Machinery safety for packaging machines

14 March 2011

Following renewed risk assessments that led to an updated machine safety design concept for a servo-driven film wrapping machine, BVM Brunner now has the flexibility to meet a variety of customer requirements while ensuring the safety of machine operators.

BVM Brunner GmbH & Co. KG, is a manufacturer of film wrapping packaging machines. Having taken an early decision to comply with EN ISO 13849-1, BVM Brunner carried out renewed machine risk assessments in order to update the safety concepts on its machines. This led to the decision to implement a new safety design for one of its machines, which incorporated comprehensive, ‘state of the art’ safety solutions from Pilz.

The machine is the Compacta Genius Servo, is an automated machine with a continuous motion, cross-sealing jaw. A safety solution was required to safeguard the operator and to complement the flexibility and easy handling required for processing a variety of products for different customers.

The Pilz Safety Calculator, PAScal, was used to determine the required PL and SIL of the safety functions according to EN ISO 13849-1. The PL and SIL requirements, together with the handling requirements, were then matched with the Pilz product range within the PAScal Calculator library.

The compact configurable safety relay, PNOZmulti Mini, was selected to monitor the safety functions. Despite its 45mm width, the multi Mini .with 20 safe inputs and 4 safe semiconductor outputs (to SIL 3, PL e), is able to cover all safety functions of the machine, including E-Stop, light barriers and safety gates. The PC-based drag-and-drop PNOZmulti Configurator also minimised initial set up and enabled individual configuration for different customers and products.

The mechanical safety gate switches were replaced with low maintenance, non-contact magnetic safety switches, PSENmag, which offered high tolerances for set up and switching distance, a clearly visible status indicator and reduced engineering time due to plug in cables.

In order to maximise the productivity of packaging machines, high quality diagnostics are needed. Pilz is able to offer a variety of operator displays that can convey relevant information to operators and maintenance engineers, while its PVIS 'intelligent diagnostics' technology provides plain text messages with precise information on the location of the fault, clearly defined responsibilities, as well as an integrated ‘root cause’ display. This ensures that production can be restarted quickly, minimising costly downtime.

Today, most packaging machines incorporate servo and motion control technology. The Pilz Motion Control (PMC) family covers motors, servo drives and motion controllers. The PMCprimo Drive, for example, combines the functions of a servo amplifier, motion controller and PLC in a single unit – with the added benefit of an integrated safe stop function. The new PMCprotego offers even more safety functionality, including safe reduced speed, safe operational stop and safe brake test.

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