An international seed company has installed an Ishida ‘Lilliput’ multihead weigher to increase capacity and ­provide greater control over pack fill accuracy, which is of crucial importance in this competitive business

A single seed often has the potential to produce many kilograms of fruit or vegetables. Yet a Little Wonder tomato seed, for instance, measures just two millimetres across and weighs less than 0.002g. This large ratio of value to weight means that getting products into packs is a crucial part of a seed merchant’s business and any advance in accuracy can directly affect the bottom line.

The South African company Starke Ayres markets and distributes to commercial vegetable growers in many countries across Africa, North and South America, Europe and the Mediterranean as well as Australia. The company also has a strong national retail component supplying hobbyists with vegetable and flower seeds as well as a range of pesticides and plant nutrients.

Starke Ayres produces a great variety of pack sizes, mainly within the range 0.33g to 100g. Packing seeds by hand is highly labour-intensive. In manually weighing 1,000 hybrid tomato seeds, for example, overweight at the level of over five per cent is unavoidable in order to be absolutely sure that the pack contents will measure up to the declared content.

Knowing that multihead weighing could transform this situation, Starke Ayres looked into the available options and chose an Ishida CCW-M-214W-S/005-SS. Known as the ‘Lilliput’ because of its small size (it has a 650mm x 650mm footprint and 50cc (0.05 litre hoppers), it is designed to handle very small target weights with great accuracy and speed.

The Ishida Lilliput at Starke Ayres has brought giveaway down to just two per cent, a reduction of 60 per cent.  This means for every 35 packs or so, a given batch of seed will yield one extra pack. Automatic weighing on the Ishida achieves this while practically eliminating the possibility of any underweight packs reaching the grower, something that manual weighing could never accomplish with such a low level of giveaway.

Seed is delivered to the top of the Ishida using a vacuum system. It passes through the weigher driven by gravity with the assistance of a powerful vibratory system. To prevent air currents from interfering with the process, the entire machine is enclosed in a transparent case.

At the outlet of the discharge chute of the Ishida, weighed product falls into a bagmaker. The filled and sealed bags are bundled and palleted.

With manual weighing, the packing process ran at between 15 and 20 packs per minute. The Ishida has increased this by well over 250 per cent, with a typical speed of 52 packs per minute.

Apart from the primary benefit of consistent pack weights, the new multihead has speeded up distribution and increased capacity while markedly reducing labour costs.

Starke Ayres also believes it benefited from the services surrounding the weigher. “The after sales support and training given by Ishida was outstanding,’’ says Tewie Pretorius, factory manager at the company’s vegetable seed packing plant.


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