How Pfalzgraf weighs very sticky fruit

Fresh fruits are a challenge in automatic weighing: they are not only strongly adherent but also impact-sensitive. Frozen gateau manufacturer Pfalzgraf uses a Type CCW-M 106 multi-head scale for this task.

The Pfalzgraf Konditorei GmbH in Pfalzgrafenweiler uses a linear multi-head scale to meter fruit toppings for gateaux and cakes. The Ishida weighing machine is specifically tailored to handle strongly adherent fresh products and smaller production batches. It operates semiautomatically. Its functional principle: fruits supplied on a conveyor belt are uniformly distributed into the feed chutes leading to the scale pans by an operator, who can make a visual inspection of the fruits at the same time. The multi-head weighing machine’s plastic scale pans have special scrapers and fluted inner walls to prevent adhesions. The drop heights within the weighing machine are minimized to avoid mechanical damage to the fruits (pressure and impact). After being weighed out, depositor cones lay the portions of fruit directly onto the gateaux and cakes. The variable depositor units are specifically adapted to the respective product requirements and to the shape of the baked items (round or rectangular).

Overfilling – a thing of the past

The Pfalzgraf confectioner uses the multi-head weighing machine to process a wide product spectrum in two-shift operation. Raspberries, strawberries, forest fruits, mandarins and fruit mixtures are used as toppings on baked products. Filling weights are between 240 and 2,500 g at a maximum speed of 16 cycles/minute. However, accuracy is a decisive

++ Left: Depositor cones put precisely metered fruits directly onto gateaux and cakes

++ Right: The DACS-G check-weighing scale monitors compliance with the statutory provisions criterion in view of the highly-priced fruits. According to Production Manager Stephan Koller, the scale allowed a significant productivity increase. “The volumetric metering previously used gave us 20 to 30 g excess fruit on each product, whereas nowadays we have virtually no more over-filling.” This achieved a short pay-back period. Another benefit mentioned by Koller is the way the plant handles products very gently. Damage to the sensitive fruits is largely avoided. Processing wet fruit necessitates frequent thorough cleaning procedures. Koller describes the water-tight machine as “outstandingly hygiene-friendly”. The scale can be disassembled down to the housing without using tools. Product-carrying pans and chutes go into the dishwasher, and the main body is washed down with a water spray.

The Pfalzgraf confectioner

The Pfalzgraf Konditorei GmbH family business, founded in 1985 and with 150 employees, is one of the market leaders for high-quality confectionery in the European out-of-house market. Daily sales amount to around 20,000 frozen gateaux and cakes of 70 different varieties.

Pfalzgraf also relies on Ishida technology at the end of the production line. A DACS-G check-weighing scale tests the weight of the gateaux and cakes, which are by then already fully packed. Pushing a button allows a change between two settings, thus covering a rather large weight range. The Dislocating Force Limiter (DFL) function also automatically separates the scale’s sensor from the weighing conveyor if there are external sources of disturbance. The check-weighing scale restarts operation immediately afterwards.

Finally, the products pass through the Ishida IX-GA 4075 X-ray inspection system, which reliably detects foreign bodies 1 mm or more in diameter. Gateaux and cakes might contain small granite stones, for example, that could enter the product together with the fruit. The X-ray inspection system also identifies metal, glass and plastic contamination.

To monitor for foreign bodies, the machine measures the density of the gateaux and cakes. An X-ray beam is passed through the baked products, and photodiodes record the incoming rays. Depending on the level of the X-ray radiation received, the diodes send a signal for conversion into a greyscale image. If inclusions with a density greater than that of the product are present, they appear as dark spots on the image. Cavities and cracks are lighter in color, because more X-rays penetrate here.

The machine learns

The patented technology is based on software with a selflearning image processing algorithm. That means the accuracy increases with each inspection process. Koller says: “That allowed us to adapt the system to the specific properties of our products. A more precise protocol for the comparison can then be created with each inspection process.” All that is necessary for calibration is to X-ray a test object two or three times. A data-logging system provides proof of correct production processes, and also supplies information for process optimization purposes.

After automatic set-up, the easy-to-operate machine is ready for use within 90 seconds. Fine adjustments can then be made during ongoing production. Up to 100 programmable preset adjustments allow quick product change. +++

— Author: Herbert Hahnenkamp, Managing Director of Ishida GmbH

Note: A large fire in May 2015 almost completely destroyed the Pfalzgraf confectioner’s premises. The company completed rebuilding in a record time of nine months. We reported Pfalzgraf’s restart in baking+biscuits international, Issue No. 1/2017.