In these times of rising costs, companies are increasingly reliant on pre-processing in automation. Even in the food industry automated production processes have gained in significance - hygiene is of equal importance as efficiency for the mechanical processing of foodstuffs. 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 the perfect solution for all these varied drive applications.
High quality stainless steel air vane motors are especially suited to these challenging applications. Deprag Schultz GmbH u Co’s Advanced Line motor series provides systems engineers with quality stainless steel drives which combine many beneficial features. The robust, sealed design of their external parts in non-corrosive top quality stainless steel means that the vane motors are predestined for use in the food industry. The smooth surfaces are easy to clean and the drives repel steam and cleaning agents. The air motors are completely sealed, air cannot leak out and dirt cannot penetrate. The seal is so good that the air motor can even be used underwater. The motor does not even need 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. The main benefit is the power density. Depending on the version it has a fifth of the mass of a normal electric motor or a third of its size. The air motor provides almost constant power over wide torque ranges.
The motor works along a simple principle. The compressed air generated by a compressor rotates the air motor. This functions in a vane motor by the rotor running 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 the rotation begins.
The air motors has the added benefit of being cool in comparison to other drive systems when under increasing load. The expansion cools the frictional heat created. This therefore makes the air motor particularly suited to applications in critical surroundings. They carry the ATEX conform seal of approval 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. Compressed air is basically an unproblematic energy source, there are no dangers from electrical wiring and no danger of a short circuit.
The air motor is very flexible, it can be optimally operated in a wide field under varying loads. Motor power can be adapted by altering the operating pressure, the speed can be smoothly controlled by throttling the air supply. For specific applications there are special vanes available. 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 and 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 20W to 1.2kW with idle speeds of between 16 and 24,000rpm. “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 Dagmar Dübbelde, Product Manager for air motors at Deprag. The sophisticated modular principle offers an outstanding price-performance ratio.
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 heating up to 80 degrees 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. A Deprag Advanced Line motor is just such a robust device and can reliably drive a propeller mixer in a magnet agitator with power at 300W and nominal speed of 700rpm. In the preparation of kebab skewers an air vane motor is the perfect choice for rotating a skewer over two belts into pieces of meat, onions and peppers.
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. In order 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.
When used in an application for winding the air motor can be operated at 4bar, eg so that the power provided remains constant when rolls of material are becoming smaller as they are used up. In order to extend the torque range even further Deprag provides an option with spring-loaded vanes which are known as forced start vanes. Use of these spring-loaded vanes means that it is possible to operate the air motor at an operating pressure of less than 1bar.
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,” explained Dübbelde.
