Energy efficient bearings prove their worth at textile plant
December 7, 2012
By Special to Manufacturing AUTOMATION
Along with the rest of Indonesian industry, Leuwijaya Utama textile company (Leuwitex) was confronted with a government-enforced increase in electricity costs. For a company with 300 textile weaving machines and 176 twisting machines consuming 2,120 megawatt-hour (MWh) hour per month in their Bandung factory, this represented a major increase in operating costs, and one that needed a speedy reaction in order to reduce the effect on the threat to bottom line profitability.
Immediately after the increases were announced, the management of the Leuwitex Bandung factory set about searching for ways to reduce energy consumption throughout the entire factory. As well as ensuring unnecessary lighting and standby machinery were switched off, they took a detailed look at the production. The factory, one of three in Indonesia, produces some of the most sought-after fabrics in Indonesia, and exports to Middle East, Malaysia and Europe.
Focus on twisting machines
To produce the daily volume of almost two tons of fabric, the Bandung factory has the usual range of textile machinery including electric motors, weaving machines, spinning machines and twisting machines. First investigations showed that 30 per cent of the factory’s energy consumption was consumed by the twisting machines, an important piece of machinery that is critical to fabric quality. So as well as taking measures to correct electric motor energy losses and optimizing frequency converters for the overall electricity supply, the team at the plant discussed the energy consumption of the twisting machinery.
Mechanically these machines are fairly straightforward: a series of lines of high precision spindles driven by two powerful motors. Frictional losses and energy losses occur in the rotational motion as these machines operate 24 hours per day, by virtue of the quality of the bearings fitted at each end of each spindle. With 176 twisting machines, each with 256 spindles, this was clearly an opportunity for energy saving.
Evaluating the options
Leuwitex’s plant manager decided on a very practical and specific way to investigate a way to reduce energy consumption for the long term. He would select three of the most likely ways to optimize bearing cost and frictional losses and put them to test in his spindles. The three potential solutions were:
1. New bearings from the supplier of those in the original spindles
2. Low-cost bearings from local Chinese manufacturer
3. SKF energy efficient bearings, which claimed to offer up to 30 per cent friction savings
He fitted the bearings to three separate spindle lines and ran them for three months, monitoring specifically the energy consumption of those three lines. The result was an overwhelming victory for the energy efficient bearing, with around 10 per cent total energy savings. Extrapolating this result to the expected lifetime of the spindles would conclusively save the most energy and deliver the lowest total cost of operation.
Extending tests to a production run
The next test was to fit the energy efficient bearings to 10 twisting machines and begin a production run. The initial test was extended by adding more lines of spindles while keeping the original 10 operating. Regular product quality checks among all the machines convinced the plant manger that he had indeed found his answer to the best bearings for his textile machinery from both energy efficiency and bearing performance point of view.