems, including power and gravity fed, circular conveyors or pocket sorters,” says Dumayne. “The latter are used frequently for sorting goods in e-commerce or retail, such as toys, office supplies, clothing and shoes. They are also a popular solution for clean and reliable transport in laundries and printers.”

In overhead conveying systems, xiros ball bearings can be used directly as skate wheels, which can be adapted to the respective roller carrier system. By doing this, weights up to 5kg at speeds of up to 60 metres per minute can be transported.

The design of these ball bearings also plays an important role when it comes to safe conveying, with little wear and in a quiet manner. For example, with a bag sorter for transporting clothing textiles, the system usually consists of an aluminium guide rail with hooks for the bags. There are single-row ball bearings on the hooks, which run in a closed U-profile. Plastic covers are always used with the metallic ball bearings so that the bearings do not wear out on the aluminium profile and the system is quieter than running metal on metal.

However, single-row bearings have a fundamental disadvantage, especially on winding travel, such as when transporting a heavy jacket – the centrifugal forces ensure that the single-row ball bearings in the guide rail are subject to axial forces and the system is therefore less resilient. Igus has also found a special solution for this problem: a double-row, deep groove ball bearing. The two rows of balls run side-by-side with a connected cage. As a result, there is much less movement in the bearing and the system runs more smoothly. The double-row bearing has good cornering load capacity reducing the risk of axial overload. In addition, there are cover discs on both sides, which protect the ball bearing from contamination.