An Ishida RV multihead weigher with an IP69K rating is providing protection against humidity and water ingress in order to accurately weigh and pack large volumes of peeled and cooked whole potatoes at specialist Friweika.
The company explains that potatoes are “wet” products, containing around 80% water, and at Friweika they are conveyed to the multihead weighers using streams of water. In addition, very frequent water-based cleaning is needed to avoid the build up of starch deposits, which also contain corrosive fruit acids.
The IP69K rating of the Ishida model, which is unprecedented in any multihead weigher, makes it the world’s most resistant to wear and to water ingress.
The 10-head weigher forms part of a new line, packing up to 2.5 tones per hour on a 24/7 basis at Friweika’s 140,000-tonnes-per-year processing operation at Weidendorf, Germany.
The importance of continuing reliable operation of the weigher is underlined by what would happen if it were forced to shut down. The sensitive potatoes would rapidly discolour, with the immediate loss of two tons of production.
In addition to its reliability, the weigher’s design also ensures gentle handling of the potatoes. Thanks to their round shapes, an almost flat dispersion table and level dispersion feeders are enough to keep them moving smoothly to the pool hoppers. Inter-hopper drop distances are kept short, and the double-opening weigh hoppers release the product onto a discharge chute that delivers each weighment to a special distribution system, which can handle both 500g retail and larger wholesale or catering packs.
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More photos: Solution for weighing and packaging potatoes
For the 500g packs, a single mobile funnel places successive weighments into an array of six separate funnels. In a single cycle, these then dip simultaneously into three rows of two thermoformed trays, releasing the product. To make 2kg or 5kg catering packs, this distribution system is wheeled aside and replaced by a four funnel array, which can fill either four or two packs per cycle.
A further important point about Ishida’s development of the RV-Series is that the exceptional toughness and water-resistance were achieved with no sacrifice of speed or accuracy. The accuracy routinely achieved at Friweika is excellent, as Production Manager Michael Gerischer confirms.
“Actually, cooked potatoes are not an expensive product, but considering the volume we produce, we are keen to minimize giveaway,” he explains. “With 500g trays, for example, it doesn’t exceed 1.5%.”
A single operator runs both the new weigher and the thermoforming machine. Changing pack formats is largely a matter of pressing buttons, to bring about pre-programmed adjustments, and swapping over the distribution systems. Maintenance requirements are described by Friweika as “very low”.
