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Tuesday Apr 27
Keeping Weight Errors Low
New checkweighing equipment keeps product giveaway to a minimum
Klinge Chemicals of Glasgow, Scotland is a manufacturer of food-grade and pharmaceutical potassium chloride (KCl) products. Klinge uses a 2/3 KCl and 1/3 sodium chloride formula to produce LoSalt, a low-sodium alternative to table salt that is available to the retail, catering and industrial food manufacturing markets in 40 countries.
Given the various uses of LoSalt, the product is packaged in 75-, 90-, 250-, 350- and 700-g tubs for retail sale. Industrial food markets generally receive 25- and 50-kg packages, while LoSalt is packaged in 1- and 3-kg sachets for catering markets.
European regulations strictly enforce product weight compliance. To ensure compliance in final product weights, Klinge Chemicals operators were sampling just 0.4% of production output. Every 15 minutes, line operators took 5 tubs off the line and weighed them for accuracy. Necessary adjustments were made to the filling heads based on the sampling results.
During the inspections, when operators found an under-filled tub, the entire batch since the last sampling—as many as 1,250 tubs—had to be checked for weighing compliance. To save time on inspections, it was easier to overfill the tubs.
In addition to inefficient weighing practices, sampling results were handwritten on record sheets, which were then filed with a separate printout for traceability purposes. This slow process made it difficult to identify net weight trends.
After analyzing two years of reports on tub-fill levels, Klinge Chemicals concluded it gave away an average of 56 tons of product annually. The cost of this alone justified the purchase of a new checkweighing system.
The manufacturer installed an Avery Weigh-Tronix in-line checkweigher and average weight monitoring software technologies. The Checkpoint S-MB was integrated into the production line after the filling heads. Using electromagnetic force restoration (EMFR) weigh cells, each tub is weighed automatically after being filled. The weight is then recorded, allowing Klinge to optimize fill levels with 100% product sample of LoSalt tubs produced. EMFR weigh cells are an electronic version of a simple beam scale.
With the new checkweigher and weight monitoring system in place, Klinge saves an estimated 70 pallets of LoSalt each year. The instant data capture in the monitoring system also provides statistics for production and quality control, ensuring that LoSalt tubs are filled with the appropriate amount of product.
“We are completely satisfied with the equipment and the amount of time and money it saves,” said Klinge Chemicals Plant Manager Steve Lockie. “The checkweigher has more than paid for itself.”
The checkweigher technology recognizes up to five weight classes for out-of-tolerance products. If the average weight of the product is too high, the supervisor can adjust the filling head to reduce the amount deposited into each tub. If weights are too low, a ram-pusher mechanism rejects the tubs into a receiving bin for proper disposal. According to Lockie, total rejected tubs due to poor filling are now less than 0.5%.
Current statistical information, status bar and nominal weights are displayed directly on an LCD touch-screen built into the front panel of the checkweigher. Setting and production adjustments are easily made by way of menu-guided operation and navigation icons.
The flexibility of the new system makes it possible for Klinge Chemicals to weigh products in sizes ranging from 0 to 1,500 g, satisfying the varying sizes of LoSalt tubs that are produced.
“The checkweigher can output up to 130 tubs per minute, but we’re consistently running product in the 80 to 90 output range; sometimes reaching up to full capacity,” Lockie said.
Source: www.foodengineeringmag.com – April 2010
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