New alliance increases reach of pneumatic vibrators

Through bearings and power transmission distributor Bearings International (BI), pneumatic and electric vibrators manufacturer OLI has released a new range of pneumatically powered centrifugal vibrators to the South African market.

BI CEO Burtie Roberts explains that the company has increased the range it has available on request for South Africa to six pole motors, with a maximum power of 30 000 kilogram-force (kgF). This vibrator is already available in Russia. The minimum centrifugal force of the vibrators is from a 0.04 kW single phase motor generating 4 kgF.

OLI has three main divisions offering optimal solutions for all requirements. The industrial vibrators division focuses on vibrating equipment, the flow aids division deals with flowability problems and the concrete consolidation division specialises in reliable and efficient concrete compaction.

“In South Africa, we have a stockpile worth over R16million, in Johannesburg. This means that 99% of our orders are available ex-stock, which, in turn, enables us to deliver immediately, depending on the location it needs to be delivered to using road transport,” Roberts says.

Further, he points out that the vibrators from OLI are made from premium-grade aluminium alloy, cast iron and steel alloy, which means that the OLI range is ideal for heavy-duty applications, where the heat and pressure are high.

The pneumatic and electric vibrators supplied from OLI use F-class insulating materials, which have been tested to operate at 155 ºC. Roberts explains that this number was reached by hot-spot measuring and by adding the ambient temperature of the machine.

“Electrical machines are usually designed with an average temperature below the rated hot-spot temperature to allow for acceptable life. Insulation does not suddenly fail if the hot-spot temperature is reached, but useful operating life declines rapidly,” he explains.

OLI products are also rated at IP 66, which means that the pneumatic and electric vibrators can handle water projected in powerful jets, from the water nozzles that are 12.5 mm in diameter or larger, with the water blasting out at 100 kPa against the vibrator enclosures from 3 m away, without any harmful effects.

He explains that these high-quality measures have been tested using a step-by-step approach that identifies all possible failures in a design, manufacturing or assembly process; in, for example, the motor bodies, bearing flanges and shafts, with each designed using failure modes and effects analysis.

OLI uses vacuum-pressure impregnation, a process by which a fully wound electric apparatus stator or rotor is completely submerged in a resin. Roberts emphasises that through a combination of dry and wet vacuum and pressure cycles, the resin is assimilated throughout the insulation system.

“Once thermally processed, the impregnated windings become a monolithic and homogenous structure. The resulting benefits are higher dielectric strength, increased mechanical strength, greater thermal inductivity and superior protection against the ingress of water, chemicals and contaminants,” Roberts explains.

Depending on the size of the pneumatic or electric vibrators, the materials used to create it differ. He says that smaller vibrators are created using aluminium cast alloy, used for its strength and cost, with larger vibrators and motors being made from ductile cast iron that has the same tensile strength as mild steel.

Owing to OLI vibrators being distributed throughout South Africa and Africa through BI, there have been little to no challenges in supplying its clients with pneumatic and electric vibrators, Roberts points out. This is in line with OLI’s global policy of providing vibrators for clients whenever needed.

“OLI has a team of technical specialists in South Africa who can provide technical assistance and advice for screening, feeding or flow-aid applications problems in the mining, food, pharmaceuticals or civil concrete industries,” he concludes.