Pneumatic locking unit - a part of Aventics' safety philosophy

26 September, 2017

"Safety starts in the design and selection of components," states Aventics' global account manager, Andreas Blume. The expert for machine safety at Aventics takes the LU6 pneumatic locking unit as an example to explain the importance of safe components as the first step. The LU6 series can take on safety-relevant functions as both a static lock and a dynamic brake: The lock element can be used as a holding unit to block a movement and as a brake unit for emergency stop or off. Proper use has been verified by the IFA (Institute for Occupational Safety and Health) and documented with a DGVU test certificate.

Additionally, the locking element has been developed, designed, and manufactured in line with the Machinery Directive 2006/42/EC, with the EN ISO 4414 and EN-ISO 13849-2 standards also taken into consideration. This makes the LU6 locking unit ideal for use in safety-relevant controls. With up to five million switching cycles in holding operation and up to two million dynamic braking cycles according to ISO 15552, the components are extremely reliable (B10 reliability parameter).

Engineers can thus employ the LU6 in safety-related controls up to performance level c, category 1. If additional control measures are integrated in accordance with ISO 13849-1, the locking unit can even be used for controls up to performance level e, category 4. Safety functions like 'stopping a dangerous movement' can be safely implemented. And safety is ensured no matter the mounting orientation: Whether installed horizontally, vertically, or diagonally, in the event of a pressure drop or failure, the LU6 locking unit reliably holds and clamps the piston rods or comparable round bars by means of springs.

 Sensor and switching variants increase performance level

The second step in planning safety-related control parts is correctly integrating the components into the machine or system. Engineers take many different approaches to ensure machine safety. The opening and closing of the LU6 is monitored by an integrated sensor, increasing the degree of diagnostic coverage of the locking unit to 99% and resulting in a higher performance level. "For all of our safety-relevant components, we provide not only the relevant reliability ratings such as MTTFD, B10, or PFHD, but also circuit examples for different mounting orientations - all online," said Blume. These examples were given a positive rating by the IFA, the Institute for Occupational Safety and Health of the German Social Accident Insurance.

The LU6 locking unit comes in seven sizes and covers the spectrum of piston rods with diameters measuring from 32 to 125 mm and stroke lengths up to 2850 mm. The maximum holding force is 12,000 N while the maximum ambient and medium temperature is +70degC for the dynamic braking function.

www.aventics.co.uk