The machine's user can also set how precise the machine's control over the product should be. Frank used beans to demonstrate how the sorting machine sorts beans. "The slightest variation in the bean's colour is detected by the sorter. Even if this means the bean is not yet unfit for consumption', says Frank. "Our machines are getting better at detecting minuscule differences in products. This is, however, completely dependent on the client's wishes. A cheaper supermarket will sort the beans less strictly than a 'premier brand chain store'. Since our machines do not see slight blemishes as a bad product, less product ends up in the rubbish bin. This is a small percentage, but ends up being a large number. When someone produces 5 000 tonnes per year, and can waste 1 percent less in this way, it ends up being 50 tonnes per year. The precision of our sorting machines therefore means less waste."
The sorting process differs widely per product. The size, as well as condition of the product plays a role in the choice of sorting machine. "A wet products falls differently to a dry one", says Frank. "Firstly, the products are moved to a conveyor belt by means of a vibration plate. This spreads the product out, making everything visible. Then the product is scanned using a Smart Surround View. This is a combination of a camera and, optionally, a laser. The colour and shape are recognised by the camera. The laser recognises the product's structure. How these two are set determines how strictly the product will be sorted. Lastly, the small and unwanted products are blown by air valves into a separate area."
Tomra manufactures various kinds of sorting machines. One makes use of a conveyor belt, while the other uses free fall. Each has its own advantages. "With wet products we use a conveyor belt. Unwanted objects are blown away at the end", explains Frank. "Free fall is used with dry of frozen products. This ensures that there is, regardless of the conditions, a optimum controlled product flow. Unwanted products are not separate out by means of air valves. Larger objects are sorted by means of rubber flaps because air is not effective."
An important aspect of the sorting process is, according to Frank, to keep the product in sharp focus. Contrast is key. "As long as we can create contrast with regards to colour, form or other biological properties, we can perfect the sorting process", he says. "In order to achieve this, the machine's stability is of utmost importance. The lighting output must be constant, which is why we use LED lighting in our latest machines. Keeping the camera, and lighting unit, clean is crucial in order to keep down times to a minimum. All our machines are equipped with systems which solve this as optimally as possible. This is so the machines can keep running throughout the season."
Besides creating contrast, and processing an image, it is also important to remove that bad bean or bit of plastic from the product flow, whilst keeping the good product. "Tomra has developed a special air valve to achieve this. It has a very fast switching time and uses as little air as possible", explains Frank. "This results in much less wastage of good products. If a client that processes 5 000 tonnes of product can reduce his wastage from 1% to 0,5 percent, by using a Tomra machine, this has a direct effect on their turnover, as well as the end product. They can produce 25 tonnes more than before. Besides getting better quality, they will make a return on their investment that much faster."
The manufacturer from Leuven also advises their clients about defects in the production line. According to this sorting specialist, it is important to recognise, and remove, the defective products as quickly as possible. "In a chips line, we want to remove the rotten potatoes before they get cut", he says. "Smaller defects can be peeled off, so the client can have less defects and more revenue. This is not only good for the client, but also for the environment."