Driving to produce more pot noodles

By investing in new automation equipment, Unilever’s production plant in South Wales has exceeded its daily production targets and has synchronised its pot noodle manufacturing process with the packaging section. Dean Palmer reports Unilever Best Foods’ manufacturing plant in Crumlin, South Wales currently produces around 150 million pot noodle snacks per year, and so reducing downtime on the production lines and increasing throughput are crucial to the business. Production line three at the site has recently been automated. The line comprises a number of pasta mixing and processing operations and a feed into the next section completes the packaging process. As project manager at Unilever, Mark Edwards, explained: “We have upgraded all three lines with Unidrive variable speed drives [from Control Techniques]. Line three had been running Control Techniques’ Vector drives for 10 years and these had performed well, but we wanted to bring the whole line under PLC control and so chose Unidrive with UD73 plug-in modules to give us Profibus connectivity.” Edwards continued: “The result has been excellent, with the line exceeding its daily targets. The most crucial factor has been synchronism of the drives from the process and through to the packaging section.” There are 12 Unidrives on this section of line one, varying from 1.1kW for the fryers, up to 7.5kW for the roller drives and communicating via Profibus with the PLC. Each motor on the line (Leroy Somer MV AC motors) is fitted with a 1024 ppr incremental encoder feeding back to its drive. The speed of the line as a whole is taken from a reference on the rotary cutter Unidrive and is digitally locked, with a small offset on two of the drives on the stretcher conveyor and steamer to provide slight stretching of the noodles. Adjustment of this offset gives a direct correlation with the weight of the noodles in each pot. If any drive fails, the line stops, with the exception being the sheeter drive, which will continue until all noodles have been processed through. In the cutter section, three drives are in a separate control loop, with absolute encoders providing precise synchronism. At the end of this section, an additional encoder provides a reference signal for the subsequent packaging section. “The PLC only provides initiation and switches on fans and pumps,” added Edwards. “All of the programming is on the co-processor modules within the drives themselves. This gives us added flexibility if there is a problem and means that the whole line doesn’t stop unnecessarily. We find that Unidrive is ideal and all three lines are fitted with them [a total of 31 drives].” Control Techniques’ Unidrive encompasses open loop V/F, open loop sensor-less Vector, closed loop Flux Vector and AC brushless servo, all in a single package. Each control mode can be easily and quickly changed from the on-board keypad or through UniSoft, a Windows-based configuration software tool. So users need only specify, stock and commission one AC drive product.