Safeguarding a Palletizing System at Unilever Heilbronn

The palletizing system for the fully automatic packaging of sauce thickeners at the Heilbronn plant of the major corporation Unilever was retrofitted with a safety concept from Safety System Products from Spaichingen. SSP solved the challenges posed by tight space constraints, blind danger zones, and interlinked systems by using safety roller doors and the "tGard" trapped key interlock system from Fortress Safety.

It was important to the customer to have a holistic and safe concept for retrofitting its palletizing system for sauce thickeners from a single source.

The Challenge

Safety System Products not only assisted in finding a complete concept but also delivered the appropriate products for it. Hard-to-see danger zones, long overrun times, and numerous access gates were to become the main challenges.

Anyone entering the production halls at Unilever in Heilbronn can hardly miss it and knows immediately that safety is a top priority here: high above every system, a sign reads: "No work at Unilever in Heilbronn is so important that it is carried out at the expense of our safety."

However, the major corporation Unilever naturally does not rely on signs alone; after all, the approximately 630 employees at the Heilbronn site should be safe around the clock.

Safety Light Curtains from ReeR

The palletizing system, which is operated in a 3-shift system, is expected to output a total of 70 pallets per shift. This leaves very little time for manual removal, so the pallets must be fed in and out fully automatically. Non-contact protective devices, i.e., light curtains with a muting function, are often used for this purpose. These ensure the operation of the machine while simultaneously providing optimal protection for the operator. In so-called muting, the objects to be fed in and out are detected by upstream muting sensors, which temporarily deactivate the light curtain.

This allows pallets or other objects above a certain size to be fed in and out without shutting down the system. Human entry into the system is still prevented. However, the muting of safety light curtains not only requires compliance with high normative standards but, as with all non-contact protective devices according to EN ISO 13855, also compliance with safety distances.

Although Safety System Products can easily offer muting solutions with the "Janus" safety light curtains from the Italian manufacturer ReeR, this was not feasible due to the tight space conditions and the short distance to the hazard area of the palletizing system. However, a solution was found with the custom-developed "airlock" from Safety System Products, which offers the functionality of muting but does not have to fully accommodate the safety distances according to EN ISO 13855.

Airlock Is Realized with ReeR Light Curtains and Safety Fence from SSP.

The task presented a real challenge to the employees of SSP. The TYPE C standard "DIN EN 415-10:2014-07" sets precise requirements when applying bypassing functions in conjunction with ESPE (Electro-Sensitive Protective Equipment). Varying pallet widths, different number of layers, a long overrun time of the hazardous movements, and the limited space conditions made it impossible to realize the discharge of full pallets using conventional muting functions while complying with all relevant standards.

However, with SSP's extensive product range, the employees were able to create an airlock by combining ESPE and a safe roller door, making it possible to safely discharge pallets of different sizes and widths without wasting large distances and thus valuable production space. With this solution, the directly adjacent workstation could be made significantly safer while simultaneously increasing the productivity of the machine.

With a roller door and safety light curtains, automatic feeding in and out is also made possible, but unlike muting, the safety distances do not have to be maintained.

Safe Access Control with tGard and "Safety-Key"

Naturally, it must be possible to enter the multiple-interlinked palletizing system for maintenance purposes. Unilever had provided several access gates for this. Due to the overrun times of the system, however, interlocking guard devices such as a safety sensor were not sufficient. A guard locking system, which only permits entry into the danger zone once the system is shut down, therefore had to be used. Since the danger zone is blind (not fully visible), the ISO EN 14119 standard also stipulates that trapping the operator inside must be prevented.

Safety System Products provides a remedy here with the interlocking system from Fortress Safety. tGard is the name of the simple and robust safety gate switch from the company Fortress Safety from England. The combination of guard locking and a trapped key interlock system enables access control and safe entry into danger zones. The principle of operation is incredibly simple: before maintenance personnel enter the system, access is requested via a button. The key is only released after the machine has come to a standstill. Subsequently, the safety key is pulled to open the gate and is then taken into the system with them.

If the safety gate is then accidentally closed, the system cannot be started without the key. Thanks to its modular design, it can easily be adapted to customer-specific requirements. Whether safety key, emergency release, emergency stop, or indicator light, tGard offers a variety of configuration options. Installation is quick and easy, as tGard can be attached directly to gates or aluminum profiles without additional mounting plates or brackets. tGard complies with all current machinery safety standards, possesses protection class IP65, and can be installed in systems with high safety requirements (PLd).

Satisfied Customer

Even several months after the commissioning of the system, the customer is highly satisfied. They decided on the company Safety System Products because the overall concept was unique and the advice was very competent. The tGard safety switches and SSP's own developed "airlock principle" were decisive for the awarding of the contract. "Thanks to the airlock principle, we were able to save a lot of space compared to a classic muting solution," praises Unilever. Furthermore, the operation and access using tGard are very intuitive for the operators, thereby significantly improving not only safety but also the process.

If you would like to find out more about SSP's extensive safety portfolio, request free catalogs and further information.

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