By replacing the standard induction motors used on its ring spinning machines with WMagnet motors from WEG, Buettner has reduced its annual power consumption by 33 per cent and increased its machine utilisation by 80 per cent. These dual gains have delivered substantial savings in production costs and improved the company's profitability.
Buettner is a Brazilian company that has been active in the textile sector for over 100 years; it currently produces more than 2million bath towels per month for export to around 40 countries. The markets in which Buettner operates are highly competitive, so the company is always seeking ways to increase efficiency and reduce costs.
It was with these two objectives in mind that Buettner purchased three WMagnet motors from WEG in order to assess their performance on the company's ring spinning machines. In fact Buettner reduced its annual power consumption by 33 per cent and increased its machine utilisation by 80 per cent. The outstanding success of the motors means that WMagnet motors are now set to become a standard fitment on all of the 45 ring spinning machines operated by the company. Aires Fantoni, Electrical Maintenance supervisor at Buettner, states: "Our goal is to replace all of our standard induction machines with WEG WMagnet motors within three years."
The ring spinning machines are where raw cotton is transformed into threads of the desired thickness for each product, and then wound onto spools. Previously the machines operated with standard induction motors at two discrete speeds; this meant that it was necessary to stop the machine for each gear change – a process that resulted in substantial losses in production time.
Seeking to overcome this problem, WMagnet motors were installed; these are controlled by WEG frequency inverters that vary the machine speed from zero to 1800rpm. Fontoni says: "This arrangement means that our personnel no longer need to stop the machine to change gears; and we also benefit from the soft start provided by the WEG VFD, which reduces machine wear."
The advantages of the motor replacement programme to Buttner are many. In addition to lower maintenance costs (practically zero), the variation of motor speed with constant torque and energy savings increases both the reliability and the performance of the company's production line.
Marek Lukaszczyk, European Marketing Manager for WEG, comments: "We can deliver the same package of benefits with these motors across a wide range of applications – conveyors, compressors elevators – anywhere where variable speed with constant torque and high efficiency are required. As demonstrated by the Buettner application, the WMagnet motors are ideal for applications where eliminating a gearbox is essential; the motors can do this because they can operated self-ventilated over a wide speed range.
"The space saved by gearbox removal is complemented by the size of the WMagnet motor itself. Compared to an equivalent induction motor, the volume of the PM motor is reduced by roughly 47 per cent, resulting in a higher torque/volume ratio and a reduced weight by as much as 36 per cent. Moreover, the PM motor is at least one frame size smaller than the induction motor; and in some cases it can be two frame sizes lower. Reducing the frame size, the cooling system is consequently reduced for the same torque/power ratio, resulting in a significant reduction of noise.
"Finally, as regards energy efficiency, the high-energy magnets in our WMagnet motors have lower Joule losses in the rotor compared to conventional squirrel cage induction motors. As Joule losses account for a significant portion of the total losses in induction motors, replacing the squirrel cage construction with magnets ensures far greater efficiency – easily exceeding the requirements of new harmonised IE (International Efficiency) grading standards IE2 and IE3 that will replace the current voluntary EFF labelling scheme (EN 60034-2:1996) around 2010."
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