A Safety Solution for Sugar

Leuze offered a sugar company a safety solution of the whole process, from the weigh of beets to intralogistics processes. Protection sensors and laser scanners allow complete control of the entire system

Ranked among the leading sugar and food companies in Europe, and with operations all over the world, the Südzucker Group prioritizes quality. To ensure that this is reflected in its products, it uses modern, technical systems and reliable, automated processes. This applies from the manufacturing process to the intralogistics processes – which involve removing the sugar bags and pails, loaded on euro palettes, from storage in the high-bay warehouse – right through to the loading of the freight trucks docking in the loading bay. Working together with Südzucker, Leuze developed an efficient safety solution. As a result, the clout and competitiveness of the Ochsenfurt location in Germany is constantly growing.

This is where the sugar beets arrive and are processed.
This is where the sugar beets arrive and are processed.

The stages to obtain sugar: from the weighing process to silos

On its journey to becoming the sugar, that is ultimately removed from storage in the high-bay warehouse and loaded into freight trucks, a beet must first pass through numerous stages. The first one is the weighing process. Each day during a sugar campaign from September to January, several thousand metric tons of beet are delivered to the Ochsenfurt site by regional farmers. First, these beets must be weighed, their soil content estimated and their sugar content determined. Safety must be ensured at all times, in this case meaning that no one is in the danger zone of the tilting platforms while the freight trucks are being unloaded. This is ensured by multiple MLD protective sensors installed by Leuze. These sensors form part of the safety concept that has been developed for Südzucker by Leuze safety experts. During a sugar campaign, the seven sugar towers on the factory premises are filled. These towers serve as silos, and contain the entire supply until the next harvest. The next stages in the process are juice extraction, clarification, evaporation and crystallization through to re-use and recycling of the byproducts animal feed, molasses and fertilizer.

The Südzucker sugar towers are silos in which the supply is stored.
The Südzucker sugar towers are silos in which the supply is stored.

The high-bay warehouse offers over 72,000 storage spaces

With approximately 230 employees, the sugar factory in Ochsenfurt is one of the largest important of the group’s factories. It specializes in the further processing of crystalline sugar to liquid and paste refined products for use in the food processing industry, apiaries and bakeries. These products include liquid sugar for soft drinks, fondants for filings and glazes on baked goods, and bee feed.
The high-bay warehouse at the Ochsenfurt factory is enormous: it offers over 72,000 storage spaces. The seven aisles can house up to 6000 euro palettes, on which bagged merchandise and pails are stored. The bagged goods in the high-bay warehouse have already been secured to the euro palettes with stretch film, to safeguard the merchandise during transportation. Pails of merchandise are secured shortly before they are loaded onto the freight truck. On average, a complete turnover of the warehouse stock takes no more than four weeks.

The conveyor is loaded with pallets by a cross conveyor.
The conveyor is loaded with pallets by a cross conveyor.

Protective sensors to guarantee transfer and material transportation

Depending on the quantity of merchandise taken out of storage, between 10 and 25 sugar freight trucks leave the Ochsenfurt factory each day. A maximum of two freight trucks can be loaded simultaneously. The loading process is assisted by up to two electric low lift trucks working simultaneously. When a freight truck docks, the warehouse logistician uses SAP to retrieve the relevant merchandise directly from the high-bay warehouse.
The ordered euro palettes arrive at the end of the intralogistics process chain via roller conveyors: a five-track gravity conveyor that is loaded with pallets by a cross conveyor. The five roller conveyors of the gravity conveyor are positioned very close together. The euro palettes to be conveyed that have been safeguarded for transportation are transferred directly to the gravity conveyor and transported to their transfer point. The warehouse logistician determines which of the five conveyors is controlled by entering the respective order. Euro palettes that have not been secured are diverted onto a separate film wrapper before they are supplied. This process is safeguarded by MLD protective sensors from Leuze. Here, these pallets are packaged in film for transport safeguarding so that they too are secured to their euro palette. When the pallets reach the end of the slightly sloping transport system, they are stopped by mechanical brakes. The low lift trucks pick up the pallets at the transfer point, transport them to the docked freight trucks and load them directly.

Access guarding of the five-track system is performed by two afety laser scanners.
Access guarding of the five-track system is performed by two afety laser scanners.

A new safety concept was required

A creative solution was required because it is essential that the area in which pallets are transferred onto the gravity conveyor and the danger zone behind this area are safeguarded against the entry of people by safety technology. Simultaneously, it was important that in each case, the safety solution would only release the conveyor onto which a pallet was most recently output.
A new safety concept was required to meet these extended requirements. This concept also needed to offer gapless safety for automatic processes – and at the same time guarantee an efficient material flow as well as high system availability. Therefore, Leuze worked together with Südzucker to performe a full safety check of the system.

The low lift trucks pick up the pallets and load them on the freight trucks.
The low lift trucks pick up the pallets and load them on the freight trucks.

A vertical protective field covers all of the tracks

Now, access guarding of the five-track system for removing pallets from storage is performed by two vertical Leuze RSL 400 safety laser scanners. Together they form a vertical protective field that covers all of the tracks.
From the system control, the safety system receives the information about the track onto which the pallet is output, and adapts the protective fields of the two laser scanners accordingly shortly before the passage of the pallet. If the transverse side-tracking skate transfers a pallet, the system control is notified of this, and a protective field in the size of the pallet and at the corresponding point is selected. After the passage of the pallet, the protective fields of the safety laser scanners are reset to their original size. In doing so, they fully “close” the conveyor area again. In this way, gapless safety during the transport cycles is ensured. This solution also ensures high reliability and availability.
The safety system does not require any additional signals, for example from muting sensors. This means that there are also no system-related structural limitations. The solution is tamperproof and ideal for retrofitting existing systems: the two safety laser scanners are controlled by the safety concept’s own pre-programmed compact safety controls, and are integrated into the system via two-channel safety outputs. Any necessary adaptations of the software for the compact controls and the configuration of the protective fields of the laser scanners are easy to carry out, optionally also as a Leuze service for the respective application requirements.