09/27/2011

www.gupta-verlag.de/polyurethanes

New Sonderhoff mixing and dosing features for high process reliability and dimensional precision

Process accuracy, economy, and safe operation for high-quality seals
With the DM 30x, the DM 40x and the SD - DM 402/403 dosing cell, Sonderhoff Engineering, Cologne, Germany, offers a mixing and dosing system that can mix two or more components of different materials with the MK 600 or the MK 400 precision mixing head. Its compact, modular design can be integrated into nearly any customer specific product concept. The low pressure mixing and dosing plants and the dosing cell deliver top performance and safety, and enables optimum foam gasketing, gluing and potting of various parts, in semi or fully-automated operation. The mixing and dosing units process materials at a constantly high level of metering and dimensional precision as well as consistency. State of the art sensors and actuators in the dosing cell ensure the effective control of safe systems and processes. The Flow Control flow measuring system gives precise material metering. The Stop-Drop DVS-3 mixing chamber shut-off device ensures that exactly the defined material is applied in just the right dimensions, particularly at the coupling of the sealing. Sonderhoff's patented high-pressure water rinsing technology, which cleans the mixing chamber from the residues of the chemical foam reaction, brings an array of additional benefits, especially with regard to quality and efficiency. It saves costs for wastewater treatment and special disposal because the high-pressure water rinsing technology works with mere tap water that is allowed to flow into the regular sewer drainage system. These advantages outweigh the conventional solvent based cleaning of the cured remains of the sealing material from the mixing chamber. The automatic logging of all set-up, material and process data enables tracking of the preceding production sequence at any time. The Safety package makes an important contribution to ensuring continuously high machine availability, together with planned preventive maintenance by Sonderhoff technicians. New optional machine functions provide additional process reliability
Customers can order additional optional functions for the dosing cell that further increase the reliability and reproducible precision of production processes. Sonderhoff Engineering has developed five new safety functions, which are available as options for the SD - DM 402/403 dosing cell as well as for the DM 30x and DM 40x series mixing and dosing systems: Airclean                              pneumatic nozzle cleaner
Mec Clean                           mechanical nozzle cleaner
Nozzle Control                      dispensing nozzle calibration
Weight Control                     electronic dosing weight control
Nucleation Control II              air nucleation measurement and control unit Always a clean nozzle
One of the key factors in reliable processes and good sealings is the immaculate cleanliness of the output nozzle and the precise material metering. Sonderhoff's patented high-pressure water rinsing is the standard equipment of its mixing and dosing systems to rinse the mixing chamber from cured residues of the reactive sealing material which can clog the dosing nozzle. The high-pressure water cleaning prevents this from happening. In addition, Sonderhoff Engineering offers two new cleaning functions as options for its mixing and dosing system: The Airclean pneumatic cleaning blower removes material residues from the nozzle tip, especially for gasket materials with very low viscosity. The Mec Clean mechanical nozzle cleaning system removes hardened material residues from the nozzle with specially developed rotating cleaning elements.[image_0][image_1]The intervals of these cleaning functions can be freely adjusted in the machine program of the mixing and dosing systems, based on individual user needs and component requirements. [image_2_right] Precise gasket contours with the new dispensing nozzle calibration
Manufacturers of system components across industries expect the gaskets in their components to meet the highest quality standards. This includes highest dimensional precision and exact positioning of gaskets in what are sometimes very tight component tolerances.In particular, at the coupling of a foam gasket, the amount of seal material must be very precisely metered, so that the structural component is completely sealed and the nterior is protected against outside influences. Depending on the viscosity of the material used, due to tight component tolerances material residues can accumulate on and in the output nozzle. This can have a negative influence on the precision of the contours of the gasket on the component. The wrong angle of the nozzle to the application surface, for example due to a deflection of the nozzle, can also lead to changes in the position and dimension of the gasket on the component. Sonderhoff Engineering has solved this special task with the newly developed Nozzle Control, a nozzle measuring unit. Two laser sensors at right angles check for the presence and measure the position of the dispensing nozzle. For the measuring of the nozzle position in the X, Y and Z dimensions the output nozzle will be passed through laser light barriers and the position coordinates of the nozzle sides are compared with the nominal values in the machine program. If they are outside the tolerances, there is a signal and the nozzle position is changed to comply with the settings in the machine program. In case, the measuring of the dispensing nozzle results in the finding of contamination, the mixing head is automatically sent to the rinsing station where the nozzle is cleaned. Thus, the new Nozzle Control measuring unit additionally ensures that the nozzle is always perfectly clean and correctly positioned, for accurate contours of the gasket on the component. The "calibrated” dosing weight control increases the process precision of mixing and dosing systems
Manufacturers which produce according to total quality management expect their systems to deliver "calibrated” and demonstrable process accuracy. The electronic dose weight control improves the repeat precision of the set dose weight, for reproducible high quality of the resulting sealing.[image_3]At regular intervals set by the user, a calibrated electronic scale measures the constant amount of seal material. It compares the weighed material with the targeted output quantity set in the machine program. Any discrepancies are detected quickly and the applied amount of the seal material will be precisely adjusted as needed. This is one of the key parameters for accurate metering. The interplay of consistently precise metering and constant processing speed of the mixing and dosing head, as well as the exact control of the gasket joint, results in accurate dimensions of the sealing on the structural component. New measurement and control unit provides optimum air nucleation
The Nucleation Control II - the air nucleation measurement and control unit -makes sure the air nucleation is at the ideal level, for the evenly fine-cell foam structure that is one of the major contributors to a consistently high level of gasket quality.[image_4_right]The cell structure and density of the foam gasket applied to a structural component is greatly affected by the air nucleation. The automatic measurement and control of the dissolved air in the A component plays a decisive role in this. Sonderhoff has succeeded to improve this measurement. The improved air nucleation measurement and control unit is a test method that can measure the nucleation of the starting material significantly more accurately than previous methods. In particular, the continuous control and documentation of the air nucleation measurements offer an additional safeguard and the highest ease of use for the machine operators. A special sensor continuously measures the current air nucleation in the foam seal material before and after application, and compares it with the pre-set target values of the used gasket material. If there are deviations, the air nucleation is adjusted accordingly. With the Nucleation Control II Sonderhoff Engineering has introduced an optional function that, in addition to other setting parameters of the Sonderhoff mixing and dosing machines, further improves the dimensional accuracy and consistency of the sealing by an optimally fine-tuned and continuously controlled air nucleation. Conclusion
With the optional features of dispensing nozzle calibration, electronic dosing weight control, mechanical and pneumatic cleaning as well as with the air nucleation and control unit Sonderhoff Engineering has given further competitive advantages to their DM 30x and DM 40x series of mixing and dosing systems and to their SD - DM 402/403 dosing cell. The precise interplay of existing multiple setting parameters and the new optional functions of the Sonderhoff mixing and dosing systems enables the customer to produce optimal sealing results for various gasket applications with highest dimensional precision and process reliability. As a result the content of structural components is actually better protected even under extreme environmental conditions.

www.gupta-verlag.de/polyurethanes