A 14 head Ishida CCW-R multihead weigher is enabling leading German fruit and nut snack specialist Farmer’s Snack to meet increasing demand for pocket-sized packs.
The multihead weigher forms the core element of a new packing line, installed by Farmer’s Snack after winning a major contract from a discount retailer. The line primarily handles the weighing and filling of pocket-sized bags with a fill weight of 40g, but is also able to pack 150g flat bags. The weigher meets specifications with regard to speed and can process up to 140 bags per minute. In view of the high value of the company's products, weighing accuracy is also an important factor. Maximum weighing accuracy is 0.1g and the standard deviation (weighing consistency) for a filled bag is well below 1g.
"Compared with our other multihead weighers those are particularly good figures, which we can achieve with just a few adjustments," says Boie Karstens, a member of the management team at Farmer’s Snack. "We were also pleasantly surprised by how well the weighing of sticky snacks works." He expects the multihead weigher, which operates in 2- or 3-shift mode, to pay for itself within three years.
The line packs trail mix (‘’Studentenfutter’’) and nut and fruit mixes with chocolate under the Farmer's Snack brand, as well as several product mixes for discount retailers and airline snacks. To ensure that the system can handle both free-flowing and sticky products, Farmer's Snack uses specifically adapted dispersion feeder tables, radial feeder troughs and hoppers for each type of product.
For nut products, a dispersion table with an incline of 10° and narrow radial feeders made of polished flat stainless steel are used. For products containing sticky fruits, these are swapped for a plastic-coated dispersion table made of corrugated sheet metal with a 20° incline and radial feeder troughs of the same design with an incline of 6°. The hoppers on the weigher are also fitted with double-opening plastic doors with an anti-stick ribbed finish.
The snack products reach the multihead weigher from above, via an elevator. A highly sensitive sensor below the dispersion table controls the supply to the vibrating radial feeder troughs and ensures an even product flow to the hoppers. The 14 pool hoppers, arranged in a ring, hold the product for a short time and feed a further set of 14 weigh hoppers. As soon as a weigh hopper becomes empty and requires product, a signal is sent to the corresponding pool hopper. Within a fraction of a second, a microprocessor determines those weigh hoppers whose combination comes closest to the target weight. Unlike conventional multihead weighers, the Ishida CCW-R model can calculate three optimal weight combinations, double check them and then select the one nearest to the target weight - all in a single cycle. This minimises error discharges, increasing efficiency, while also enhancing weighing accuracy and consistency. Below the weigher, the precisely dosed portions are filled directly into bags via a timing hopper.
An intuitive graphical user interface makes it easier to operate the multihead weigher. The benefit for Farmer's Snack is that downtime is minimal, as daily product changeovers can be carried out simply by calling up the relevant pre-set on the weigher’s touch screen display. Application-specific dispersion tables and radial feeders can also be replaced in just a few movements, without the use of tools.
For Farmer's Snack, the investment in packing technology has been a great success. "Before investing, we tested the weigher with our products and achieved an output that no other provider could offer for an equivalent 14-head model,” says Boie Karstens. “The fact that the machine was available for quick delivery was another advantage."
