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Uptime justifies cost of OEM maintenance

Battle of the clichés: “a penny saved is a penny earned” versus “penny wise and pound foolish.” When it comes to regular maintenance for machines, the latter appears to win hands down.

Battle of the clichés: “a penny saved is a penny earned” versus “penny wise and pound foolish.” When it comes to regular maintenance for machines, the latter appears to win hands down.


That certainly came through in a presentation this spring by Ralf Wittstock, responsible for maintenance and planning at the German facilities of Bericap (Budenheim, Germany), one of the world’s largest molders of plastic closures and the leader in Europe with €470 million/yr in turnover, molding 48 billion closures per annum. He spoke at the Arburg technology days/open house; Wittstock put the standing-room only audience of molders at ease quickly, opening with his name and stating, “Yes, we were invited by Arburg to speak here, but all of the numbers are ours.”


The molder in Germany runs a fleet of 84 injection molding machines, 68 of them from Arburg—11 of them older Arburg 305s: “The machines are 18 years old and they run fine”—with an additional 16 from other suppliers. Cycle times vary from 5.5-30 seconds with shot weights ranging between 15-200g. Polyethylene (high density, low density, and linear low density) accounts for more than 90% of the plastics processed, with operations 6-7 days/week, 24 hours/day.


The firm’s official preventive maintenance (PM) program took shape in 1998 when Bericap agreed to allow Arburg to inspect 24 of the newer presses annually and perform necessary maintenance on these; the remaining 33 were not inspected by the OEM. “From the start management questioned whether we needed this. It costs money. But then we had a machine go down unexpectedly for a longer time, and the reason (a hydraulic seal) could have been prevented. That was the ‘ah-ha’ moment for management,” Wittstock recalled.


The molder worked with Arburg to devise its PM program to include basic calibration and recording of actuator valves; measurement/adjustment of platen parallelism; calibration of additional control valves; a general visual inspection; and, of course, a safety check.


Since 1998, recording of these values, and the performance of the machines, gave Bericap enough information so that in 2007 it decided the inspections were required only every 24 months. The increased interval also means it now can have all 57 of the machines inspected for about the same amount of effort. Currently two or three machines are inspected monthly, coordinated with mold maintenance.


Inspections cut machine downtime by 36%


“At the start, everyone focused on the costs of the PM program,” recalled Wittstock. But over time Bericap saw that the downtime of machines with inspection contracts was 36% lower than those without contracts. “As far as costs/benefits, the ratio of effort to increased added-value is just 1:3,” he said. ISO inspectors look favorably on the program, he added. About 50% of maintenance costs are associated with machines’ hydraulics. “From our other facilities we know this is actually low; oftentimes up to 75% of costs for maintenance and repairs come from hydraulics,” he explained. The most common problems are defective valves and pumps, and leaks.


Of the costs associated with PM of hydraulics, Wittstock said about 75% can be attributed to contamination (solids, water, air) and the condition of the oil used. As a result of that finding the processor in 2006 introduced an oil and filter management program, with twice-yearly testing of oil quality for purity, copper content, iron content, neutralization number, and water. “Oil changes are no longer performed based on operation hours but instead based on oil quality,” he said. Bypass filters are installed on the firm’s new presses in order to maintain oil’s purity. New oil drums always are filtered before use. Bericap’s goal with oil filtering is to achieve purity class 15/12/9 according to ISO 4406 (no more than 15 particles larger than 4 µm, 12 larger than 6 µm, and 9 larger than 14 µm are present in 100 ml of oil). Copper content, one of the contaminants measured regularly, is indicative of corrosive or abrasive wear, and iron content indicates wear on pistons, cylinders, and pumps and valves, among other components.


The neutralization number of the oil is the acidic constituent content of it, he explained, and allows Bericap to track relative changes. “The absolute value is not significant,” he said, but the tracking has Bericap convinced it likely can keep its oil checks at just biannual intervals. Some molders in the audience questioned whether this interval was too long, but Wittstock said that, at least based on results since 2006, it appears to be at least frequent enough.


Wittstock allowed that, due to the oil and filter management program’s youth, comparison figures for spare parts’ costs and machine downtime still were not available. But some concrete benefits of the PM and oil/filter program already are very evident. “Unplanned downtime is approaching zero; this has been the huge advantage of our program,” he said. Ongoing goals include a reduction in spare parts’ costs and a two-to-three-fold increase in oil service life. Bericap recently switched from standard HLP hydraulic oil to HLP-D (detergents) oil. “The viscosity index is still the same but the new oil’s viscosity doesn’t change as much due to temperature changes (of the oil),” he said. The change has improved machine startup, he said, and also brought other benefits.


Output up 50%, energy use down 38%


Energy conservation initiatives, like the PM and oil/filter management programs undertaken by Bericap and described above, are no longer options so much as they are necessary tools that can be used to lower operating costs, maintain factory efficiency, and even support environmental sustainability.


That certainly is the view at PakTech (Eugene, OR), which brought in its molding machinery supplier, Husky Injection Molding Systems (Bolton ON, Canada), when the processor of carrier handles for bottles wanted to improve operations and expand upon its existing location. Husky experts in April 2007 visited PakTech’s 43,000-ft2 facility, which housed 11 molding machines (including six Husky H400 RS 80-70 presses). At the time, PakTech manufactured about 144 different products and operated five days a week.


Husky’s factory planning team helps processors achieve maximum Overall Equipment Efficiency (OEE) by improving operating efficiency, cutting costs and conserving energy. After a two-week assessment of PakTech’s facility, several factory planning recommendations were made to streamline the company’s infrastructure and energy consumption dramatically. These included:


• Implementation of a new chilled water technology system—including variable-frequency drives, upgraded chillers, towers, pumps and tanks, and flow rate improvements—reducing energy consumption by 34%.


• An upgrade to the resin handling system, including a new railcar unloading system.


• An improved electrical system to optimize power quality through reductions in kilowatt demand and amps, as well as increasing the power factor to 95%, which resulted in a 5% reduction in energy consumption.


The team from Husky also offered some general energy saving tips including the recommendation to stagger machine startups, correctly size equipment, switch machines off for idle periods longer than 20 minutes, pause the circulation of water through molds when not in use, optimize compressed air usage, and periodically check for barrel insulation quality. Based on these and other recommendations, along with the company’s growth expectations, the existing facility had the capability to increase production by as much as 50% while still using the existing equipment.


At PakTech, the improved chilled water system reduced consumption and resulted in energy bill savings of $15,000-$18,000 per year. “With our new presses and new processing system we’re saving about 38% in energy costs and energy use,” says Dan Shook, PakTech’s general director.
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