As a member of a working group (formed by an industrial research consortium that sponsors development projects), SOTEX worked with the Steinbeis Transfer Center for Drive Engineering and Robotics in Engineering and SIVUS, to develop a new machine technology that would make it possible to clean and dry turned parts immediately after they have been made on a high performance processing unit.
The problem with the cleaning technology used to date is that it interrupted production and material flow – with serious knock-on effects on quality. The new method makes it possible to achieve the desired surface finish quality. Components are carefully removed by a turning machine which hands them over to the cleaning unit. A suction/blowdry unit then cleans and dries the part.
The alignment of each individual part, which has already been set by the mechanical process, is used to direct the stream of air onto the component. Each part is processed individually to reduce damage caused to surfaces by collisions during cleaning. To achieve the desired levels of cleanliness in keeping with the timing laid down by the processing system, cleaning and drying has to be spread over a number of cycles. At the first station, parts undergo wet cleaning. Then several blow-dry units are used to carry out the drying.
To generate enough energy to remove swarf from the surfaces small volumes of water are added to the suction air. To do this, the stream of air is temporarily diverted to a reservoir containing the detergent. The resulting air and water turbulence creates a high number of “phase boundaries” which significantly improve the effectiveness of the cleaning process. During testing, it was calculated that the detergent only needed sucking in for 0.5 seconds to remove all swarf sticking to the component. In the remaining time, while the part is moving to the next station, superfluous detergent is removed from the unit.
At the next blow-dry station, air is targeted at high speed onto the part to loosen and remove any liquid that remained after wet washing. This is especially effective if it is done at close proximity. The high speed of the air stream generated within the chambers of the cleaning unit lift the component, cleaning and drying it from all sides. Apart from cleaning the outer surfaces of the part, this makes it possible to clean right inside contours, holes and undercuts.
The cleaning unit has eight stations set around a rotary indexing table. The cycle time is dictated by the timing of the main processing unit. To link the cleaning unit into the production process it has to be placed where the parts come out of the processing unit. Cleaned and dried parts are then moved on for further processing or palletized by machine. To test the types of applications and components the cleaning process can be used on, a test station was linked up to a six spindle machining centre used at a leading local engineering tool manufacturer, successfully achieving cycle times of six seconds.
Prof. Dr.-Ing. habil. Eberhard Köhler
Steinbeis Transfer Center Drive Engineering and Robotics in Engineering (Chemnitz)