Stainless steel air motors are a good option for the food and beverage industry, which has to focus on hygiene when implementing automated production processes, says automation and air-motor company Deprag.

With rising costs, companies are increasingly reliant on preprocessing in automation; however, in the food and beverage industry, hygiene is just as important as efficiency.

Whether for the production of fruit juice drinks or the preparation of kebab skewers, the handling of flour, the cutting of dough or the use of packaging machines, air motors are an ideal solution for all these varied drive applications, says Deprag.

The company offers air motors, automation, screwdriving technology and air tools for various industries, with its engineers having spent decades developing and continuously improving their pneumatic motors.

Deprag’s Advanced Line motor series provides systems engineers with stainless steel drives which combine many beneficial features. The robust, sealed design of Advanced Line’s external parts in noncorrosive stainless steel means that the vane motors are predestined for use in the food industry.

Further, the smooth surfaces of the motors are easy to clean and the drives repel steam and cleaning agents. The air motors are completely sealed and, therefore, air cannot leak out and dirt cannot penetrate. The seal sufficiently allows the air motor to be used underwater as well.

Additionally, the motor does not require a special housing. The motor spindle also withstands chemical cleaning agents and has a particularly long-life radial shaft sealant ring.

There are many advantages in using this pneumatic motor as a drive, with the main benefit being that of power density. Depending on the version, Deprag’s air motors have a fifth of the mass of a normal electric motor or a third of its size, and the air motor provides almost constant power over wide torque ranges.

The motor works through a simple principle, whereby compressed air is generated by a compressor, which works in the air motor to rotate it. This functions in a vane motor where the rotor runs within an off-centre cylinder. There are vanes in the slots of the rotor which are pressed against the outer cylinder wall by centrifugal force. Working chambers are created for the expanding compressed air. It is this expansion of the compressed air which is changed into kinetic energy and starts the rotation.

The air motors have the added benefit of cool operating temparatures, compared with other drive systems, when under increasing load. The expansion of the compressed air cools the frictional heat created within the motor. This therefore makes the air motor particularly suited to applications in critical surroundings.

Deprag’s air motors carry the ATEX-directive conform seal of approval – for controlling exp- losive atmospheres – and are therefore authorised for use in potentially explosive environments. This is particularly important in the food industry for the processing of flour as flour dust could ignite if certain temperatures are exceeded.

The use of an air motor prevents overheating and the ignition of gases, as compressed air is basically an unproblematic energy source with no dangers from electrical wiring and, therefore, no danger of an electrical short circuit.

The air motor is flexible, allowing for its use in a wide field and under varying loads. Motor power can be adapted by altering the operating pressure and motor speed can be controlled by throttling the air supply.

For specific applications, specialised vanes can be used. Damage from overload is basically impossible. Once the air motor reaches stalling torque, (about twice the nominal torque), the air motor just stops. As soon as the load is removed, then it runs again without problems. This can be done as often as required.

The Deprag pneumatic motors can also be operated without oil, which is often essential for food industry cleanroom environments.

The range of Advanced Line stainless steel motors covers 20 W to 1.2 kW, with idle speeds of between 16 rpm and 24 000 rpm. “It is due to this wide spectrum of stainless steel motors that we are the leader in this market segment. We are able to provide the ideal solution for any job description,” explains Deprag air motors product manager Dagmar Dübbelde.

The air motor fulfils all sterilisation and hygienic requirements for use in the food industry. When manufacturing fruit juice drinks, a mixture is placed in large containers which, after mixing, is heated up to 80 °C, and then juice cartons are filled with the sterile liquid. Agitators are used for mixing and stirring which must be driven by heat-resistant and robust motors.

Winding drives are also prevalent in production processes for the food industry. Packaging machines use them to wind plastic film and keep it taut. The compressed air of the motor must be constant in order to maintain this tautness. To reduce air consumption, the motor can be throttled using supply air and run with reduced operating pressure as it is designed to be energy efficient.

The robust, efficient air motors can be adapted to the required torque and operating speed of any application. “Around 85% of our air motor projects are special solutions which we are able to quickly and simply adapt from our standard products for each individual customer”, explains Dübbelde.