Salt producer watches its weight

Klinge Chemicals, Glasgow, Scotland, manufactures pharmaceutical- and food-grade potassium chloride products. The company's edible product line is manufactured using a ratio of two-thirds potassium chloride and one-third sodium chloride to create Lo®Salt, a low-sodium alternative to table salt that is available to the retail, catering and industrial food-manufacturing markets in 40 countries.

Almost all of the packaging of LoSalt occurs in-house at Klinge's Glasgow manufacturing facility. Product is offered in a variety of package sizes for each of the markets served, including 75-, 90-, 250-, 350- and 700-g tubs for retail sale, 1- and 3-kg sachets for catering, and 25- and 50-kg packages for industrial food manufacturing.

Weighing product is essential to keep up with strict European regulations for weight compliance. In the past, during the production of LoSalt tubs, operators would sample just 0.4 percent of production output. Every 15 minutes, line operators would take five tubs off of the line and weigh them for accuracy. Based on the results, they would then make the necessary adjustments to the filling heads.

When operators found an underfilled tub, they had to go back and check the entire batch since the last checked sample. This could be as many as 1,250 tubs, so it was easier and less time consuming to overfill the tubs.

Another problem with this system was that results were handwritten on record sheets and then filed with a separate printout for traceability purposes. This was a slow process and one that made it difficult to identify net-weight trends.

The checkweighing equipment is installed after the filling heads on the packaging line.

After two years, when Klinge analyzed its reports on fill levels for this time frame, it concluded that product giveaway averaged about 56 tons per year. The cost of this alone justified the purchase of a new checkweighing system. To improve filling accuracy, Klinge purchased a Checkpoint S-MB checkweigher along with average-weight monitoring software from Avery Weigh-Tronix. The equipment was installed after the filling heads in the production line. During the packaging process, after the tubs are filled, they are conveyed to the checkweigher where each one is weighed automatically with an Electromagnetic Force Restoration (EMFR) weighcell and then the weight is recorded. This allows Klinge to optimize fill levels with a 100-percent product sample of LoSalt tubs produced. EMFR weighcells are an electronic version of a simple beam scale. A coil is attached to one end of the beam, and a load is applied to the other. The amount of electrical current required to hold the coil at a neutral position within a magnetic field is proportional to the applied load. Since the weighcell calculates weight based on changing current rather than on physical motion, it provides an extremely fast response time, explains Avery Weigh-Tronix. This method also compensates for temperature and vibration.

With the new checkweigher and weight-monitoring system in place, Klinge says it is now saving an estimated 70 pallets of LoSalt each year. The instant data capture in the monitoring system also provides accurate 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," says Klinge plant manager Steve Lockie. "The checkweigher has more than paid for itself." The checkweigher allows up to five weight classes to be set 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 percent.

The new system also makes it possible for Klinge to weigh product of a variety of weights and sizes, with metric capabilities, from 0 to 1,500 g. This satisfies all five sizes of LoSalt tubs produced.

To learn more about inspection and monitoring, visit Packaging Digest's PACKAGING AUTOMATION technology channel at www.packagingdigest.com/info/controls/

"The checkweigher can accommodate up to 130 tubs per minute, but we're consistently running product in the eighty- to ninety-tub-per-minute output range, sometimes reaching full capacity," Lockie says.

The average-weight monitoring system records data and stores it on a portable Smartcard or on a PC, eliminating the need for operators to keep handwritten records, which reduces reporting errors. An LCD touchscreen is built into the front panel of the checkweigher. Current statistical information, a status bar and nominal weights are displayed directly on-screen. Users can easily change settings and can make production adjustments by way of menu-guided operation and navigation icons.

More information is available:
Avery Weigh-Tronix, 877/888-1646. www.wtxweb.com.