Loose wheel with PA6 hub and PUR tread, Ast

Loose wheel in PUR with hub in PA6, ESD

This is a loose wheel with a tread in polyurethane and a hub in nylon, made electrically conductive for surroundings where static electricity has to be led away. The tread has a hardness of 98 degrees Shore A, a firm polyurethane with low rolling resistance and good load capacity. What separates the series from an ordinary wheel is the ESD property: the material leads static charge away to the floor instead of letting it build up in the cart and the goods.

The ESD function matters where a spark or a discharge can damage sensitive equipment or disturb a process. When the wheel rolls, a charge otherwise builds that can jump across to components, circuit boards or staff. An electrically conductive wheel gives the charge a path down into a dissipative floor, so the potential is held low. For that to work the floor and the whole chain have to be conductive, not just the wheel.

The polyurethane tread at 98 Shore A rolls easily and carries properly without being squashed, and at the same time it is gentler on the floor than steel and hard plastic and runs more quietly. Cast PUR takes abrasion and resists most oils, greases and mild chemicals. With many starts and stops, as on an assembly line for electronics, the wheel gets going easily and keeps a smooth run.

A comparison helps. An ordinary, non-conductive polyurethane wheel can carry more for the same size because the ESD additive in the material lowers the load capacity somewhat; here it sits at up to 160 kg per wheel. A softer conductive rubber wheel damps better but rolls heavier. This firm PUR tread is a middle choice: conductive, floor-friendly and load-capable enough for carts in electronics and cleaner production.

The hub is cast in PA6, a light and corrosion-free nylon that gives a stiff body and holds its shape under load. Inside sits a ball bearing that gives low friction and a smooth run, even after the wheel has stood still for a time. The combination of a light hub and a ball bearing suits carts that are moved often without you wanting to fight them.

The wheels come in diameters from 100 to 125 mm and handle load capacities up to 160 kg per wheel. A larger diameter rolls more easily over joints and lowers the rolling resistance, while a smaller one keeps the overall height down where space is tight. Since this is a loose wheel it is supplied without a bracket and mounted straight onto its own axle through the hub.

Where does it fit? The ESD wheel sits under carts and underframes in electronics manufacturing, clean rooms, laboratories and production of sensitive components, where static electricity is a risk. It also works where regulations call for dissipative equipment. On a dissipative floor the wheel becomes part of the chain that keeps the whole work station safe from static.

Think about the operating environment. Polyurethane is happy in dry to slightly damp indoor surroundings and at normal temperature. The ESD property only works together with a conductive floor and a dissipative chain in the rest of the setup. If the wheel stands still for a long time under full load, the tread can take a temporary flat spot that rolls out after a while; that is normal for elastic materials.

Do you want to know whether the load capacity is enough and how the whole chain has to be conductive for the ESD protection to work? Get in touch and we will go through floor, load and requirements together.