Prove Their Worth at PT. Leuwijaya Utama, Indonesia
Along with the rest of Indonesian industry, PT. Leuwijaya Utama textile company, (Leuwitex), was confronted with a government-enforced increase in electricity costs in July 2010. For Leuwitex, it meant an increase of approximately 18%. For a company with 300 textile weaving machines and 176 twisting machines consuming 2,120 kWh 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 profitablility.
Immediately after the increases were announced, the management of the Leuwitex Bandung factory set about searching for ways to reduce energy consumption. As well as ensuring unnecessary lighting, standby machinery, etc., was switched off, they took a detailed look at production. The factory, one of three in Indonesia, produces some of the most sought after fabrics in the country, and exports to Middle East, Malaysia and Europe.
Over the years, Leuwitex has developed its design and manufacturing techniques to create a range of fabrics, including a lot of custom-made fabric, that customers report has exceptional feel, design and wear properties and has placed them among the top 10 producers in Indonesia.
Attention Turned to 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, twisting machines, etc. First investigations showed that 30% 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 energy consumption of the twisting machinery was discussed.
Mechanically, the twisting machines are fairly straightforward: a series of lines of high-precision spindles are driven by two powerful motors. Frictional 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 having 256 spindles, this was clearly an opportunity for energy saving.
Tests Compare Three Options
Mr. Zenzen, Leuwitex 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. These potential “solutions” were :
- New bearings from the supplier of those in the original spindles.
- Low cost bearings of local Chinese manufacture.
- SKF Energy Efficient bearings, claiming up to 30% friction saving.
The company 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 SKF Energy Efficient bearing, with around 10% 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.
“Having satisfied myself on the energy savings issue,” said Zenzen, I needed to also be sure that the overall SKF bearing performance was equally reliable in the spindles that are so critical to the final product quality. The twisting machines have two contra-spinning spindles rotating in synchrony in opposite directions. To maintain product quality it is of utmost importance that these two spindles are rotating exactly as expected through the entire and continuous spinning/twisting operation.”
The Winner Advances to a Production Trial
Zenzen’s next test was to fit SKF Energy Efficient bearings to 10 twisting machines and begin a production run. “I was delighted to find that the product quality was exactly the same as before with constant, uniform delivery of the various designs, material thickness and feel. This was especially important because we were in the process of expanding and also replacing some machinery in readiness for a new fabric product, and needed to be sure we could rely on the machinery.”
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 Zenzen that he had indeed found his answer to the best bearings for his textile machinery from both energy efficiency and bearing performance points of view. “I was extremely happy at the outcome of this project,” said Zenzen. “We took the right amount of time to be sure we had done all that was needed to be certain we had chosen the best solution for our original short-term energy cost problem, and at the same time came to agree that it was equally the correct solution for our long-term plans as well.”
Efficiencies Add Up
The Leuwitex Bandung factory now has 25,600 SKF Energy Efficient bearings installed on its machinery and are reaping the energy and financial rewards that Zenzen first envisaged when he started his energy efficiency project.
More about SKF Energy Efficient bearings
The SKF Energy Efficient (E2) deep groove ball bearing is one of the SKF family of energy efficient bearings. SKF E2 deep groove ball bearings reduce frictional losses in a bearing by 30% or more when compared to a comparably sized standard SKF bearing. The performance increase comes from an optimized internal geometry, low friction grease and a special low-friction polyamide cage. Designed for grease-lubricated, light- to normal-load applications, SKF E2 deep groove ball bearings also consume less lubricant than comparable SKF Explorer bearings and enable longer bearing service.
Shielded SKF Energy Efficient deep groove ball bearings can last twice as long as comparably sized shielded standard SKF bearings. This means that the number of bearings needed to run an application over its lifetime can be halved. In instances where an application is run-to-failure, these E2 bearings can conceivably outlast other components in the application. Typical examples of applications for SKF E2 deep groove ball bearings include electric motors, pumps, conveyors, fans and, of course, textile spindles.