Aluminium worm geared motors selected for conveyors

LAC Conveyor Systems has chosen Lenze aluminium worm geared motors for its range of pallet roller conveyors. LAC sells mainly to UK machine building customers, often in the food and packaging industries. The company's modular pallet roller conveyors are often used in end-of-line applications, typically downstream of a palletiser. The choice of Lenze aluminium worm geared motors was based on the need for rapid response to market demands, and for a cost-effective geared motor that is adaptable and simple to mount.

Pallet conveyors can be either standalone units with stop/start functions, or they can form a fully automated zero-pressure accumulation system. They are designed for the heavy end of the market, with pallets or drums fed onto the conveyor by machine or fork truck. LAC designs its conveyors for heavy-duty use, with thick-walled rollers driven by chain, a fully enclosed side frame of 5mm folded steel, and an external shaft-mounted motor. Normally loads are up to 1500kg, but LAC also designs for 2500kg loads; part of LAC's philosophy is to keep downtime to a minimum, even when conveyors receive rough treatment.

Loads are typically driven at speeds from 4-14m/min and this relates to gearbox output speeds 16-56rpm, a range where worm gears are well suited and economical. The Lenze range of aluminium worm geared motors covers power ratings from 60W to 2.2kW with output speeds 10 to 260rpm and many models available from stock. Geared motors are bolted to the side frame of the conveyor using a standard gearbox flange. The roller shaft passes through directly into the hollow shaft of the gearbox. This optimised mounting means that the gearbox replaces one bearing and takes half the load from the roller. Motors have a wide voltage range, a thermal switch and metal cowls as standard. The gearboxes are grease lubricated for a maintenance-free life of 15,000 hours.

Rapid deliveries

LAC's customers are demanding ever-shorter lead times; instead of a standard delivery of six weeks, customers and, in particular, those in the food industry, often look for times of two weeks or less. Furthermore, food industry customers may need frame construction in 304 or 316 stainless steel with modifications to remove dirt traps. This puts pressure on the design engineers and component suppliers such as Lenze. However, the end customer gets one further and major advantage: LAC has a sufficiently large manufacturing facility to build and test the conveyor on site before it is shipped.

In a recent contract, LAC provided a roller pallet conveyor for a sterilisation plant. Medical equipment was loaded onto steel jigs on the conveyor by a six-axis robot. The robust construction of the conveyor minimised the deflections, which was essential for the positioning accuracy of the loading and unloading robots. The loads then travelled around a rectangle with chain transfer units for the 90-degree corners, stopping at the sterilisation cabinet. A reject spur was added to allow isolation of faulty loads without stopping production.

The sterilisation plant was one case where Lenze inverters were needed to position the jigs accurately for the robots to load and unload. The inverters slow the load to a stop using a fixed profile, which greatly improves the accuracy of the stop position compared to an uncontrolled stop. Although many conveyors run at fixed speed without inverters, sometimes the final speed required is uncertain. Also certain types of loads can be unstable and liable to toppling, and here the inverter can act as a soft start/stop. The Lenze SMV inverter with IP65 protection is a good choice, as it can be bolted directly to the machine frame. Food industry customers generally prefer a stainless steel enclosure, and here the simple and low-cost IP20 smd inverter is suitable for enclosed mounting.

Chris Unwin, Sales Manager at LAC Conveyor Systems, comments: "Being a privately owned company, we are able to design and manufacture in-house almost all types of conveyors systems. The choice of geared motor is an important element of our customer service. Lenze worm geared motors are a good fit, combining availability with economy".